Journal articles: 'Steel – Fatigue'

1

Bhat, Sunil, and Vijay G. Ukadgaonker. "Fatigue Life Enhancement of Welded Steel-Steel Composite during Crack Growth from Weak to Strong Steel: An Experimental Validation." Key Engineering Materials 417-418 (October 2009): 825–28. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.825.

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Strength mismatch effect across weld interfaces, generated by welding weak and strong steels, influences fatigue and fracture properties of a welded bimetallic composite. Advancing fatigue crack tip in weak parent steel is shielded from the remote load when it reaches near the interface of ultra strong weld steel. Entry of crack tip plasticity into weld steel induces load transfer towards weld which dips crack growth rates thereby enhancing the fatigue life of the composite. A computational model for fatigue life prediction of strength mismatched welded composite under K dominant conditions is validated by experimental work in this paper. Notched bimetallic compact tension specimens, prepared by electron beam welding of weak alloy and strong maraging steels, are subjected to fatigue testing in high cycle regime.

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García-Diez, Ana Isabel, Juan José Galán-Díaz, Manuel Ángel Graña-López, and Mar Toledano-Prados. "Study of the Rotary Bending Fatigue Resistance of 30MnB5, 41CrS4 and 30MnVS6 Steels." Applied Sciences 12, no. 5 (February 24, 2022): 2369. http://dx.doi.org/10.3390/app12052369.

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In this study, a comparative analysis of the fatigue behavior of four types of steels, three of quenching and tempering (30MnB5 subjected to two different heat treatments and 41CrS4) and one microalloyed (30MnVS6), was carried out. The objective of the study is to determine if it is feasible to replace the quenching and tempering steel traditionally used in the manufacture of commercial vehicle axles (30MnB5) with alternative ones with the same composition but with modifications in their microstructure that improve their mechanical properties; a quenched and tempered chromium steel (41CrS4) and one that is microalloyed (30MnVS6). For this, rotary-bending fatigue tests have been carried out on the four types of steels with different stress levels. The fatigue resistance of quenched and tempered steels and microalloyed steel was evaluated using the fit of Basquin’s experimental data. Where possible, the fatigue limit was determined using the maximum likelihood method. It was concluded that, in general, the fatigue resistance of chromium-alloyed steel is higher than that of the reference steel, while the rest have lower fatigue resistance. On the other hand, it was determined that the fatigue limit of microalloyed steel is higher than the reference one and that of the reference steel is higher than that of the other two steels.

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Tohgo, Keiichiro, Tomoya Ohguma, Yoshinobu Shimamura, and Yoshifumi Ojima. "Influence of Strength Level of Steels on Fatigue Strength and Fracture Morphology of Spot Welded Joints." Key Engineering Materials 462-463 (January 2011): 94–99. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.94.

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In this paper, fatigue tests and finite element analyses are carried out on spot welded joints of mild steel (270MPa class) and ultra-high strength steel (980MPa class) in order to investigate the influence of strength level of base steels on fatigue strength and fracture morphology of spot welded joints. From the fatigue tests the following results are obtained: (1) Fatigue limit of spot welded joints is almost the same in both steels. (2) Fatigue fracture morphology of spot welded joints depends on the load level in the ultra-high strength steel, but not in the mild steel. From discussion based on the finite element analyses the following results are obtained: (3) The fatigue limit of spot welded joints can be predicted by stress intensity factors for a nugget edge, fracture criterion for a mixed mode crack and threshold value for fatigue crack growth in base steel. (4) Plastic deformation around a nugget in spot welded joints strongly affects the fatigue fracture morphology.

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Hu, Zhi Gang, Ping Zhu, Jin Meng, and Xin Min Lai. "Experimental Comparison of Fatigue Characterizations between TRIP and DP Steels." Advanced Materials Research 97-101 (March 2010): 671–74. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.671.

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Advanced high strength steels are increasingly utilized to realize the lightweight of automotive body for economical and ecological considerations. The fatigue durability of notched components is one of the significant evaluation parameters for reasonable material selection. Strain-controlled fatigue experiments of low-alloy TRIP steel and DP steel with 590MPa grade were performed at room temperature in this study. Experimental results indicate that both fatigue life and cyclic stress amplitude of TRIP steel are superior to those of DP steel at the same strain amplitude. Furthermore, local strain-life models of two steels were determined with linear regression method to predict the fatigue life of notched body structures with finite element method. It can be concluded that TRIP steel can provide more excellent potential than DP steel for the lightweight design of notched automotive structures from the viewpoint of fatigue resistance.

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Akiniwa, Yoshiaki, Keisuke Tanaka, and Hidehiko Kimura. "Measurement of Stress Distribution Near Fatigue Crack in Ultra-Fine Grained Steel by Synchrotron Radiation." Materials Science Forum 490-491 (July 2005): 118–23. http://dx.doi.org/10.4028/www.scientific.net/msf.490-491.118.

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Single-edge-notched specimens of ultrafine-grained steel were fatigued. The mean grain size of the steel is about 2 micrometers. Propagation behavior of fatigue cracks was observed with the crack closure. The resistance of the crack propagation of ultrafine-grained steel was larger than that of conventional steels. The crack closure acted as an important role for the larger resistance of fatigue crack propagation. After fatigue tests, stress distribution near the fatigue crack was measured by monochromatic X-rays from synchrotron radiation. The irradiated area was 100 µm x 100 µm. Residual and loading stress distributions ahead of the crack tip and on the crack wake was measured at the maximum stress intensity factor and zero applied load. The stress was determined by sin2ψ method. The measured stress was compared with the value calculated by FEM and the fatigue crack propagation model. The stress distribution at the maximum load and residual stresses agreed very well with the calculated results. The crack opening stress calculated by the residual stresses agreed with the experimental result.

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Sugimoto, Koh Ichi, Junji Tsuruta, and Sung Moo Song. "Fatigue Strength of Formable Ultra High-Strength TRIP-Aided Steels with Bainitic Ferrite Matrix." Key Engineering Materials 345-346 (August 2007): 247–50. http://dx.doi.org/10.4028/www.scientific.net/kem.345-346.247.

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Formable ultra high-strength TRIP-aided steel with bainitic ferrite matrix structure (TBF steel) contributes to a drastic weight reduction and an improvement of crash safety of automobile. In this study, fatigue strength of 0.2%C-1.5%Si-1.5%Mn TBF steels was investigated. High fatigue limit was achieved in TBF steels austempered at 400-450oC, containing a large amount of stable retained austenite. The fatigue limit was linearly related with mobile dislocation density, as well as TRIP effect of retained austenite. When compared to conventional martensitic steel, the TBF steel exhibited lower notch-sensitivity or higher notched fatigue performance. Complex additions of 0.5%Al, 0.05%Nb and 0.2%Mo considerably improved the notched fatigue performance, as well as the smooth fatigue strength. This was associated with the stabilized retained austenite and refined microstructure which suppress fatigue crack initiation and/or propagation.

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Gao, Zhijun, Guangfei Pan, Shuize Wang, Yu Song, Honghui Wu, and Xinping Mao. "Effect of Mg on Inclusion and High Cycle Fatigue Behavior in Titanium Microalloyed Beam Steel." Metals 13, no. 4 (April 13, 2023): 760. http://dx.doi.org/10.3390/met13040760.

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In this paper, the fatigue behavior of titanium microalloyed beam steels were studied by high cycle fatigue test and fatigue crack growth rate test. The effect of Mg addition on the fatigue behavior in titanium microalloyed beam steel was systematically analyzed. According to the experimental results, the addition of magnesium can effectively modify the inclusions by reducing the size of Al2O3 and TiN and promoting the formation of finer complex inclusions with a MgO·Al2O3 core in titanium microalloyed high-strength beam steel. Inclusion number of the experimental steels had far less of an impact on the fatigue characteristic than inclusion size. With the heterogeneous nucleation effect of MgO·Al2O3, the inclusions are refined after the Mg addition. Beam-2 steel’s tensile strength decreased by approximately 54 MPa, while its fatigue strength increased by about 33 MPa, showing favorable fatigue resistance. These findings are essential for optimize the fatigue properties of titanium microalloy steel and promote the development of automobile beam steel with excellent fatigue properties.

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8

Islam, M. A., and Yo Tomota. "Fatigue Strength and Fracture Mechanisms of IF28 Steels." Advanced Materials Research 15-17 (February 2006): 804–9. http://dx.doi.org/10.4028/www.scientific.net/amr.15-17.804.

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Interstitial free (IF) steels are widely used as thin sheet in the automobile industries because of their many favorable properties. Although, fatigue properties of IF steels do not have significant importance to auto body makers, however, they are very concerned about the tensile and fatigue strength of the steels used for structural purposes to ensure safety of passengers. So, fatigue results of this steel might help researchers to understand the behaviors of high strength steels. In this study cyclic and static properties have been studied at room temperature in the air. Initiative has also been taken to observe the fatigue fracture morphology of this steel. Experimental results show that the fatigue limit is corresponding to about 40% of tensile strength and 80% of the yield strength of this steel. Fractographic observations reveal a mixed type of fracture mode (intergranular and transgranular cracking) fractures.

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Park, Jeong Yeol, Byoung Koo Kim, Dae Geun Nam, and Myung Hyun Kim. "Effect of Nickel Contents on Fatigue Crack Growth Rate and Fracture Toughness for Nickel Alloy Steels." Metals 12, no. 2 (January 18, 2022): 173. http://dx.doi.org/10.3390/met12020173.

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In terms of steel alloying elements, generally, nickel is used as an austenite stabilizing element to increase the toughness of steel. The low temperature materials, such as nickel alloy steels with a nickel content of 3.5% to 9%, stainless steel and Invar, show excellent toughness at low (173 K) and cryogenic (108 K) temperatures. In particular, in the shipbuilding industry, it is mainly used for liquefied ethane and Liquefied Natural Gas (LNG) carriers, and research on low-temperature steels are attracting attention again as regulations on environmental issues are strengthened in recent years. Therefore, in this study, fatigue and fracture performances of nickel alloy steel containing 9% or less among nickel alloy steels are evaluated. Moreover, we assess the Fatigue Ductile to Brittle Transition (FDBT) of nickel alloy steels based on crack tip opening displacement (CTOD). In order to discuss the fatigue and fracture performances of nickel alloy steels, microstructure analysis carried out. As a result, CTOD and Fatigue Crack Growth Rate (FCGR) of nickel alloy steels increases as nickel contents increase. In addition, FDBT of 9% nickel alloy steel is the lowest compared to other nickel alloy steels.

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10

Plumtree, Alan, and M. M. Mirzazadeh. "Fully Reversed Uniaxial Tension-Compression High Cycle Fatigue Behaviour of Shot-Peened Steels." Key Engineering Materials 488-489 (September 2011): 21–24. http://dx.doi.org/10.4028/www.scientific.net/kem.488-489.21.

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The effect of shot-peening on the uniaxial fatigue behaviour of four engineering steels, heat treated to a similar final hardness was investigated. Forged 0.39%C and 0.72%C steels, a quenched and tempered 0.51%C steel and a 0.50%C powder forged (PF) steel were fatigue tested under fully reversed (R=-1) push-pull loading conditions. Following long life (107) cycling, shot-peening had little effect on the fatigue limit of the 0.39%C and 0.72%C steels whereas the fatigue limit of the PF steel increased 10.4%. Conversely, the fatigue limit of the quenched and tempered steel decreased 12.0% after shot-peening. The results showed that the beneficial effects of shot-peening, such as compressive residual stresses and work hardening, balanced the effects of surface roughness since crack initiation tended to occur below the surface. Microhardness profiles showed that the greatest amount of cyclic softening in the shot-peened regions occurred in the hot rolled steels. Softening was accompanied by a decrease in the depth of surface hardness.

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11

Wu, Guo Sheng, and Yu Tao Wang. "Study on Thermal Fatigue Performance of Cold Work Roll Steel." Applied Mechanics and Materials 117-119 (October 2011): 817–20. http://dx.doi.org/10.4028/www.scientific.net/amm.117-119.817.

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Thermal stability and thermal fatigue performance tests of four kinds of cold work roll steels were done. There are indications that after isothermal 2～6 hours under conditions of 400°C～720°C, the best is 8Cr5SiMoV steel, its thermal stability grows up as isothermal time increase; the second is 8Cr4MoV steel; the worse are 8Cr5MoV steel and 9Cr3MoV steel; and all the thermal stability of four kinds of cold work roll steels are lower than 400°C. Thermal fatigue performance of four kinds of cold work roll steels are basically same as their thermal stability, i.e. the best is 8Cr5SiMoV steel, and the second is 8Cr4MoV steel.

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12

Guo, Peng Cheng, Shuai Liu, Peng Hui Ma, Jiang Ying Meng, Fu Cheng Zhang, and Li He Qian. "Fatigue Deformation Behavior of Fe-Mn-C-(Al) TWIP Steels." Materials Science Forum 879 (November 2016): 1524–28. http://dx.doi.org/10.4028/www.scientific.net/msf.879.1524.

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The effects of Al on the monotonic deformation behavior of Fe-Mn-C twinning-induced plasticity (TWIP) steels have been extensively investigated; however, how the addition of Al affects the fatigue properties of these steels is unknown. The present paper deals with the cyclic deformation properties of Fe-22Mn-0.6C-0Al and Fe-22Mn-0.6C-3Al steels by means of total strain-controlled low-cycle fatigue tests. The total strain amplitude ranges from 0.002 to 0.01. The evolved microstructures of fatigued samples were observed by transmission electron microscopy. Results show that the addition of Al has a significant effect on the cyclic deformation behavior, fatigue lifetime and evolved microstructure of Fe-Mn-C TWIP steel.

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13

Chopra, O. K., and D. J. Gavenda. "Effects of LWR Coolant Environments on Fatigue Lives of Austenitic Stainless Steels." Journal of Pressure Vessel Technology 120, no. 2 (May 1, 1998): 116–21. http://dx.doi.org/10.1115/1.2842228.

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Fatigue tests have been conducted on Types 304 and 316NG stainless steels to evaluate the effects of various material and loading variables, e.g., steel type, strain rate, dissolved oxygen (DO) in water, and strain range, on the fatigue lives of these steels. The results confirm significant decreases in fatigue life in water. Unlike the situation with ferritic steels, environmental effects on Types 304 and 316NG stainless steel are more pronounced in low-DO than in high-DO water. Experimental results have been compared with estimates of fatigue life based on a statistical model. The formation and growth of fatigue cracks in air and water environments are discussed.

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14

Qin, Xinmao, Xixia Liu, Huaze Huang, and Cunhong Yin. "Effect of Wear on Alternating Bending Fatigue Life of 20CrNi2Mo Martensitic Steel." Lubricants 12, no. 5 (April 30, 2024): 157. http://dx.doi.org/10.3390/lubricants12050157.

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Bending fatigue failures are commonly related to the wear behavior in an active system. The surface wear and plastic deformation of the tribolayer play crucial roles in the wear–bending fatigue behaviors of steels. In particular, the lamellar structure of martensitic steel leads to its unique wear–bending fatigue behavior. In this work, the wear–bending fatigue testing method and device were introduced to explore the wear–bending fatigue behavior of the martensitic steel. The effect of wear on the alternating bending fatigue life of 20CrNi2Mo martensitic steel was studied under low and high fatigue stress. The influence of wear debris on the fatigue life at two different sliding speeds was also analyzed. The results show that the fatigue life decreased with the wear load increased under high bending stress. Moreover, for systems with nanoscale wear debris on the steel surface, the wear–bending fatigue lifetimes are significantly enhanced compared with large wear debris.

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15

Hsu, Chin Chuan, and Ho Hua Chung. "Analysis of Influence of Aluminum Content on Inclusion Characteristic and Fatigue Life of Bearing Steel Using Statistics of Extreme Values." Advanced Materials Research 939 (May 2014): 11–18. http://dx.doi.org/10.4028/www.scientific.net/amr.939.11.

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In this study, we predicted the maximum nonmetallic inclusion size of bearing steel using statistics of extreme values (SEV) approach, and discussed that the influence of aluminum content on the nonmetallic inclusion characteristic and fatigue life of bearing steel. The inclusion size and type was measured and identified by a scanning electron microscopy (SEM) and an energy dispersive spectrometer (EDS) respectively. The result shows that most inclusions in steels are oxysulfide and alumina cluster. A tendency was also found that the alumina size increases with increasing aluminum content, but the oxysulfide size almost remains unchanged. Furthermore, alumina clusters were formed in steel if more deoxidizer aluminum was added to the molten steel during metallurgical process. In addition, the fatigue life of steel is inversely proportional to alumina size, but it seems independent of oxysulfide size. Therefore, this study suggests that the dominant factor of influence on the fatigue life of bearing steel is alumina instead of oxysulfide. The results reported here would be beneficial to steel manufacturers attempting to improve the fatigue resistance of bearing steels.

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Haftirman, K. S. Basaruddin, M. Afendi, and A. R. Syayuthi. "Assessment of Fatigue Strength in Small-Specimen of AISI 3140 Steel." Applied Mechanics and Materials 786 (August 2015): 116–20. http://dx.doi.org/10.4028/www.scientific.net/amm.786.116.

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The fatigue strength on small-specimen of mild steel material subjected to rotating bending load has been investigated. Specimen materials were used AISI 3140 steel. The tests were carried out the specimen diameter of 2 and 1 mm at laboratory air. The results obtained can be summarized that fatigue strength of diameter 2 mm was higher than that of diameter 8 and 1 mm for AISI 3140 steel material. Assessment of fatigue strength in small-specimen of carbon steel material has been done based on experimental and the cross-sectional analysis. Fatigue strength of AISI 3140 steel was lower than that of SS400 and S45C steels. The size effect concentration were determined the ratio of fatigue strength small-specimen to the normative specimen. The cross-sectional A was decrease with increasing coefficient of cross-section size. These results were significant impact of the size effect on fatigue strength on metal materials.

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Gui, Long Ming, Xiao Chun Jin, Hong Tao Li, and Mei Zhang. "High Cycle Fatigue Performances of Advanced High Strength Steel CP800." Advanced Materials Research 989-994 (July 2014): 238–41. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.238.

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A low carbon content and improved steel making practices have imparted advanced high strength steel (AHSS) CP800 with superior combination of strength, ductility and weldability. Its performance in fatigue, however, is not well understood. Stress-controlled high cycle fatigue (HCF) tests were conducted to obtain stress vs. fatigue life curve (S-N curve), and the fatigue limit of CP800. The follow HCF performances were obtained. , SRI1=1940MPa, b=-0.09972, Nc1=2.89×106, and R2= 0.88. The collected material data are used as a basis of comparison of CP800 with more common grades of structural steel. CP800 steel shows high strength, comparable ductility, and high fatigue limit level. The test results indicate that compare to that of lower strength common grades of structural steels, CP800 steel has a much higher fatigue endurance limit (say, 476MPa), about 0.6 of its tensile strength (TS). Thus, provides a distinct advantage.

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Zhang, Yifeng, Wei Chen, Hanbing Yan, Xuefeng Wang, Hanping Zhang, and Shijing Wu. "The Effect of Atmospheric Chloride Ions on the Corrosion Fatigue of Metal Wire Clips in Power Grids." Atmosphere 14, no. 2 (January 25, 2023): 237. http://dx.doi.org/10.3390/atmos14020237.

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Corrosion fatigue is an important factor that limits the life of grid materials including wire clips. In order to study the effect of corrosion fatigue and to select suitable grid steels, this paper focuses on the corrosion fatigue properties of Q235 carbon steel, Q235 galvanized steel, and 316L stainless steel in the corrosive environments of air, 2wt% NaCl, 5wt% NaCl, and 8wt% NaCl. Through the fatigue test in the corrosive environment, and the surface morphology scanning and microstructure observation of the fracture, the following conclusions are drawn: the three materials are more susceptible to corrosion fatigue in the Cl− environment, and the higher the Cl− concentration, the greater the likelihood of fracture caused by corrosion fatigue for these three materials. By analyzing the surface roughness, dimples, and cracks in the microstructure, it is found that 316L stainless steel is highly sensitive to Cl− corrosion under cyclic stress, and Q235 galvanized steel is more resistant to Cl−. By plotting the stress fatigue life curve of Q235 galvanized steel, it is found that the corrosion fatigue life decreases as the Cl− concentration increases. For wire clips in areas with severe Cl− pollution, Q235 galvanized steel should be selected to achieve the best anti-corrosion fatigue effect; at the same time, the original parts should be repaired or replaced in a timely manner based on the predicted corrosion fatigue life.

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Knoring, Semyon D., Victor V. Platonov, Nikolay G. Popov, and Valery M. Shaposhnikov. "Comparison of fatigue characteristics of 38ХН3МФА and 40ХН high-tensile-strength steels based on test results." Transactions of the Krylov State Research Centre 4, no. 394 (November 23, 2020): 63–69. http://dx.doi.org/10.24937/2542-2324-2020-4-394-63-69.

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Object and purpose of research. The object of work is steel “38ХН3МФА”, planned for use in the propeller shafts manufacture of the lead-ship (project 10510), and less strong steel “40XH”, used in the propeller shafts manufacture for icebreakers of lower ice categories and lower power. The purpose of the study is to compare the fatigue strength of these steel grades. Materials and methods. Investigations of the fatigue strength characteristics of steels were carried out by cyclic tests of flat notched specimens in air and cylindrical specimens in fresh water. Main results. It is shown that lowest fatigue strength results correspond to external cyclic loading of specimens with stress concentrator (notch). But even in these conditions, fatigue strength of 38ХН3МФА steel is better than that of 40XH steel. As for the tests of smooth samples in fresh water, 38ХН3МФА steel also has a clear advantage over 40XH steel. Conclusion. The studies have shown that fatigue strength characteristics of 38ХН3МФА steel in the air and in corrosive environment exceed those of 40XH steel. Environmental sensitivity and stress concentration of 38ХН3МФА steel turned out to be higher than for 40KH steel.

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Mohammad, Khairul Azhar, Edi Syam Zainudin, S. M. Sapuan, Nur Ismarrubie Zahari, and Ali Aidy. "Fatigue Life for Type 316L Stainless Steel under Cyclic Loading." Advanced Materials Research 701 (May 2013): 77–81. http://dx.doi.org/10.4028/www.scientific.net/amr.701.77.

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The paper presents the determination of fatigue life of 316L stainless steel at room temperature. Plenty of steel in the world has been investigated for a lot of application in the science and technology market. The mechanisms of fatigue of 316L stainless steels were studied and investigated. Fatigue tests of specimens were performed in accordance with ASTM E466-96. The fatigue tests were performed in constant load amplitude, constant frequency of 5 Hz with load ratio R=0.1. Fracture surface of specimens were examined by using Scanning Electron Microscope (SEM). The results showed that the endurance fatigue limit of 316L stainless steel was 146.45 MPa.

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Tan, Zhaoqiang, Yong Liu, Xiaolin Huang, and Songlin Li. "Fatigue Behavior of Alloy Steels Sintered from Pre-Alloyed and Diffusion-Bonding Alloyed Powders." Metals 12, no. 4 (April 12, 2022): 659. http://dx.doi.org/10.3390/met12040659.

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Porosity and phases are considered to be two key factors for the fatigue performance of powder metallurgy steels. In this paper, the fatigue strengths of the alloy steels sintered from two typical types of powders, pre-alloyed Fe-Cr-Mo (Astaloy CrM), and diffusion-bonding alloyed Fe-Cu-Mo-Ni (Distaloy AE), were comparatively analyzed in view of the geometry of porosity, the phases constitution, and fractography of fracture. Different modes of fatigue fracture were distinguished between the two materials. Namely, a trans-particle fracture is predominant in the Disitaloy AE steel due to the heterogeneous phases which consist of soft phases in powder interior and hard phases along powder borders. In contrast, the fatigue fracture of the Astaloy CrM steel with a homogeneous mono-phase of martensite is characterized by an inter-particle fracture at the sintering necks. Moreover, the fatigue endurance limit of the Distaloy AE steel was not pronouncedly improved by increasing sintering temperature in comparison with the Astaloy CrM steel. This was attributed to the softening of the network constructed by martensite at sintering necks. A modified Murakami model which considers micro-scale defect and micro-hardness is effective to predict the fatigue performance of the alloy steels sintered from pre-alloyed and diffusion-bonding alloyed powders, respectively.

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Sadek, Mohamed, Jens Bergström, Nils Hallbäck, and Christer Burman. "20 kHz 3-point bending fatigue of automotive steels." MATEC Web of Conferences 165 (2018): 22020. http://dx.doi.org/10.1051/matecconf/201816522020.

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The 20 kHz load frequency enables fatigue tests for very high cycle fatigue life, 109-1013 cycles, within conveniently short time. In automotive applications, many components are subjected to flexural loading and hence bending fatigue is an important test mode. Ultrasound fatigue test instruments have been used successfully in several assessments of fatigue strength and more commonly in uniaxial loading. Here, a 3-point bending fatigue test rig operating in resonance at 20 kHz load frequency has been designed to test plane specimens at R=0.1 loading. The test rig design and stress calculations are presented. Testing for fatigue strength was conducted using the staircase method with 15 specimens of each steel grade, specimens reaching 108 cycles were considered run-outs giving fatigue strength at 108 cycles. Additional 15 specimens of each grade were tested for S-N curves with the upper limit above 109 cycles. Two different common automotive steels, 38MnSiV5, a micro-alloyed ferritic-pearlitic steel, and 16MnCr5, a carburizing martensitic steel, were tested. The fatigue strengths achieved from the staircase testing are 340 and 419 MPa stress amplitudes for the 38MnSiV5 and 16MnCr5 steels, respectively. The S-N curves of the steels appear to be quite flat in the tested life range 107 – 109.

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Jiang, Jianbo, Chenyang Huang, Huiyong Ban, and Letian Hai. "High-Cycle Fatigue Properties of Titanium-Clad Bimetallic Steel with Different Interfacial Conditions." Buildings 13, no. 3 (March 14, 2023): 758. http://dx.doi.org/10.3390/buildings13030758.

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Titanium-clad (TC) bimetallic steel is an advanced composite steel consisting of metallurgically bonded titanium alloy and structural steel. This paper compared the high-cycle fatigue properties of three types of TC bimetallic steels, including two hot-rolled bonding types with different bonding strengths and an explosion-bonded type. The three types of TC bimetallic steels were all manufactured from TA2 titanium alloy as the cladding metal and Q355B structural steel as the substrate metal, of which the thicknesses are 2 mm and 8 mm, respectively. Based on the comparison results, the qualitative relationship between the bonding interface strength and the manufacturing methods with the basic mechanical and high-cycle fatigue properties was obtained. It was found that the different manufacturing methods and the bonding degree of the two component metals resulted in the different nonlinear yield plateau in the TC bimetallic steel. The high bonding strength seems to affect the failure mode of the tensile coupons. The bonding interface shear strength only slightly affects the tensile performance, which exhibits visible effects only when the test strain reaches the fractured state. In addition, three failure modes in total were found in the high-cycle fatigue tests for the three types of TC bimetallic steel. The manufacturing methods and the bonding interface strength significantly affect the fatigue phenomena of the TC bimetallic steel. The hot-rolled bonding TC bimetallic steel with high bonding strength has a 10% improvement in fatigue performance than the one with low bonding strength. Despite this, the manufacturing methods significantly affect the fatigue ratio, while the influence of the bonding strength on the high cycle fatigue performance is limited. The research outcomes can provide reference for the selection of different manufacturing methods and interfacial conditions for the use of TC bimetallic steel in structural engineering.

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Xing, Zhiguo, Zhiyuan Wang, Haidou Wang, and Debin Shan. "Bending Fatigue Behaviors Analysis and Fatigue Life Prediction of 20Cr2Ni4 Gear Steel with Different Stress Concentrations near Non-metallic Inclusions." Materials 12, no. 20 (October 21, 2019): 3443. http://dx.doi.org/10.3390/ma12203443.

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To investigate the relationship between inclusions and bending fatigue behaviors in 20Cr2Ni4 steel under different stress concentrations. This paper designs a new experimental method to prefabricate different size stress concentrations near the inclusions, and then conducts a new type of bending fatigue test to study the inclusions and their surrounding stress distributions in 20Cr2Ni4 steel. A microhardness tester was combined with laser etching equipment to realize the prefabrication of different stress concentrations at arbitrary positions around any inclusion on the gear steel surface. This method provides an experimental basis for the quantitative analysis of the relationship between stress distribution and fatigue life around the inclusions of heavy-duty gear steels. We also predict the bending fatigue lives of heavy-duty gear steels with different types of inclusions, stress states, and spatial distributions. Then, based on the prefabricated notch parameters and the state of inclusions in the steel, a mathematical model of quantitative analysis is proposed, which can accurately predict the fatigue limit of heavy-duty gear steel. The research results can be applied to the actual use of heavy-duty gears and to the accurate life estimation based on the state of gear stress, thereby providing a quantitative reference model for subsequent gear steel production and gear part processing.

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Hu, Fang Zhong, Wei Jun Hui, and Qi Long Yong. "High-Cycle Fatigue Fracture Behavior of Microalloyed Bainitic Steels for Hot Forging." Advanced Materials Research 634-638 (January 2013): 1746–51. http://dx.doi.org/10.4028/www.scientific.net/amr.634-638.1746.

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High-cycle fatigue fracture behavior of microalloyed bainitic steels with three different carbon and vanadium contents were studied using rotating-bending fatigue test and compared with the ferrite-pearlite type microalloyed steel F38MnVS. The results indicated that the fatigue properties of the microaIloyed bainitic steels had a significant relation to the microstructures in forging condition. Compared with the ferrite-pearlite type microalloyed steel F38MnVS, the bainitic steels possessed higher fatigue strength and lower fatigue limit ratio σ-1/Rm. It was found that the bainitic transformation temperature was decreased and the hardness of the bainitic ferrite was enhanced, at the same time, the fatigue strength was increased, however, the fatigue limit ratio was lower. Furthermore, according to the SEM images of the fracture surface of fatigue specimens, it was revealed that the fatigue cracks mainly initiated along the bainitic ferrite laths in the specimen surface and preferred to propagate along the length direction of laths.

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OUNPANICH, Duangporn, Yukio MIYASHITA, Yoshiharu MUTOH, and Kenji YOSHII. "113 Fatigue Strength of Fabricated Structure Steel." Proceedings of the Materials and processing conference 2006.14 (2006): 37–38. http://dx.doi.org/10.1299/jsmemp.2006.14.37.

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Uusitalo, J., L. Pentti Karjalainen, Delphine Retraint, and M. Palosaari. "Fatigue Properties of Steels with Ultrasonic Attrition Treated Surface Layers." Materials Science Forum 604-605 (October 2008): 239–48. http://dx.doi.org/10.4028/www.scientific.net/msf.604-605.239.

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Severely deformed surface layers have been created by ultrasonic attrition technique on four steel sheets to investigate their influence on fatigue behaviour. A low-carbon (0.05%) ferritic steel and a medium-carbon (0.47%) normalized ferritic-pearlitic steel were selected to study the effect of carbon content on fatigue properties of carbon steels. Two stainless steels, Type 316L and Type 301LN, were also tested to study the influence of stability of the austenitic structure. Microstructural features were characterized by hardness measurements, X-ray diffraction and optical and electron microscopy. Fatigue properties were determined in flexural bending in the range 104 to 107 cycles. Crack nucleation and propagation stages were followed. In the attrition treatment thin severely deformed surface layers were found to form. Highly increased hardness was measured in these layers, especially for stainless steels, where also strain-induced martensite was formed. Drastic improvement in fatigue resistance was observed for all steels due to the surface nanocrystallization treatment.

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Han, Wen Qin, and Jin Yu Zhou. "The Study on the Fatigue Test and Reliability for the Steel of Train Wheel." Applied Mechanics and Materials 198-199 (September 2012): 146–49. http://dx.doi.org/10.4028/www.scientific.net/amm.198-199.146.

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To obtain fatigue design data of the train wheel steel , the fatigue tests were carried out for the steel of K type and B type train wheel separately, which fatigue limit was measured using the fluctuation method, the fatigue life of two kinds of wheel steels were tested using the grouping method at the three stress levels, two different materials and different structures have an influence on the fatigue properties of the wheels using reliability principle. The fatigue life distribution of the B type is scattered relatively . S-N curve equation and P-S-N curve equation of the two kinds of steel were calculated . The theoretical basis were put up for developing design standards and safety evaluation of the both wheel.

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Lee, Geun An, Seo Gou Choi, Dong Jin Yoon, Hee Woong Lee, and Kyoung Hoan Na. "Forming Technology for Cold Forging Processes of Ball Stud Using Non-Heat-Treated Cold Forging Materials." Materials Science Forum 475-479 (January 2005): 3247–50. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.3247.

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A microalloyed (MA) forging steel is non-heat-treated materials that have been replacing for conventional quenched and tempered (Q/T) structural steels since the MA forging steels are very cost-effective compared with Q/T steels for the production of automotive parts. However, due to a high strength and low elongation, it has been difficult to apply the MA cold forging steel to the ball stud for automobile. In this study, finite element analyses were carried out to investigate the forming loads, the stress and strain distributions of the workpiece in the cold forging processes of the ball stud using the MA cold forging steel. Compression test at room temperature and fatigue test were also performed to obtain the flow stress and fatigue life, respectively. From these results, it was found that the fatigue life was greatly affected by the strength in the neck region of the ball stud and the cold forging processes should be designed to improve the fatigue life of the ball stud used the MA cold forging steel.

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Kim, Kuk Cheol, Byung Hoon Kim, Jin Ik Suk, Dong Soo Kim, and Jeong Tae Kim. "The Effect of Alloy Elements on Cyclic Fatigue Behavior of Bucket Candidate Materials for USC Power Plants." Advanced Materials Research 26-28 (October 2007): 1141–44. http://dx.doi.org/10.4028/www.scientific.net/amr.26-28.1141.

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The demand for ultra supercritical (USC) power plants has increased due to the need for high thermal efficiency and reduced CO2 emissions. For turbine materials, high-cycle and lowcycle fatigue life at USC service temperatures are needed to verify material integrity due to the heat-up and cool-down process of power plant operation and due to turbine variations during operation. In this paper, fatigue characteristics for 9~12 Cr steels as candidate USC bucket materials were investigated. First, the fatigue life between DS2B2 and COST B2 steel were compared. COST B2 is the commercial steel with improved high temperature properties by adding boron, and DS2B2 is the new steel developed by Doosan by adding Co and adjusting Mo and W based on the same Mo equivalent value (%wt. Mo + 1/2 %wt. W). DS2B2 steel was found to have longer low cycle fatigue life than COST B2. Second, the effect of boron on fatigue life for bucket materials based on COST B2 steel was investigated. At room temperature, as boron content increased, low cycle fatigue life became superior, whereas, at 593oC the fatigue life was similar. For high cycle fatigue, as boron content increased, fatigue life increased due to the strengthening effect by the addition of boron.

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Zhang, Xiao Peng, Cheng Cheng Zhang, and Huai Nian Xing. "Test Study on Fatigue Property for Forging and Casting Steels of Grade E." Advanced Materials Research 712-715 (June 2013): 82–86. http://dx.doi.org/10.4028/www.scientific.net/amr.712-715.82.

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The forging steel of grade E and casting steel of grade E are usually applied to making train coupler. The fatigue property tests have been carried out for the forging steel of grade E and the casting steel of grade E by using the up and down method and grouping method in the paper. The two kinds of steels fatigue limits have been obtained with the up and down method. With the grouping method, the P-S-N curve equations of high-cycle fatigue have been obtained. The confidence level is 90% and the probabilities of failure are 10%, 20%, 30% and 40%. The test results show that the fatigue property of the forging material are superior to the casting apparently . To some extent, the test results are valuable for fatigue reliability designating of train coupler.

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Luo, Ze Fu, Shi Ming Cui, Yan Zeng Wu, and Qing Yuan Wang. "Super Long Life Fatigue Properties of Rail Steel U71Mn and U75V." Advanced Materials Research 690-693 (May 2013): 1753–56. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.1753.

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Railway track steel, U71Mn and U75V were fatigued in this study, with the help of ultrasonic fatigue test system, to investigate the high cycle fatigue life behaviors. The results showed that the fatigue damage still occurs when the fatigue life exceeds 107, and the evolution of S-N curve showed a ladder type. This test showed that the traditional view of fatigue design and life prediction method were unable to meet the requirements of machinery and equipment working in gigacycle fatigue range, very high cycle fatigue behavior of fatigue has become a major challenge for researchers. The scanning electron microscope analysis of crack initiation was performed to clarify the mechanism of very high cycle fatigue failure.

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Petan, Luca, Janez Grum, Juan Antonio Porro, José Luis Ocaña, and Roman Šturm. "Fatigue Properties of Maraging Steel after Laser Peening." Metals 9, no. 12 (November 28, 2019): 1271. http://dx.doi.org/10.3390/met9121271.

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Maraging steels are precipitation hardening steels used for highly loaded components in aeronautical and tooling industry. They are subjected to thermomechanical loads and wear, which significantly shorten their service life. Improvements of their surface mechanical properties to overcome such phenomena are of great interest. The purpose of our research was to investigate the influence of pulse density and spot size of a laser shock peening (LSP) process on the surface integrity with the fatigue resistance of X2NiCoMo18-9-5 maraging steel. Surface integrity was analyzed through roughness, residual stress, and microhardness measurements. The tests performed on resonant testing machine confirmed LSP is a promising process for increasing fatigue resistance of a component. Fatigue crack occurs, when the resonance frequency decreases. This moment, when the fatigue crack initiation phase ends and the fatigue crack propagation phase starts, was chosen as the moment of failure. We have proved LSP is a successful method in improving fatigue resistance of maraging steel by appropriate combination of laser spot size and pulse density tested in our research.

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34

Seitl, Stanislav, Pavel Pokorný, Petr Miarka, Jan Klusák, Zdeněk Kala, and Ludvík Kunz. "Comparison of fatigue crack propagation behaviour in two steel grades S235, S355 and a steel from old crane way." MATEC Web of Conferences 310 (2020): 00034. http://dx.doi.org/10.1051/matecconf/202031000034.

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Utilization of various steel grades in civil engineering allows designing bridges, bridge elements or simple structures according to their fracture mechanical properties. The service intervals of structures, which are going to be in use for a long time, cannot be calculated only on the basis of tensile and brittle fracture properties but also on the knowledge of the resistance to the fatigue crack growth. This contribution presents a comparison of the fatigue behaviour of two modern steel grades S235 J2, S355 J2 and a steel extracted from an old crane way. The comparison of these steel grades is done by fatigue crack propagation tests (the results of the experimental tests are described using concept of the stress intensity factor range ΔK). The fatigue properties are discussed and recommendations for the use of the steels are stated.

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35

Huang, Zhi Yong, Nicolas Ranc, and Danièle Wagner. "Dislocations Gliding Study by IR Thermography in C-Mn Steels with Different Solute Atoms Content in the Gigacycle Fatigue Domain." Key Engineering Materials 664 (September 2015): 177–87. http://dx.doi.org/10.4028/www.scientific.net/kem.664.177.

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Tests were performed on two Carbon-Manganese steels (A42 and A48 steels, French standard) in the gigacycle fatigue domain thanks to a piezoelectric fatigue machine working at 20000Hz. During the tests, temperature recordings were achieved by an infrared camera for various stress amplitudes. The main difference between the two steels compositions was the aluminum content (0.045% for the A42 steel and 0.004% for the A48 steel), and the carbon content (0.140% for the A 42 steel and 0.198% for the A48 steel). In the A48 steel, the few aluminum content induces a higher free content of solute nitrogen in the lattice. Mechanical spectroscopy tests were performed and gave qualitative results on the solute contents repartition in the lattice. The temperature increase recorded during the fatigue tests for the two steels are different at the beginning of the tests. The differences can be explained by the different repartition of the solute atoms which induces a different dislocation gliding between the two materials. At the end of the tests, the thermal recordings are similar and attributed to the evolution of the solute atoms repartition and the dislocation structure.

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36

Jayaprakash, Murugesan, and Yoshiharu Mutoh. "Fretting Fatigue Behaviour of 12-Cr Steels and Strength Prediction." Materials Science Forum 783-786 (May 2014): 920–25. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.920.

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In the present study fretting fatigue behaviour of 12-Cr steels at 300°C has been investigated under three different contact pressures. For comparisons fretting fatigue behaviour of 12-Cr steels at room temperature has also been investigated. The result showed that with an increase in contact pressure and temperature, the fretting fatigue significantly reduces. Finite element analyses were carried out to evaluate the stress distribution (tangential stress and compressive stress) at the contact during fretting fatigue. Tangential stress range – compressive stress range diagram (TSR-CSR diagram) were constructed for 12-Cr steel at room temperature and at 300°C. Then, a generalized TSR-CSR diagram to predict fretting fatigue strength of 12-Cr steel regardless of contact pressure and temperature was constructed.

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37

Hutař, Pavel, Ivo Kuběna, Miroslav Šmíd, Martin Ševčík, Tomáš Kruml, and Luboš Náhlík. "Description of Small Fatigue Crack Propagation in ODS Steel." Advanced Materials Research 891-892 (March 2014): 911–16. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.911.

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The oxide dispersion strengthened (ODS) steels are widely studied as possible candidate material for fission and fusion technology. Due to application of the ODS materials, mainly low cycle fatigue is important. Therefore, small crack initiation and propagation for rather high stress amplitude are in focus. The main aim of the presented work is description of the small fatigue crack propagation for ODS-EUROFER steel. Due to limited quantity of ODS steel special miniaturized cylindrical specimens for fatigue testing were designed. Crack propagation law based on plastic part of J-integral is presented and applied for mentioned material. The resulting fatigue crack propagation rates for ODS-EUROFER steel and EUROFER 97 are compared and discussed.

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38

Myl’nikov, V. V., D. I. Shetulov, O. B. Kondrashkin, E. A. Chernyshov, and A. I. Pronin. "CHANGES IN FATIGUE RESISTANCE OF STRUCTURAL STEELS AT DIFFERENT LOADING SPECTRA." Izvestiya. Ferrous Metallurgy 62, no. 10 (November 3, 2019): 796–802. http://dx.doi.org/10.17073/0368-0797-2019-10-796-802.

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Fatigue strength of widely used engineering structural steels was studied at various frequencies of loading according to the scheme of cantilever bending of the rotating cylindrical samples. Fatigue resistance index is tangent of angle of inclination of fatigue curve to axis of longevity. It is established that 40 and 45 steels belong to the group of materials in which decrease in frequency of loading leads to cyclic softening and decrease in fatigue resistance, which is numerically expressed by increasing slope of fatigue curve. Tests of the samples made of 40X steel had shown that increase in frequency of loading cycles leads to a noticeable decrease in slope of fatigue curve parameter, i.e. to an increase in fatigue resistance. Decrease in fatigue resistance parameter is associated with an increase in hardening of material of the samples (parts) surface layers which reduces fatigue damage to the surface itself. Dependence of the fatigue curve slope tangent on surface damage at changing loading cycles frequency is shown and it is stated that, regardless of frequency, damage of material surface layers increases along the slope of fatigue curve. For each of these groups mathematical relations are defined. The correlation coefficient providing degree of convergence of experimental results with the constructed fatigue curve was adopted as a criterion of cyclic behavior stability of steels. It is revealed that increase in behavior stability of 40X steel is observed with increase in cyclic deformation rate. Tests of 45 steel have shown that decrease in cyclic strength with increase in loading frequency does not affect fatigue stability of material. Increased dispersion of experimental results was observed in 40 steel at low loading frequency, despite the high values of cyclic strength at given loading frequency. On the basis of conducted experiments, dynamics of behavior of real machine parts and structures subjected to cyclic loads operating was determined in the studied loading spectrum.

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39

Janssen, M. H. E., M. J. M. Hermans, M. Janssen, and I. M. Richardson. "Fatigue Performance of Laser Brazes in Advanced High Strength Steels." Materials Science Forum 638-642 (January 2010): 3254–59. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.3254.

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Advance high strength steels (AHSS), like dual phase (DP) and transformation induced plasticity (TRIP) steels, offer high strength and toughness combined with excellent uniform elongation. However, the higher alloying content of these steels limit their weldability and the thermal cycle of welding processes destroys the carefully designed microstructure. This will result in inferior mechanical properties of the joint. Therefore, joining processes with a low heat input, like brazing, are recommendable. Data regarding mechanical properties of joints in DP and TRIP steel is limited, especially for brazed joints. Results with respect to the fatigue lifetime of laser brazed butt joints are presented. In DP and TRIP steel, crack initiation takes place at the braze toe. In DP steel the crack propagates through the base metal. In TRIP steel, however, the crack may either follow the interface or may continue through the steel depending on the maximum stress level. The different failure mechanisms are explained on the basis of process conditions, the microstructure and the stress state.

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40

Wada, Kentaro, Soma Yoshimura, Tomoko Yamamoto, Yoshihiro Ohkomori, and Hisao Matsunaga. "Shear-mode Crack Initiation Behavior in the Martensitic and Bainitic Microstructures." MATEC Web of Conferences 165 (2018): 04009. http://dx.doi.org/10.1051/matecconf/201816504009.

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Fully reversed torsional fatigue tests were conducted to elucidate the behaviour of shear-mode crack initiation and propagation in one martensitic and two bainitic steels. The relationship between the crack initiation site and microstructure was investigated by means of an electron backscatter diffraction (EBSD) technique. From the S-N diagram, two notable results were obtained: (i) the shear-mode crack was initiated on the prior austenitic grain boundary in martensitic steel, while in bainitic steels, the crack was initiated along the {110} plane; one of the slip planes of bcc metals, and (ii) the torsional fatigue limit of lower bainitic steel with finer grains was 60 MPa higher than that of upper bainitic steel with coarser grains even though the hardnesses were nearly equivalent. The mechanism determining the torsional fatigue strength in these steels is discussed from the viewpoint of microstructure morphology.

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41

Bogdanovich, Alexander, Oleg Yelovoy, Leonid Sosnovskiy, Victor Komissarov, and Sergey Tyurin. "Local Damages During Rolling And Mechano-Rolling Fatigue For The Mechanical System Shaft – Roller (0.45 Carbon Steel – 25XGT Steel, 20XH3A Steel – 20XH3A Steel)." Acta Mechanica et Automatica 9, no. 4 (December 1, 2015): 259–64. http://dx.doi.org/10.1515/ama-2015-0041.

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Abstract The report provides a description of local damages which are formed in the process of wear-fatigue tests. The analysis of local surface wave-like damages during rolling and mechano-rolling fatigue for the shaft-roller mechanical system under steady-state and multi-stage loading conditions is given. It is shown that the study of local wear-fatigue damage was made possible by new methods of testing and measuring wear-fatigue tests and damages, which are described in the report. New characteristics to estimate the parameters of the local wear-fatigue damage are proposed. The concept of local fatigue curves is introduced. The laws of local wear-fatigue damage for the shaft - roller system are analysed.

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42

Gu, Chao, Min Wang, Yanping Bao, Fuming Wang, and Junhe Lian. "Quantitative Analysis of Inclusion Engineering on the Fatigue Property Improvement of Bearing Steel." Metals 9, no. 4 (April 24, 2019): 476. http://dx.doi.org/10.3390/met9040476.

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The fatigue property is significantly affected by the inner inclusions in steel. Due to the inhomogeneity of inclusion distribution in the micro-scale, it is not straightforward to quantify the effect of inclusions on fatigue behavior. Various investigations have been performed to correlate the inclusion characteristics, such as inclusion fraction, size, and composition, with fatigue life. However, these studies are generally based on vast types of steels and even for a similar steel grade, the alloy concept and microstructure information can still be of non-negligible difference. For a quantitative analysis of the fatigue life improvement with respect to the inclusion engineering, a systematic and carefully designed study is still needed to explore the engineering dimensions of inclusions. Therefore, in this study, three types of bearing steels with inclusions of the same types, but different sizes and amounts, were produced with 50 kg hot state experiments. The following forging and heat treatment procedures were kept consistent to ensure that the only controlled variable is inclusion. The fatigue properties were compared and the inclusions that triggered the fatigue cracks were analyzed to deduce the critical sizes of inclusions in terms of fatigue failure. The results show that the critical sizes of different inclusion types vary in bearing steels. The critical size of the spinel is 8.5 μm and the critical size of the calcium aluminate is 13.5 μm under the fatigue stress of 1200 MPa. In addition, with the increase of the cleanliness of bearing steels, the improvement of fatigue properties will reach saturation. Under this condition, further increasing of the cleanliness of the bearing steel will not contribute to the improvement of fatigue property for the investigated alloy and process design.

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43

Ounpanich, Duangporn, Yoshiharu Mutoh, and Kenji Yoshii. "E-10 Effect of Fabricating Process on Fatigue Behavior of HSLA Steel(Session: Fatique/SCG)." Proceedings of the Asian Symposium on Materials and Processing 2006 (2006): 102. http://dx.doi.org/10.1299/jsmeasmp.2006.102.

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44

Hietala, Mikko, Markku Keskitalo, and Antti Järvenpää. "The Comparison between Mechanical Properties of Laser-Welded Ultra-High-Strength Austenitic and Martensitic Steels." Key Engineering Materials 841 (May 2020): 132–37. http://dx.doi.org/10.4028/www.scientific.net/kem.841.132.

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The paper investigates experimentally the usability of ultra-high-strength stainless steel and abrasion resistant steel in laser-welded sandwich structures. The fatigue and shear strength of laser joints were investigated using lap joints that were welded using two very different energy inputs. Also the effect of multiple weld tracks was investigated. The properties of separate laser welds were characterized by hardness testing and optical microscopy. Results of the hardness measurements showed that there was softened area at heat-affected-zone and weld metal of the ultra-high-strength stainless steel welds. AR steels weld metal was harder than base metal and there was softened zone in heat-affected-zone of the weld. The shear strength of tested single weld joints of the ultra-high-strength stainless steel was higher compared abrasion resistant steel single weld joints, but stronger joint can be made with multiple weld seams for abrasion resistant steel. Fatigue strength of investigated ultra-high-strength stainless steel lap joint was lower than fatigue strength of abrasion resistant steel lap joint in the low-cycle regime, but there was no practical difference in fatigue limit (10e7 cycles).

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Tang, C. Q., Z. C. Xia, X. Z. Li, and B. T. Yao. "Positron Lifetimes and Microhardness in Thermal Fatigued 4Cr5MoSiV Steel." Australian Journal of Physics 53, no. 6 (2000): 829. http://dx.doi.org/10.1071/ph00041.

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Positron lifetimes and microhardness have been measured as a function of the thermal fatigue cycle number N in 4Cr5MoSiV steel. It is found that with increasing N: (a) the positron lifetime parameters τ1, τ2, I1, I2 and ôτ and the microhardness parameter MH all exhibit quasi-periodic up-and-down variation; (b) these parameters have the same period of variation; and (c) the period of up-and-down variation becomes gradually longer. The variation of MH reveals that fatigue hardening and fatigue softening occur alternately in the process of thermal fatigue. The variations of positron lifetime parameters reveal variations of defects in the fatigued materials. These variations are attributed to microdeformation and dynamic recovery dominating alternately in the process of thermal fatigue.

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46

Miyazono, M., Norio Kawagoishi, Qing Yuan Wang, Eiji Kondo, and Takanori Nagano. "Effects of Microstructure and Humidity on Fatigue Strength of Maraging Steel." Key Engineering Materials 385-387 (July 2008): 113–16. http://dx.doi.org/10.4028/www.scientific.net/kem.385-387.113.

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Rotating bending fatigue tests were carried out for maraging steels with different grain size in moist air in order to investigate the effects of humidity, grain size and reversion austenite on fatigue strength of the steel. Fatigue strength was decreased by humidity, and the decrease in fatigue strength was large in larger grain sized steel. Both of the initiation and propagation of a crack were promoted by humidity. Many cracks initiated at the specimen surface and intergranular cracks were observed at specimen surface and on fracture surface when humidity was high. The decrease in fatigue strength by humidity was suppressed by formation of reversion austenite.

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47

Pejkowski, Łukasz, Dariusz Skibicki, and Jan Seyda. "Fatigue behaviour of selected materials under multiaxial asynchronous loadings." MATEC Web of Conferences 300 (2019): 15006. http://dx.doi.org/10.1051/matecconf/201930015006.

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Four types of materials: PA38 aluminium alloy, E235 steel, E355 steel and 1.4301 austenitic steel were subjected to low-cycle multiaxial loadings. All tests were strain-controlled and typical, thin-walled, hollow specimens were used. Various synchronous and asynchronous loadings were applied. The analysis of experimental results involved: cyclic stress-strain response, fatigue life and observation of microcracks behaviour on the surfaces of fatigued specimens. Obtained results indicate that the difference in the strain components frequency of the asynchronous loadings has a significant influence on the fatigue behaviour of the materials.

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Hu, Yang. "Effect of Boron on Mechanical Properties and Fatigue Life of Spring Steel for Automobile Suspension." Journal of Physics: Conference Series 2437, no. 1 (January 1, 2023): 012064. http://dx.doi.org/10.1088/1742-6596/2437/1/012064.

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Abstract Three Si-killed 55SiCrA suspension spring steels with different boron contents (0, 23 ppm and 43 ppm) were obtained by vacuum induction levitation melting furnace. Through hot tensile, torsional Bauschinger and rotating bending fatigue tests, the microstructure, precipitate, tensile strength, percentage of area reduction, elastic sag resistance and fatigue life of spring steel were analyzed, respectively. Boron accelerated the dynamic recrystallization at 800 ºC and prevented the formation of reticular proeutectoid ferrite and coarse pearlite in steel, then made the tempered troostite of heat-treated spring steel become fine and uniform. However, much BN and boron carbide formed along prior austenite grain boundaries in spring steel containing 43 ppm boron and was retained after quenching and tempering, leading to the decrease of ductility and fatigue life of spring steel. Therefore, 23 ppm boron was the best content for increasing hot ductility and ductility at room temperature of spring steel, and improved its tensile strength and elastic sag resistance, finally, the fatigue life increased from 5.3 × 107 cycles to 8.2 × 107 cycles.

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49

Juhas, Pavol. "The Effects of Notches on the Fatigue Strength of Steel Structures." MATEC Web of Conferences 279 (2019): 02001. http://dx.doi.org/10.1051/matecconf/201927902001.

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The paper informs about the research devoted to load–carrying capacity, fatigue strength and life–time of welded steel structures. The experimental programme comprises fatigue tests of constructional steel S380 (QStE 380 TM). In the first stage 35 specimens were tested: 9 without any weld connection, 14 with transverse milled butt weld and 12 with transverse rough butt weld. The applied loading in this stage was harmonic with constant stress range. All tests ended by fatigue failure. The second part of the research comprised the tests with block simulated loading with variable stress range. The third part applied continuous recording of stresses and strains in critical sections, that gave information about the local failure development in time. Data sets have allowed to define fatigue properties of investigated steel and degradation effects of used welds including the initiation time of remarkable changes in stress-strain stage expressed through the total kinetic energy. The degradation effects of welds on fatigue strength of structural steels were confirmed, especially it was the case of rough welds - without additional milling. Additionally, the differences in the fatigue curves inclinations were indicated that can depend on the level of fatigue strength. The applied approach gives an opportunity to analyse the effects of actual loading process and improve the methodology of judgement of fatigue strength and life-time of steel elements. Reasonable fatigue properties of this steel suggest it for using also in severe technology structures.

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Popovych, P., L. Poberezhny, O. Shevchuk, I. Murovanyi, L. Poberezhna, A. Hrytsanchuk, and Y. Koval. "Corrosion-fatigue failure of tractor trailers metal materials in aggressive environments." Koroze a ochrana materialu 64, no. 2 (June 1, 2020): 45–51. http://dx.doi.org/10.2478/kom-2020-0007.

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AbstractThe processes of corrosion-fatigue failure of materials in contact with mineral fertilizers are insufficiently studied. As a result of joint influence of atmospheric corrosion and mechanical loads, about 70 to 80 % of machine parts get out of order, 20 to 25 % of which are failures caused by operating overload due to the strength loss because of atmospheric corrosion. A large part of metal structures of agricultural vehicles used to transport mineral fertilizers is under the direct influence of aggressive environments and dynamic loads that occur during the motion by field roads. Saturated solutions of the most aggressive working environments used in agricultural production, in particular ammonium sulphate and nitrophosphate are investigated to reduce fatigue resistance of ordinary steels groups – St3 and St5 and quality steels – 10 Steel, 15 Steel, 20 Steel, 25 Steel when loaded at all levels. The fatigue endurance limit decreases in comparison with air up to 2.02 times in a solution of ammonium sulphate, and to 2.32 times in a solution of nitrophosphate. In organic fertilizer environments, compared to distilled water, the conditional fatigue endurance limit increased to 9 %. The properties of the given materials as an inhibitor of corrosion-fatigue failure were discovered and proved.

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Journal articles on the topic 'Steel – Fatigue'

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