Journal articles on the topic 'Microstructure impact simulation results'
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1
Ye, Xiao Yu, Kai Hua Zhang, and Jun Zuo. "The Effects of Rolling Process on Microstructures and Properties of High Nb X80 Grade Pipeline Steel." Advanced Materials Research 641-642 (January 2013): 538–42. http://dx.doi.org/10.4028/www.scientific.net/amr.641-642.538.
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In Gleele-3500 Thermal Simulation Test Machine，conduct Thermal Simulation Experiment for High Niobium X80 Grade Pipeline Steel at Different Deformation Temperature, Deformation Extent and Coiling Temperature. Analysis the Microstructure Was Influenced by Different Rolling Process. According to the Thermal Simulation Experiments, Designed Test Scheme of Controlled Rolling and Controlled Cooling and Completed the Trial. the Results Showed that: for High Niobium X80 Grade Pipeline Steel, the Microstructures Are Acicular Ferrite and Have Good Mechanical Properties. the Low Temperature Impact Toughness Are More than 300J in -20°C and -40°C.
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Zhi, Ying, Xiang Hua Liu, and Zhen Fan Wang. "Simulation to Static Recrystallization of Nb Micro Alloyed Steel by Cellular Automaton." Advanced Materials Research 418-420 (December 2011): 1622–28. http://dx.doi.org/10.4028/www.scientific.net/amr.418-420.1622.
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The model of cellular automaton (CA) for simulating the static recrystallization of Nb micro alloyed steel after hot deformation was established. The static precipitation of micro alloyed elements on the impact of static recrystallization was considered in the mode. The microstructure evolution of austenite static recrystallization of Nb micro alloyed steel was simulated dynamically, such as the the volume fraction, kinetics curve of static recrystallization, dislocation density and grain shape, were quantitatively, accurately and visually described. According to the simulation results by cellular automaton, the effects of the deformation temperature, strain rate, and other processing parameters on the microstructure of the austenite static recrystallization of Nb micro alloyed steel were analyzed. The simulation results could provide a theoretical reference for the control of the microstructure and property of Nb micro alloyed steel.
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Węglowski, Marek Stanislaw, Marian Zeman, and Miroslaw Lomozik. "Physical Simulation of Weldability of Weldox 1300 Steel." Materials Science Forum 762 (July 2013): 551–55. http://dx.doi.org/10.4028/www.scientific.net/msf.762.551.
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In the present study, the investigation of weldability of new ultra-high strength - Weldox 1300 steel has been presented. The thermal simulated samples were used to investigate the effect of welding cooling time t8/5 on the microstructure and mechanical properties of the heat affected zone (HAZ). In the frame of these investigation the microstructure was studied by the light (LM) and transmission electron microscopies (TEM). It has been shown that the microstructure of the Weldox 1300 steel is composed of tempered martensite, and inside the laths the minor precipitations mainly V(CN) and molybdenum carbide Mo2C were observed. Mechanical properties of parent material were analysed by the tensile, impact and hardness tests. In details the influence of cooling time in the range of 2,5 - 300 s. on hardness, impact toughness and microstructure of simulated HAZ was studied by using welding thermal simulation test. The results show that the impact toughness and hardness decrease with the increase of t8/5 under the condition of a single thermal cycle in simulated HAZ. The continuous cooling transformation diagrams (CCT-W for welding conditions) of Weldox 1300 steel for welding purposes was also elaborated. The steel Weldox 1300 for cooling time in the range of 2,5 - 4 s showed martensite microstructure, for time from 4 s to 60 s mixture of martensite and bainite, and for longer cooling time mixture of ferrite, bainite and martensite. The results indicated that the weldability of Weldox 1300 steel is limited and to avoid the cold cracking the preheating procedure or medium net linear heat input should be used.
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Worswick, Michael J., Ryan George, Alex Bardelcik, Luke Ten Kortenaar, and Duane Detwiler. "Thermal Processing History and Resulting Impact Response of a Hot-Formed Component with Tailored Properties – Numerical Study." Applied Mechanics and Materials 566 (June 2014): 34–40. http://dx.doi.org/10.4028/www.scientific.net/amm.566.34.
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The impact modeling of a hot-formed component with tailored mechanical properties is studied to understand the influence of the thermal processing history and how the final properties of the component will affect its impact response. This paper presents a numerical study of the forming and quenching process and subsequent impact simulations. The processing simulations serve to predict the final microstructure and hardness distribution within a lab-scale B-pillar component that is processed using a tool with separate heated and cooled regions. A remapping algorithm is used to translate the results of the forming simulation to the impact simulation. A strain-rate sensitive material model is applied to model the response of these tailored microstructures during impact events. A comparison between a component that is fully hardened and a tailored component with regions of lower strength but increased ductility is presented in this work. Simulations that do not consider the onset of fracture predict superior peak impact load and energy absorption of the fully martensitic component due to its higher overall strength. However, the bainitic regions within the tailored component exhibit much higher ductility. Current work is addressing the introduction of failure criteria into simulations of tailored hot stamped components under impact loading for which the tailored component is expected to demonstrate superior resistance to cracking relative to the fully hardened component.
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Lian, Jun, Bo Hong Gu, and Wei Dong Gao. "Microstructure Model for Finite Element Analysis of 4-Step 3-D Rectangular Braided Composites under Ballistic Impact." Key Engineering Materials 334-335 (March 2007): 485–88. http://dx.doi.org/10.4028/www.scientific.net/kem.334-335.485.
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This paper presents a real microstructure model which has the same fiber volume fraction and tows’ spatial configuration with 3D rectangular composites to simulate the ballistic impact damage of the composites struck by steel projectile. The commercial available FEM code of Ls-Dyna was employed to calculate the interaction between the composite targets and steel projectile. From the comparison of residual velocities between simulation and experiment, it is proven the microstructure model can simulate the ballistic penetration with higher precision than the continuum model. The acceleration vs. time curve reveals the complicated interaction between composite and projectile in ballistic penetration. The prominent advantage of the microstructure model is that it can simulate the local damage mode of the composites at real microstructure level and obtain vivid simulating results.
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Vuherer, Tomaž, Fidan Smaili, Edvard Bjelajac, Mirza Manjgo, and Gorazd Lojen. "Simulation and Mechanical Properties of Fine-Grained Heat-Affected Zone Microstructure in 18CrNiMo7-6 Steel." Materials 15, no. 19 (September 30, 2022): 6782. http://dx.doi.org/10.3390/ma15196782.
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Heat-affected zones (HAZs) in real welds are usually quite narrow, and consequently most standard mechanical tests are difficult or even impossible. Therefore, simulated microstructures are often used for mechanical tests. However, the most often used weld thermal cycle simulator produces only a few millimeters wide area of simulated microstructure in the middle of specimens. Consequently, these kind of simulated specimen are not suitable for standard tensile tests, and even for Charpy impact tests, the simulated area can be too narrow. Therefore, to investigate the mechanical properties of a fine-grain heat-affected zone in 18CrNiMo7-6 steel, two methods were used for simulation of as-welded microstructures: (a) a weld thermal cycle simulator, and (b) as an alternative, though not yet verified option, austenitizing in a laboratory furnace + water quenching. The microstructures were compared and mechanical properties investigated. The grain sizes of the simulated specimens were 10.9 μm (water-quenched) and 12.6 μm (simulator), whereby the deviations from the real weld were less than 10%. Both types of simulated specimen were used for hardness measurement, Charpy impact tests, and fatigue tests. Water-quenched specimens were large enough to enable standard tensile testing. A hardness of 425 HV, yield strength Rp02 = 1121 MPa, tensile strength Rm = 1475 MPa, impact energy KV = 73.11 J, and crack propagation threshold ΔKthR = 4.33 MPa m0.5 were obtained with the water quenched specimens, and 419 HV, KV = 101.49 J, and ΔKthR = 3.4 MPa m0.5 with the specimens prepared with the simulator. Comparison of the results confirmed that the annealed and quenched specimens were suitable for mechanical tests of FG HAZs, even for standard tensile tests. Due to the use of simulated test specimens, the mechanical properties determined can be linked to the FG HAZ microstructure in 18CrNiMo7-6 steel.
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Liu, Binchao, Rui Bao, Yamei Niu, Songsong Lu, and Kai Wang. "Peridynamic Simulation of Fatigue Crack Growth Behaviour with the Effect of Microstructure." MATEC Web of Conferences 165 (2018): 04003. http://dx.doi.org/10.1051/matecconf/201816504003.
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The purpose of this paper is to explore the influences of microstructures on crack growth behaviour in 2324-T39 aluminum alloy based on peridynamic(PD) theory. The microelastic bond-based peridynamic constitutive is modified as microplastic to describe the plasticity of aluminum alloys. A new method to establish polycrystalline models based on metallographs is adopted, and grains are reflected in simulations by setting transgranular and intergranular pairwise force in the corresponding bonds. Two kinds of microstructures are modeled according to metallographs, and a special kind of crack branch resulted from the link-up of the secondary crack with the main crack and the growth of the branched crack is successfully captured. The PD simulations reveal that microstructure orientation characteristics have an impact on crack propagation paths and crack growth modes, and it is easier for the secondary-crack resulted macroscopic crack branching to appear if grain boundaries locate not too close to the leading crack tip but within the crack tip plastic zone. The numerical results are verified by experiments and fractographic analysis.
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Li, Jin, Liang Yi Li, and Zheng Yuan. "Study of the Impact Toughness Experiment of SiCp/Al FGM and Numerical Simulation." Applied Mechanics and Materials 268-270 (December 2012): 134–37. http://dx.doi.org/10.4028/www.scientific.net/amm.268-270.134.
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This paper by cold isostatic pressing and sintering of combining the method of preparation of silicon carbide enhance aluminum functional gradient materials, and the microstructure, density, impact toughness are analyzed, the results of experiments showed that in the aluminum gradient to join in the silicon carbide enhance particles, The impact toughness of the material has been obviously improved. Using ANSYS Numerical simulation Impact process, the simulation results anastomosis with the experimental results.
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Schwich, Gideon, Thomas Henke, Joachim Seitz, and Gerhard Hirt. "Prediction of Microstructure and Resulting Rolling Forces by Application of a Material Model in a Hot Ring Rolling Process." Key Engineering Materials 622-623 (September 2014): 970–77. http://dx.doi.org/10.4028/www.scientific.net/kem.622-623.970.
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Ring rolling is a versatile incremental bulk forming process. Due to the incremental character of the process, it consists of a large number of deformation and dwell steps. Finite element (FE) simulations of bulk forming processes are capable of predicting loads, stresses and material flow. In recent years, the finite element analysis of ring rolling processes has become feasible both in terms of calculation time as well as regarding the closed loop control of the kinematic degrees of freedom [1]. Accordingly, the focus of interest now includes the prediction of the microstructure evolution. The accuracy of such numerical simulations strongly depends on the models characterizing the material behavior and boundary conditions. In this paper, a finite element based simulation study was conducted, in order to evaluate the impact of boundary conditions such as transfer time, radiation, heat transfer and friction on the target values of the ring rolling process. The results of the simulation study were compared to ring rolling experiments on an industrial size ring rolling device. A good accordance regarding the evolution of the outer diameter and radial force was observed. Strong contingencies of transfer time on the forces throughout the process were detected and considered in the simulation study. In a post processing step, the evolution of the microstructure considering the dynamic and static recrystallization as well as the grain growth was calculated using the FE results. The calculated grain sizes show good accordance with the experimentally observed microstructure of the ring before and after the rolling. Furthermore, the impact of process parameters on the evolution of the grain size was investigated.
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Mitrovic, Radivoje, Dejan Momcilovic, Olivera Eric, Ivana Atanasovska, and Nenad Hut. "Study on impact properties of creep-resistant steel thermally simulated heat affected zone." Thermal Science 16, no. 2 (2012): 513–25. http://dx.doi.org/10.2298/tsci111006142m.
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The steam pipe line (SPL) and steam line material, along with its welded joints, subject to damage that accumulates during operation in coal power plants. As a result of thermal fatigue, dilatation of SPL at an operating temperature may lead to cracks initiation at the critical zones within heat affected zone (HAZ) of steam pipe line welded joints. By registration of thermal cycle during welding and subsequent HAZ simulation is possible to obtain target microstructure. For the simulation is chosen heat resisting steel, 12H1MF (designation 13CrMo44 according to DIN standard). From the viewpoint of mechanical properties, special attention is on impact toughness mostly because very small number of available references. After simulation of single run and multi run welding test on instrumented Charpy pendulum. Metallographic and fractographic analysis is also performed, on simulated 12H1MF steel from service and new, unused steel. The results and correlation between microstructure and impact toughness is discussed, too.
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Carretero Olalla, Victor, N. Sanchez Mouriño, Philippe Thibaux, Leo Kestens, and Roumen H. Petrov. "Physical Simulation of Hot Rolling Steel Plate and Coil Production for Pipeline Applications." Materials Science Forum 762 (July 2013): 70–75. http://dx.doi.org/10.4028/www.scientific.net/msf.762.70.
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Within the techniques and equipments used to simulate industrial thermomechanical processing of High Strength Low Alloy (HSLA) pipeline steels, hot rolling laboratory mill equipped with cooling bed and coiling simulation furnace allows, not only accurate control of strains, temperatures, inter-pass times, and cooling rates but also enough amount of processed material for micro-structural characterisation and mechanical testing. Despite some differences with the industrial rolling, laboratory rolling offers a better simulation of the industrial rolling conditions than other thermo-mechanical simulators in terms of deformation mechanisms and processing constrains. This paper presents the results of simulation of different rolling schedules applied on pipeline grades in order to better understand the influence of the finishing rolling parameters namely: finish rolling temperature (FRT) and cooling routes on the microstructure and mechanical properties. It was observed that FRT and cooling rate have a strong impact on both grain refinement and precipitation behaviour, which leads to significant differences in strength and toughness. Furthermore variations of the above mentioned rolling parameters produce distinct fractions and distributions of austenite transformation products, variations in the final crystallographic texture and trigger diverse strengthening mechanisms (i.e. dislocation hardening). It was found that the accelerated cooling in a combination with a coiling simulation results in formation of microstructures with well developed low angle grain boundaries in comparison to the simulation made with air cooling. As a consequence the strength of the plates after accelerated cooling increases without changes in the Charpy impact toughness. It has been shown that the understanding of the effect of processing parameters on the microstructure of these steels is a key aspect for the optimization of their mechanical properties.
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Liu, Wen Ping, B. Zhang, Pei Qi Wang, and Qin He Zhang. "Impact Analysis of Microstructure Evolution in Hot Rolling of H-Beams." Advanced Materials Research 652-654 (January 2013): 2024–28. http://dx.doi.org/10.4028/www.scientific.net/amr.652-654.2024.
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To improve the product properties of H-beams, it is essential to understand the effects of hot rolling parameters on the microstructure evolution of the beams. For this purpose, a thermo mechanical model was built with the finite element Package ABAQUS. By re-meshing the model, multipass large-deformation hot rolling process was simulated under the boundary conditions predefined in accordance with the practical production. Based on the hot rolling simulation, an impact analysis of strain rate, initial rough rolling temperature, and time interval between passes on the microstructure evolution of H-beam austenite was conducted. The analytical results are meaningful for optimizing hot rolling parameters and improving H-beam properties.
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Lee, Seung-Wan, Sang-In Lee, and Byoungchul Hwang. "Effect of Bainitic Microstructure on Low-Temperature Toughness of High-Strength API Pipeline Steels." Korean Journal of Metals and Materials 58, no. 5 (May 5, 2020): 293–303. http://dx.doi.org/10.3365/kjmm.2020.58.5.293.
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In this study the correlation between bainitic microstructure and the low-temperature toughness of high-strength API pipeline steels was discussed in terms of crack initiation and propagation in the microstructure. Three types of API pipeline steels with different bainitic microstructures were fabricated using varying alloying elements and thermo-mechanical processing conditions, and then their microstructure was characterized by optical and scanning electron microscopy, and electron backscatter diffraction (EBSD). In particular, the effective grain size and microstructure fraction of the steels were quantitatively measured by EBSD analysis. Although all the steels were composed of polygonal ferrite (PF), and complex bainitic microstructures such as acicular ferrite (AF), granular bainite (GB), and bainitic ferrite (BF), they had different effective grain sizes and microstructure fraction, depending on the alloying elements and thermomechanical processing conditions. Charpy impact test results showed that when the martensite-austenite constituent fraction was lowest, it resulted in higher upper-shelf energy, and absorbed energy at room temperature due to the decrease in crack initiation. In contrast, excellent low-temperature toughness, such as lower ductile-brittle transition temperature and higher absorbed energy at low temperatures, could be achieved with a bainitic microstructure with fine effective grain size and high fraction of high-angle grain boundaries, which act as obstacles to prevent cleavage crack propagation.
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Han, Kun, Qing Shan Li, Mei Zhang, Ren Yu Fu, and Lin Li. "Effect of Physical Simulation Thermal Parameters on Microstructure Transition and Property Variation of Boron Steel." Advanced Materials Research 291-294 (July 2011): 919–23. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.919.
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Different physical simulation welding parameters were performed using Gleeble-3500 type thermal simulator to research the effect of thermal cycle on microstructure transition and property variation of boron steel 22MnB5. The peak temperature of welding thermal cycle was set to 1320-870°C, and cooling rates t8/5 to 6s-100s. Then microstructure observation, hardness detection, and impact toughness tests were carried out to clarify the effect of different thermal cycles. The results show that 22MnB5 has good mechanical properties, but the toughness decreases obviously under certain thermal cycles, showing cold crack sensitivity of 22MnB5. Martensite and ferrite are the main microstructure under different peak temperature and t8/5.
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Li, Shu Rui, Xue Min Wang, Chao Chao Zheng, and Xin Lai He. "The Oxide Inclusion and Heat-Affected-Zone Toughness for Low Carbon Bridge Steels." Advanced Materials Research 562-564 (August 2012): 31–34. http://dx.doi.org/10.4028/www.scientific.net/amr.562-564.31.
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By welding thermo-simulation and actual welding practices, the microstructure and properties of low carbon bridge steels has been studied with the aid of optical microscope, scanning electron microscope. The experimental results show that by the oxide introducing melting technology there are many complex inclusions composed of oxide containing Ti and MnS. These inclusions are spherical and they are distributed homogeneously. During the welding thermo-simulation these oxide inclusions will promote the nucleation of acicular ferrite and make the microstructure in HAZ finer. Therefore the toughness in HAZ is good whether in welding thermo-simulation even if the heat input reaches to 200kJ/cm. In actual welding the heat input is 88kJ/cm and the low temperature impact energy still can reach 110J.
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Qiao, Gui-ying, Xiu-lin Han, Xiao-wei Chen, Xu Wang, Bo Liao, and Fu-ren Xiao. "Transformation of M/A Constituents during Tempering and Its Effects on Impact Toughness of Weld Metals for X80 Hot Bends." Advances in Materials Science and Engineering 2019 (July 17, 2019): 1–10. http://dx.doi.org/10.1155/2019/6429045.
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Impact toughness of the weld metal is one of the important factors affecting the quality of hot bends, which is strongly dependent on the microstructure transformation during hot bending and tempering. In this study, three kinds of weld metals with different Ni contents were selected, and then the effects of tempering temperature on the microstructure impact toughness of weld metals for hot bends were investigated by simulation conducted on a Gleeble-3500 thermal simulator. The results show that the nonmetallic inclusion particles in weld metals can become the nuclear core of acicular ferrite like in as-welded metal. So, the overlapping acicular ferrite microstructure is obtained in the weld metal after direct cooling from the reheating temperature. During tempering, the overlapping acicular ferrite microstructure is degenerated, and martensite/austenite (M/A) constituents in the acicular ferrite microstructure decompose into ferrites and carbides. The resulting carbide particles mainly distribute along the acicular ferrite grain boundaries. With the increase of the tempering temperature, the carbide particles coarsen, which decreases the impact toughness of the weld metal of hot bends. Addition of Ni to weld metals can refine the acicular ferrite and improve the impact toughness.
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Sun, Jun Sheng, and Hong Quan Wang. "Microstructures and Properties of HAZ of JB800 Bainite Steel." Applied Mechanics and Materials 670-671 (October 2014): 65–69. http://dx.doi.org/10.4028/www.scientific.net/amm.670-671.65.
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JB800 steel has grain boundary allotriomorphic ferrite and granular bainite (FGBA/BG), and it is a kind of high strength low alloy steels, which has simple produce procedure, lower cost and excelled property. The law of microstructure transformation in CGHAZ, hardness, and impact toughness in HAZ of JB800 steel were studied by means of thermal simulation. The test results show that under the general condition of welding process (t8/5=5~50s), microstructure of CGHAZ is composed of mixture microstructure of Martensite and Bainite and with the increase of cooling rate, the content of Martensite will decrease, but that of Bainite will increase; when t8/5 is 20s, CGHAZ zone have better impact toughness, which is composed of 95% Martensite and 5% Bainite. Therefore t8/5 should be controlled at about 20s to get better impact toughness.
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Węglowski, M. St, M. Zeman, and A. Grocholewski. "Effect of Welding Thermal Cycles on Microstructure and Mechanical Properties of Simulated Heat Affected Zone for a Weldox 1300 Ultra-High Strength Alloy Steel." Archives of Metallurgy and Materials 61, no. 1 (March 1, 2016): 127–32. http://dx.doi.org/10.1515/amm-2016-0024.
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In the present study, the investigation of weldability of ultra-high strength steel has been presented. The thermal simulated samples were used to investigate the effect of welding cooling time t8/5 on microstructure and mechanical properties of heat affected zone (HAZ) for a Weldox 1300 ultra-high strength steel. In the frame of these investigation the microstructure was studied by light and transmission electron microscopies. Mechanical properties of parent material were analysed by tensile, impact and hardness tests. In details the influence of cooling time in the range of 2,5 ÷ 300 sec. on hardness, impact toughness and microstructure of simulated HAZ was studied by using welding thermal simulation test. The microstructure of ultra-high strength steel is mainly composed of tempered martensite. The results show that the impact toughness and hardness decrease with increase of t8/5 under condition of a single thermal cycle in simulated HAZ. The increase of cooling time to 300 s causes that the microstructure consists of ferrite and bainite mixture. Lower hardness, for t8/5 ≥ 60 s indicated that low risk of cold cracking in HAZ for longer cooling time, exists.
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Yang, Liu Qing, Yong Li Sui, Pei Pei Xia, Hai Hong Zhao, and Zhang Hua Yin. "Microstructure and Properties of Weld CGHAZ under Different Heat Input for X90 Pipeline Steel." Materials Science Forum 850 (March 2016): 943–49. http://dx.doi.org/10.4028/www.scientific.net/msf.850.943.
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Two kinds of industry trial X90 pipeline steels which have different chemical composition were chosen as test objects, and the grain coarsening, microstructural characteristics and the variation rules of low-temperature impact toughness in weld CGHAZ of this two steel under different welding heat input were studied by physical thermal simulation technology, SEM, optical microscope and Charpy impact tests. The results showed that the microstructure in weld CGHAZ of 1# steel was mainly bainite ferrite (BF) and most of the M/A constituents were blocky or short rod-like; the grains of 2# steel were coarse and there was much granular bainite (GB). Meanwhile M/A constituents became coarser and their morphology changed from block to long bar; alloy content of X90 pipeline steel under different weld heat input had great effect on the grain size of original austenite. When heat input was lower than 20KJ/cm, the impact toughness in CGHAZ of lower alloy content pipeline steel was good; as heat input increased, impact toughness in CGHAZ of 1# steel increased to the values between 260J and 300J when heat input was between 20KJ/cm and 25KJ/cm and the dispersion of impact energy was small. The impact toughness of 2# steel decreased gradually and the impact energy had the obvious dispersion.
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Sun, Jun Sheng, Yi Qun Sun, En Li Jiao, and Hou Xiao Wang. "Prediction of CGHAZ Microstructure and Property of JG590 Steel with Weld Simulation Technology." Advanced Materials Research 531 (June 2012): 173–76. http://dx.doi.org/10.4028/www.scientific.net/amr.531.173.
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A three-dimensional analytical calculation model of GMAW heat transfer was established, and the weld temperature field of JG590 with different welding parameters was analyzed by numerical simulation. The phase transformation in CGHAZ of JG590 steel was studied by physical simulation. SH-CCT diagrams, the effects of weld thermal cycle on microstructure, impact toughness and hardness were obtained. The results show that the critical cooling time of bainite, ferrite and pearlite appeared are respectively 8s, 110s and 150s. The critical cooling time that martensite takes to finish transferring is 35s. When t8/5 is below 10s, CGHAZ has a better toughness and when t8/5 is beyond 15s, there is a wide range decrease on the toughness. In this paper prediction of CGHAZ microstructure and property of JG590 steel was realized based on the analytical calculation model of GMAW heat transfer and physical simulated results mentioned above
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Dawidowska, K. "Aortic Valve Geometry Modeling – Review." Advances in Materials Science 16, no. 4 (December 1, 2016): 29–37. http://dx.doi.org/10.1515/adms-2016-0020.
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Abstract The present work is a review of publications covering computer simulation of aortic valve operation and material properties of aortic valve components studies. Particular attention is paid to the anisotropy of material and geometric properties. The methods of geometric models developing by using specified research methods and/or diagnostic imaging devices are presented. The microstructure of the aortic valve is also described and its impact on material properties definition introduced. The various ways of describing the aortic valve leaflet anisotropic properties are mentioned. Often exploited simplifications and their impact on the simulation results is also presented.
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Ben Ahmed, Amal, Ahmad Bahloul, Mohamed Iben Houria, Anouar Nasr, and Raouf Fathallah. "Multiaxial fatigue life estimation of defective aluminum alloy considering the microstructural heterogeneities effect." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 233, no. 9 (August 16, 2018): 1830–42. http://dx.doi.org/10.1177/1464420718792024.
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The Al–Si–Mg high-cycle fatigue behavior is mainly affected by the microstructural heterogeneities and the presence of casting defects. This attempt aims to develop an analytical approach based on the evaluation of the highly stressed volume caused by local porosities and defined as the affected area methodology. The proposed approach is able to predict the aluminum alloy fatigue response by considering the effect of microstructure described by the secondary dendrite arm spacing and its correlation with the defect size effect. A representative elementary volume model is implemented to evaluate the stress distribution in the vicinity of the defect and to determine its impact on the high-cycle fatigue resistance. Work hardening due to cyclic loading is considered by applying the Lemaitre–Chaboche model. The Kitagawa–Takahashi diagrams corresponding to different microstructures and for two loading ratios: R σ = 0 and R σ = −1 were simulated based on the AA method. Simulations were compared to the experimental results carried out on cast aluminium alloy A356 with T6 post heat-treatment. The results show clearly that the proposed approach provides a good estimation of the A356-T6 fatigue limit and exhibits good ability in simulating the Kitagawa–Takahashi diagrams for fine and coarse microstructures.
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Zhang, Yue, Jun Xiao, Wei Liu, and Aimin Zhao. "Effect of Welding Peak Temperature on Microstructure and Impact Toughness of Heat-Affected Zone of Q690 High Strength Bridge Steel." Materials 14, no. 11 (May 31, 2021): 2981. http://dx.doi.org/10.3390/ma14112981.
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The effect of peak temperature (TP) on the microstructure and impact toughness of the welding heat-affected zone (HAZ) of Q690 high-strength bridge steel was studied using a Gleeble-3500 thermal simulation testing machine. The results show that the microstructure of the inter critical heat-affected zone (ICHAZ) was ferrite and bainite. The microstructure of fine grain heat-affected zone (FGHAZ) and coarse grain heat-affected zone (CGHAZ) was lath bainite (LB), lath martensite (LM), and granular bainite (GB), but the microstructure of FGHAZ was finer. With the increase in peak temperature, the content of LB and GB decreased, the content of LM increased, and the lath bundles of LM and LB gradually became coarser. With the increase in peak temperature, the grain size of the original austenite increased significantly, and the impact toughness decreased significantly. When the peak temperature was 800 °C, the toughness was the best. For CGHAZ, the peak temperature should be less than 1200 °C to avoid excessive growth of grain and reduction of mechanical property.
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Ding, Qing Feng, Tian Sheng Wang, Wen Yan Liu, Xian Jun Wang, Wen Bin Liu, and Ming Li. "Microstructure and Properties of Grade 700MPa Pressure Vessel Steel with Large Heat Input Welding." Applied Mechanics and Materials 182-183 (June 2012): 1537–40. http://dx.doi.org/10.4028/www.scientific.net/amm.182-183.1537.
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The microstructure and properties of grade 700MPa steel with large heat input welding and its heat affected zone (HAZ) were investigated by use of the metallography, scanning electron microscopy, mechanical testing and welding thermal simulation. The results showed that the mechanical properties of the steel meet the technical requirements, namely the yield strength ReL≥570 MPa, the tensile strength 685MPa≤Rm≤830MPa, the elongation A≥17%, the -20°C impact energy KV2≥54J and the -20°C impact energy of HAZ≥47J. The steel also had good match between strength, toughness and anti-high heat input welding, the microstructure was tempered sorbite with small dispersed composite inclusions, which promoted the formation of acicular ferrite and were beneficial to the improvement of HAZ toughness.
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Kossakowski, Paweł Grzegorz, and Wiktor Wciślik. "Effect of Critical Void Volume Fraction fF on Results of Ductile Fracture Simulation for S235JR Steel under Multi-Axial Stress States." Key Engineering Materials 598 (January 2014): 113–18. http://dx.doi.org/10.4028/www.scientific.net/kem.598.113.
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The article describes an example of the GTN material model parameters determination and application. The main objective of the study was to determine experimentally the value of the critical volume fraction of voids fFfor S235JR steel and to assess the impact of this parameter on the numerical force-elongation curve under the multi-axial stress state. Value of fFwas obtained by the quantitative analysis of the material microstructure at fracture surfaces. For a sake of comparison, two other values of fF, described in the literature, were also used in numerical simulations.
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Laitinen, Risto O., David A. Porter, L. Pentti Karjalainen, Pasi Leiviskä, and Jukka Kömi. "Physical Simulation for Evaluating Heat-Affected Zone Toughness of High and Ultra-High Strength Steels." Materials Science Forum 762 (July 2013): 711–16. http://dx.doi.org/10.4028/www.scientific.net/msf.762.711.
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Physical simulation of the most critical sub-zones of the heat-affected zone is a useful tool for the evaluation of the toughness of welded joints in high-strength and ultra-high-strength steels. In two high-strength offshore steels with the yield strength of 500 MPa, the coarse grained, intercritical and intercritically reheated coarse grained zones were simulated using the cooling times from 800 to 500 °C (t8/5) 5 s and 30 s. Impact and CTOD tests as well as microstructural investigations were carried out in order to evaluate the weldability of the steels without the need for expensive welding tests. The test results showed that the intercritically reheated coarse grained zone with the longer cooling time t8/5=30 s was the most critical sub-zone in the HAZ due to the M-A constituents and coarse ferritic-bainitic microstructure. In 6 mm thick ultra-high-strength steel Optim 960 QC, the coarse grained and intercritically reheated coarse grained zones were simulated using the cooling times t8/5 of 5, 10, 15 and 20s and the intercritical zone using the cooling times t8/5 of 5 and 10 s in order to select the suitable heat input for welding. The impact test results from the simulated zones fulfilled the impact energy requirement of 14 J (5x10 mm specimen) at -40 °C for the cooling times, t8/5, from 5 to 15 s, which correspond to the heat input range 0.4-0.7 kJ/mm (for a 6 mm thickness).
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Li, Pengyi, Shan Hu, Yanxiong Liu, Lin Hua, and Fei Yin. "Surface Nanocrystallization and Numerical Modeling of 316L Stainless Steel during Ultrasonic Shot Peening Process." Metals 12, no. 10 (October 6, 2022): 1673. http://dx.doi.org/10.3390/met12101673.
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Surface nanocrystallization of metals and alloys via high-frequency ultrasonic shot peening (USP) can significantly increase the mechanical properties of the materials. However, the relationship between the external process parameters and the internal microstructure of the materials is still unclear and an accurate numerical model to simulate the USP process is urgently required for better control of the grain refinement process. In this study, we successfully realized surface nanocrystallization of 316L stainless steel using USP with an ultrasonic frequency and amplitude of 20 kHz and 50 μm, respectively. The microstructure evaluation of 316L stainless steel during USP was revealed. We established a finite element numerical model to simulate the high-frequency USP process and calculated the plastic strain and stress distribution of 316L stainless steel during the grain refinement process. We investigated the effects of the ultrasonic frequency, working distance, and ultrasonic amplitude on the plastic strain and stress distribution on the materials using the finite element simulation method. The dynamic behavior of the shot during the USP process was studied using a high-speed camera, and the FE simulation results agreed well with the experimental results. We also investigated the impact of multiple shots during the USP process by the high-speed camera observation and FE simulation. Research results indicate that high-frequency USP is an effective method to obtain large-scale bulk nanocrystalline materials and the finite element simulation can help materials scientists and engineers to better understand the relationship between the process parameters and microstructure evaluation of 316L stainless steel.
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Zong, Yun, and Chun-Ming Liu. "Continuous Cooling Transformation Diagram, Microstructures, and Properties of the Simulated Coarse-Grain Heat-Affected Zone in a Low-Carbon Bainite E550 Steel." Metals 9, no. 9 (August 27, 2019): 939. http://dx.doi.org/10.3390/met9090939.
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In order to provide important guidance for controlling and obtaining the optimal microstructures and mechanical properties of a welded joint, the continuous cooling transformation diagram of a new low-carbon Nb-microalloyed bainite E550 steel in a simulated coarse-grain heat-affected zone (CGHAZ) has been constructed by thermal dilatation method in this paper. The welding thermal simulation experiments were conducted on a Gleeble-3800 thermo-mechanical simulator. The corresponding microstructure was observed by a LEICA DM2700M. The Vickers hardness (HV) and the impact toughness at −40 °C were measured according to the ASTM E384 standard and the ASTM E2298 standard, respectively. The experimental results may indicate that the intermediate temperature phase transformation of the whole bainite can occur in a wide range of cooling rates of 2–20 °C/s. In the scope of cooling rates 2–20 °C/s, the microstructure of the heat-affected zone (HAZ) mainly consists of lath bainite and granular bainite. Moreover, the proportion of lath bainite increased and granular bainite decreased as the cooling rate increasing. There is a spot of lath martensite in the microstructure of HAZ when the cooling rate is above 20 °C/s. The Vickers hardness increases gradually with the increasing of the cooling rate, and the maximum hardness is 323 HV10. When the cooling time from 800 °C to 500 °C (t8/5) is 5–15 s, it presents excellent −40 °C impact toughness (273–286 J) of the CGHAZ beyond the base material (163 J).
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Lu, Guoyang, Zijian He, Pengfei Liu, Zhihao He, Gaoyang Li, Hao Jiang, and Markus Oeser. "Estimation of Hydraulic Properties in Permeable Pavement Subjected to Clogging Simulation." Advances in Civil Engineering 2022 (January 21, 2022): 1–13. http://dx.doi.org/10.1155/2022/5091895.
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Permeable pavements are often affected by pore clogging, which leads to their functional failure and reduced service life. However, the clogging mechanism and its impact on the permeability and complex pore microstructures in pervious pavement remain unclear. The aim of current study is to quantify the clogging behavior in pervious pavement materials and carry out investigations on the development of pore characteristics and permeability. Novel polyurethane-bound pervious mixture (PUPM) was adopted for comparative study in present research with conventional Porous Asphalt (PA). The Aachen Polishing Machine (APM) was selected to perfectly serve as a simulator for clogging process of pavement in the actual service condition. The permeability and pore microstructure of the pervious pavement material were then characterized by using the self-developed permeameter and X-ray Computed Tomography (CT) scanning, respectively. The development of pore characteristics in terms of clogging was experimentally illustrated. Based on the pore characteristics, the flow behavior of PUPM subjected to different clogging periods was predicted based on the developed non-Darcy flow model. The developed experiments and analysis can further strengthen the understanding of the clogging mechanism within the porous pavement material. The results can also serve for the optimization of the pervious pavement design in the engineering application.
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Łomozik, Mirosław. "Microstructure, Toughness and Hardness of a Simulated HAZ in Steel S1100QL and of the HAZ of an Actual MAGWelded Joint Made Using a Metallic Flux-Cored Wire." Biuletyn Instytutu Spawalnictwa, no. 6 (2021): 47–65. http://dx.doi.org/10.17729/ebis.2021.5/5.
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Simulation tests discussed in the article involved structural steel S1100QL having a yield point of more than 900 MPa. The simulations included single (Tmax = 1250°C) and double welding thermal cycle (Tmax = 1250°C + 600°C, Tmax = 1250°C + 760°C and Tmax = 1250°C + 900°C) as well as cooling times t8/5 = 3, 5 and 10 s. Specimens with the simulated heat affected zone (HAZ) were subjected to impact strength tests performed at a temperature of -40°C and +20°C, Vickers hardness tests (HV10) and microscopic metallographic tests (involving light microscopy). Test results were presented in diagrams and photographs. Related comparisons included results of the structural, hardness and toughness tests of simulated HAZs with analogous results obtained during the actual repair welding of a MAG-welded joint made of steel S1100QL. The final part of the article contains discussion concerning the test results and the statement concerning the obtainment of the significant conformity of the phase composition and the morphology of the microstructure as well as the average hardness values of the HAZ areas obtained in the simulations and those of the HAZ area obtained in the actual welded joint. In relation to all tested simulation variants, the impact energy of the simulated HAZ area of steel S1100QL satisfied the minimum criterion of KV = 27 J both in relation to a test temperature of -40°C and that of +20°C. The number of repeated (1 through 4) thermal cycles having preset parameters did not trigger explicitly noticeable changes in impact energy values as regards the simulated HAZ of steel S1100QL.
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Song, Nan Nan, Fan Zhang, You Feng He, and Qiang Zhu. "Experimental and Simulation Study of Microstructure of the Aluminium Alloy 319s in Induction Reheating Process." Solid State Phenomena 192-193 (October 2012): 281–86. http://dx.doi.org/10.4028/www.scientific.net/ssp.192-193.281.
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Semi-solid processing of metallic alloys has been developing over the last 30 years. Millions of components are now manufactured by semi-solid processing. A semi-solid processing so called thixoforming requires reheating the feedstock to a semi-solid state in relatively short time interval with a uniform temperature distribution as well as an optimum liquid fraction. Microstructure, which makes significant impact on processing parameters and quality of the component, changes during the reheating process. The main objective of this study is to establish a quantitative relationship of the microstructure and the induction heating process parameters of the aluminum alloy 319s. This quantitative relationship is employed in the numerical simulation of calculating solid/liquid fraction changes during induction heating process. The simulation results are then successfully applied in aiding optimization of process parameters to make an automobile engine turbocharger compressor wheel, which has very complex geometry.
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Deng, Wangqun, Haibo Feng, Jianjun Wang, and Yongfeng Yang. "Effect of Surface Morphology on Dynamic Characteristics of Cam-Follower Oblique Impact System." Shock and Vibration 2019 (January 22, 2019): 1–10. http://dx.doi.org/10.1155/2019/3956169.
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The effects of the fractal characteristics on the dynamic characteristics of the oblique impact system are studied via considering the normal contact stiffness with fractal dimension parameter of the microstructure of the interface in this paper. The normal distribution is used to describe the trend of contact line length. The effects of the position parameters and the scale parameters are analyzed. The simulation results show that the increasing of the interface roughness can make the system response more stable. The system response eventually evolves into chaos as the fractal dimension increases. The system response changes between quasiperiod and chaos affected by the contact line length with a normal random distribution.
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Yanikömer, Neslihan, Rahim Nabbi, and Klaus Fischer-Appelt. "Impact of Radiation-Induced Microstructures on the Integrity of Spent Nuclear Fuel (SNF) Elements in Long-Term Storage." Safety of Nuclear Waste Disposal 1 (November 10, 2021): 17–18. http://dx.doi.org/10.5194/sand-1-17-2021.
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Abstract. The current safety concept provides for a period in the range of 40 years for interim storage of spent fuel elements. Since the requirement for proof of safety for to up to 100 years arises, the integrity of the spent fuel elements in prolonged interim storage and long-term repositories is becoming a critical issue. In response to this safety matter, this study aims to assess the impact of radiation-induced microstructures on the mechanical properties of spent fuel elements, in order to provide reliable structural performance limits and safety margins. The physical processes involved in radiation damage and the effect of radiation damage on mechanical properties are inherently multiscalar and hierarchical. Damage evolution under irradiation begins at the atomic scale, with primary knock-on atoms (PKAs) resulting in displacement cascades (primary damage), followed by the defect clusters leading to microstructural deformations. In this context, we have developed and applied a multiscale simulation methodology consistent with the multistage damage mechanisms and the corresponding effects on the mechanical properties of spent fuel cladding and its integrity. Within the improved hierarchical modelling sequence, the effect of the radiation field on the fuel element cladding material (Zircalloy-4) is assessed using Monte Carlo methods. A molecular dynamics method is employed to model damage formation by PKAs and primary damage defect configurations. The formation of clusters and evolution of microstructures are simulated by extending the simulation sequence to a longer time scale with the kinetic Monte Carlo (KMC) method. Transferring the calculated radiation-induced microstructures into macroscopic quantities is ultimately decisive for the structural/mechanical behaviour and stability of the cladding material, and thus for long-term integrity of the spent fuel elements. Results of the multiscale modelling and simulations as well as a comparison with experimental results will be presented at the conference session.
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Fadly, Muhammad Syaiful, Anindito Purnowidodo, and Putu Hadi Setyarini. "Karakteristik Fiber Metal Laminate Akibat Beban Impak Balistik Dari Peluru Kaliber 9 mm Full Metal Jacket (FMJ)." Jurnal Rekayasa Mesin 12, no. 1 (May 31, 2021): 103. http://dx.doi.org/10.21776/ub.jrm.2021.012.01.12.
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<p class="Abstract"><span lang="EN-GB">Estimated damage levels from ballistics impact zone provide valuable information to make bulletproof materials more effective. Therefore, this study aims to determine the impact of ballistics including hole shape, hole depth, macro, and microstructure on fiber metal laminate. The characteristics of ballistics impact for each configuration target is obtained from experiment and comparison based on simulations with finite element method. Test experiments used short-barreled fire guns at a distance of 5 meters with a normal attack angle based on the National Institute of Justice standard. Simulation with Johnson-Cook plasticity models for aluminum plate and orthotropic material model for kevlar/epoxy. The experiment and simulation results showed that the projectile is able to perforate the first layer (aluminum plate) and the second layer (Kevlar/epoxy) while the last layer (backplate) is deformed to form a bulge. The aluminum plate is perforated by the failure of petaling formation on the backside and spread of dimple fracture around the area of the petal which indicates ductile fracture while kevlar/epoxy is perforated by projectile with failure of fiber fracture on primary yarn, fiber pull-out, fiber stretching and fiber rupture.</span></p>
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Liu, Xin, Zhengzhao Liang, Siwei Meng, Chunan Tang, and Jiaping Tao. "Numerical Simulation Study of Brittle Rock Materials from Micro to Macro Scales Using Digital Image Processing and Parallel Computing." Applied Sciences 12, no. 8 (April 11, 2022): 3864. http://dx.doi.org/10.3390/app12083864.
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The multi-scale, high-resolution and accurate structural modeling of rocks is a powerful means to reveal the complex failure mechanisms of rocks and evaluate rock engineering safety. Due to the non-uniformity and opacity of rocks, describing their internal microstructure, mesostructure and macro joints accurately, and how to model their progressive fracture process, is a significant challenge. This paper aims to build a numerical method that can take into account real spatial structures of rocks and be applied to the study of crack propagation and failure in different scales of rocks. By combining the failure process analysis (RFPA) simulator with digital image processing technology, large-scale finite element models of multi-scale rocks, considering microstructure, mesostructure, and macro joints, were created to study mechanical and fracture behaviors on a cloud computing platform. The Windows-Linux interactive method was used for digital image processing and parallel computing. The simulation results show that the combination of a parallel RFPA solver and digital image modeling technology can achieve high-resolution structural modeling and high-efficiency calculation. In microscopic simulations, the influence of shale fractures and mineral spatial distribution on the fracture formation process can be revealed. In the mesostructure simulation, it can be seen that the spatial distribution of minerals has an impact on the splitting mode of the Brazilian splitting model. In the simulation of a joined rock mass, the progressive failure process can be effectively simulated. According to the results, it seems that the finite element parallel computing simulation method based on digital images can simulate the multi-scale failure process of brittle materials from micro to macro scales. Primarily, efficient parallel computing based on a cloud platform allows for the multi-scale, high-resolution and realistic modeling and analysis of rock materials.
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Xu, Hong, Mou Rui Zhang, and Li Juan Zhu. "Numerical and Experimental Investigation on Hot Stamping of Ultra-High Strength Steel." Advanced Materials Research 941-944 (June 2014): 1720–25. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.1720.
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In the automotive industry, hot stamping of ultra-high strength steel offers the possibility to reduce vehicle weight and enhance safety performance. However, the imperfect technology restricts its application. To investigate the hot stamping technology further, numerical simulation and forming experiment were made in this paper with a door beam as an example. After process parameters analysis, the evolution of sheet during the whole process were predicted through the simulation, according which the microstructure of the part were full martensite and no fracture was produced. A door beam was well-formed in the experiment based on the results of simulation, and then a series of tests as metallographic observation, hardness test, tensile test and side impact test were carried out, studying its performance in practice.
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Song, Yiwen, Chi Zhang, James Spencer Lundh, Hsien-Lien Huang, Yue Zheng, Yingying Zhang, Mingyo Park, et al. "Growth-microstructure-thermal property relations in AlN thin films." Journal of Applied Physics 132, no. 17 (November 7, 2022): 175108. http://dx.doi.org/10.1063/5.0106916.
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AlN thin films are enabling significant progress in modern optoelectronics, power electronics, and microelectromechanical systems. The various AlN growth methods and conditions lead to different film microstructures. In this report, phonon scattering mechanisms that impact the cross-plane (κz; along the c-axis) and in-plane (κr; parallel to the c-plane) thermal conductivities of AlN thin films prepared by various synthesis techniques are investigated. In contrast to bulk single crystal AlN with an isotropic thermal conductivity of ∼330 W/m K, a strong anisotropy in the thermal conductivity is observed in the thin films. The κz shows a strong film thickness dependence due to phonon-boundary scattering. Electron microscopy reveals the presence of grain boundaries and dislocations that limit the κr. For instance, oriented films prepared by reactive sputtering possess lateral crystalline grain sizes ranging from 20 to 40 nm that significantly lower the κr to ∼30 W/m K. Simulation results suggest that the self-heating in AlN film bulk acoustic resonators can significantly impact the power handling capability of RF filters. A device employing an oriented film as the active piezoelectric layer shows an ∼2.5× higher device peak temperature as compared to a device based on an epitaxial film.
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Łomozik, Mirosław. "Microstructure, Toughness and Hardness of the Simulated HAZ Area of Steel S1300QL." Biuletyn Instytutu Spawalnictwa, no. 6 (December 2021): 15–27. http://dx.doi.org/10.17729/ebis.2021.6/2.
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The introduction contains information (found in available reference publications) concerning the weldability of steel S1300QL. The introduction also presents general information concerning the effect of the microstructure and the chemical composition of filler metals used in the welding of high-strength steels on the mechanical properties of weld deposit. The subject of simulation tests (discussed in the article) was structural steel S1300QL having a yield point of more than 900 MPa S1300QL. Simulations involved both single (Tmax = 1250°C) and double welding thermal cycles (Tmax = 1250°C + 600°C, Tmax = 1250°C + 760°C and Tmax = 1250°C + 900°C) as well as cooling times t8/5 = 3 s, 5 s and 10 s. Specimens with simulated HAZ areas were subjected to impact strength tests performed at a temperature of -40°C and +20°C, Vickers hardness tests (HV10) and microscopic metallographic tests involving the use of light microscopy. The test results are presented in related diagrams and photographs. The final part of the article contains a discussion concerning test results and concluding remarks. The tests revealed that, in terms of the test steel, the number of repetitions of thermal cycles having pre-set parameters did not explicitly translated into changes of impact energy values concerning the simulated HAZ areas. The tests also revealed that recommended thermal cycles making it possible to obtain the required combination of the high toughness and hardness of the simulated HAZ area of steel S1300QL (similar to that of the base material) were double thermal cycles of maximum temperature Tmax1 = 1250°C + Tmax2 = 600°C and Tmax1 = 1250°C + Tmax2 = 900°C combined with cooling times t8/5 = 5 s and 10 s and all numbers of repeated thermal cycles.
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Wang, Qing Feng, Cheng Jia Shang, R. D. Fu, Ya Nan Wang, and Wayne Chen. "Physical Simulation and Metallurgical Evaluation of Heat-Affected Zone during Laser Welding of Ultrafine Grain Steel." Materials Science Forum 475-479 (January 2005): 2717–20. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.2717.
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Two major challenges in relation to laser welding are abrupt change in metallurgical aspects and actual assessment of the mechanical properties due partly to very narrow heat affected zone (HAZ) and partly to high mechanical properties gradient. The rapid thermal cycle of laser welding imposed on the HAZ was physically simulated using a Gleeble™ dynamic simulator equipped with a special isothermal quenching device (ISO-Q™), and a relatively large volume of HAZ with a homogeneous microstructure was obtained. The thermal cycles were determined from actual laser welding followed by laser tempering. Estimations of microstructure and mechanical properties of the simulated HAZs of an ultrafine grain steel imposed by laser welding with or without post-weld laser tempering were performed. The results indicate that the simulated HAZs, depending on the thermal history, are composed of lathy martensite with different pocket size and dislocation density. The impact toughness of as-welded HAZ is improved in contrast to the base material, but is further degraded by a following laser tempering, which, however, alleviates the abrupt change in hardness of as-welded HAZ.
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Simeone, D., P. Garcia, O. Tissot, and L. Luneville. "Late stage coarsening kinetics induced by a phase-dependent mobility: A phase field study of FeCr in the spinodal regime." Journal of Applied Physics 131, no. 16 (April 28, 2022): 165110. http://dx.doi.org/10.1063/5.0084957.
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An efficient algorithm is presented in this work to compute the late stage coarsening kinetics within the phase-field framework. Microstructures resulting from off-critical quenches over large time periods have been simulated in the FeCr system, which exhibits substantial variations in atomic mobilities between the Fe-matrix and Cr-rich precipitates. To understand the impact of such a phase-dependent mobility on the microstructure, 2D simulations have been performed in the spinodal regime using a constant, symmetric, and phase-dependent mobility. Detailed analyses of these simulations highlight the fact that the more realistic situation where atomic mobility is non-uniform induces a competition between coalescence and coarsening of precipitates. We use these simulations to shed light upon previously published numerical and experimental results.
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Simeone, D., P. Garcia, O. Tissot, and L. Luneville. "Late stage coarsening kinetics induced by a phase-dependent mobility: A phase field study of FeCr in the spinodal regime." Journal of Applied Physics 131, no. 16 (April 28, 2022): 165110. http://dx.doi.org/10.1063/5.0084957.
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An efficient algorithm is presented in this work to compute the late stage coarsening kinetics within the phase-field framework. Microstructures resulting from off-critical quenches over large time periods have been simulated in the FeCr system, which exhibits substantial variations in atomic mobilities between the Fe-matrix and Cr-rich precipitates. To understand the impact of such a phase-dependent mobility on the microstructure, 2D simulations have been performed in the spinodal regime using a constant, symmetric, and phase-dependent mobility. Detailed analyses of these simulations highlight the fact that the more realistic situation where atomic mobility is non-uniform induces a competition between coalescence and coarsening of precipitates. We use these simulations to shed light upon previously published numerical and experimental results.
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Suikkanen, P. P., Jukka Kömi, and L. Pentti Karjalainen. "Processing Low and Ultra-Low Carbon Bainitic Steels with Excellent Property Combinations." Materials Science Forum 500-501 (November 2005): 535–42. http://dx.doi.org/10.4028/www.scientific.net/msf.500-501.535.
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Six experimental low and ultra-low carbon C-Mn-Mo-Nb-B and one conventional TMCP steel heats have been prepared to study the effects of chemical composition and hot deformation on the microstructure and the strength-toughness properties. In physical simulation tests, it was found that the deformation of austenite below the non-recrystallization temperature enhances the formation of higher-temperature bainitic morphologies and polygonal ferrite. On the other hand, hardness exhibits relatively low sensitivity to the degree of deformation below Tnr, whereas the deformation results in a distinct refinement in the microstructures, as determined by SEM-EBSD measurements, suggesting an improvement in the impact toughness. Simultaneous alloying with Mo-Nb-B seemed to be most efficient to provide high hardness and strength. Hot rolling trials indicated that the yield strength in the range 500-700 MPa with the excellent toughness down to –80 °C can be achieved in low carbon (≈ 0.03%) bainitic grades.
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Frivaldsky, Michal, Miroslav Pavelek, Pavol Spanik, Dagmar Faktorova, and Gabriela Spanikova. "Approximation of complex organic tissue for investigation of the electromagnetic impact." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 38, no. 4 (July 1, 2019): 1334–46. http://dx.doi.org/10.1108/compel-10-2018-0395.
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Purpose The purpose of this paper is to study the performance of the approximated model of biological tissue for development of complex 3 D models. The comparison of results from the complex model of liver tissue and results from the approximated model is provided to validate the proposed approximation method. Design/methodology/approach The proposed model of hepatic tissue (respecting its heterogeneous character up to the microstructure of hepatic lobules) is used for analysis of current field distribution within this tissue. Initially, the complex model of tissue structure (respecting the heterogenous structure) is presented, considering its complicated structure. Consequently, the procedure for the approximation of a complex model is being described. The main motivation is the need for simple, fast and accurate simulation model, which can be consequently used within more complex modeling of human organs for investigation of negative impacts of electrosurgical equipment on heterogenic tissue structure. For these purposes, the complex and approximated model are mutually compared and evaluated. Findings The obtained results are exploitable for the analysis of the probability of injury formation in sensitive tissue structures, and the approximated model shall serve for optimization of complex and time-consuming analyses. Research limitations/implications Research limitations include development of precise and fast electro-magnetic simulation model of biological tissue. Practical implications Practical implications is focused on the optimization processes of the electro-surgical procedures. Originality/value The originality of the paper concerns the approximation method of organic tissue modeling.
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Yang, Liu Qing, Yu Liu, Bin Feng, Yu Ran Fan, and Deng Zun Yao. "Microstructure and Mechanical Properties of X80 Induction Heating Bends." Materials Science Forum 762 (July 2013): 158–64. http://dx.doi.org/10.4028/www.scientific.net/msf.762.158.
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By using physical thermal simulation technology, combined with metallographic analysis, tensile tests, impact and hardness tests, effects of heating temperature and cooling speed on microstructure and mechanical properties of X80 induction heating bends were investigated. The results show that as the heating temperature rises, TS of X80 induction heating bends increases gradually. However, when the heating temperature rises above 1100°C, plasticity and toughness of the bends begin to decrease, and grain growth tends to be obvious. When the heating temperature is 1050°C, X80 induction heating bends have a good strength and toughness. As the cooling rate increases, strength and toughness of X80 bends are improved considerably. In the cooling rate range between 20°C/s and 30°C/s, the microstructure of X80 bends is mainly composed of polygonal ferrite and granular bainite. Due to the very high dislocation density inside granular bainite and the fine and dispersed M-A constituents, X80 induction heating bends have a very good strength and toughness.
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Turneaure, Stefan J., and Y. M. Gupta. "Real-time microstructure of shock-compressed single crystals from X-ray diffraction line profiles." Journal of Applied Crystallography 44, no. 3 (May 6, 2011): 574–84. http://dx.doi.org/10.1107/s0021889811012908.
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Methods to obtain and analyze high-resolution real-time X-ray diffraction (XRD) measurements from shock-compressed single crystals are presented. Procedures for extracting microstructural information – the focus of this work – from XRD line profiles are described. To obtain quantitative results, careful consideration of the experimental geometry is needed, including the single-crystal nature of the sample and the removal of instrumental broadening. These issues are discussed in detail. Williamson–Hall (WH) and profile synthesis (PS) analysis procedures are presented. More accurate than WH, the PS procedure relies on a forward calculation in which a line profile is synthesized by convoluting the instrumental line profile with a line profile determined from a diffraction simulation. The diffraction simulation uses the actual experimental geometry and a model microstructure for the shocked crystal. The shocked-crystal microstructural parameters were determined by optimizing the match between the synthesized and measured line profiles. XRD measurements on an Al crystal, shocked along [100] to 7.1 GPa using plate-impact loading, are used to demonstrate the WH and PS analysis methods. In the present analysis, the microstructural line broadening arises because of a distribution of longitudinal elastic microstrains. The WH analysis resulted in FWHM longitudinal microstrain distributions of 0.22 and 0.38% for Lorentzian and Gaussian line shape assumptions, respectively. The optimal FWHM longitudinal microstrain for the PS method was 0.35% with a pseudo-Voigt distribution (40% Lorentzian–60% Gaussian). The line profile measurements and PS analysis presented in this work provide new insight into the heterogeneous distribution of elastic strains in crystals undergoing elastic–plastic deformation during shock compression. Such microstrain distribution measurements are complementary to continuum measurements, which represent averages of the heterogeneous strains or stresses. The PS analysis is a general method capable of incorporating microstructural models more complex than the microstrain distribution model used in this work. As a next step, the PS method will be applied to line profiles of multiple diffraction peaks to separate strain- and size-broadening effects in shocked crystals.
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Yang, Di Xin, and Yuan Fang Sun. "Thermal Simulation Study of 900MPa Grade High-Strength Low Alloy Steel in Welding Procedures." Materials Science Forum 704-705 (December 2011): 1128–32. http://dx.doi.org/10.4028/www.scientific.net/msf.704-705.1128.
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Hydraulic support is an important part of fully mechanized equipments. The constructional steels of hydraulic support with international advanced level mainly adopt the high-strength welding structural steel with its tensile strength of more than 700~1000MPa.This paper analyzes the chemical compositions features of S890 high-strength low alloy steel for 900MPa grade.The Influence of welding parameters,peak temperature and on the microstructures and mechanical properties of welding HAZ of S890 high-strength low alloy steel were investigated by thermo-simulated tests, The influence of welding heat input on the mechanical behaviors of the welded joint was also investigated. The results show that the microstructures of S890 steel change from tempered martensite to bainite and a little ferrite , pearlitic when welding heat input changes from low to high, and accompany the austenite grains coarsening ,so the impact toughness and hardness of welding HAZ at lower peak temperatures and shorter are higher than that at higher peak temperature and long . Welding HAZ produced by the second weld bead will overlap partially with the HAZ produced by the first weld bead. In this area, primitive microstructure tempers again or partial re-phase transformations and re-cools,but the area involved in the overlap is limited,so the influence on the properties of S890 steel is not obvious. In covered arc welding,the influence on the welded join strength of S890 steel is not distinct when heat input change in a certain scope, but the plasticity of the welded join falls off steeply as heat input increases. Keywords: S890 steel; high-strength low alloy steel; weld performance; hydraulic supports
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Zhuravleva, T. B., and I. M. Nasrtdinov. "Impact of microstructure and horizontal heterogeneity of broken cirrus clouds on mean solar radiation fluxes in the visible spectral region: results of numerical simulation." Optika atmosfery i okeana 34, no. 10 (2021): 792–802. http://dx.doi.org/10.15372/aoo20211006.
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Huang, E. Wen, Chung Kai Chang, Wen Jay Lee, Soo Yeol Lee, Jun Wei Qiao, and Chung Hao Chen. "Thermal-Effect Study on a Carbon-Carbon Composite Using Synchrotron X-Ray Measurements & Molecular Dynamics Simulation." Materials Science Forum 777 (February 2014): 35–39. http://dx.doi.org/10.4028/www.scientific.net/msf.777.35.
Full textAbstract:
Carbon-carbon composites are deemed as candidate materials for application in very high temperature reactors. In a very high temperature reactor, carbon-carbon composite materials would experience severe environmental impacts from high temperatures. As a result, we applied non-destructive ex-situ diffraction experiments to investigate the microstructure changes of the carbon-carbon composite materials experiencing different temperatures. In this study, the samples were prepared in a format of a three-dimensional pitch-based carbon-carbon composite. The samples were heated to 500 (°C), 700 (°C), and 900 (°C) for 2 minutes, respectively. In order to understand the temperature effect on carbon-carbon composite, we facilitated the high penetration of the synchrotron X-ray diffraction at National Synchrotron Radiation Research Center to examine the evolution of microstructures subjected to heat treatment. The results show that the lattice parameters of a-axis and c-axis evolve upon heating. The molecular dynamics simulation results suggest that the early-stage rearrangement is originated from the release of the defects.
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Kang, Zhi Qiang, Yu Bo Zhang, Xue Yang, Guo Hui Feng, and Lin Zhang. "Numerical Study on the Impact of Second Phase Content on the Solidification of Al-Pb Hypermonotectic Alloys." Materials Science Forum 896 (March 2017): 209–15. http://dx.doi.org/10.4028/www.scientific.net/msf.896.209.
Full textAbstract:
Based on the Euler-Euler method and the conservation equation, a mathematical model for describing the non-steady processes of mass transfer, transmission, heat transfer, solute transport and nonstationary process of nucleation in liquid-liquid separation of Al-Pb monotectic alloys was established. The influence of the second phase content on the solidification microstructure of Al-Pb alloy was analyzed by numerical simulation by combining the calculated temperature field and velocity field with the kinetic equation of controlling solidification microstructure evolution. The results show that the lower the second phase content is, the more uniform the temperature field distribution is, and the lower the velocity of the second phase droplets is. The average diameter and volume fraction of the second phase droplets in the Al-5wt%Pb alloy samples were lower than that in the Al-10wt%Pb alloy samples under the same conditions. It is concluded that the lower the content of the second phase, the liquid - liquid phase separation and decomposition behavior of liquid immiscible liquid in the immiscible zone are relatively slow, and the more easily the droplets of the second phase are distributed uniformly in alloy solidification structure of the matrix.
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Zong, Yun, and Chun Ming Liu. "Microstructure and Properties of HAZ in Low-Carbon Bainite E550 Steel during Double-Pass Welding Thermal Cycle." Materials Science Forum 913 (February 2018): 317–23. http://dx.doi.org/10.4028/www.scientific.net/msf.913.317.
Full textAbstract:
Investigations on the microstructure and properties of the Coarse-Grained Heat-Affected Zone (CGHAZ) and intercritical reheated Coarse-Grained Heat-Affected Zone (ICCGHAZ) of a low-carbon bainite E550 steel were carried out using thermal simulation technology in this paper.Double-pass welding thermal cycle were performed on Gleeble-3800 thermal simulator, tempering heat treatment of the critical coarse crystal zone carried out in a box resistance furnace, low impact energies at -40 °C and Vickers hardness determined, and the microstructure were observed. The experimental results show that the microstructure of CGHAZ (Tp1 is 1320 °C) was dominated by coarse granular bainite and Lath bainite Ferrite, the impact toughness of CGHAZ was poor. The toughness of the CGHAZ was improved after second welding heat cycle except intercritical two-phase heating. When the peak temperature of the second thermal cycle(Tp2) was 650 °C, martensite-austenite (M-A) constituent of original CGHAZ wasdecomposed and refined, impact toughness and hardness were all higher than that of CGHAZ; When Tp2 is 750 °C, there was a ” necklace” distribution of massive M-A constituent in this ICCGHAZ, the impact energy at -40 °C prominently decreased and Hardness went up; When Tp2 was in the temperature range of 850 °C ~1100 °C, the microstructure was mainly finer granular bainite, the toughness of CGHAZ could be effectively improved; When Tp2 was over 1100 °C, M-A constituents become coarse, the toughness declined slightly . The changing of hardness was the opposite of toughness but the hardness fluctuation was comparatively small. After tempering at different temperature (520 °C~640 °C) , the grain boundary "necklace" structure of ICCGHAZ was still obvious, some of the M-A constituent were decomposed, the hardness decreased, the lowest hardness was obtained in 610 °C.