JOURNAL OF IRON AND STEEL RESEARCH INTERNATIONAL

钢铁研究学报(英文版)

Home | About Journal | Editorial Board | Instruction for Authors | Subscriptions | Advertisement | Contacts Us | Chinese

　

Office Online

　

　

　

　

　

　

Editor-in-chief

　

Journal Online

　

　

Forthcoming Articles

　

　

　

　

Download Articles

　

　

Quick Search

Advanced Search

	2017 Vol. 24 No. 11
	Published: 2017-11-15

	1073	Xiao-gang Wang,Ming-xin Huang,*
		Temperature dependence of Lüders strain and its correlation with martensitic transformation in a medium Mn transformation-induced plasticity steel
		The Lüders deformation behavior in a medium Mn transformation-induced plasticity (TRIP) steel is investigated at different temperatures ranging from 25 to 300°C. It demonstrates that the Lüders band appears at all testing temperatures but with varied Lüders strains which do not change monotonically with temperature. The martensitic transformation is simultaneously observed within the Lüders band in varying degrees depending on the testing temperature. It is well verified that the martensitic transformation is not responsible for the formation of Lüders band, and a reasonable explanation is given for the non-monotonic variation of Lüders strain with increasing temperature.
		2017 Vol. 24 (11): 1073-1077 [Abstract] ( 147 ) [HTML 1KB] [PDF 0KB] ( 280 )

	1085	Zhi-bao Xu,Wei-jun Hui,*,Zhan-hua Wang,Yong-jian Zhang,Xiao-li Zhao,Xiu-ming Zhao
		Mechanical properties of a microalloyed bainitic steel after hot forging and tempering
		Mechanical properties of a newly developed microalloyed bainitic steel were investigated after the hot forging, air cooling and tempering process. The microstructure of the as-forged bainitic steel mainly consists of granular bainite and ~20 vol.% martensite. The fraction of retained austenite remains unchanged until tempering at 200°C, above which it decreases significantly. The increase of tempering temperature leads to decreases of both ultimate tensile strength and total elongation but decreases of both yield strength and reduction of area. The maximum and minimum values of impact toughness were observed after tempering at around 200 and 400°C, respectively. These effects are mainly attributed to the decomposition of martensite/austenite constituents and the tempering effects in martensite. The tempering of the forged bainitic steel at around 200°C results in an excellent combination of strength and toughness, which is comparable to that of the conventional quenched-and-tempered 40Cr steel. Therefore, low-tempering treatment coupled with post-forging residual stress relieving is a feasible method to further improve the mechanical properties of the bainitic forging steel.
		2017 Vol. 24 (11): 1085-1094 [Abstract] ( 165 ) [HTML 1KB] [PDF 0KB] ( 237 )

	1095	Shan Chen, Guang-zhen Wang, Chun Liu, Chen-chong Wang, Xian-ming Zhao, Wei Xu*
		Correlation of isothermal bainite transformation and austenite stability in quenching and partitioning steels
		The possible decomposition of metastable austenite during the partitioning process in the high-end quenching and partitioning (Q&P) steels is somewhat neglected by most researchers. The effects of primary martensite and alloying elements including manganese, cobalt and aluminum on the isothermal decomposition of austenite during typical Q&P process were studied by dilatometry. The transformation kinetics was studied systematically and resulting microstructures were discussed in details. The results suggested that the primary martensite decreased the incubation period of isothermal decomposition by accelerating the nucleation process owing to dislocations especially on phase and grain boundaries. This effect can be eliminated by a flash heating which recovered dislocations. Co addition significantly promoted the bainite transformation during partitioning while Al and Mn suppressed the isothermal bainite transformation. The bainite transformation played an important role in carbon distribution during partitioning, and hence the amount and stability of austenite upon final quenching. The bainite transformation during partitioning is an important factor in optimizing the microstructure in Q&P steels.
		2017 Vol. 24 (11): 1095-1103 [Abstract] ( 150 ) [HTML 1KB] [PDF 0KB] ( 248 )

	1104	Lian-bo Luo,,Wei Li,,Yu Gong,,,Li Wang,Xue-jun Jin,,*
		Tensile behavior and deformation mechanism of quenching and partitioning treated steels at different deforming temperatures
		The effects of deforming temperatures on the tensile behaviors of quenching and partitioning treated steels were investigated. It was found that the ultimate tensile strength of the steel decreased with the increasing temperature from 25 to 100°C, reached the maximum value at 300°C, and then declined by a significant extent when the temperature further reached 400°C. The total elongations at 100, 200 and 300°C are at about the same level. The steel achieved optimal mechanical properties at 300°C due to the proper transformation behavior of retained austenite since the stability of retained austenite is largely dependent on the deforming temperature. When tested at 100 and 200°C, the retained austenite was reluctant to transform, while at the other temperatures, about 10 vol.% of retained austenite transformed during the tensile tests. The relationship between the stability of retained austenite and the work hardening behavior of quenching and partitioning treated steels at different deforming temperatures was also studied and discussed in detail. In order to obtain excellent mechanical properties, the stability of retained austenite should be carefully controlled so that the effect of transformation-induced plasticity could take place continuously during plastic deformation.
		2017 Vol. 24 (11): 1104-1108 [Abstract] ( 119 ) [HTML 1KB] [PDF 0KB] ( 259 )

	1109	Han-bo Jiang,Xi-nan Luo,Xiao-yan Zhong,*,Hui-hua Zhou,Cun-yu Wang,Jie Shi,Han Dong
		In-situ microstructural evolutions of 5Mn steel at elevated temperature in a transmission electron microscope
		The microstructural evolutions of 5Mn steel during various heat treatments have been investigated by in-situ transmission electron microscopy (TEM). The specimen of 5Mn steel was prepared using focused ion beam (FIB) milling, which allowed the selection of specific morphology of interest prior to the in-situ observation. The complete austenization at 800°C was verified at the atomic scale by minimizing thermal expansion and sample drift in a heating holder based on micro-electro-mechanical-systems. During annealing at 650°C, the formation of reverted austenite was dynamically observed, while the morphologies of austenite laths of 5Mn steel after in-situ heating were quite similar to that after ex-situ intercritical annealing. During annealing at 500°C, the morphological evolution of cementite and associated Mn diffusion were investigated. It was demonstrated that a combination of FIB sampling and high temperature in-situ TEM enables us to probe the morphological evolution and elemental diffusion of specific areas of interest in steel at high spatial resolution.
		2017 Vol. 24 (11): 1109-1114 [Abstract] ( 135 ) [HTML 1KB] [PDF 0KB] ( 233 )

	1115	Ju-hua Liang,Zheng-zhi Zhao,*,Cai-hua Zhang,Di Tang,Shu-feng Yang,Wei-ning Liu
		Microstructure evolution and mechanical properties influenced by austenitizing temperature in aluminum-alloyed TRIP-aided steel
		The Fe-0.21C-2.2Mn-0.49Si-1.77Al transformation induced plasticity (TRIP)-aided steel was heat treated at various austenitizing temperatures under both TRIP-aided polygonal ferrite type (TPF) and annealed martensite matrix (TAM) processes. The microstructure evolution and their effects on mechanical properties were systematically investigated through the microstructure observation and dilatometric analysis. The microstructure homogeneity is improved in TPF steel heated at a high temperature due to the reduced banded martensite and the increased bainite. Compared with the mechanical properties of the TPF steels, the yield strength and elongation of the TAM steels are much higher, while the tensile strength is lower than that of TPF steels. The stability of intercritical austenite is affected by the heating temperature, and thus the following phase transformation influences the mechanical properties, such as the bainite transformation and the precipitation of polygonal ferrite. Obvious dynamic bainite transformation occurs at TAM850, TAM900 and TAM950. More proportion of polygonal ferrite is found in the sample heated at 950°C. The bainite transformation beginning at a higher temperature results in the wider bainitic ferrite laths. The more proportion of polygonal ferrite and wide bainitic ferrite laths commonly contribute to the lower strength and better elongation. The uniform microstructure with lath-like morphology and retained austenite with high average carbon content ensures a good mechanical property in TAM850 with the product of strength and elongation of about 28 GPa·%.
		2017 Vol. 24 (11): 1115-1124 [Abstract] ( 109 ) [HTML 1KB] [PDF 0KB] ( 223 )

	1125	Mei Xu,Yong-gang Yang,Jia-yong Chen,Di Tang,Hai-tao Jiang,Zhen-li Mi,*
		Effects of strain states on stability of retained austenite in medium Mn steels
		Based on uniaxial tensile and plane strain deformation tests, the effects of strain states on the stability of RA (retained austenite) in medium Mn steels, which were subjected to IA (intercritical annealing) and Q&P (quenching and partitioning) processing, were investigated. The volume fractions of RA before and after deformation were measured at different equivalent strains. The transformation behaviors of RA were also investigated. The stability of RA differed across two different transformation stages at the plane strain state: the stability was much lower in the first stage than in the second stage. For the uniaxial tension strain state, the stability of RA corresponded only to a single transformation stage. The main reason was that there were two types of transformations from RA in the medium Mn steel for the plane strain state. One type was that the martensite originated in the strain-induced stacking faults (SISF). The other type was the strain-induced directly twin martensite at a certain equivalent strain. However, for the uniaxial tension state, only the strain-induced twin martensite was observed. Dislocation lines and dislocation tangles were also observed in specimens deformed at different strain states. In addition, complex microstructures of stacking faults and lath-like phases were observed within a grain at the plane strain state.
		2017 Vol. 24 (11): 1125-1130 [Abstract] ( 154 ) [HTML 1KB] [PDF 0KB] ( 247 )

	1131	Chao Tian, Jian-hui Liu*, Heng-chang Lu, Han Dong
		Estimation of maximum inclusion by statistics of extreme values method in bearing steel
		A statistic method, statistics of extreme values (SEV), was described in detail, which can estimate the size of maximum inclusion in steel. The characteristic size of the maximum inclusion in a high clean bearing steel (GCr15) was evaluated by this method, and the morphology and composition of large inclusions found were analyzed by scanning electron microscopy (SEM). When standard inspection area (S0) is 280 mm2, the characteristic size of the biggest inclusion found in 30 standard inspection area is 23.93 μm, and it has a 99.9% probability of the characteristic size of maximum inclusion predicted being no larger than 36.85 μm in the experimental steel. SEM result shows that large inclusions found are mainly composed of CaS, calcium-aluminate and MgO. Compositing widely exists in large inclusions in high clean bearing steel. Compared with traditional evaluation method, SEV method mainly focuses on inclusion size, and the estimation result is not affected by inclusion types. SEV method is suitable for the inclusion evaluation of high clean bearing steel.
		2017 Vol. 24 (11): 1131-1136 [Abstract] ( 94 ) [HTML 1KB] [PDF 0KB] ( 226 )

	1137	Chuan-feng Meng,,Lei Zhang,,Cun-yu Wang,,Yu-jie Zhang,Ying-hui Wei,*, Yi-de Wang,Wen-quan Cao
		Microstructure and mechanical properties of 20Si2CrNi3MoV steel treated by HDQP process
		A combined process of hot-deformation plus two-step quenching and partitioning (HDQP) treatment was applied to a low-carbon 20Si2CrNi3MoV steel, and transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Vickers hardness and tension test were used to characterize the microstructure and mechanical properties. More stable retained austenite due to fine microstructures and typical curved micromorphology is obtained, and the newly-treated steel obtains more retained austenite because of the effect of hot deformation. The retained austenite fraction increases and then decreases with the increasing quenching temperature from 200 to 350°C. The maximum retained austenite fraction (18.3%) and elongation (15%) are obtained to enhance the ductility.
		2017 Vol. 24 (11): 1137-1142 [Abstract] ( 129 ) [HTML 1KB] [PDF 0KB] ( 267 )

	1143	Ting Cheng,,,Rong Zhu,,*,Kai Dong,
		Effect of methane-hydrogen mixtures on flow and combustion of coherent jets
		Coherent jets are widely used in electric arc furnace (EAF) steelmaking to increase the oxygen utilization and chemical reaction rates. However, the influence of fuel gas combustion on jet behavior is not fully understood yet. The flow and combustion characteristics of a coherent jet were thus investigated at steelmaking temperature using Fluent software, and a detailed chemical kinetic reaction mechanism was used in the combustion reaction model. The axial velocity and total temperature of the supersonic jet were measured via hot state experiments. The simulation results were compared with the experimental data and the empirical jet model proposed by Ito and Muchi and good consistency was obtained. The research results indicated that the potential core length of the coherent jet can be prolonged by optimizing the combustion effect of the fuel gas. Besides, the behavior of the supersonic jet in the subsonic section was also investigated, as it is an important factor for controlling the position of the oxygen lance. The investigation indicated that the attenuation of the coherent jet is more notable than that of the conventional jet in the subsonic section.
		2017 Vol. 24 (11): 1143-1151 [Abstract] ( 119 ) [HTML 1KB] [PDF 0KB] ( 231 )

	1152	Qiang Gao,,Yi Min,,*,Cheng-jun Liu,,Mao-fa Jiang,
		Structural behavior of F- in mould flux melt of CaO-SiO2-Al2O3-Na2O-CaF2 system
		The influence of fluorine on the structure of CaO-SiO2-Al2O3-Na2O-CaF2 continuous-casting-type slag was measured by Raman spectroscopy, and the degree of polymerization of mould flux and the structural behavior of F- in the melt were investigated by classifying and quantifying the structural species of F- ions. The results exhibit that the main structural units of Si-O tetrahedra are Q0, Q1 and Q2, and the actual measured number of non-bridging oxygen ions in the ［SiO4］-tetrahedra (denoted by NBO/T) increases from 2.73 to 3.44 with increasing the molar ratio of F to (F+O) (denoted by XF/X(F+O)) from 0.06 to 0.19. It means that the degree of polymerization of melt structure decreases with an increase in XF/X(F+O). In addition, most of F- ions were distributed in Si-O tetrahedra and Al-O tetrahedra. With increasing XF/X(F+O), the complex structural units Al-O tetrahedra are gradually replaced by discrete structural units AlF4- because of the breakage of Al-O bonds in Al-O tetrahedra by F- ions, and the Si-O (bridging oxygen) bonds of Si-O tetrahedra are broken to form ［SiOnF4-n］-tetrahedra by F- ions coordinating with Si4+.
		2017 Vol. 24 (11): 1152-1158 [Abstract] ( 138 ) [HTML 1KB] [PDF 0KB] ( 241 )

	1159	Yu-jun Li,Huan Li,Peng Lan,Hai-yan Tang,Jia-quan Zhang*
		Thermo-elasto-visco-plastic finite element analysis on formation and propagation of off-corner subsurface cracks in bloom continuous casting
		The formation and propagation of the popular off-corner subsurface cracks in bloom continuous casting were investigated through thermo-mechanical analysis using three coupled thermo-mechanical models. A two-dimensional thermo-elasto-visco-plastic finite element model was developed to predict the mould gap evolution, temperature profiles and deformation behavior of the solidified shell in the mould region. Then, a three-dimensional model was adopted to calculate the shell growth, temperature history and the development of stresses and strains of the shell in the following secondary cooling zones. Finally, another three-dimensional model was used to analyze the stress distributions in the straightening region. The results showed that the off-corner cracks in the shell originated from the mould owing to the tensile strain developed in the crack sensitive regions of the solidification front, and they could be driven deeper by the possible severe surface temperature rebound and the extensive tensile stress in the secondary cooling zone, especially upon the straightening operation of the bloom casting. It is revealed that more homogenous shell temperature and thickness can be obtained through optimization of mould corner radius, casting speed and secondary cooling scheme, which help to decrease stress and strain concentration and therefore prevent the initiation of the cracks.
		2017 Vol. 24 (11): 1159-1167 [Abstract] ( 110 ) [HTML 1KB] [PDF 0KB] ( 212 )

	181	Xue-min Yang . Jin-yan Li . Fang-jia Yan . Dong-ping Duan . Jian Zhang
		Critical assessment of three kinds of activity coefficients of carbon and related mixing thermodynamic functions of Fe–C binary melts based on atom–molecule coexistence theory
		Raoultian activity coefficients γ0C of C in infinitely dilute Fe–C binary melts at temperatures of 1833, 1873, 1923, and 1973 K have been determined from the converted mass action concentrations N’C of C in Fe–C binary melts by the developed AMCT-Ni model based on the atom–molecule coexistence theory (AMCT). The obtained expression of γ0C by the developed AMCT-Ni model has been evaluated to be accurate based on the reported ones from the literature. Meanwhile, three activity coefficients γC, f%,C, and fH,C of C coupled with activity aR,C or a%,C or aH,C have been obtained by the developed AMCT-Ni model and assessed through comparing with the predicted ones by other models from the literature. The first-order activity interaction coefficients εCC, eCC, and hCC related to γC, f%,C, and fH,C are also determined and assessed in comparison with the reported ones from the literature. Furthermore, the integral molar mixing thermodynamic functions such as ΔmixHm,Fe-C, ΔmixSm,Fe-C, and ΔmixGm,Fe-C of Fe–C binary melts over a temperature range from 1833 to 1973 K have been determined and evaluated to be valid based on the determined ones from the literature.
		2017 Vol. 24 (11): 181-199 [Abstract] ( 127 ) [HTML 1KB] [PDF 0KB] ( 216 )

钢铁研究学报(英文版)

　

News

　

　

·	《钢铁研究学报》第二届青年编委招募

·	Call for Papers for the Special Issue on “Corrosion and wear of materials in extreme environments”

·	Call for Papers for the Special Issue on “Resources Recycling of Solid Wastes from Ironmaking and St

·	Call for Papers for the Special Issue on "Numerical Simulation of Multiphase and Multiscale Metallur

·	Call for Papers for the Special Issue on “Application of AI in steelmaking and ferrous materials”

　　　　　　　　　　More

　

Author Center

　

　

Instruction for Authors

　

　

Copyright Agreement

　

Links

　

　　　　　　　　　　More

Copyright © JOURNAL OF IRON AND STEEL RESEARCH INTERNATIONAL　
Supported by: Beijing Magtech