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Analysis of Hot Rolling Routes of AZ31B Magnesium Alloy and Prediction of Tensile Property of Hot-rolled Sheets

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Journal of Wuhan University of technology(Materials Science) 2017年第2期32卷 451-458页

作者：范沁红徐海洁 MA Lifeng JIA Weitao HUANG Zhiquan LIU Guangming LIN Jinbao FANG Daqing Shanxi Provincial Key Laboratory of Metallurgical Equipment Design and Technology Taiyuan University of Science and TechnologyTaiyuan 030024 China The key laboratory of Electromagnetic Processing of Materials Ministry of Education Northeastern University Shenyang 110004 China

At the initial rolling temperature of 250 to 400 ℃, AZ31B magnesium alloy sheets were hot rolled by four different rolling routes. Microstructures and mechanical properties of the hot-rolled magnesium alloy sheets were analyzed by optical microscope and tensile tests respectively. Based on the Hall-Petch relation, considering the average grain size and grain size distribution, the nonlinear fitting analysis between the tensile strength and average grain size was carried on, and then the prediction model of tensile strength of hot-rolled AZ31B magnesium alloy sheet was established. The results indicate that, by rolling with multi-pass cross rolling, uniform, fine and equiaxial grain microstructures can be produced, the anisotropy of hot-rolled magnesium sheet can also be effectively weakened. Strong correlation was observed between the average grain size and tensile property of the hot-rolled magnesium alloy sheet. Grain size distribution coefficient d（CV） was introduced to reflect the dispersion degree about a set of grain size data, and then the Hall-Petch relation was perfected. Ultimately, the prediction accuracy of tensile strength of multi-pass hot-rolled AZ31B magnesium alloy was improved, and the prediction of tensile property can be performed by the model.

关键词： AZ31B magnesium alloy rolling route microstructure and mechanical property prediction

Characterization of hot deformation behavior of wear-resistant steel BTWl using processing maps and constitutive equations

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Journal of Iron and Steel Research(International) 2018年第10期25卷 1054-1061页

作者： Peng-tao Liu Qing-xue Huang Li-feng Ma Tao Wang College of Mechanical Engineering Taiyuan University of Technology Taiyuan 030024 Shanxi China Shanxi Provincial Key Laboratory of Metallurgical Equipment Design and Technology Taiyuan University of Science and Technology Taiyuan 030024 Shanxi China Heavy Machinery Engineering Research Center of the Ministry Education Taiyuan University of Science and Technology Taiyuan 030024 Shanxi China

In order to predict flow instability of wear-resistant steel BTW1, the hot compressions of wear-resistant steel BTW1 were firstly performed at the temperature of 900-1150 ℃ and at the strain rate of 0.05-15 s-1. Then, the constitutive relation was established based on Arrhenius-type hyperbolic sine equation. The results demonstrated that the flow stress depended on the deformation temperature and strain rate. When the deformation temperature kept constant, the flow stress increased as the strain rate increased. When the strain rate remained constant, the flow stress decreased as the temperature increased. The flow stresses calculated by constitutive equations were in a good agreement with experimental results. The apparent activation energy for deformation in the above processing region was estimated to be 369 kJ tool-1. A processing map could be obtained by the superimposition of an instability map on a power dissipation map. Based on the analysis of processing map and the microstructures, the theological instability regimes of strain rate and temperature for hot deformation of wear-resistant steel BTWl had been identified.

关键词： Wear-resistant steel BTW 1 Processing map Constitutive equation Hot deformation Dynamicrecrystallization

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Journal of Iron and Steel Research(International) 2014年第10期21卷 931-937页

作者： Qing-xue HUANG Xiao-rong YANG Li-feng MA Cun-long ZHOU Guang-ming LIU Hai-bing LI shanxi provincial key laboratory of metallurgical Device design Theory and technology Taiyuan University of Science and Technology Superplasticity Institute Jilin University

Stainless steel （S S）/carbon steel （C S） clad plates were generated by means of the all-around weld of interface and vacuuming （AAWIV） followed by hot rolling, wherein AAWIV was utilized for controlling the interface oxidation during hot rolling. The structure near the interface was analyzed by optical microscopy （OM）, scanning electron mi- croscopy （SEM） and transmission electron microscopy （TEM）. The mechanical properties of SS/CS clad plates were investigated by tensile and shear as well as bend tests. The SS/CS interface is relatively flat and no visible separation appears. Line scanning analysis shows that diffusion of Cr and Ni from SS to CS and C from CS to SS occurred during bonding. Higher dislocation densities are observed in both layers of parent plates adhering to the interface. The SS/ CS clad plates reveal higher yield, tensile and shear strengths. Both macroscopic delamination at the interface and fracture of base CS as well as intergranular fracture appearance of flyer plate are observed in the tensile test. The shear specimen fails in a ductile manner and the bend specimen tested shows no visible crack at the interface. Taking both interracial structure and mechanical properties into account, the SS/CS clad plates exhibit sound bonding by the process of AAWIV and hot rolling.

关键词： clad interface structure AAWIV strength

Numerical model establishment and verification of cold pilgering on cycle feed rate

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Journal of Iron and Steel Research(International) 2018年第4期25卷 398-408页

作者： Zhi-bing Chu Dong Wei Lian-yun Jiang Duo Zhang Qing-xue Huang Yu-gui Li Heavy Machinery Engineering Research Center of Ministry of Education Taiyuan University of Science and Technology Taiyuan 030024 Shanxi China shanxi provincial key laboratory of metallurgical Device design Theory and technology Taiyuan University of Science and Technology Taiyuan 030024 Shanxi China

A numerical model was established to calculate the cycle feed rate through studying the case of a cold pilger mill with the 304 stainless steel pipe. Firstly, the precise constitutive equation of 304 stainless steel was obtained through nonlinearly fitting the true stress-strain data from unidirectional tensile test. Then, the numerical method to calculate the equivalent deformation was determined according to the plastic deformation feature of the steel tube during cold rolling and the incremental theory. Finally, the cycle feed rate of cold roiled 304 stainless steel pipe was extracted when formulating springback through utilizing above results comprehensively and unloading law. Stress state, metal flow, finished pipe size and distribution of residual stress were obtained by finite element method to calculate the whole rolling process when the cycle feed rate was 10 mm, and the optimized model was verified through finished pipe size.

关键词： Cycle feed rate Cold pilgering 304 stainless steel pipe Constitutive relationship Incremental theory Unloading law Residual stress experiment

Hot deformation behavior of a novel bimetal consisting of BTW1 and Q345R characterized by processing maps

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Frontiers of Mechanical Engineering 2019年第4期14卷 489-495页

作者： Pengtao LIU Lifeng MA Weitao JIA Tao WANG Guanghui ZHAO College of Mechanical Engineering Taiyuan University of TechnologyTaiyuan 030024China Shanxi Provincial Key Laboratory of Metallurgical Equipment Design and Technology Taiyuan University of Science and TechnologyTaiyuan 030024China College of Mechanical Engineering Taiyuan University of Science and TechnologyTaiyuan 030024China

Only a few studies have been conducted on the flow behavior of the novel BTW1/Q345R bimetal,which is widely used in coal equipment.In this work,compression tests were conducted on BTW1/Q345R bimetal at a temperature range of 950°C–1200°C and strain rates of 0.05,0.5,5,and 15 s^−1 by using a Gleeble-3800 thermomechanical simulator.A constitutive equation was validated by referring to the Arrhenius equation during the characterization of hot workability.The computed apparent activation energy of the BTW1/Q345R bimetal was 360 kJ/mol,and processing maps under different strain conditions were drawn.Analysis of the stress-strain relationship revealed that work hardening exerted a dominant effect on the thermal deformation of the BTW1/Q345R bimetal.The processing maps predicted that the optimal processing interval will increase with strain.Results showed that thermal deformation of the BTW1/Q345R bimetal should proceed when the temperature range varies from 1182°C to 1200°C and the strain rate interval is from 4.2 to 15 s^−1.

关键词： BTW1/Q345R bimetal constitutive equation processing map work hardening

Effect of Reduction on Bonding Interface of Hot-rolled Wear-resistant Steel BTW1/Q345R Cladding Plate

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Journal of Wuhan University of technology(Materials Science) 2018年第4期33卷 952-958页

作者：支晨琛马立峰 HUANG Qingxue HUANG Zhiquan LIU Pengtao The Coordinative Innovation Center of Taiyuan Heavy Machinery equipment Taiyuan University of Science and TechnologyTaiyuan 030024China Shanxi Provincial Key Laboratory of Metallurgical Equipment Design and Technology Taiyuan University of Science and TechnologyTaiyuan 030024China School of Mechanical Engineering Taiyuan University of TechnologyTaiyuan 030024China

Wear-resistant cladding plates consisting of a substrate（Q345 R） and a clad layer（BTW1） were bonded through hot rolling at the temperature of 1 200 ℃ and a rolling speed of 0.5 m/s. The microhardness of the cladding plate was also tested after being heat treated. The microstructure evolution on the interface of BTW1/Q345 R sheets under various reduction rates was investigated with a scanning electron microscope（SEM） and EBSD. It is found that the micro-cracks and oxide films on the interface disappear when the reduction is 80%, whereas the maximum uniform diffusion distance reaches 10 μm. As a result, a wide range of metallurgical bonding layers forms, which indicates an improved combination between the BTW1 and the Q345 R. Additionally, it is discovered that the unbroken oxide films on the interface are composed of Mn, Si or Cr at the reductions of 50% and 65%. The SEM fractography of tensile specimen demonstrates that the BTW1 has significant dimple characteristics and possesses lower-sized dimples with the increment in reduction, suggesting that the toughness and bonding strength of the cladding plates would be improved by the increase of reduction. The results reveal that a high rolling reduction causes the interfacial oxide film broken and further forms a higher-sized composite metallurgical bonding interface. The peak microhardness is achieved near the interface.

关键词： BTW1/Q345R clad plate hot-rolled bonding reduction oxide films fractography

Micro Extrusion of Ultrafine Grained Titanium Prepared by ECAP

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Journal of Wuhan University of technology(Materials Science) 2017年第2期32卷 437-443页

作者：王效岗 LIU Jianlong ZHAO Xicheng LIU Xiaoyan XIE Haibo JIANG Zhengyi shanxi Province metallurgical equipment design Theory and technology key laboratory (provincial Department to Build National key laboratory Training Base) Taiyuan University of Science and Technology Taiyuan 030024 China metallurgical Engineering College Xi'an University of Architecture and Technology Xi'an 710055 China School of Mechanical Materials and Mechatronic Engineering University of Wollongong Wollongong NSW 2522 Australia

Micro compression and micro extrusion experiments of ultrafine grained titanium cylindrical specimens in diameters of 4, 2, and 1 mm prepared by equal channel angular pressing（ECAP） were conducted on the micro plastic forming test machine. The effects of specimen size, grain size, deformation temperature and extrusion speed on the flow stress and forming properties of the ultrafine grained pure titanium were investigated. The flow stress of ultrafine grained pure titanium specimen decreases with decreasing specimen size. The yield limit of pure titanium with refined grain prepared by ECAP is significantly greater than that of coarse grained specimen. Also the research results show that the flow stress of specimen increases with decreasing deformation temperature and with the increase of the strain rate, and the ultrafine grained pure titanium possesses good micro forming properties at deformation temperature of 300 ℃.

关键词： micro forming ECAP pure titanium flow stress micro extrusion

Analysis of High-Cr Cast Iron/Low Carbon Steel Wear-resistant Laminated Composite Plate Prepared by Hot-rolled Symmetrical Billet

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Computer Modeling in Engineering & Sciences 2018年第10期117卷 109-123页

作者： Yanwei Li Yugui Li Peisheng Han Shun Wang Zhengyi Jiang Xiaogang Wang shanxi provincial key laboratory of metallurgical Device design Theory and technology(State key laboratory Cultivation Base of Province-Ministry Co-Construct) Taiyuan University of Science and TechnologyTaiyuanChina School of Mechanical Materials and Mechatronic EngineeringUniversity of WollongongWollongong NSW2522Australia

This study developed a new technology for preparing high-chromium cast iron(HCCI)/low-carbon steel(LCS)wear-resistant composite plates by hot rolling at a 1050°C and a rolling speed of 0.2 m/s.The effects of different rolling reductions(30%,45%,and 60%)on the microstructure(interface and HCCI layer)and mechanical properties(bonding strength,hardness,and wear resistance)of the composite plate were studied.SEM images showed that when the reduction was increased,no impurities and interlayers were found between the microscopic interfaces after hot rolling,and the bonding interface exhibited a wave-like shape.EDS analysis showed that the Cr element diffusion between two metals after hot rolling was promoted when the reduction was increased,thereby improving the bonding quality under the same rolling temperature and rolling speed.Experiments showed that due to the stress release effect of the LCS of the cladded layer,the macro-slab shape after hot rolling performed well,and the brittle HCCI layer underwent thermoplastic deformation without cracking.Moreover,the increase of rolling reduction improved the bonding quality.As the rolling reduction was increased,the volume fraction of Cr-carbides in the HCCI layer also increased,resulting in an increase of hardness and wear-resistance.

关键词： High chromium cast iron symmetrical billet hot rolled laminated composite plate

Effect of extrusion speed on microstructure and mechanical properties of the Mg-Ca binary alloy

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Journal of Magnesium and Alloys 2021年第4期9卷 1304-1310页

作者： Jingren Li Aiyue Zhang Hucheng Pan Yuping Ren Zhuoran Zeng Qiuyan Huang Changlin Yang Lifeng Ma Gaowu Qin key laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China State key laboratory of Rolling and Automation Northeastern UniversityShenyang110819China Department of Materials Science and Engineering Monash UniversityVic.3800Australia Institute of Metal Research Chinese Academy of SciencesShenyang 110016China State key laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’anShaanxi 710072China Shanxi Provincial Key Laboratory of Metallurgical Equipment Design and Technology Taiyuan University of Science and TechnologyTaiyuan 030024China

This work reported the effect of extrusion speeds on the microstructures and mechanical properties of Mg-Ca binary alloy.The results showed that yield strength of the as-extruded Mg-1.2wt.%Ca alloys decrease from∼360MPa to∼258MPa as the ram speed increases from 0.4mm/s to 2.4 mm/s,and the elongation increases from∼3.9%to∼12.2%.The microstructure changes from bimodal grain feature to the complete dynamical recrystallization(DRX)with increase of the extrusion speed.The ultrafine DRXed grains in size of∼0.85μm,the numerous nano-Mg_(2)Ca particles dispersing along the grain boundaries and interiors,as well as the high density of residual dislocations,should account for the high strength.It is believed that the high degree of dynamic recrystallization and the resulting texture randomization play the critical roles in the ductility enhancement of the high-speed extruded Mg alloys.

关键词： Extrusion speed Microstructure Mechanical properties Mg-Ca alloy