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Influence of texture distribution in magnesium welds on their non-uniform mechanical behavior:A CPFEM study

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Journal of Materials Science & Technology 2020年第11期42卷 168-176页

作者： Weijie Ren Dejia Liu Qing Liu renlong xin Joint International Laboratory for Light Alloys(MOE) College of Materials Science and EngineeringChongqing UniversityChongqing 400044China College of Materials Science and Engineering East China Jiaotong UniversityNanchang3300J3China Key Laboratory for Light-weight Materials NanjingTech UniversityNanjing211816China

Recent studies indicate that the texture distribution in friction stir welded(FSW)Mg alloys can be tailored and hence improve the joint *** this work,a crystal plasticity finite element modeling(CPFEM)was performed to understand the effects of texture distribution in stir zone(SZ)on the nonuniform plastic deformation and fracture *** total,six kinds of observed or purposely tilted texture distributions were ***"concave-convex"appearance,as commonly observed in the tensile sample,was successfully *** reveals that the mirror-symmetrical distribution of basal planes in the region of easy to activate basal slip(EABS)determined the"concave-convex"appearance in *** asymmetrical appearance exchanged on plane A and plane B when the directions of basal planes were switched in the two EABS ***,the asymmetrical feature of plastic deformation was changed with varying the texture distribution in ***"embossed"feature became more obvious in SZ-center first,and then gradually weakened with the c-axis rotated away from the weld plate *** necking was successfully simulated in SZ-center of FSW-H joint and in SZ-side of FSW-L *** might determine the observed fracture *** believe that this simulation study is helpful for further improving the performance of FSW Mg joints.

关键词： Friction stir welding Magnesium alloy CPFEM Non-uniform deformation Fracture

Evolution mechanism of lamellarαand interlayeredβduring hot compression of TC21 titanium alloy with a widmanst?tten structure

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Chinese Journal of Aeronautics 2022年第3期35卷 475-483页

作者： Xiaoyu ZHENG Ke WANG Cheng ZHANG renlong xin Qing LIU International Joint Laboratory for Light Alloys(MOE) School of Materials Science and EngineeringChongqing UniversityChongqing 400044China

TC21 titanium alloy,as an important metal to fabricate the aircraft structural components,has attracted great attentions recently.A TC21 titanium alloy with widmanst?tten structure was isothermally *** on the microstructure observation,the evolution of initialβgrain,Grain Boundaryαphase(α;),lamellar a and interlayeredβwas systematically *** results showed that,with the increasing of height reduction,theα;underwent an evolution process from bending/kinking to breaking inducing the corresponding blurring of initial coarse b grain ***,a significant phase transformation from a to b took place at the terminations of brokenα;.The evolution of lamellarαand interlayeredβin the colony was closely related to their deformation *** the a colony,the interlayered b experienced a larger deformation amount than lamellarα.The higher distortion energy promoted the occurrence of Dynamic Recovery(DRV)and Dynamic Recrystallization(DRX)to generate many Low Angle Boundaries(LABs)and High Angle Boundaries(HABs)in interlayered b,which induced an apparent grain refinement of b *** the contrary,the lower distortion energy and low deformation temperature suppressed the occurrence of DRV/DRX and restrained the globularization of lamellarα.Furthermore,the microstructure observation clearly revealed that the shearing separation mechanism dominated the evolution of the a phase from lamellar to short bar-like morphology.

关键词： Globularization Grain refinement Hot deformation Interlayeredβ Lamellarα Titanium alloy

Influence of extrusion ratio on microstructure and texture developments of high-temperature extruded AZ31 Mg alloy

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Science China(Technological Sciences) 2012年第2期55卷 490-495页

作者： LI NaLi HUANG GuangJie xin renlong LIU Qing Department of Materials Science and Engineering Chongqing UniversityChongqing 400044China

Experiments were conducted to evaluate the effects of extrusion ratio on the microstructure and texture developments of AZ31 Mg alloy during forward extrusion. The forward extrusion was undertaken at 400℃ with extrusion ratios of 10, 18, and 25 after the alloy was homogenized at 410℃ for 12 h. Partially recrystallized microstructures were observed in all the extruded rods examined. The texture of the large elongated deformed grains appeared strongly centered at （1010） dominating the extrusion texture, while the recrystallized grains exhibited much more randomized texture. For the alloy with the largest ER （25）, coarse secondary recrystallized grains were found which presented a different texture component with （11 2 0） parallel to the ED. The occurrence of the coarse secondary recrystallized grains in the alloy with the largest ER might be attributed to that the large ER raised the die exit temperature during extrusion and thus promoted significantly grain growth after the extruded rod exited from extrusion die. The intensities of different texture components varied with ER because ER affected the contents of the deformed grains, DRX grains and coarse secondary recrystallized grains. In particular, the maximum intensity of fiber texture was decreased as ER increased due to the decrease of the large elongated deformed grains.

关键词： magnesium alloy extrusion ratio texture

Dislocation Slip and Crack Nucleation Mechanism in Dual‑Phase Microstructure of Titanium Alloys:A Review

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Acta Metallurgica Sinica(English Letters) 2023年第3期36卷 353-365页

作者： Ke Wang Honghui Li Yu Zhou Jingfeng Wang renlong xin Qing Liu International Joint Laboratory for Light Alloys(MOE) School of Materials Science and EngineeringChongqing UniversityChongqing 400044China

The study on the deformation mechanism of titanium alloys is beneficial to revealing the influence of microstructure on mechanical properties,and then providing guidance for the optimization of microstructure and *** most near-αandα+βtitanium alloys,slip is the dominant deformation ***,investigating the slip initiation and slip transfer behavior,as well as crack nucleation mechanism,is essential to reveal the fundamental relationship between microstructure and mechanical ***,due to the coexistence of grain boundary and phase boundary in dualphase microstructure of titanium alloys,the phase content,grain size,grain boundary misorientation andα/βorientation relationship would affect the slip initiation and transfer behavior,resulting in a very complex plastic deformation *** on the previous investigations of deformation mechanism of near-αandα+βtitanium alloys,this review first analyzed the sequence of slip initiation betweenαandβphases and discussed the main factors affecting the slip initiation inα***,the basic rule of slip transfer and the influence of different interfaces on slip transfer were ***,the mechanism of crack nucleation and effect of microstructure on crack nucleation were analyzed based on slip transfer behavior.

关键词： Deformation mechanism Slip initiation Slip transfer Crack nucleation

Evaluation of the reliability of twin variant analysis in Mg alloys by in situ EBSD technique

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Journal of Magnesium and Alloys 2019年第2期7卷 258-263页

作者： Feiya Liu Changfa Guo renlong xin Guilin Wu Qing Liu Joint International Laboratory for Light Alloys(MOE) College of Materials Science and EngineeringChongqing UniversitySha Zheng Jie 174Sha Ping Ba DistrictChongqingChina College of Materials Science and Engineering China Jiliang UniversityHangzhouChina

Electron backscatter diffraction(EBSD)is an orientation mapping technique,which has been widely used to study texture evolution and twinning *** work aims to study the variant of{10¯12}twins during tensile deformation of AZ31 Mg *** in-situ tensile stage was used,and coupled with EBSD technique,the variants of twins can be analyzed without releasing the tensile *** on the EBSD maps,the first and second smallest misorientation angles(M_(1)and M 2)between each active twin and respective potential variants were calculated,and the distribution of M_(1)values with tensile strain was *** results indicated that{10¯12}twins were deviated from their ideal orientations with strain *** criteria of M_(1)2°were suggested to be applied to select the data points for reliable variant ***,it confirmed that the deviation of twin relationship was ascribed to the profuse basal glide in matrices and/or twins.

关键词： Twinning Variant identification Magnesium alloy Lattice rotation EBSD

Examination of dynamic recrystallization during compression of AZ31 magnesium

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Science China(Technological Sciences) 2009年第1期52卷 176-179页

作者： xin renlong WANG BingShu CHEN xingPin HUANG GuangJie LIU Qing College of Material Science and Engineering Chongqing UniversityChongqing 400030China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400030China

This study aimed to investigate dynamic recrystallization (DRX) behavior during compression of magnesium alloy AZ31. Cylinder samples were cut from the extruded rod and hot rolled sheet AZ31 for compression test. The samples were compressed using a Gleeble 1500D at a temperature of 300°C and a strain rate of 0.01 s?1. Grain orientations and misorientation angles across grain boundaries for the tested samples were obtained by using electron backscatter diffraction (EBSD) technique. The results showed that strong basal texture was observed after 50% compression (ε = 0.69) on both the extruded and hot rolled samples, which have different initial textures. It was observed that with increased strain, DRX grains gradually rotated to basal orientation, and grain boundaries with misorientation angle of near 30° was formed in the samples. At the strain of 0.69, a high fraction of high-angle (> 60°) boundaries was present in the extruded sample, whereas almost no high angle boundaries were observed in the hot rolled sheet sample.

关键词： magnesium alloy dynamic recrystallization EBSD misorientation

Effect of free-end torsion on microstructure and mechanical properties of AZ31 bars with square section

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Journal of Materials Science & Technology 2021年第10期69卷 20-31页

作者： Bo Song Zhiwen Du Ning Guo Qingshan Yang Fang Wang Shengfeng Guo renlong xin School of Materials and Energy Southwest UniversityChongqingChina School of Metallurgy and Materials Engineering Chongqing University of Science and TechnologyChongqing401331China College of Materials Science and Engineering Chongqing UniversityChongqingChina

In this study,a rolled AZ31 bar with square section was *** reciprocating torsion was performed to maintain the shape of the *** microstructure evolution of AZ31 bar during torsion and its influence on compressive anisotropy were investigated in *** showed that reciprocating torsion can simultaneously enhance yield strength in three compressive directions,and reduce compressive *** torsion generated profuse dislocations and{10–12}twin boundaries to harden the micro-hardness and yield *** torsion can also generate new texture component which is mainly from the orientation of newly generated{10–12}*** new twin-structures will be responsible for the reduction in compressive ***,uneven deformation features in twisted sample were systematically investigated.

关键词： AZ31 Square bar Torsion Twin Texture Anisotropy

Investigation on the Mechanical Properties and Shape Memory Effect of Landing Buffer Structure Based on Ni Ti Alloy Printing

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Chinese Journal of Mechanical Engineering 2023年第4期36卷 415-424页

作者： Zhenglei Yu renlong xin Zezhou Xu Yining Zhu Xiaolong Zhang Shijie Hao Zhihui Zhang Ping Liang State Key Laboratory of Automotive Simulation and Control Jilin University Key Lab of Bionic Engineering Ministry of Education Jilin University Agriculture College Yanbian University State Key Laboratory of Heavy Oil Processing China University of Petroleum

With the deepening of human research on deep space exploration, our research on the soft landing methods of landers has gradually deepened. Adding a buffer and energy-absorbing structure to the leg structure of the lander has become an effective design solution. Based on the energy-absorbing structure of the leg of the interstellar lander, this paper studies the appearance characteristics of the predatory feet of the Odontodactylus scyllarus. The predatory feet of the Odontodactylus scyllarus can not only hit the prey highly when preying, but also can easily withstand the huge counter-impact force. The predatory feet structure of the Odontodactylus scyllarus, like a symmetrical cone, shows excellent rigidity and energy absorption capacity. Inspired by this discovery, we used SLM technology to design and manufacture two nickel-titanium samples, which respectively show high elasticity, shape memory, and get better energy absorption capacity. This research provides an effective way to design and manufacture highmechanical energy-absorbing buffer structures using bionic 3D printing technology and nickel-titanium alloys.

关键词： Bionic protective structure Odontodactylus scyllarus NiTi alloy 3D printing Numerical simulation Recoverability

Texture control by {10-12} twinning to improve the formability of Mg alloys: A review

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Journal of Materials Science & Technology 2019年第10期35卷 2269-2282页

作者： Bo Song Qingshan Yang Tao Zhou Linjiang Chai Ning Guo Tingting Liu Shengfeng Guo renlong xin School of Materials and Energy Southwest UniversityChongqing 400715China School of Metallurgy and Materials Engineering Chongqing University of Science and TechnologyChongqing 401331China College of Materials Science and Engineering Chongqing University of TechnologyChongqing 400054China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China

Texture control of wrought Mg alloys, particularly in rolled Mg alloy sheets, has been an important research topic for the past several decades because it has significant influence on stretch formability at room temperature. For Mg alloys, {10-12} twinning can be easily activated and causes a 86.3° lattice rotation. Thus, pre-twinning deformation is considered as an effective and low-cost method for texture control in wrought Mg and its alloys. Furthermore, it has been verified that texture control via pre-twinning deformation can remarkably improve stretch formability of rolled Mg alloy sheets. In this review, recent researches on texture control via twinning deformation and its influence on stretch formability will be critically reviewed. The main contents include the micro-mechanism and impact factors of control in twin-orientation, plastic processing techniques of pre-inducing twins and the application of pre-induced twins in improvement of stretch formability. Finally, further research directions on this field were proposed.

关键词： Mg alloys Texture Twinning Recrystallization Formability