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Grain refinement in the coarse-grained region of the heat-affected zone in low-carbon high-strength microalloyed steels

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International Journal of Minerals,Metallurgy and Materials 2010年第6期17卷 737-741页

作者： Ran Wei cheng-jia shang Kai-ming Wu International Research Institute for Steel Technology Wuhan University of Science and Technology Wuhan 430081 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

The microstructural features and grain refinement in the coarse-grained region of the heat-affected zone in low-carbon high-strength microalloyed steels were investigated using optical microscopy, scanning electron microscopy, and electron backscattering dif- fraction. The coarse-grained region of the heat-affected zone consists of predominantly bainite and a small proportion of acicular ferrite. Bainite packets are separated by high angle boundaries. Acicular ferrite laths or plates in the coarse-grained region of the heat-affected zone formed prior to bainite packets partition austenite grains into many smaller and separate areas, resulting in fine-grained mixed microstruc- tures. Electron backscattefing diffraction analysis indicates that the average crystallographic grain size of the coarse-grained region of the heat-affected zone reaches 6-9 μm, much smaller than that of anstanite grains.

关键词： microalloyed steels welding grain refinement bainite acicular ferrite

Surface Nanocrystallization of Nb-Ti Stabilized 439M Ferritic Stainless Steel

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Journal of Iron and Steel Research International 2014年第9期21卷 891-896页

作者： Yao-chun ZHANG Chao CHEN cheng-jia shang Dong-yang LI Nuclear Equipment Division CNNC China Nuclear Power Engineering Co.Ltd. School of Materials Science and Engineering University of Science and Technology Beijing Department of Chemical and Materials Engineering University of AlbertaEdmonton T6G2V4AlbertaCanada

A new nanocrystallization process was designed, which included punching the surface coating to generate dislocation network or cells and recovery treatment to turn the dislocation cells into nano-sized grains. The effort was made to increase the service life of Nb-Ti stabilized 439M stainless steel surface with medium passive ability, particularly to enhance the outmost surface layer by nanocrystallization for improving resistances to corrosion. Electrochemical properties, electron work functions （EWFs）, nano-mechanical properties of the nanocrystallized surfaces were investigated. It was demonstrated that the nanocrystallized 439M stainless steel surface exhibited improved resistance to corrosion in 0.5 mol/L H2 SO4 solution. However, the nanoci＇ystallized 439M stainless steel surface exhibited decreased resistance to corrosion in 3.5% NaCl solution.

关键词： nanocrystallization corrosion ferritic stainless steel punching recovery

Nucleation Analysis of Variant Transformed from Austenite with Σ_(3) Boundary in High-Strength Low-Alloy Steel

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Acta Metallurgica Sinica(English Letters) 2021年第4期34卷 523-533页

作者： Bin-Bin Wu Zhi-Quan Wang cheng-jia shang Yi-Shuang Yu Devesh Misra Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing100083China State Key Laboratory of Metal Material for Marine Equipment and Application Anshan114000China Laboratory for Excellence in Advanced Steel Research Department of MetallurgicalMaterials and Biomedical EngineeringUniversity of Texas at El Paso500 WUniversity AvenueEl PasoTX79968USA

We elucidate here the effects of annealing twins on phase transformation products based on electron back-scatter diffraction analysis and corresponding microstructure visualization and quantification *** and bainite were obtained by rapid continuous cooling and isothermal processing at different temperatures,respectively,which were designed to study variants formed in austenite with Σ_(3) *** isothermal transformation near martensite start(M_(s))temperature was most conducive in obtaining the highest content of twin-related V_(1)/V_(2) variant *** on the classical nucleation theory of martensite and bainite,respectively,the role of austenite Σ_(3) boundary in martensite and bainite transformation is illustrated.

关键词： Steel AusteniteΣ_(3)boundary Variant Phase transformation Martensite Bainite

Recent progress in third-generation low alloy steels developed under M^3 microstructure control

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International Journal of Minerals,Metallurgy and Materials 2020年第1期27卷 1-9页

作者： Zhen-jia Xie cheng-jia shang Xue-lin Wang Xue-min Wang Gang Han Raja-devesh-kumar Misra Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China Institute of Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China Laboratory for Excellence in Advanced Steel Research Department of MetallurgicalMaterials and Biomedical EngineeringUniversity of Texas at El PasoEl PasoTX 79968USA

During the past thirty years, two generations of low alloy steels(ferrite/pearlite followed by bainite/martensite) have been developed and widely used in structural applications. The third-generation of low alloy steels is expected to achieve high strength and improved ductility and toughness, while satisfying the new demands for weight reduction, greenness, and safety. This paper reviews recent progress in the development of third-generation low alloy steels with an M^3 microstructure, namely, microstructures with multi-phase, meta-stable austenite, and multi-scale precipitates. The review summarizes the alloy designs and processing routes of microstructure control, and the mechanical properties of the *** stabilization of retained austenite in low alloy steels is especially emphasized. Multi-scale nano-precipitates, including carbides of microalloying elements and Cu-rich precipitates obtained in third-generation low alloy steels, are then introduced. The structure–property relationships of third-generation alloys are also discussed. Finally, the promises and challenges to future applications are explored.

关键词： third-generation low alloy steels multi-phase microstructure meta-stable retained austenite multi-scale precipitates

Molybdenum alloying in high-performance flat-rolled steel grades

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Advances in Manufacturing 2020年第1期8卷 15-34页

作者： Pello Uranga cheng-jia shang Takehide Senuma Jer-Ren Yang Ai-Min Guo Hardy Mohrbacher CEIT and TECNUN University of NavarraSan SebastianSpain Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083People's Republic of China Graduate School for Nature Science Okayama UniversityOkayamaJapan Institute of Materials Science and Engineering Taiwan UniversityTaipeiTaiwanPeople's Republic of China CITIC Metal Beijing 100027People's Republic of China Department of Materials Engineering KU LeuvenLeuven 3001Belgium NiobelCon bvba Schilde 2970Belgium

Considerable progress in developing flat-rolled steel grades has been made by the Chinese steel industry over the recent two *** increasing demand for high-performance products to be used in infrastructural projects as well as in production of consumer and capital goods has been driving this development until *** installation of state-of-the-art steel making and rolling facilities has provided the possibility of processing the most advanced steel *** production of high-performance steel grades relies on specific alloying elements of which molybdenum is one of the most *** is nearly self-sufficient in molybdenum *** paper highlights the potential and advantages of molybdenum alloying over the entire range of flat-rolled steel *** aspects of steel property improvement with respect to particular applications are indicated.

关键词： HSLA steel Quench&tempering Direct quenching Press hardening Quenching&partitioning Precipitation

Properties and homogeneity of 550-MPa grade TMCP steel for ship hull

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International Journal of Minerals,Metallurgy and Materials 2010年第2期17卷 179-184页

作者： Yi Nie cheng-jia shang Xin Song Yang You Chuang Li Xin-lai He School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Department of Physics and Chemistry Henan Polytechnic University Jiaozuo 454000 China

Ultra low carbon steels by the thermal mechanical control process（TMCP） with less Ni,Cr,and Mo contents have been developed for 550 MPa grade heavy gauge ship hulls and offshore *** relationships among microstructures,process,and properties of the studied steel have been investigated.A series of accurate control technologies have been developed for this kind of *** microalloying and TMCP＋relaxation precipitation control（RPC）＋accelerated cooling process were employed to optimize the mechanical properties and ensure the homogeneity of the 80-mm thick *** microstructures of thin plates slightly changed from surface to center,but the micro-structures of the heavy gauge plate（80 mm） changed *** the simple composition,it can meet the requirement of thin plates by adopting a few *** for thick plates（80 mm）,a little higher Cu and Ni contents should be *** steels can meet the needs without *** these ways,the properties of the steels can be optimized,and the cost can be decreased notably.

关键词： microalloyed steel thick plate microstructure mechanical properties microalloying relaxation precipitation accelerated cooling

Life Prediction of Newly Developed Ferritic Stainless Steels for Automotive Muffler

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Journal of Iron and Steel Research International 2014年第1期21卷 125-130页

作者： Chao CHEN Yue ZHENG Yue ZHANG Xiao-hui LU cheng-jia shang Nuclear Equipment Division CNNC China Nuclear Power Engineering Co.Ltd. School of Materials Science and Engineering University of Science and Technology Beijing Nuclear and Radiation Safety Center MEP

Corrosion mechanism of automotive mufflers was investigated by SEM （scanning electron microscope） and XRD （X-ray diffractomer） analysis. 409L and newly developed 439M steels were evaluated in terms of condensate corrosion tests for 5 periods, 10 periods and 20 periods separately. The relative lifetimes of 409L and 439M steels were predicted according to the extreme value analysis method and pitting corrosion models. Modelling studies dem- onstrated that the predicted relative lifetime of 439M ferrite stainless steel is 6.8 times that of 409L steels. The extreme value analysis method was also successfully used in the road test. The estimated maximum corrosion depth of the 439M muffler is 0. 55 ram.

关键词： stainless steel SEMi XRD modelling study pitting corrosion

Determining role of heterogeneous microstructure in lowering yield ratio and enhancing impact toughness in high-strength low-alloy steel

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International Journal of Minerals,Metallurgy and Materials 2021年第5期28卷 816-825页

作者： Yi-shuang Yu Bin Hu Min-liang Gao Zhen-jia Xie Xue-quan Rong Gang Han Hui Guo cheng-jia shang Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China Institute of Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Metal Material for Marine Equipment and Application Anshan 114021China

Here we present a novel approach of intercritical heat treatment for microstructure tailoring,in which intercritical annealing is introduced between conventional quenching and *** induced a heterogeneous microstructure consisting of soft intercritical ferrite and hard tempered martensite,resulting in a low yield ratio(YR)and high impact toughness in a high-strength low-alloy *** initial yielding and subsequent work hardening behavior of the steel during tensile deformation were modified by the presence of soft intercritical ferrite after intercritical annealing,in comparison to the steel with full martensitic *** increase in YR was related to the reduction in hardness difference between the soft and hard phases due to the precipitation of nano-carbides and the recovery of dislocations during *** excellent low-temperature toughness was ascribed not only to the decrease in probability of microcrack initiation for the reduction of hardness difference between two phases,but also to the increase in resistance of microcrack propagation caused by the high density of high angle grain boundaries.

关键词： heterogeneous microstructure yield ratio impact toughness intercritical heat treatment high-strength low-alloy steel

Tailoring Variant Pairing to Enhance Impact Toughness in High-Strength Low-Alloy Steels via Trace Carbon Addition

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Acta Metallurgica Sinica(English Letters) 2021年第6期34卷 755-764页

作者： Yi-Shuang Yu Zhi-Quan Wang Bin-Bin Wu Jing-Xiao Zhao Xue-Lin Wang Hui Guo cheng-jia shang Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China Key Laboratory for Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China State Key Laboratory of Metal Material for Marine Equipment and Application Anshan 114021China

Alloying can make conventional metals reach ultra-high strength,but this usually comes at dramatic loss of *** this work,a desirable strength–toughness combination in high-strength low-alloy steel achieved via trace carbon *** significance of carbon in tailoring variant pairing and tuning impact toughness was elucidated from the perspective of crystallography and *** the carbon content increases,the packets and blocks are refined,and the-40 impact toughness *** enhancement of impact toughness results from the higher density of block boundaries,and the fracture mode shifts from brittle fracture to ductile–brittle combined fractures,then to ductile fracture due to the increased *** the carbon content would lower the martensite start temperature(M_S)temperature and driving force for martensitic transformation,and increase the strength of austenite matrix,which in turn contributes to producing more V1/V2 variant pairs to accommodate the transformation strain.

关键词： High-strength low-alloy steel Carbon Impact toughness Variant pairing Phase transformation