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Numerical simulation of microstructure and microporosity morphology in directional solidification of aluminum-copper alloys:Effect of copper content and withdrawal rate

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China Foundry 2025年第1期22卷 33-44页

作者： Wei Yuan Hai-dong Zhao Xu Shen Chun Zou Yuan Liu Qing-yan Xu National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials South China University of TechnologyGuangzhou 510640China Key Laboratory for Advanced Materials Processing Technology(Ministry of Education) Tsinghua UniversityBeijing 100084China

Microporosity formed in the solidification process of Al alloys is detrimental to the alloy properties.A two-dimensional cellular automaton(CA)model was developed to simulate the microstructure and microporosity formation in Al-Cu alloys,considering variations in Cu content and solidification *** results indicate that the Cu content primarily influences the growth of *** validate the model,directional solidification experiments were conducted on Al-Cu alloys with varing Cu contents and withdrawal *** experimental results of dendrites and microporosity characteristics agree well with the predictions from the developed model,thus confirming the validity of the *** alloy’s liquidus temperature,dendrite morphology,and hydrogen saturation solubility arising from different Cu contents have significant effects on microporosity *** withdrawal rate primarily affects the nucleation of hydrogen microporosity by altering cooling rates and dendritic growth rates,resulting in different microporosity characteristics.

关键词： microporosity dendrites cellular automaton Al-Cu alloys directional solidification

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From Concept to Field Trials: Design, Analysis, and Evaluation of a Novel Quadruped Robot with Deformable Wheel-Foot Structure

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IEEE Transactions on Robotics 2025年 41卷 3143-3161页

作者： Ju, Zhongjin Wei, Ke Xu, Yundou Yanshan University Parallel Robot and Mechatronic System Laboratory of Hebei Province Qinhuangdao066004 China Yanshan University Key Laboratory of Advanced Forging and Stamping Technology and Science Ministry of Education of China Qinhuangdao066004 China

This study introduces a novel quadruped robot, the TerraAdapt, furnished with an innovative deformable wheel-foot integrated structure. This unique design grants the robot the flexibility to alternate between wheeled and footed modes of locomotion, making it efficient in traversing diverse terrains, from smooth indoor floors to challenging outdoor landscapes laden with obstacles. The study delineates an in-depth design and analysis of the deformable wheel and its integrated wheel-foot structure using screw theory. We engineer a 2RRR-RP wheel-foot mode-switching mechanism by modifying a 2RRR spatial six-bar mechanism with an additional RP branch. This mechanism aids in seamless transitioning between different movement modes. Moreover, a 2RRR parallel structure is employed to construct the footed mode *** substantiate the viability and efficacy of the proposed design, we carry out extensive motion simulations and construct an experimental prototype for field testing. The field trials reveal the robot's adeptness in adapting to varied terrains, highlighting the possible advantages of incorporating the proposed deformable wheel into micro mobile robot designs. © 2004-2012 IEEE.

关键词： Machine design

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Coordinated Regulation of Bonding Interfacial Structure and Mechanical Properties of Al/Mg Alloy Composite Plates by Electrically Assisted Rolling

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Chinese Journal of Mechanical Engineering 2025年第1期38卷 246-260页

作者： Tingting Zhang Xingrun An Yan Wang Gongbo Bian Tao Wang College of Mechanical and Vehicle Engineering Taiyuan University of TechnologyTaiyuan 030024China Engineering Research Center of Advanced Metal Composites Forming Technology and Equipment of Ministry of Education Taiyuan University of TechnologyTaiyuan 030024China National Key Laboratory of Metal Forming Technology and Heavy Equipment Taiyuan University of TechnologyTaiyuan 030024China College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China.

Current research on the fabrication of rolled composite plates primarily focuses on processing and bonding *** with hot-rolling technology,the electrically assisted rolling process has demonstrated excellent performance in interfacial bonding ***,the influence of different current loading modes on the interfacial recombination process of composite panels varies *** this study,low-frequency electrically assisted rolling was used in the first pass to pre-bond a composite plate at a low reduction rate of 15%.High-frequency electrically assisted rolling was used during the second pass,and Al/Mg alloy composite plates were *** interfacial microstructure and mechanical properties of the composite plate were coordinated regulation by designing the rolling reduction *** results showed the interfacial morphology of the alternating distribution of the melt-diffusion layer,diffusion layer,and the formation of a new Al/Mg bonding *** the melt-diffusion interface,the irregular intermetallic compounds(IMCs)and the new Al/Mg bonding interface were alternately distributed,and the IMCs contained theα-Mg,Mg17Al12,and Mg2Al3 *** addition,an extremely high shear strength of 78.26 MPa was *** of the Mg alloy matrix was observed on the fracture surface of the Al alloy *** high shear strength was mainly attributed to the formation of a unique interfacial structure and the appearance of a melt-diffusion *** to the diffusion-reduction interface,the regular rectangular IMCs and the new Al/Mg bonding interface were alternately distributed,and the IMCs consisted of the Mg17Al12 and Mg2Al3 *** shear test results showed that the shear strength of the interface reached 68.69 MPa,and a regular distribution of the Mg alloy matrix with dimples and the Al alloy matrix with a necking zone was observed on the fracture surface of the Al *** strength test results revealed a maximum value of

关键词： Al/Mg alloy composite plate Electrically assisted rolling Bonding properties Interfacial structure

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Disrupting variant selection memory effect in laser powder bed fusion to improve strength-ductility synergy of Ti-6Al-4V alloys

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Journal of Materials Science and technology 2025年 219卷 19-32页

作者： Yang, C. Liu, B. Pan, L.L. Yang, Y. Zhou, Y. Cai, W.S. Liu, Le-hua National Engineering Research Center of Near-net-shape Forming for Metallic Materials Guangdong Provincial Key Laboratory for Processing and Forming of Advanced Metallic Materials South China University of Technology Guangzhou 510640 China Shenzhen Leadwell Technology Co. Ltd. Shenzhen Guangdong 518000 China

Texture formation is frequently observed in parts produced by Laser Powder Bed Fusion (L-PBF), which can induce anisotropy and may potentially degrade plasticity. In this study, we introduce a laser remelting strategy to mitigate these adverse effects. By employing experimental observations and numerical simulations, we established the relationship between melt pool thermal history, variant selection, and mechanical properties. Our results indicate that the strengthening of texture can be prevented by disrupting the variant selection memory effect when there is a difference in scanning speeds between the printing and remelting lasers. The achieved random variant orientation is attributed to the altered cooling rates and temperature gradient directions during solidification across different layers. The optimized Ti-6Al-4V alloy demonstrates high strength (1211.5 ± 13.3 MPa) and significant elongation (12.3 % ± 0.8 %), exhibiting a superior strength-ductility synergy compared to samples produced by direct printing or laser remelting with consistent parameters, as well as most reported L-PBF processed Ti-6Al-4V alloys. Our findings provide new insights into phase transformation kinetics in L-PBF of Ti-6Al-4V alloys and facilitate the optimization of this process for manufacturing high-performance components. © 2024

关键词： Titanium alloys

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Effect of two-pass rolling of textured roll and polished roll on surface topography and mechanical properties of 316L stainless steel ultra-thin strip

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Journal of Iron and Steel Research International 2025年第1期32卷 186-197页

作者： Zeng-qiang Zhang Xi Liao Zhong-kai Ren Zhen-hua Wang Ya-xing Liu Tao Wang Qing-xue Huang College of Mechanical and Vehicle Engineering Taiyuan University of TechnologyTaiyuan030024ShanxiChina Engineering Research Center of Advanced Metal Composites Forming Technology and Equipment of Ministry of Education Taiyuan University of TechnologyTaiyuan030024ShanxiChina National Key Laboratory of Metal Forming Technology and Heavy Equipment Taiyuan University of TechnologyTaiyuan030024ShanxiChina Shanxi TISCO Stainless Steel Precision Strip Co. Ltd.Taiyuan030032ShanxiChina

The textured roll and polished roll were applied instead of the ground roll in a 20-high mill to conduct two-pass rolling of 316L stainless steel strip with thickness of 0.027 *** the two-pass rolling with the textured roll and polished roll(TPR),the surface roughness of the strip is dramatically reduced,and the surface topographical anisotropy index is diminished to 30.9%of the initial *** with the strip rolled using the ground roll in both passes(GGR),the elongation of TPR rolled strip is obviously improved,and the mechanical property anisotropy is greatly *** anisotropy index of tensile strength and elongation are 42.58%and 52.59%of that of GGR rolled strip,which is mainly attributed to the significant decrease of the texture intensity of the strip by TPR *** results indicate that TPR process can obtain the stainless steel ultra-thin strip with smooth and uniform surface topography and good mechanical properties.

关键词： Textured roll Polished roll Surface topography Mechanical property Stainless steel ultra-thin strip

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Formative manufacturing of heterogeneous composite plates: a review

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Materials Today 2025年 86卷 548-574页

作者： Zhang, Jia Yang Li, Feng Niu, Wen Tao Wang, Zi Yi Cao, Mu Zi School of Materials Science and Chemical Engineering Harbin University of Science and Technology Harbin150040 China Key Laboratory of Advanced Manufacturing and Intelligent Technology Ministry of Education Harbin University of Science and Technology Harbin150080 China Heilongjiang Provincial Key Laboratory of Light Metal Materials Modification & Green Forming Technology Harbin University of Science and Technology Harbin150040 China

The integration of superior characteristics from individual components achievable in heterogeneous composite plates can be achieved through optimal material configuration and combination methods. This approach results in significant enhancements in physical, mechanical, and forming properties when compared to traditional single metal plates. However, challenges such as prolonged manufacturing cycles and the complexity of coordinating interface characteristics and microstructural properties impede the rapid advancement and widespread adoption of heterogeneous composite plate manufacturing. This study offers a comprehensive overview of the primary forming methods for heterogeneous composite plates, including rolling, extrusion, welding, hot pressing, and additive manufacturing. It addresses current challenges and anticipates potential developmental directions, such as the application of specialized energy field-assisted forming techniques and the design of heterogeneous microstructures. The exploration of new resources, the expansion of innovative concepts, the establishment of novel models, the promotion of new principles, and the adoption of transformative technologies are essential for the breakthrough development of heterogeneous composite plate manufacturing. Aligning with the national innovation-driven development strategy and the requirements of major national projects remains a fundamental objective of this research direction. © 2025 Elsevier Ltd

关键词： Hot pressing

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Numerical Simulation and Experimental Investigation on Friction and Lubrication Behaviors of Chevron Micro-Textured Valve Plate/Cylinder Block Interface With Various Area Densities

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Journal of Tribology 2025年第7期147卷 072201页

作者： Chen, Luanxia Liu, Zhanqiang Huang, Haihong Zhu, Yingying School of Mechanical Engineering Hefei University of Technology Hefei230009 China Key Laboratory of Green Design and Manufacturing of Mechanical Industry Hefei University of Technology Hefei230009 China School of Mechanical Engineering Shandong University Jinan250061 China State Key Laboratory for High-end Equipment and Advanced Technology of Metal Forming Shandong University Jinan250061 China

As the critical friction pairs of swashplate-type axial piston pumps, the cylinder block/valve plate lubricating interface is the primary source of friction, wear, and leakage in axial piston pumps. Surface micro-texturing has been widely employed in cylinder block/valve plate conjunctions to ameliorate tribological performance. However, little research has been conducted to investigate the influence of chevron micro-texture area density on the tribological behaviors and lubricating properties of cylinder block/valve plate interface both experimentally and numerically. In this article, the chevron micro-textures with various area densities were manufactured on H62 brass by micro-milling and subsequently characterized with a laser scanning confocal microscope (LSCM). The friction and wear performance of H62 brass/38CrMoAl conjunctions were obtained via disc-on-disc tribological tests to simulate the cylinder block/valve plate lubricating interface. Moreover, the load-carrying capacity of untextured and chevron micro-textured samples was numerically investigated under hydrodynamic lubrication. It was found that the chevron micro-textured surface with an area density of 30.1% displayed the lowest friction coefficient and the shallowest wear depth. Although the load-carrying capacity of chevron micro-textured samples with a high dimple area density was larger, the severe stress concentration induced by the reduced micro-texture spacing caused the increment and large fluctuations of friction coefficient. Copyright © 2024 by ASME.

关键词： Friction

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Enhanced strength-ductility synergy of Mg/Al laminate by coordinating the strain gradient of constituting layers

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Journal of Materials Science and technology 2025年 233卷 264-279页

作者： Qian, Lihua Chen, Liang Tang, Jianwei Li, Yefei Zhang, Cunsheng Kong, Xiangshan State key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Jinan250061 China Shandong University Jinan250061 China State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an710049 China School of Mechanical Engineering Xinjiang University Urumqi830047 China

Mg/Al laminate with ZK60Mg and TiB2/6061Al as constitute layers was fabricated through the porthole die co-extrusion and hot rolling. The effects of rolling and roll temperatures on the microstructure, interfacial structure, mechanical properties, and crack propagation paths were studied. The results show that the intermetallic compounds layer shows an intermittent form. The strong strain/dislocation hardening ability of Mg/Al laminate is attributed to the coupled effects of interlocking Al/β interface, strain gradient, and β layer with nanotwins and stacking faults. The complex dislocation structures such as network, loop, and array are found in the Al layer. Dislocation slip is the main deformation mode of the Al layer, while dislocation slip and dynamic recrystallization are the main deformation modes of the Mg layer. As roll temperature increases, prismatic 〈a〉 slip replaces the basal 〈a〉 slip as the most important slip mode. At a rolling temperature of 400 °C and a roll temperature of 150 °C, an optimal synergy of mechanical properties is achieved, with ultimate tensile strength, shear strength, and elongation of 262.1 MPa, 36.4 MPa, and 18.1 %, respectively. As the rolling temperature increases, the fracture mode of Mg/Al laminate changes from discontinuous plastic shrinkage to transverse and longitudinal cracks. With increasing the roll temperature, the through cracks tend to form, indicating the plasticity and bonding quality of Mg/Al laminate are effectively enhanced. © 2025

关键词： Dynamic recrystallization

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Finite element simulation of wear-resistant steel ball forging process 5

Finite element simulation of wear-resistant steel ball forgi...

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2024 5th International Conference on advanced Materials and Intelligent Manufacturing, ICAMIM 2024

作者： Pan, Peng Ge, Feng Yang, Ming Yu, Jinxi Zuo, Lingli Beijing National Innovation of Lightweight Ltd. Beijing101400 China State Key Laboratory for Advanced Forming Technology and Equipment China Academy of Machinery and Technology Beijing101400 China

Deform-3D software was used to analyse the forming characteristics of wear-resistant steel balls, material fluidity, stress-strain distribution, load-time curve, and break coefficient of three kinds of forging billets in the forging process. It was concluded that with the reduction of the height of the original billet, the damage coefficient of the middle position of the billet decreased during the final stage of billet forming. The forging ratio of the blank should be appropriately reduced to reduce the risk of forming defects in the forging process. 2025 Published under licence by IOP Publishing Ltd.

关键词： Billets (metal bars)

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稀有金属材料与工程 2025年第2期54卷 311-318页

作者： Zhang Wenxin Zhang Xiankun Shi Lei Li Shengli Jiang Yuanning Wu Chuansong State Key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong UniversityJinan 250061China Key Laboratory for Liquid-Solid Structure Evolution&Processing of Materials Ministry of EducationShandong UniversityJinan 250061China

Friction stir lap welding of AA2195 Al-Li alloy and Ti alloy was conducted to investigate the formation,microstructure,and mechanical properties of the *** show that under different welding parameters,with the decrease in welding heat input,the weld surface is *** Ti/Al joint interface is flat without obvious Ti and Al mixed structure,and the hook structure is not formed under optimal *** to the enhanced breaking effect of the stirring head,the hook structural defects and intermetallic compounds are more likely to form at the Ti/Al interface at high rotational speed of 1000 r/min,thereby deteriorating the mechanical properties of *** the heat input is beneficial to hardness enhancement of the aluminum alloy in the weld nugget *** the optimal parameters of rotation speed of 800 r/min and welding speed of 120 mm/min,the maximum tensile shear strength of joint is 289 N/mm.

关键词： Ti/Al dissimilar welding friction stir lap welding Ti alloy Al-Li alloy interface bonding mechanical property

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