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Comparative study on local and global mechanical properties of bobbin tool and conventional friction stir welded 7085-T7452 aluminum thick plate

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Journal of Materials Science & Technology 2018年第1期34卷 173-184页

作者： Weifeng Xu Yuxuan Luo Wei Zhang mingwang fu State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical University Department of Mechanical Engineering The Hong Kong Polytechnic University

7085-T7452 plates with a thickness of 12 mm were welded by conventional single side and bobbin tool friction stir welding （SS-FSW and BB-FSW, respectively） at different welding parameters. The temperature distribution, microstructure evolution and mechanical properties of joints along the thickness direction were investigated, and digital image correlation （DIC） was utilized to evaluate quantitatively the deformation of different zones during tensile tests. The results indicated that heat-affected zone （HAZ）, the local softening region, was responsible for the early plastic deformation and also the fracture location for SS-FSW samples, while a rapid fracture was observed in weld nugget zone （WNZ） before yield behavior for all BB-FSW specimens. The ultimate tensile strength （UTS） of SS-FSW joints presented the highest value of 410 MPa, 82% of the base material, at a rotational speed of 300 rpm and welding speed of 60 mm/min, much higher than that of BB-FSW joints, with a joint efficiency of only 47%. This should be attributed to the Lazy S defect produced by a larger extent of heat input during the BB-FSW process, The whole joint exhibited a much higher elongation than the slices. Scanning electron microscopic （SEM） analysis of the fracture morphologies showed that joints failed through ductile fracture for SS-FSW and brittle fracture for BB-FSW.

关键词： Aluminum alloy Friction stir welding Bobbin tool Temperature distribution Microstructure Mechanical properties

Deformation behavior and microstructure evolution of titanium alloys with lamellar microstructure in hot working process: A review

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Journal of Materials Science & Technology 2020年第4期39卷 56-73页

作者： Pengfei Gao mingwang fu Mei Zhan Zhenni Lei Yanxi Li State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of High-Performance Precision Forming Technology and EquipmentSchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityP.O.Box 542Xi’an710072China Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina

Titanium alloys have been widely used in many industrial clusters such as automotive, aerospace and biomedical industries due to their excellent comprehensive properties. In order to obtain fine microstructures and favorable properties, a well-designed multi-step thermomechanical processing(TMP) is critically needed in manufacturing of titanium components. In making of titanium components,subtransus processing is a critical step to breakdown lamellar microstructure to fine-structure in hot working process and thus plays a key role in tailoring the final microstructure and properties. To realize this goal, huge efforts have been made to investigate the mechanisms of microstructure evolution and flow behavior during the subtransus processing. This paper reviews the recent experimental and modelling progresses, which aim to provide some guidelines for the process design and microstructure tailoring for titanium alloy research community. The characteristics of the initial lamellar microstructure are presented, followed by the discussion on microstructure evolution during subtransus processing. The globularization of lamellar α is analyzed in detail from three aspects, i.e., globularization mechanism, heterogeneity and kinetics. The typical features of flow behaviors and the explanations of significant flow softening are then summarized. The recent advances in modelling of microstructure evolution and flow behaviors in the subtransus processing are also articulated. The current tantalized issues and challenges in understanding of the microstructure evolution and flow behaviors of the titanium alloys with lamellar microstructure are presented and specified in future exploration of them.

关键词： Titanium alloys Lamellar microstructure Deformation behavior Microstructure evolution

Nonlinear finite element analysis of crack growth at the interface of rubber-like bimaterials

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Science China(Physics,Mechanics & Astronomy) 2011年第10期54卷 1866-1874页

作者： YANG XiaoXiang fu mingwang WANG XiuRong LIU XiaoYing School of Mechanical Engineering and Automation Fuzhou University Fuzhou 350108 China Department of Mechanical Engineering The Hong Kong Polytechnic University Hung Horn Kowloon Hong Kong China

This paper presents the characteristics of the crack growth at the interface of rubber-rubber and rubber-steel bimaterials undertensile deformation using the non-linear finite element method. By using the commercial finite element software ABAQUS,the J integral calculations are carried out for the initial interface crack in the interfaces in-between two Neo-Hookean materials,two Mooney-Rivlin materials, Neo-Hookean and Mooney-Rivlin rubbers, Neo-Hookean and Polynomial, Mooney-Rivlin andPolynomial, and the Mooney-Rivlin and steel bi-materials. The computational results of the maximum J integral directionaround the crack tip illustrate the possible direction of crack growth initiation. furthermore, it is found that the crack bends tothe softer rubber material at a certain angle with the initial crack direction if the crack depth is relatively small. For the crackwith a larger depth, the crack propagates to grow along the interface in-between the bimaterials.

关键词： rubber-like materials bimaterials interface crack J integral crack growth non-linear finite element method

Formability enhancement in hot spinning of titanium alloy thin-walled tube via prediction and control of ductile fracture

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Chinese Journal of Aeronautics 2022年第2期35卷 320-331页

作者： Pengfei GAO Chao YU mingwang fu Lu XING Mei ZHAN Jing GUO State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of High-Performance Precision Forming Technology and EquipmentSchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHung HornKowloonHong Kong 999077China Institute of Chemical Materials China Academy of Engineering PhysicsMianyang 621900China

The damage and fracture in hot spinning of titanium alloy is a very complex process under the combined effects of microstructure evolution and stress *** this study,their dependences on processing parameters were investigated by an integrated FE model considering microstructure and damage evolution,and revealing the effects of microstructure and stress states on damage *** results show that the inner surface of workpiece with the largest voids volume fraction is the place with the greatest potential of *** is mainly attributed to the superposition effects of positive stress triaxiality and the smallest dynamic recrystallization(DRX)fraction andβphase fraction at the inner *** damage degree is decreased gradually with the increase of initial spinning temperature and roller fillet ***,it is first decreased and then increased with the increases of spinning pass and roller feed rate,which can be explained based on the variations ofβphase fraction,DRX fraction,stress state and tensile plastic strain with processing *** addition,the dominant influencing mechanisms were identified and ***,the thickness reduction without defect in the hot spinning of TA15 alloy tube is greatly increased by proposing an optimal processing scheme.

关键词： Control of ductile fracture Dynamic recrystallization Forming limit Hot spinning Titanium alloy tube

Simulation of the continuous casting process in a mold of free-cutting steel 38MnVS based on a MiLE method

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International Journal of Minerals,Metallurgy and Materials 2011年第5期18卷 562-569页

作者： fu-mingwang Yun-jin Xia Jin-long Wang Guo-zhong Li School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China Key Lab of the Ministry of Education of China for Ecologic and Recycle Metallurgy University of Science and Technology Beijing Beijing 100083 China Jiangyin Xingcheng Iron and Steel Co. Ltd. Jiangyin 214429 China

A new method called mixed Lagrangian and Eulerian （MiLE） method was used to simulate the continuous casting process in a mold of free-cutting steel *** simulation results are basically in agreement with experimental data in the literature,achieving the three-dimensional visualization of temperature distribution,melt flow,shell thickness,and stress distribution of blooms in a *** is shown that the flow velocity of steel melt becomes smaller gradually as the casting *** the flow reaches a certain depth,two types of flow patterns can be observed in the upper zone of the *** first flow pattern is to flow downwards,and the second one is to flow upwards to the *** corner temperature is higher,and the thickness is thinner than those in the *** effective stress in the corner area is much bigger than that in the mid-face,indicating that the corner area is the dangerous zone of cracking.

关键词： free-cutting steel melt flow continuous casting computer simulation

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基于压入试验的金属材料硬化行为表征方法

锻压技术 2024年第7期49卷 190-201,209页

作者：杨恒李恒傅铭旺香港理工大学机械工程学系中国香港999077 西北工业大学凝固技术国家重点实验室陕西西安710072

微介观尺度构件成形制造技术的快速发展,迫切要求实现特征尺寸小于1 mm的小尺寸材料和微构件力学性能的准确表征,但这类材料/构件尺寸限制了标准拉伸或者压缩试验的开展。压入试验由于微损、微区且试样制备简单等优点,在材料力学行为表... 详细信息

微介观尺度构件成形制造技术的快速发展,迫切要求实现特征尺寸小于1 mm的小尺寸材料和微构件力学性能的准确表征,但这类材料/构件尺寸限制了标准拉伸或者压缩试验的开展。压入试验由于微损、微区且试样制备简单等优点,在材料力学行为表征中被大量使用并表现出广泛的应用潜力。基于此,首先对基于压入试验的各向同性硬化行为表征方法进行了总结,简要介绍了球形压入、圆锥压入、棱锥压入、平面压入和纳米压痕测试表征材料应变硬化行为的原理和特征。然后,介绍了压入法表征各向异性硬化行为的原理,评述了各压入方法的优缺点。最后,总结了基于压入试验的金属材料硬化行为表征方法研究取得的主要进展和面临的主要问题和科学挑战,这对小尺寸材料和微构件力学性能准确表征方法的进一步发展及应用具有重要意义。

关键词：小尺寸材料微构件硬化行为压入试验各向异性各向同性

第Ⅱ类尺寸效应影响下金属薄板液压胀形本构模型研究

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固体力学学报 2013年第2期34卷 194-199页

作者：梁伟杨晓翔傅明旺邓将华福州大学机械工程及自动化学院福州350108 香港理工大学机械工程学系

尺寸效应是微成形研究中的热点和难点之一.目前采用经典塑性理论仍不能对金属薄板液压胀形中尺寸效应对应力变化现象的影响进行较好的解释.为了深入分析该问题,结合应变梯度塑性理论,建立了第Ⅱ类尺寸效应影响下金属薄板液压胀形本构模... 详细信息

尺寸效应是微成形研究中的热点和难点之一.目前采用经典塑性理论仍不能对金属薄板液压胀形中尺寸效应对应力变化现象的影响进行较好的解释.为了深入分析该问题,结合应变梯度塑性理论,建立了第Ⅱ类尺寸效应影响下金属薄板液压胀形本构模型.基于该模型,分析了板料厚度变化以及胀形凹模直径变化对液压胀形过程流动应力变化的影响.研究结果表明应用该本构模型能较好地解释金属薄板液压胀形中尺寸效应对应力变化的影响,验证了该本构模型的正确性.

关键词：尺寸效应本构模型应变梯度液压胀形

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骨质疏松症的中医病因病机及其治疗进展

中国骨质疏松杂志 2017年第8期23卷 1105-1111页

作者：邓昶周明旺付志斌李盛华甘肃中医药大学甘肃兰州730000 甘肃省中医院甘肃兰州730050

骨质疏松症是一种常见病症,随着人口老龄化进程加快,其预防与治疗已成为现代医学研究的热点和难点之一。近年来,中医药治疗骨质疏松的研究日益增多,在治疗骨质疏松症方面已取得一定成果。本文基于近年来的文献研究,重点从骨质疏松症的... 详细信息

骨质疏松症是一种常见病症,随着人口老龄化进程加快,其预防与治疗已成为现代医学研究的热点和难点之一。近年来,中医药治疗骨质疏松的研究日益增多,在治疗骨质疏松症方面已取得一定成果。本文基于近年来的文献研究,重点从骨质疏松症的病因病机、辨证分型、中医治疗等方面进行探析,论述当前骨质疏松症治疗工作中取得的成果,指出研究中存在的问题,并展望未来中医药治疗骨质疏松症的前景,以期给从事骨质疏松症临床与基础研究的医学工作者、科研人员提供新的思路和启发,从而更好地指导科研与临床。

关键词：骨质疏松症中医药研究进展

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基于热加工图研究粉末高温合金的热变形行为

稀有金属材料与工程 2010年第A01期39卷 231-234页

作者：宁永权姚泽坤傅明旺郭鸿镇李辉谢兴华西北工业大学陕西西安710072 香港理工大学

利用热加工图分析了FGH4096粉末高温合金的热变形行为,评定了益加工区,预测了变形失稳区;结合热加工图与组织分析建立了此合金在真应变0.65下的微观变形机制示意图。不同应变量下获得的热加工图表现出一致的特征:从"低温/低速"区到"高温... 详细信息

利用热加工图分析了FGH4096粉末高温合金的热变形行为,评定了益加工区,预测了变形失稳区;结合热加工图与组织分析建立了此合金在真应变0.65下的微观变形机制示意图。不同应变量下获得的热加工图表现出一致的特征:从"低温/低速"区到"高温/高速"区存在明显的益加工带;而"低温/高速"区和"高温/低速"区则是被预测的变形失稳区。HIPedFGH4096合金的热加工性能直接受动态再结晶的影响:在"低温/低速"和"高温/高速"下发生的完全再结晶及其粗化过程均对应着高的能量耗散率,有利于合金的热加工;而在"低温/高速"下动态再结晶受到抑制,潜在着原始颗粒边界萌生裂纹而导致变形失稳的可能性。

关键词：粉末高温合金热加工图热变形行为动态再结晶