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1
Wang, Yan, Qing Xiao Li, Shuo Ming Wang e Peng Long Han. "Study of Inclusion’s Source and Character in Different T[O] Content". Advanced Materials Research 887-888 (febbraio 2014): 187–90. http://dx.doi.org/10.4028/www.scientific.net/amr.887-888.187.
Testo completoAbstract (sommario):
Inclusion’s source and character in different T[ content are studied in the paper, molten slag and refractory material that leave in steel are also calculated. Inclusion in steel are principally come from deoxidation, accompany with the decrease of T[ content, influence of molten slag and refractory materials to inclusions are getting more and more serials. Inclusions which come from molten slag and refractory material are 88.9%, 24.6% and 18.1% defenetly. Great influence on non steady large inclusions in T[ steel, when the mold level fluctuation is large, almost 100% of inclusions in steel have slag inclusion of covering slag. When tundish liquid level fluctuation is large, about 30%~60% inclusions in steel have tundish slag.
2
Wang, Yuhang, Xian Zhang, Wenzhui Wei, Xiangliang Wan, Jing Liu e Kaiming Wu. "Effects of Ti and Cu Addition on Inclusion Modification and Corrosion Behavior in Simulated Coarse-Grained Heat-Affected Zone of Low-Alloy Steels". Materials 14, n. 4 (7 febbraio 2021): 791. http://dx.doi.org/10.3390/ma14040791.
Testo completoAbstract (sommario):
In this paper, the effects of Ti and Cu addition on inclusion modification and corrosion behavior in the simulated coarse-grained heat-affected zone (CGHAZ) of low-alloy steels were investigated by using in-situ scanning vibration electrode technique (SVET), scanning electron microscope/energy-dispersive X-ray spectroscopy (SEM/EDS), and electrochemical workstation. The results demonstrated that the complex inclusions formed in Cu-bearing steel were (Ti, Al, Mn)-Ox-MnS, which was similar to that in base steel. Hence, localized corrosion was initiated by the dissolution of MnS. However, the main inclusions in Ti-bearing steels were modified into TiN-Al2O3/TiN, and the localized corrosion was initiated by the dissolution of high deformation region at inclusion/matrix interface. With increased interface density of inclusions in steels, the corrosion rate increased in the following order: Base steel ≈ Cu-bearing steel < Ti-bearing steel. Owing to the existence of Cu-enriched rust layer, the Cu-bearing steel shows a similar corrosion resistance with base steel.
3
Wang, Linzhu, Zuobing Xi e Changrong Li. "Modification of Type B Inclusions by Calcium Treatment in High-Carbon Hard-Wire Steel". Metals 11, n. 5 (21 aprile 2021): 676. http://dx.doi.org/10.3390/met11050676.
Testo completoAbstract (sommario):
To investigate the modification of type B inclusions in high-carbon hard-wire steel with Ca treatment, Si-Ca alloy was added to high-carbon hard-steel, and the composition, morphology, size, quantity, and distribution of inclusions were observed. The samples were investigated by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The experimental thermal results showed that the modification effect of inclusion was better in high-carbon hard-wire steel with Al of 0.0053% and Ca of 0.0029% than that in steel with Al of 0.011% and Ca of 0.0052%, in which the inclusions were mainly spherical semi-liquid and liquid CA2, CA, and C12A7. The inclusion size decreased from 3.2 μm to 2.1 μm. The degree of inclusions segregation was reduced in high-carbon hard-wire steels after calcium treatment. The results indicate that the modification of inclusions is conducive to obtaining dispersed inclusions with fine size. The ratio of length to width decreased and tended to be 1 with the increase in CaO content in the inclusion. When the content of CaO was higher than 30%, the aspect ratio was in the range of 1 to 1.2. The relationship between the activity of aluminum and calcium and the inclusions type at equilibrium in high-carbon hard-wire steel was estimated using classical thermodynamics. The calculated results were consistent with the experimental results. The thermodynamic software Factsage was used to analyze the effect of aluminum and calcium additions on the type and quality of inclusions in high-carbon hard-wire steels. The modification law and mechanism of type B inclusions in high-carbon hard-wire steels are discussed.
4
Wang, Wanlin, Liwen Xue, Tongsheng Zhang, Lejun Zhou, Daoyuan Huang, Weiguang Tian e Jialin Xu. "Thermodynamics and transient behavior of the inclusion in Si deoxidized stainless steel for high-grade plate". Metallurgical Research & Technology 116, n. 6 (2019): 612. http://dx.doi.org/10.1051/metal/2019042.
Testo completoAbstract (sommario):
The experiments were carried out to determine the transient behavior of the inclusion in Si-deoxidized stainless steel for high-grade plate. The samples were taken from three heats of the steel during the whole production process from the AOD to the mold, which were subsequently examined by an automatic scanning electron microscope with field energy dispersive spectrometer (FE-SEM&EDS). It can be summarized that appropriate calcium treatment intensity could modify inclusions into liquid ones. Excessive calcium treatment above ([Ca] = 25 ppm) will increase the melting point of the inclusions, which cannot keep in the liquid region at the solidification temperature. Therefore, the calcium addition in Si-deoxidized stainless steels should be controlled to a relatively lower value ([Ca] = 10 ppm). In addition, the content of aluminum in steel also has an important influence on the control of inclusion. When the content of aluminum ([Al] = 0.012%) is too high, the inclusions in steel are difficult to be controlled within the liquid phase. The chemical evolution of the inclusions in steel at high temperature and during solidification process were comprehensively calculated, considering all types of inclusions such as calcium oxide, aluminum oxide, silicon oxide, calcium aluminate, calcium silicate, mullite, and liquid inclusion. The thermodynamic calculations are in good agreement with experimental results, which can predict the formation of the inclusions in Si-deoxidized stainless steels.
5
Shen, Ping, e Jianxun Fu. "Morphology Study on Inclusion Modifications Using Mg–Ca Treatment in Resulfurized Special Steel". Materials 12, n. 2 (9 gennaio 2019): 197. http://dx.doi.org/10.3390/ma12020197.
Testo completoAbstract (sommario):
In resulfurized special steel, MnS and Al2O3 are two main inclusions that deteriorate fatigue life and machinability. It is important that these two inclusions should be well controlled to increase steel quality and usage performance. In the present study, a Mg–Ca treatment was employed to modify the MnS and Al2O3 inclusions in resulfurized steels to reduce detrimental effects on fatigue life and machinability. In the laboratory study, Ni–Mg alloy was added to 16MnCrS5 and 49MnVS3 steels. Both Al2O3 and CaO–Al2O3 were gradually modified to MgO·Al2O3 and MgO, being surrounded by MnS, that is, a complex inclusion with an oxide core and sulfide outer layer was formed. The amount of the complex inclusion increased with Mg content. In the hot forging experiment, non-Mg treated inclusions were in the morphology of long strip, while those with Mg treatment were seen to be less deformed with spherical morphology of low aspect ratio in which case inclusions had less effect on steel mechanical properties. The Mg–Ca treatment was also applied to the manufacture of resulfurized special steel in steel plants. The scanning electron microscope–energy dispersive spectrometer and statistical results agreed well with those in the laboratory studies.
6
Yu, Huixiang, Muming Li, Jiaming Zhang e Dexin Yang. "Effect of Mn Content on the Reaction between Fe-xMn (x = 5, 10, 15, and 20 Mass pct) Steel and CaO-SiO2-Al2O3-MgO Slag". Metals 11, n. 8 (28 luglio 2021): 1200. http://dx.doi.org/10.3390/met11081200.
Testo completoAbstract (sommario):
Medium- and high-Mn steels have excellent properties but are very difficult to be commercially produced because of the high content of some alloy elements. To enhance the understanding of the reaction between medium/high-Mn steel and refining slag which is significantly different from the conventional steels, steel and slag composition and the inclusions were investigated by equilibrium reaction between Fe-xMn (x = 5, 10, 15, and 20 mass pct) and CaO-SiO2-Al2O3-MgO top slag at 1873 K in the laboratory. Furthermore, the effect of Mn content on inclusion transformation and steel cleanliness was also explored. After slag–steel reaction, both contents of MnO in slag and Si in steel increased. Most MnO inclusions in master steel transformed to MnO-SiO2 and MnO-Al2O3-MgO. With the increase in Mn content, the amount share of MnO type inclusions decreased and that of MnO-Al2O3-MgO type increased. In addition, both the number density of observed inclusions and the calculated oxygen content in inclusions increased. Thermodynamic analysis indicates that the composition change of steel and slag and the transformation of inclusions are mainly the consequence of the reaction between Mn in molten steel and SiO2 and MgO in top slag. The dissolved Mn in medium/high-Mn steel presents a strong reactivity.
7
Zhu, Tengwei, Feng Huang, Jing Liu, Qian Hu e Wei Li. "Effects of inclusion on corrosion resistance of weathering steel in simulated industrial atmosphere". Anti-Corrosion Methods and Materials 63, n. 6 (7 novembre 2016): 490–98. http://dx.doi.org/10.1108/acmm-05-2015-1538.
Testo completoAbstract (sommario):
Purpose This paper aims to investigate the atmospheric corrosion mechanism of structural materials to develop more advanced corrosion-control technologies and cost-reduction strategies. As a second phase in steels, the non-metallic oxide inclusions are considered to not only affect the mechanical properties of steel but also the corrosion resistance of steel. So, an important research goal in this paper is to investigate the indoor accelerated corrosion kinetics of Q450NQR1 weathering steel, analyzing the galvanic polarity of different inclusions in electrochemical corrosion microcell between the inclusion and steel matrix and then elucidating the influence mechanism of inclusions on corrosion resistance of weathering steel. Design/methodology/approach Two methods of inclusion modification are usually used to improve the properties of weathering steel: one is calcium treatment on aluminum killed steel and the other one is rare earth (RE) modification. Wet/dry cyclic immersion corrosion test field emission scanning electron microscopy (FE-SEM) metallographic optical microscope. Findings The indoor accelerated corrosion kinetics of Q450NQR1 weathering steel could be divided into two stages with different log (thickness loss, D)-log (time, t) fitting functions, and the effect of inclusions on the corrosion resistance of Q450NQR1 weathering steel was only reflected in the initial stages of corrosion. The inclusions of CaS in Ca-modified test steel and RE oxides and sulfides in RE-modified test steel were preferentially dissolved in acid media, slowing down the corrosion rate of steel matrix, but the non-metallic inclusion Al2O3 may accelerate the corrosion rate of the steel matrix as a form of differential aeration corrosion. Originality/value The effects of inclusions on corrosion resistance of Q450NQR1 weathering steel was investigated by dry–wet cycle immersion test and FE-SEM. The effect of inclusions on the corrosion resistance of Q450NQR1weathering steel was only reflected in the initial stages of corrosion. The inclusions of CaS in Ca-modified test steel and rare earth (RE) oxides and sulfides in RE-modified test steel were preferentially dissolved in acid media, slowing down the corrosion rate of steel matrix, but the non-metallic inclusion Al2O3 may accelerate corrosion rate of the steel matrix as a form of differential aeration corrosion.
8
Gu, Chao, Min Wang, Yanping Bao, Fuming Wang e Junhe Lian. "Quantitative Analysis of Inclusion Engineering on the Fatigue Property Improvement of Bearing Steel". Metals 9, n. 4 (24 aprile 2019): 476. http://dx.doi.org/10.3390/met9040476.
Testo completoAbstract (sommario):
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.
9
Xing, Zhiguo, Zhiyuan Wang, Haidou Wang e Debin Shan. "Bending Fatigue Behaviors Analysis and Fatigue Life Prediction of 20Cr2Ni4 Gear Steel with Different Stress Concentrations near Non-metallic Inclusions". Materials 12, n. 20 (21 ottobre 2019): 3443. http://dx.doi.org/10.3390/ma12203443.
Testo completoAbstract (sommario):
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.
10
Zhou, Xiao Lei, Zhe Shi e Gui Fang Zhang. "The Evolution of Non-Metallic Inclusions in IF Steel". Applied Mechanics and Materials 696 (novembre 2014): 62–65. http://dx.doi.org/10.4028/www.scientific.net/amm.696.62.
Testo completoAbstract (sommario):
At present, China's IF steel production has get a certain scale. But IF steel production is still in the primary stage of development. Therefore, the process control of inclusions in IF steel have become a pressing matter of the moment. This has important theoretical value and practical significance for further development of IF steel production in China. According to the size, the inclusions can be divided into super micro inclusions, micro inclusions and micro inclusions in the steel. According to the deformation capacity, inclusions can be divided into plastic inclusions, semi plastic inclusion and brittle inclusion.
11
Lan, Fangjie, Changling Zhuang, Changrong Li, Guangkai Yang e Hanjie Yao. "Effect of Calcium Treatment on Inclusions in H08A Welding Rod Steel". Metals 11, n. 8 (31 luglio 2021): 1227. http://dx.doi.org/10.3390/met11081227.
Testo completoAbstract (sommario):
The effect of calcium treatment on inclusions in H08A welding rod steel was studied by industrial experiment and using thermodynamics theory. The effects of inclusion composition, morphology, quantity, and size in H08A welding rod steel before and after calcium treatment were studied by metallographic microscope, scanning electron microscope (SEM), and energy dispersive spectrometer (EDS). Thermodynamic studies show that the addition of calcium can form various forms of xCaO·yAl2O3, under the condition that the composition of molten steel remains unchanged, the control of calcium content is the key to generate low melting point calcium-aluminate complex non-metallic inclusions and improve the quality of molten steel. The production practice in steel plant shows that for welding rod steels, the calcium content in a suitable range can meet the requirements of calcium treatment. Effective calcium treatment can not only transform the high melting point Al2O3 inclusions into the low melting point complex non-metallic inclusions between 3CaO·Al2O3 and 12CaO·7Al2O3, but also make the original shape-diversified inclusions into the spherical calcium-aluminate complex non-metallic inclusions. Meanwhile, the total number of inclusions and large-scale inclusions in welding rod steel are reduced, and the inclusions tend to disperse in the steel, which is very conducive to the improvement of steel quality. The results show that the modification path of magnesium aluminate spinel in steel is as follows: Al2O3 → MgO-Al2O3 → MgO-CaO-Al2O3. In addition, calcium treatment can modify MgO-Al2O3 spinel in steel into liquid MgO-CaO-Al2O3 complex non-metallic inclusions with low melting point.
12
Pan, Xiaoqian, e Jian Yang. "Probable Maximum Sizes of Inclusions Predicted by SEV and PSD for BH Steels of Automobile Exposed Panel with Different Sulfur Contents". Metals 10, n. 5 (14 maggio 2020): 637. http://dx.doi.org/10.3390/met10050637.
Testo completoAbstract (sommario):
This study attempted to estimate the maximum size of inclusions in the ultra-low carbon Bake Hardening (BH) steels of automobile exposed panel. The Probable Maximum Sizes (PMS) of inclusions at the different steelmaking stages for BH steel with different sulfur contents were predicted by two methods of Statistics of Extreme Values (SEV) and Particle Size Distribution (PSD). The S content does not show a relationship with the PMS prediction of inclusions in the molten steel in which Al2O3 is the main inclusion, while the higher content of S leads to a larger PMS value in the slab, due to more number of large-sized Al2O3-MnS inclusions formed during solidification. The PMS value in the slab is greater than that in the molten steel for BH steel. Thus, the PMS of inclusions in the slab cannot be estimated from the molten steel samples. The SEV can be used to predict well the PMS values at different steelmaking stages for BH steels. However, the PSD of exponential function cannot predict well the PMS value in the slab for BH steel when considering all kinds of inclusions due to the large influence of small-sized MnS with high number density on the PSD of exponential function. When only considering Al2O3-MnS inclusions, the PSD of exponential function can make a reasonable PMS prediction in the slab, because the size distribution of Al2O3-MnS with large size can follow the exponential function.
13
Xue, Zhengliang, Yuqing Weng e Zhengbang Li. "Zero Inclusion Steel and its Oxide Inclusions Characteristics". steel research international 76, n. 10 (ottobre 2005): 735–39. http://dx.doi.org/10.1002/srin.200506089.
Testo completo
14
Yu, Huixiang, Dexin Yang, Muming Li e Ni Zhang. "Effect of CaO–SiO2–Al2O3–MgO top slag on solute elements and non-metallic inclusions in Fe-xMn(x = 10, 20 mass pct) steel". Metallurgical Research & Technology 118, n. 3 (2021): 302. http://dx.doi.org/10.1051/metal/2021025.
Testo completoAbstract (sommario):
Medium/high manganese steels have broad application prospects in automotive industry, cryogenic material, etc. because of excellent properties. Precise control on steel composition and improvement of cleanliness are very important for commercial production of these steel grades. In this study, the effect of CaO–SiO2–Al2O3–MgO slag on solute elements and inclusions of Fe-xMn(x = 10, 20 mass pct) steel was studied and discussed. After slag/steel reaction, the concentration of Mn and S in steel reduced, while Si increased. Most MnO type inclusions, which were the main inclusions in master high manganese steel, transformed to MnO–SiO2 type and MnO–Al2O3–MgO type, with MnO–SiO2 sharing the majority. Thermodynamic analysis indicates that the change of solute elements and inclusions was mainly the result of reaction SiO2(s) + 2[Mn] = 2MnO(s) + [Si] between molten steel and top slag as well as slag desulphurization. Increase of oxygen potential of the reaction system would restrain the reaction. Because of the inclusion absorption by top slag, large sized inclusions decreased and steel cleanliness improved greatly after CaO–SiO2–Al2O3–MgO slag was added.
15
Li, Xiang, Xiao Long, Linzhu Wang, Shouhao Tong, Xiutao Wang, Yin Zhang e Yutang Li. "Inclusion Characteristics in 95CrMo Steels with Different Calcium and Sulfur Contents". Materials 13, n. 3 (30 gennaio 2020): 619. http://dx.doi.org/10.3390/ma13030619.
Testo completoAbstract (sommario):
In order to study the effect of Ca and sulfur contents on the characteristics of inclusions, industrial experiments using 95CrMo steel were conducted. SEM-EDS detections and stereological analysis were used to probe the characteristics of inclusions, including their compositions, morphologies, size, number density, and distribution. The results indicate that there were mainly three types of inclusions in 95CrMo steel billets with 6–18 ppm Ca and 30–100 ppm S: inclusions with single-phased morphology mainly composed of oxides; isolated MnS/CaS-only inclusions; inclusions with multi-phased morphology. The three-dimensional inclusion size distribution suggests that there were more Type-1 inclusions with a small size in low S containing steels. The average diameter of all types of inclusions increased with increasing Ca or S content in 95CrMo steel, indicating that the formation of MnS and CaS coarsened their size. The density distribution of inclusions indicates that the more inclusions there are, the more easily they aggregate and collide. Moreover, it is presumably concluded that the formation of sulfide in the outer layer of oxide inclusions weaken the attraction between oxide inclusions. The equilibrated transformation and formation of inclusions during the cooling process of 95CrMo steel was discussed based on thermodynamic calculation. The equilibrated transformation trajectory of inclusions in 95CrMo steel during the cooling process was Ca2SiO4 + MgO → Ca3MgSi2O8 → Spinel + CaS, which was corresponding to the detected results. The precipitation regular of sulfide was obtained. The formation mechanism for three types of inclusions was discussed.
16
Dervis Mujagic, Sc, Sc Aida Imamovic e Sc Mustafa Hadzalic. "NONMETALLIC INCLUSIONS IN AUSTENITIC STAINLESS STEEL AISI 303 MICROALLOYED WITH ZIRCONIUM AND TELLURIUM". International Journal of Advanced Research 9, n. 01 (31 gennaio 2021): 903–10. http://dx.doi.org/10.21474/ijar01/12368.
Testo completoAbstract (sommario):
The control of formation of nonmetallic inclusion and the characterization present the basis of improvement of steel product properties and lead to sustainable development in design of new steel grades. In order to produce steels with better machinability, such as AISI 303 grades, a modification of inclusions with carefully designed chemical composition is presented. Sulphur by creating sulphide inclusions reduces friction and cutting resistance, and increases the brittleness of the chip.Considering its harmful effect in steel, as well as the fact that non-metallic inclusions have been insufficiently tested for this type of high-alloyed steel, the aim of this research is to determine effects of microalloying on the possibility of modification of non-metallic inclusions. Modification with zirconium favorably affects the ductile properties of steel, and a step forward in this study is a modification of inclusions with tellurium.It is of particular importance to determine the behavior of non-metallic inclusions in the process of production of the structural part and in subsequent exploitation. Therefore, plastic processing of austenitic stainless steel was also carried out, forging and rolling with two different level of processing.
17
Al-Gahtani, Masoud, Sunilkumar Pillai e Ahmad Al-Raddadi. "Characterization of Non-Metallic Inclusions in API Steel Grades Using Automated Energy Dispersive X-Ray". Materials Science Forum 916 (marzo 2018): 217–20. http://dx.doi.org/10.4028/www.scientific.net/msf.916.217.
Testo completoAbstract (sommario):
Non-metallic inclusions in API steel grades deteriorate steels’ mechanical properties and their resistance to hydrogen induced cracking. The formation and evolution of inclusion during liquid steel processing was investigated by analyzing samples taken from different stages of the steel making process in API X52 and X60 steel grades. Scanning electron microscope (SEM) with automated feature EDX analyzer (INCAF 250) was used to identify each inclusion in terms of its size, area and composition. It was found that non-metallic inclusions in API X52 and X60 grades from steelmaking and casting samples were mainly Al2O3, Ca–Al and Ca-Mg-Al. In this work changes in inclusion composition, size and area fraction from ladle processing to casting were mapped and this information was used to improve steel cleanness and product quality.
18
Sidorova, Elena, Andrey V. Karasev, Denis Kuznetsov e Pär G. Jönsson. "Modification of Non-Metallic Inclusions in Oil-Pipeline Steels by Ca-Treatment". Metals 9, n. 4 (28 marzo 2019): 391. http://dx.doi.org/10.3390/met9040391.
Testo completoAbstract (sommario):
Corrosion rate in different steel grades (including oilfield pipeline steels) is determined by the presence of non-metallic inclusions (NMI) in steels. Specifically, the effect of different inclusions on the quality of steels depends on their characteristics such as size, number, morphology, composition, and physical properties, as well as their location in the steel matrix. Therefore, the optimization and control of NMI in steels are very important today to obtain an improvement of the material properties of the final steel products. It is well known that a Ca-treatment of liquid steels in ladle before casting is an effective method for modification of non-metallic inclusions for improvement of the steel properties. Therefore, the NMI characteristics were evaluated in industrial steel samples of low carbon Ca-treated steel used for production of oil-pipelines. An electrolytic extraction technique was used for extraction of NMI from the steel samples followed by three-dimensional investigations of different inclusions and clusters by using SEM in combination with EDS. Moreover, the number and compositions of corrosion active non-metallic inclusions were estimated in hot rolled steel samples from two different heats. Finally, the corrosion resistance of these steels can be discussed depending on the characteristics of non-metallic inclusions present in the steel.
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Yu, Zhe, e Chengjun Liu. "Modification Mechanism of Spinel Inclusions in Medium Manganese Steel with Rare Earth Treatment". Metals 9, n. 7 (21 luglio 2019): 804. http://dx.doi.org/10.3390/met9070804.
Testo completoAbstract (sommario):
In aluminum deoxidized medium manganese steel, spinel inclusions are easily to form during refining, and such inclusions will deteriorate the toughness of the medium manganese steel. Rare earth inclusions have a smaller hardness, and their thermal expansion coefficients are similar to that of steel. They can avoid large stress concentrations around inclusions during the heat treatment of steel, which is beneficial for improving the toughness of steel. Therefore, rare earth Ce is usually used to modify spinel inclusions in steel. In order to clarify the modification mechanism of spinel inclusions in medium manganese steel with Ce treatment, high-temperature simulation experiments were carried out. Samples were taken step by step during the experimental steel smelting process, and the inclusions in the samples were analyzed by SEM-EDS. Finally, the experimental results were discussed and analyzed in combination with thermodynamic calculations. The results show that after Ce treatment, the amount of inclusions decrease, the inclusion size is basically less than 5 μm, and the spinel inclusions are transformed into rare earth inclusions. After Ce addition, Mn and Mg in the spinel inclusions are first replaced by Ce, and the spinel structure is destroyed to form CeAlO3. When the O content in the steel is low, S in the steel will replace the O in the inclusion, and CeAlO3 and spinel inclusions will be transformed into Ce2O2S. By measuring the total oxygen content of the steel, the total Ce content required for complete modification of spinel inclusions can be obtained. Finally, the critical conditions for the formation and transformation of inclusions in the Fe-Mn-Al-Mg-Ce-O-S system at 1873K were obtained according to thermodynamic calculations.
20
Khoroshilov, A. D., e K. V. Grigorovich. "Thermodynamic features of the modifi cation of non-metallic inclusions by calcium in low-carbon steels deoxidized by aluminum". Izvestiya. Ferrous Metallurgy 62, n. 11 (23 dicembre 2019): 860–69. http://dx.doi.org/10.17073/0368-0797-2019-11-860-869.
Testo completoAbstract (sommario):
Low-carbon steels deoxidized by aluminum are the main group of structural steels produced in Russiaand all over the world. These steels work in key sectors of the economy – construction, automotive, mining and transportation of minerals, etc. The deoxidation of steel melt by aluminum leads to the formation of non-metallic inclusions, which can significantly affect quality of rolled products and reduce the manufacturability of production due to overgrowth of submergednozzles during continuous casting. So, ceteris paribus, only due to contamination of steel with non-metallic inclusions, the following differences in technical and economic indicators can be observed: sorting by surface defects, reduced yield of cast slabs, increased corrosion wear rate, sorting by ultrasonic inspection defects, etc. Due to the particular shape, size and state of aggregation, non-metallic inclusions based on aluminum deoxidation products are difficult to remove from the steel melt. An effective way to reduce steel pollution by similar inclusions is modifying their composition to a liquid state of aggregation with calcium, which requires careful preparation of the molten slag and metal. The article describes in detail the main thermodynamic features of this process. On the example of IF-steel, we present calculation of the target range of calcium content to ensure the inclusion modification to a liquid state depending on aluminum concentration in the steel melt. The limiting sulfur concentrations in the metal melt are determined depending on aluminum and calcium contents, which ensure prevention of the formation of refractory sulfide shells on oxide non-metallic inclusions.
21
Huang, Weishan, Jing-Li Luo, Hani Henein e Josiah Jordan. "Sulfide stress cracking assessment of low-alloy L80 casing steel in H2S environment". Anti-Corrosion Methods and Materials 66, n. 4 (1 luglio 2019): 379–87. http://dx.doi.org/10.1108/acmm-08-2018-1984.
Testo completoAbstract (sommario):
Purpose This paper aims to evaluate the sulfide stress cracking (SSC) resistance of L80 casing steels with different alloying chemistries (e.g. Ti-B and Mn-Cr-Mo) by correlating the reduction in area ratio with the mechanical property, inclusion and carbide. Design/methodology/approach SSC tests were conducted in 5.0 Wt.% sodium chloride and 0.5 Wt.% acetic acid solution saturated with H2S using constant load tensile method. The microstructure and fracture morphology of the steel were observed using scanning electron microscope. The inclusion and carbide were identified by energy dispersive spectroscopy and auger electron microscope. Findings Among all the testing steels, electric resistance welding (ERW) L80-0.5Mo steel demonstrates the highest SSC resistance because of its appropriate mechanical properties, uniform microstructure and low inclusion content. The SSC resistance of L80 steels generally decreases with the rising yield strength. The fracture mode of steel with low SSC resistance is jointly dominated by transgranular and intergranular cracking, whereas that with high SSC resistance is mainly transgranular cracking. SSC is more sensitive to inclusions than carbides because the cracks are easier to be initiated from the elongated inclusions and oversized oxide inclusions, especially the inclusion clusters. Unlike the elongated carbide, globular carbide in the steel can reduce the negative effect on the SSC resistance. Especially, a uniform microstructure with fine globular carbides favors a significant improvement in SSC resistance through precluding the cracking propagation. Originality/value The paper provides the new insights into the improvement in SSC resistance of L80 casing steel for its application in H2S environment through optimizing its alloying compositions and microstructure.
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Zhao, Ding Guo, Shu Huan Wang e Ming Jian Guo. "Analysis of Inclusion Microstructure in Material Engineering of Steel". Advanced Materials Research 568 (settembre 2012): 324–27. http://dx.doi.org/10.4028/www.scientific.net/amr.568.324.
Testo completoAbstract (sommario):
The sample of oxide inclusion was obtained in the different stage of steelmaking for the 65 steel. The microstructure was observed by using scanning electron microscopy (SEM) to analyze the composition and type of inclusions. It was shown that the microscopic inclusions in the high carbon steel were mainly massive and cluster Al2O3, spherical and slope silicate inclusion, calcium-aluminates inclusions and sulphide complex inclusions. The measures including raw material requirement, improving of the converter, LF refining and continuous casting operations were put forward to decrease inclusion.
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Shu, Wei, Xue Min Wang, Cheng Jia Shang e Xin Lai He. "The Influence of Oxide Inclusion on Austenite Grain Size and Heat Affected Zone Toughness for Low Carbon Steels". Materials Science Forum 715-716 (aprile 2012): 617–22. http://dx.doi.org/10.4028/www.scientific.net/msf.715-716.617.
Testo completoAbstract (sommario):
The low carbon steels were smelted with special oxide introduction technique and the HAZ properties has been studied with thermal simulation. The optical microscope, SEM and TEM were used to analyze the composition, size and distribution of the inclusions, and the mechanical properties after thermal simulation were also investigated. The influence of oxide inclusions on the austenite grain size was also studied. The results show that after the smelting the inclusion is complex, in the core is Ti oxides about 1-3 micron and around it is MnS. When the reheat temperature is below 1000, the size of austenite grain is the same for experimental steel and base steel. However, when the reheat temperature is over than 1100, the size of austenite grains in experimental steel is one third of that in base steels. After thermal simulation, with thet8/5increasing the toughness of HAZ decreased. The austnite grain size also increased. The microstructure is composed of intergranular ferrite and intragranular acicular ferrite. Therefore by introducing the fine oxide inclusion to the steel the austenite grain was refined and during the phase transformation the acicular ferrite formed at inclusions at first. These two factors are the main causes to improve the toughness of heat affected zone for steels produced by oxide metallurgy technique.
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Wang, Linzhu, Junqi Li, Shufeng Yang, Chaoyi Chen, Huixin Jin, Xiang Li, Changling Zhuang e Jiantao Ju. "Industrial experiment study on inclusion evolution in 95CrMo Steel". Metallurgical Research & Technology 116, n. 5 (2019): 518. http://dx.doi.org/10.1051/metal/2019015.
Testo completoAbstract (sommario):
In order to clarify the evolution mechanism of inclusions in 95CrMo, the industrial experiments were conducted. The composition, morphology and size of inclusions during refining and solidifying processes were analyzed by SEM-EDS detection and thermodynamic calculations. The inclusion evolution during refining process in molten 95CrMo steel can be concluded as: Al2O3 → Al2O3-MgO-CaO/CaS → Al2O3-MgO-SiO2-CaO-CaS, which is affected by slag-metal reaction and corrosion of refractory. The change of inclusion size during refining was analyzed based on their collision and floatation behavior. The composition of inclusions in billets indicate that there were mainly five types of inclusions, including spinel with sharp angle, spherical oxide inclusion composed of Al2O3, MgO, SiO2 and CaO, oxide-sulfide inclusion with single phase, inclusion with duplex phase, and MnS inclusion. The type of inclusions affects their size. The thermodynamic results indicate that most complex oxides formed in molten steel and no spinel generated during cooling process. CaS formed in the molten steel after tundish metallurgy and there were still some CaS precipitated in solid steel. MnS precipitated after steel solidification. The calculated results based on FACTSAGE 7.1 are in agreement with experimental results on the whole.
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Balart, M. J., Claire L. Davis, Martin Strangwood e J. F. Knott. "Cleavage Initiation in Ti-V-N and V-N Microalloyed Forging Steels". Materials Science Forum 500-501 (novembre 2005): 729–36. http://dx.doi.org/10.4028/www.scientific.net/msf.500-501.729.
Testo completoAbstract (sommario):
The effects of matrix microstructure and features of non-metallic inclusion (morphology, type, volume fraction and size) on cleavage initiation in medium-carbon Ti-V-N and V-N microalloyed resulphurized forging steels have been determined by examining fracture surfaces produced in room temperature Charpy impact tests. The steels were generally Al-deoxidised but one V-N steel was Si-deoxidised. It has been found that, in the Ti-treated steel, having a ferrite-pearlite microstructure, brittle fracture initiation occurred at cracked coarse (Ti,V)(C,N) single phase or [(Ti,V)(C,N)/Al2O3/MnS] multi-phase inclusions. In the Ti-free steels, cleavage initiation was dependent on matrix microstructure and non-metallic inclusions. In the low strength Ti-free steels, with a ferrite-pearlite microstructure, the absence of a continuous grain boundary ferrite layer led to initiation from interfacing pearlite colonies. For the bainitic microstructure, cleavage initiated close to the notch, but the microstructural feature responsible could not be identified. For the ferritepearlite microstructure in the Si-deoxidised V-N steel, cleavage initiated at cracked Mn-Al-(Ca) silicate inclusions. The higher matrix strength and more continuous nature of grain boundary allotriomorphic ferrite in the V-N steel deoxidised with Al was associated with cleavage initiation from V-rich (V,Ti)(C,N)-containing inclusions. These were generally of smaller size than those in the Ti-treated steels.
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Wu, Yan Hui, Ding Guo Zhao, Shu Huan Wang e Jian Sheng Li. "Research on the Controlling Technic of Conclution in If Steel". Advanced Materials Research 557-559 (luglio 2012): 151–54. http://dx.doi.org/10.4028/www.scientific.net/amr.557-559.151.
Testo completoAbstract (sommario):
Combining with the production experience in steel making and rolling plant, the oxide inclusions of IF steel were investigated. In the operation process, the inclusions of IF steel are main Al2O3-TiN. They are granular and dispersed in the steel, and most of sizes are 1~5μm. In the inclusion center, the Al2O3 plays the role of TiN heterogeneous nucleation center. So reducing the Al2O3 inclusion is essential to stabilize the Ti content and strengthen the fixtation to C and N in steel. The quantity of Al2O3 inclusion was closely relation to the operation process. The Al2O3 inclusions can be significantly reduced by taking some measure.
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Ryabov, A. V., T. V. Prokaeva e Yu E. Amosova. "Free-Cutting Cr–Ni–Mo Steel". Solid State Phenomena 284 (ottobre 2018): 276–80. http://dx.doi.org/10.4028/www.scientific.net/ssp.284.276.
Testo completoAbstract (sommario):
The paper presents theoretical and practical study of formation of non-metallic inclusions in a medium-carbon free-cutting structural steel. FactSage software package was used for thermodynamic modelling of inclusion behaviour. Formation temperature and the amount of aluminium oxides, boron nitrides, manganese sulphides and aluminium nitrides were calculated. Inclusions in the steel form in the sequence Al2O3 > BN > MnS > AlN. The object of practical research was a cast billet of A38KhGMAR grade steel. It was melted in a laboratory induction furnace; boron and nitrogen were introduced after deoxidation of the melt with primary aluminium. Quality analysis included determination of chemical composition, macro-and microstructure, type and shape of non-metallic inclusions. Fine and uniformly distributed boron nitride inclusions were obtained throughout the metal matrix; their distribution was studied both qualitatively and quantitatively. Beside isolated particles, boron nitrides are also presented as a component of complex inclusions with manganese sulphides. Inclusion morphology is mostly spherical. The size of BN inclusions varies from 0.41 to 7.23 μm.
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Xiao, Bu Qing, Sheng Fu Li, Xiao Tao Tian e Jian Xing Wang. "Study of Micro-Inclusion of Grade 45 Steel". Advanced Materials Research 634-638 (gennaio 2013): 1869–73. http://dx.doi.org/10.4028/www.scientific.net/amr.634-638.1869.
Testo completoAbstract (sommario):
According to the production process of grade 45 steel(120tBOF→slag refining→ CC), some system analysis are introduced to research on the type composition and quantity of micro-inclusions, and the effect of slag washing production process on the cleanliness of casting slab is evaluated. The results of the study show that: The content of T[O] is 48.75ppm in normal slab, The content of T[O] is 56.2ppm in head slab, The content of T[O] is 49.2ppm in compound casting slab.The main types of micro-inclusion in slab are MnS inclusion and Al2O3 inclusion. The quality of micro-inclusions is 14.32/mm2 in the normal slab, the quality of micro-inclusions is 17.68 /mm2 in the head slab, the quality of micro-inclusions is 27.94 /mm2 in the compound casting. In the normal slab, the average total volume ratio of micro-inclusions is 0.0458%. The particle size of micro-inclusions is smaller. The particle size of less than 10μm in micro-inclusions is the largest and is about 80%.
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Li, Yang, Zhou Hua Jiang, Shi You Yin, Ying Zhuang e Ming Li. "Formation and Control of Inclusions during Steelmaking Process". Applied Mechanics and Materials 52-54 (marzo 2011): 1681–86. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.1681.
Testo completoAbstract (sommario):
The variation of non-metallic inclusions and total oxygen contents in different steel grades were investigated by taking samples in steelmaking process, including gear steel, anchor chain steel, hard wire steel, bearing steel and spring steel. The inclusions mainly were Al2O3, MnS, and their composite inclusions in aluminum killed steel at the beginning of LF refining due to addition of FeAl alloy during the tapping from EAF and feeding of Al wire in LF process, and then Al2O3 inclusion changed to the Al2O3 - CaO composite inclusions after feeding of SiCa wire. The inclusions at the beginning of LF refining mainly were MnS, SiC and their composite inclusions in non-aluminum killed steel due to addition of the composite deoxidation and slagging agents (mainly including CaC2 and SiC) when EAF taping, while the inclusions in tundish mainly were MnS, CaO - SiO2 - Al2O3 composite oxide - sulfide inclusions. It is showed that the inclusions in bearing steel and spring steel samples were mainly globular oxide inclusions and silicate inclusions with higher rated results. Therefore, the refining process should be improved to remove globular oxide inclusions. The inclusions in molten steel were controlled by enhancing the diffusion deoxidation process, adjusting and controlling the basicity and composition of refining slags, respectively, and satisfactory results were obtained. The industrial test shows that the total oxygen content of the aluminum killed steel in the test heat after feeding wire reached the minimum value, which indicates that the optimized slag has a strong ability of absorbing Al2O3 inclusions. For non-aluminum killed steel, the total oxygen content was 0.0027 % to 0.0029 % in rolled products. The inclusions in the end of refining and rolled product were small and dispersed composite inclusions, and the separate Al2O3 inclusions can not be found in the non-aluminum killed steel after optimization of the refining process.
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Zhang, Tongsheng, Rensheng Li, Wanlin Wang, Shifan Dai, Peisheng Lv e Yan Tian. "Research on the variation of the inclusion and sulfur content in Pipeline steel". Metallurgical Research & Technology 118, n. 2 (2021): 214. http://dx.doi.org/10.1051/metal/2021010.
Testo completoAbstract (sommario):
Pipeline steel is widely used in various industries, and the sulfur content and inclusions in steel have a significant impact on performance, which determines whether the steel quality is qualified. The experiments were carried out to explore the sulfur content and inclusion evolution of pipeline steel which was deoxidized by Si–Mn–Al with “EAF-LF-VD-T-CC”. The samples of molten steel and slag were taken during the process of LF-VD-Tundish after EAF tapping. The kinetics model was established to simulate the desulfuration process of molten steel in actual production, obtaining a result which the error is within 3 ppm. It can be summarized that proper calcium treatment can transform the inclusion into a liquid inclusion, the value of [Ca] ranges from 25 to 45 ppm. Too high and lower calcium treatment can cause the compositions of inclusions to deviate from the liquid phase area, while too low calcium treatment will increase the overall size and density of the inclusions. In addition, the evolution of inclusion in steel at refining temperature and during solidification process was comprehensively calculated, considering all types of inclusions such as calcium oxide, magnesium oxide, aluminum oxide, calcium sulfide, spinel, calcium aluminate and liquid inclusion. The thermodynamic calculations are in good agreement with experimental results, which can predict the formation of the inclusions in Si–Mn–Al deoxidized pipeline steel.
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Liu, Yang, Jing Li, Jinpeng Ge e Dingli Zheng. "Effect of Acid Slag Treatment on the Inclusions in GCr15 Bearing Steel". High Temperature Materials and Processes 38, n. 2019 (25 febbraio 2019): 760–66. http://dx.doi.org/10.1515/htmp-2019-0024.
Testo completoAbstract (sommario):
AbstractBy laboratory slag/steel reaction equilibrim experiments, the viriation of oxygen content, inclusion compositions and inclusion sizes were studied. The effect of acid slag treatment on the transition mechanisms of D-type inclusions and the precipitation of TiN inclusions in GCr15 bearing steel were explored. The obtained results showed that the dominant inclusions in steel were plastic and smaller Al2O3-SiO2-MnO. The melting point were lower than 1400°C treated by the acid refining slag of 35.1%CaO-15%Al2O3-43.9%SiO2-6%MgO and there was no TiN found. The evolution of MgO·Al2O3 inclusions is: MgO·Al2O3→ MgO·Al2O3·SiO2·MnO→ Al2O3·SiO2·MnO. Mg and Al from MgO·Al2O3 inclusions were displaced by [Si] and [Mn] in steel liquid , and formation of plastic Al2O3-SiO2-MnO inclusions finally, whose compositions distribution were uniform. Mg and Si, Mn were complementary in inclusions as to the spatial distribution.
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Zhang, Hongliang, Guanghong Feng, Xin Liu, Baoshan Wang e Xuming Liu. "Effect of Sulfur Content on the Composition of Inclusions and MnS Precipitation Behavior in Bearing Steel". Metals 10, n. 5 (27 aprile 2020): 570. http://dx.doi.org/10.3390/met10050570.
Testo completoAbstract (sommario):
MnS inclusions in bearing steel have long been considered to significantly affect the fatigue life of bearing steel. In this paper, the sizes of inclusions in bearing steel with different sulfur contents were analyzed and the precipitation behavior of MnS was calculated using thermodynamics. Furthermore, the positive role of MnS in bearing steel was discussed. Results showed that when the size of inclusions in bearing steel was increased, the proportion of MnS components in composite inclusions gradually decreased. When the sulfur content was increased, the shape of inclusions changed from a particle shape to a strip shape. With increasing MnS content, the inclusion ratio of Al2O3 was significantly reduced in the Al2O3–CaO–MgO–MnS quaternary inclusion system, particularly for MnS proportions greater than 20%. The content of sulfur in bearing steel significantly affects the precipitation temperature of MnS. When sulfur content increases from 0.001% to 0.007%, the precipitation temperature of MnS increases from 1493 K to 1633 K as the precipitation of MnS moves from the austenite solid phase to the liquid and solid phases, and the precipitation size of MnS inclusions significantly increases. The size of oxide inclusions should be controlled to improve MnS wrap oxide inclusions in steel. Based on these results, a composition control with high sulfur levels and low oxygen levels should be adopted to improve the fatigue performance of steel.
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Li, Weifu, Yi Wang, Weijian Wang, Ying Ren e Lifeng Zhang. "Dependence of the Clogging Possibility of the Submerged Entry Nozzle during Steel Continuous Casting Process on the Liquid Fraction of Non-Metallic Inclusions in the Molten Al-Killed Ca-Treated Steel". Metals 10, n. 9 (8 settembre 2020): 1205. http://dx.doi.org/10.3390/met10091205.
Testo completoAbstract (sommario):
In the current study, the nozzle clogging behavior and inclusion composition in Al-killed Ca-treated steels were observed to investigate the relationship between the liquid fraction of non-metallic inclusions and the clogging possibility of the submerged entry nozzle. Clogging materials were mainly MgO-Al2O3 with less than 20% liquid phases, while most of the inclusions were full liquid CaO-Al2O3-MgO in tundish at the casting temperature. Thus, it was proposed that the nozzle clogging can be effectively avoided by modification of solid inclusions to partial liquid ones rather than full liquid ones. There was a critical value of liquid fraction of inclusions causing the nozzle clogging. A critical condition of the inclusion attachment on the nozzle wall was a function of cosθN−S+cosθI−S<0. With the increase of T.Ca content in steel, the evolution route of inclusions was solid MgO-Al2O3→liquid CaO-Al2O3-MgO→solid CaS and CaO. To avoid the clogging of the submerged entry nozzle (SEN) under the current casting condition, the appropriate T.Ca concentration range in Al-killed Ca-treated steels can be enlarged from the 100% liquid inclusion zone of 10–14 ppm to the 20% liquid inclusion zone of 4–38 ppm.
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Li, Zhuang, Di Wu, Wei Lv, Zhen Zheng e Shao Pu Kang. "Investigations on Low Environmental Impact Machining Processes of Free Cutting Austenitic Stainless Steels". Applied Mechanics and Materials 377 (agosto 2013): 112–16. http://dx.doi.org/10.4028/www.scientific.net/amm.377.112.
Testo completoAbstract (sommario):
In the present paper, sulfur, RE (rare earth) and bismuth were added to an austenite stainless steel. Low environmental impact machining processes of free cutting austenitic stainless steels was investigated by machinability testing. The results show that a significant amount of grey and dispersed inclusions were found in steel B. The inclusions are typical sulfide inclusions, and bismuth element is attached to double end of manganese sulfide inclusions. Some inclusions exhibit globular shape due to the presence of rare earths elements in steel B. Chip morphology was improved in steel B under the same turning conditions. The machinability of steel B is much better than that of steel A. This is attributed to the presence of free-cutting additives of sulfur, RE and bismuth in the austenitic stainless steels. Satisfactory mechanical properties were also obtained under the conditions of our experiments. The reasons why satisfactory mechanical properties were obtained may lie in that the sulfides and bismuth are soft phase, and the presence of rare earths elements contributes to the improvement of the toughness of the austenitic stainless steels.
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Zhang, Yang, Li e Wu. "Transformation of Oxide Inclusions in Stainless Steel Containing Yttrium during Isothermal Heating at 1473 K". Metals 9, n. 9 (1 settembre 2019): 961. http://dx.doi.org/10.3390/met9090961.
Testo completoAbstract (sommario):
To provide fundamental information on the control of rare earth inclusions in solid steel, two 18 mass% Cr-8 mass% Ni stainless steels with different yttrium additions were prepared using an electric resistance furnace and the evolution of yttrium-based oxide inclusions during heat treatment of the steels at 1473 K was investigated. In both as-cast steels, homogeneous spherical Al-Y-Si(-Mn-Cr) oxide inclusions were observed; however, the steel with larger yttrium additions also had some heterogeneous oxide inclusions with double phases. After heating, a new oxide phase with higher yttrium content precipitated from the original inclusions and resulted in partitioning to Y-rich and Al-rich parts in both steels. The average size and number density of inclusions slightly increased, and the morphology of inclusions changed from spherical to irregular. The transformation mechanism during isothermal heating was proposed to be the mutual effects of (i) internal transformation of the yttrium-based inclusions owing to crystallization of glassy oxide and (ii) interfacial reaction between inclusions and the steel matrix.
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Liu, Zhen, Bo Song, Zhanbing Yang, Xiaokang Cui, Longfei Li, Lei Wang e Zirui Song. "Effect of Cerium Content on the Evolution of Inclusions and Formation of Acicular Ferrite in Ti-Mg-Killed EH36 Steel". Metals 10, n. 7 (29 giugno 2020): 863. http://dx.doi.org/10.3390/met10070863.
Testo completoAbstract (sommario):
Ce has been widely used in oxide metallurgy for modifying inclusions and refining microstructure. Effect of Ce contents on the evolution and characteristics of non-metallic inclusions and the formation of acicular ferrite (AF) in Ce-treated Ti-Mg-killed EH36 steel was investigated. The results showed that the main type of inclusions in Ti-Mg deoxidized steel was MgO·Al2O3-MnS. After 0.014%, 0.024% and 0.037% Ce were added into the steels, dominant inclusions became CeAlO3-MgO-MnS, Ce2O2S-MgO-MnS and Ce2O2S-MnS, respectively. The precipitation of pure MnS was suppressed in the steel with 0.024% Ce, while the number density of total inclusions increased significantly in the steel with 0.037% Ce, causing the inclusions distributing densely. Ce addition refined the microstructure of tested steels by promoting AF formation and polygonal ferrite distributing evenly. Dispersive distribution, low lattice mismatch against α-Fe, as well as lower number density of pure MnS caused the highest number density of effective inclusions (nucleus of AF formation) in 0.024% Ce-treated steel.
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Liu, Yu, Dongwei Fan, Raymundo Arróyave e Ankit Srivastava. "Microstructure-Based Modeling of the Effect of Inclusion on the Bendability of Advanced High Strength Dual-Phase Steels". Metals 11, n. 3 (5 marzo 2021): 431. http://dx.doi.org/10.3390/met11030431.
Testo completoAbstract (sommario):
Advanced high strength dual-phase steels are one of the most widely sought-after structural materials for automotive applications. These high strength steels, however, are prone to fracture under bending-dominated manufacturing processes. Experimental observations suggest that the bendability of these steels is sensitive to the presence of subsurface non-metallic inclusions and the inclusions exhibit a rather discrete size effect on the bendability of these steels. Following this, we have carried out a series of microstructure-based finite element calculations of ductile fracture in an advanced high strength dual-phase steel under bending. In the calculations, both the dual-phase microstructure and inclusion are discretely modeled. To gain additional insight, we have also analyzed the effect of an inclusion on the bendability of a single-phase material. In line with the experimental observations, strong inclusion size effect on the bendability of the dual-phase steel naturally emerge in the calculations. Furthermore, supervised machine learning is used to quantify the effects of the multivariable input space associated with the dual-phase microstructure and inclusion on the bendability of the steel. The results of the supervised machine learning are then used to identify the contributions of individual features and isolate critical features that control the bendability of dual-phase steels.
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Wartiainen, Anna-Mari, Markus Harju, Satu Tamminen, Leena Määttä, Tuomas Alatarvas e Juha Röning. "A tool for finding inclusion clusters in steel SEM specimens". Open Engineering 10, n. 1 (7 luglio 2020): 642–48. http://dx.doi.org/10.1515/eng-2020-0068.
Testo completoAbstract (sommario):
AbstractNon-metallic inclusions, especially large or clustered inclusions, in steel are usually harmful. Thus, the microscopic analysis of test specimens is an important part of the quality control. This steel purity analysis produces a large amount of individual inclusion information for each test specimen. The interpretation of the results is laborious and the comparison of larger product groups practically impossible. The purpose of this study was to develop an easy-to-use tool for automatic interpretation of the SEM analysis to differentiate clustered and large inclusions information from the manifold individual inclusion information. Because of the large variety of the potential users, the tool needs to be applicable for any steel grade and application, both for liquid and final product specimen, to analyse automatically steel specimen inclusions, especially inclusion clusters, based on the INCA Feature program produced data from SEM/EDS. The developed tool can be used to improve the controlling of the steel purity or for automatic production of new inclusion cluster features that can be utilised further in quality prediction models, for example.
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Wu, Zhanfang, Zhenyu Liu, Shengtao Qiu e Xiangyang Li. "Effect of composition and morphology of non-metallic inclusions on fracture toughness in as-cast AHSS". Metallurgical Research & Technology 116, n. 6 (2019): 623. http://dx.doi.org/10.1051/metal/2019052.
Testo completoAbstract (sommario):
A set of water-cooling copper-chill mold equipment is designed to study the precipitation behavior of different inclusion types in test steel under different cooling conditions, as well as its effects on the steel mechanical properties. As the results reveal, slow cooling treatment near the solidus temperature of test steel is conducive to forming more MnS + Al2O3 composite inclusions. The impact energy (−16 °C) of slow-cooled cast ingots at the core position is 28% higher than that of the air-cooled ingots. Scanning electron microscopy analysis of the specimens shows that small cracks are formed around single Al2O3 inclusions, but no cracks were found around composite inclusions. A calculation model of the tessellated stress of composite inclusions in steel is introduced to verify this phenomenon. The calculation demonstrates that, with a cover of ductile MnS, stress concentration around the composite inclusion is significantly decreased as compared with the single Al2O3 inclusion in the test steel.
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Liu, Xiao, e Long Mei Wang. "Thermodynamic Analysis and Observation of Inclusions in 2205 Duplex Stainless Steel with Rare Earth Metals". Advanced Materials Research 512-515 (maggio 2012): 1833–39. http://dx.doi.org/10.4028/www.scientific.net/amr.512-515.1833.
Testo completoAbstract (sommario):
The effect of rare earth metals on modifying inclusions of 2205 duplex stainless steel was studied by metallographic examination, SEM and electron spectroscopy. Thermodynamic calculation was used to analyze the formation of RE inclusions in 2205 duplex stainless steel. According to the composition of 2205 duplex stainless steel liquid and thermodynamic data, it may calculate and predict the kinds of RE inclusions. And the result shows that aluminosilicate complex inclusion and sulfide inclusion can be entirely replaced by RE2O2S and RES that are spherical.
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Wu, Guo Sheng, Zhi Yun Fu e Zhong Wang. "Effects of Rare Earths on Inclusions Distribution and Modality of 8Cr4MoV Cold Work Roll Cast Steel". Advanced Materials Research 1049-1050 (ottobre 2014): 171–74. http://dx.doi.org/10.4028/www.scientific.net/amr.1049-1050.171.
Testo completoAbstract (sommario):
A study of rare earth effects on inclusion modality of 8Cr4MoV cold work roll steels was carried out in the laboratory, the steels smelting by a 50kg vacuum induction furnace, atmospheric casting, processing sample after annealing, then inspecting the steels’microstructure, inclusion modality and composition; The results showed that the steels’ microstructure fine, micro-hardness increased with increasing rare earth content, while the average size of inclusions decreased significantly, also the morphology and composition of inclusions significantly changed from the angular black manganese sulfide to the ball white sulfur oxides of rare earth, and thus played roles of deoxidation, desulfurization, purification and deterioration of liquid steel , it will help improving the fatigue performance of the work roll.
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Lipiński, T., e A. Wach. "Size of Non-Metallic Inclusions in High-Grade Medium Carbon Steel". Archives of Foundry Engineering 14, n. 4 (1 dicembre 2014): 55–60. http://dx.doi.org/10.2478/afe-2014-0086.
Testo completoAbstract (sommario):
Abstract Non-metallic inclusions found in steel can affect its performance characteristics. Their impact depends not only on their quality, but also, among others, on their size and distribution in the steel volume. The literature mainly describes the results of tests on hard steels, particularly bearing steels. The amount of non-metallic inclusions found in steel with a medium carbon content melted under industrial conditions is rarely presented in the literature. The tested steel was melted in an electric arc furnace and then desulfurized and argonrefined. Seven typical industrial melts were analyzed, in which ca. 75% secondary raw materials were used. The amount of non-metallic inclusions was determined by optical and extraction methods. The test results are presented using stereometric indices. Inclusions are characterized by measuring ranges. The chemical composition of steel and contents of inclusions in every melts are presented. The results are shown in graphical form. The presented analysis of the tests results on the amount and size of non-metallic inclusions can be used to assess them operational strength and durability of steel melted and refined in the desulfurization and argon refining processes.
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Burja, Jaka, Mitja Koležnik, Barbara Šetina Batič e Jožef Medved. "Effect of Zr Additions on Non-Metallic Inclusions in X11CrNiMo12 Steel". Metals 10, n. 9 (2 settembre 2020): 1183. http://dx.doi.org/10.3390/met10091183.
Testo completoAbstract (sommario):
The production of clean steel is associated with high-quality steel grades for demanding applications. The formation of oxide inclusions mainly depends on the deoxidation practice; it is usually carried out through Al additions, but alumina inclusions can have detrimental effects. An alternative zirconium inclusion modification was used in a creep-resistant steel to improve the cleanliness of laboratory-made steel. The thermodynamics behind the inclusion modification are presented, the reaction products are identified and the steel cleanliness improvement is quantified. The resulting influence of zirconium addition on non-metallic inclusions and mechanical properties is discussed. While the Zr additions drastically reduce the non-metallic inclusion size and area, additions above a certain amount result in the formation of zirconium nitrides that ultimately soften the martensitic steel due to the depletion of nitrogen in solid solution.
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Chen, Liangjun, Yong Wan, Jie Li, Weiqing Chen, Yindong Yang e Alexander McLean. "A New Method for Plasticization of Inclusions in Saw-Wire Steel by NaF Addition". Metals 10, n. 6 (27 maggio 2020): 704. http://dx.doi.org/10.3390/met10060704.
Testo completoAbstract (sommario):
In this study, a new method is proposed for the plasticization of inclusions by taking advantage of the behavior of alkali metals in lowering the inclusion melting point. A series of experiments with NaF additions to molten steel were carried out using a carbon tube furnace followed by simulated rolling tests using the solidified ingots and characterization of inclusions with the help of automated scanning electron microscopy. Compositional changes of the steel and evolution of gaseous species were evaluated using thermodynamic software FactSage 7.2 (ThermFact Inc., Montreal, QC, Canada). Based on this approach, NaF/steel/inclusion interactions and the effects of NaF addition on the melting point, size and deformability of inclusions were clarified. The modification of MnO-SiO2 inclusions by NaF also promoted the removal of inclusions and improved the cleanliness of steel. The results show that with the addition of NaF, the melting point of inclusions is greatly reduced, the deformability is improved, and the removal of inclusions is enhanced, all of which indicates a good prospect for industrial application.
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Chen, Shao Chun, Rong Zhu, Li Qiu Xue, Teng Chang Lin e Jing She Li. "Study on Properties and Inclusion of Environmental Automatic Steel Alloyed with Tin Element". Applied Mechanics and Materials 448-453 (ottobre 2013): 88–93. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.88.
Testo completoAbstract (sommario):
A new environment-friendly automatic steel alloyed with tin element Y20Sn has been developed. In test, new steel possess good machinability and mechanical property, which reach Chinese National Standard of corresponding automatic steel GB/T8731-88. In steel, the shape of inclusions is mainly spherical or spindly, which volume is small and distribution is evenly. Such style of inclusion can fairly improve the steel machinability, and doesnt impair its mechanical property at the same time. As the main inclusion in developed automatic steel, MnS inclusion is one important factor which influences the machinability of steel. In the steel alloyed with tin, tin exist around MnS inclusions or are attached to MnS inclusion will influence the formation mechanism of MnS inclusion, that is the important reason why tin element influence machinability of developed automatic steel Y20Sn.
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Shen, Ping, Lei Zhou, Qiankun Yang, Zhiqi Zeng, Kenan Ai e Jianxun Fu. "Modification of MnS inclusion by tellurium in 38MnVS6 micro-alloyed steel". Metallurgical Research & Technology 117, n. 6 (2020): 615. http://dx.doi.org/10.1051/metal/2020066.
Testo completoAbstract (sommario):
In 38MnVS6 steel, the morphology of sulfide inclusion has a strong influence on the fatigue life and machinability of the steel. In most cases, the MnS inclusions show strip morphology after rolling, which significantly affects the steel quality. Usually, the MnS inclusion with a spherical morphology is the best morphology for the steel quality. In the present work, tellurium was applied to 38MnVS6 micro-alloyed steel to control the MnS inclusion. Trace tellurium was added into 38MnVS6 steel and the effect of Te on the morphology, composition, size and distribution of MnS inclusions were investigated. Experimental results show that with the increase of Te content, the equivalent diameter and the aspect ratio of inclusion decrease strikingly, and the number of inclusions with small aspect ratio increases. The inclusions are dissociated and spherized. The SEM-EDS analysis indicates that the trace Te mainly dissolves in MnS inclusion. Once the MnS is saturated with Te, MnTe starts to generate and wraps MnS. The critical Te/S value for the formation of MnTe in the 38MnV6 steel is determined to be approximately 0.075. With the increase of Te/S ratio, the aspect ratio of MnS inclusion decreases and gradually reaches a constant level. The Te/S value in the 38MnVS6 steel corresponding to the change of aspect ratio from decreasing to constant ranges from 0.096 to 0.255. This is most likely to be caused by the saturation of Te in the MnS inclusion. After adding Te in the steel, rod-like MnS inclusion is modified to small inclusion and the smaller the MnS inclusion, the lower the aspect ratio.
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Liu, Yang, e Nanfu Zong. "Effects of Al-Mg alloy treatment on behavior and size of inclusions in SUH 409L stainless steel". Metallurgical Research & Technology 115, n. 1 (22 novembre 2017): 111. http://dx.doi.org/10.1051/metal/2017085.
Testo completoAbstract (sommario):
Different types of steel were produced by different deoxidization processes to investigate effects of Al-Mg alloy treatment on the behavior and size of inclusions in stainless steels. Both industrial experiments and thermodynamic calculations were studied. Results showed that irregular and clustered Al2O3 inclusions are dominant in aluminum killed stainless steels. Using Al-Mg alloy treatment, size of Al2O3 inclusions could be reduced, irregular and clustered Al2O3 inclusions can be changed into the spherical MgO ⋅ Al2O3 inclusions. Changes in size and number of inclusions result from that Al-Mg alloy treatment could significantly affect the nucleation process of MgO ⋅ Al2O3 inclusions in molten steel. When the content of Mg is enough, larger inclusions can be reduced by the Al-Mg alloy treatment, and inclusions can keep fine.
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Zeng, Yan Ping, Shao Hua Li e Ke Tong. "Micro-Behavior of Inclusions in X80 Pipeline Steel under Tensile Loading". Applied Mechanics and Materials 248 (dicembre 2012): 224–30. http://dx.doi.org/10.4028/www.scientific.net/amm.248.224.
Testo completoAbstract (sommario):
Specially designed SEM in-situ tensile tests have been conducted to trace the entire process of crack initiation and propagation induced by inclusions in X80 pipeline steel. The main inclusions are complex oxides containing aluminum, calcium and magnesium with round or oval shape, and their sizes are in the range of 3~20μm. Cracks initiate firstly in inclusions and also easily initiate among inclusions if they distribute in the steel as an inclusion chain. The size of an inclusion has little effect on the initiation stress of the first crack, which mainly depends on the yield strength of the steel. Once a crack initiates in X80 pipeline steel, it zigzag propagates along the direction of maximum shear stress that orients in about 45° to the loading direction till failure. In the process of crack propagation, the crack experiences propagation, anti-crack, bluntness and new micro-cracks initiation again and again. These valuable experimental results reveal the harmful effect of inclusions in micro-scale and are helpful for understanding failure mechanisms of the advanced steel components.
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Guo, Xipeng, Joel Godinez, Nicholas J. Walla, Armin K. Silaen, Helmut Oltmann, Vivek Thapliyal, Abhishek Bhansali, Eugene Pretorius e Chenn Q. Zhou. "Computational Investigation of Inclusion Removal in the Steel-Refining Ladle Process". Processes 9, n. 6 (16 giugno 2021): 1048. http://dx.doi.org/10.3390/pr9061048.
Testo completoAbstract (sommario):
In a steel-refining ladle, the properties of manufactured steel can be notably degraded due to the presence of excessive inclusions. Stirring via gas injection through a porous plug is often used as part of the steel-refining process to reduce these inclusions. In this paper, 3D computational fluid dynamics (CFD) modeling is used to analyze transient multiphase flow and inclusion removal in a gas-stirred ladle. The effects of gas stirring with bubble-inclusion interaction are analyzed using the Euler–Euler approach for multiphase flow modeling, while the effects of inclusions aggregation and removal are modeled via a population balance model (PBM).
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Kang, Jian, Yan-Chong Yu, Jin-Ling Zhang, Chao Chen e She-Bin Wang. "Effect of rare earth on inclusion evolution in industrial production of HRB500E steel". Metallurgical Research & Technology 118, n. 2 (2021): 220. http://dx.doi.org/10.1051/metal/2021022.
Testo completoAbstract (sommario):
The effect of rare earth (RE) on inclusion in HRB500E steel was studied based on plant trials. The results showed that S decreased by 47.6% after 0.0059% RE treatment. In samples without RE treatment, the inclusions change from Al2O3-MnO to ellipsoidal Al2O3-MnO-CaO complex inclusion, and the size of such inclusions is ≤ 2 µm and isolated strip MnS inclusion with the size of ≥ 2 µm. With RE treatment, Al2O3-MnO-CaO inclusions are transformed into spherical or ellipsoidal REAlO3 and REAlO3-MnS. The size of such inclusions is ≈ 1.5 µm and single MnS inclusions were not found. The number density and size of inclusions changed significantly after RE treatment. Thermodynamic calculations show that the Gibbs free energy of RE inclusions is more negative and more stable. The transformation model of inclusions is established to illustrate the modification of inclusions during the smelting process.