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SSRN 2024年

作者： Hou, Qing-Qing Wei, Guoqing Zhang, Qi Liu, Xuepeng Zhang, Yifan Meng, Xuan Li, Haixin Li, Zhipeng Wu, Yucheng Luo, Laima School of Materials Science and Engineering Singapore School of Materials Science and Engineering Hefei University of Technology Hefei230009 China Institute of Industry & Equipment Technology Anhui Province Key Lab of Aerospace Structural Parts Forming Technology and Equipment Hefei University of Technology Hefei230009 China Electron Microscopy Centre of Lanzhou University Lanzhou University Lanzhou730000 China Science and Technology Co LTD China Beijing Key Laboratory of Microstructure and Property of Advanced Materials Beijing University of Technology Beijing100124 China National-Local Joint Engineering Research Centre of Nonferrous Metals and Processing Technology Hefei230009 China Engineering Research Center of High Performance Copper Alloy Materials and Processing Ministry of Education Hefei230009 China

For tungsten (W), doping with second-phase particles is a commonly employed method to enhance its properties. Experiments have observed that oxide dispersion-strengthened tungsten alloys (ODS-W) exhibit superior and more stable ultimate tensile strength (UTS) at elevated temperatures. To elucidate this phenomenon, in situ tensile deformation experiments were conducted on ODS-W using transmission electron microscopy at temperatures up to 1273 K. Under the influence of temperature and tensile stress, a phase transition from BCC to FCC occurred near the oxide interfaces in W. This BCC–FCC phase transformation was corroborated by combining molecular dynamics simulations (MD) with density functional theory (DFT), confirming that the transformed FCC W matrix possesses an exceptional adhesion work, significantly enhancing the bonding strength at the W-oxide interfaces. Based on these observations, this work provides a plausible explanation for the high UTS retention of ODS-W at high temperatures. These findings offer valuable insights into the development of oxide-strengthened alloys for high-temperature applications and present a novel perspective on the mechanisms of second-phase reinforcement. © 2024, The Authors. All rights reserved.

关键词： Density functional theory

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Towards Ultralow Friction or Even Superlubricity in Inconel 718 Tube Drawing Representing Metal forming Under Large-Amplitude Sliding

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SSRN 2022年

作者： Zhang, Duo Li, Heng Liu, Chongde Zheng, Yuanyang Wang, Zheng Fu, Mingwang State Key Laboratory of Solidification Processing School of Materials Science and Engineering Northwestern Polytechnical University Xi’an710072 China Shaanxi Key Laboratory of High-Performance Precision Forming Technology and Equipment Northwestern Polytechnical University Xi’an710072 China Department of Mechanical Engineering Research Institute for Advanced Manufacturing The Hong Kong PolytechnicUniversity HungHom Kowloon Hong Kong

Friction has a crucial impact in different physical domains and industries. Friction sometimes plays a positive factor to facilitate and promote the happening of various physical behaviors and phenomena, while in most scenarios, it has a negative impact to generate severer wear, damage, fracture of the materials/tools, increasing the need force, consuming more energy, and resulting in higher production cost. In metal forming, friction coefficient mostly falls into the range from 0.1 and 1. When the friction coefficient is reduced to ultralow, even to superlubricity with the friction coefficient smaller than 0.01, the above-described issues and phenomena can be efficiently solved to a large extent. The friction behavior is affected by friction pair (component materials and surface coating), surface state (roughness, lubricant) and boundary conditions (pressure, contact area and sliding amplitude). Large-amplitude sliding of the contact surface occurred frequently in metal forming may result in the change of tribological morphology and complicate the above-listed issues. Thus, reducing friction coefficient and even achieving superlubricity is a critical challenge to be solved in metal forming with large-amplitude sliding. In the study, by using Inconel 718 superalloy tube as case material and, firstly, tube/sheet drawing was firstly designed as a universal method to representing the large-amplitude sliding of contact interface in metal forming. To obtain the friction coefficient under the large-amplitude sliding, ex-situ drawing experiment and finite element model were designed with different contact areas or size effect, pressure, lubricants, surface roughness and surface deposited layer. Secondly, the friction mechanism under the large-amplitude sliding was revealed by in-situ drawing experiments and macro/micro scaled modeling, viz., tube drawing FE model with lubrication pocket and molecular dynamics model. Thirdly, the coupling influence mechanisms of contact are

关键词： Surface roughness

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Functional gradient material of Ti-6Al-4V and γ-TiAl fabricated by electron beam selective melting 26

Functional gradient material of Ti-6Al-4V and γ-TiAl fabric...

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26th Annual International Solid Freeform Fabrication Symposium - An Additive Manufacturing Conference, SFF 2015

作者： Ge, Wenjun Lin, Feng Guo, Chao Key Laboratory for Advanced Materials Processing Technology Ministry of Education of China Tsinghua University Beijing100084 China Center for Bio-manufacturing and Rapid Forming Technology Department of Mechanical Engineering Tsinghua University Beijing100084 China

Additive Manufacturing (AM) technologies are very promising in fabricating functionally graded materials. Electron Beam Selective Manufacturing (EBSM) is one widely used AM technology capable of fabricating a variety of materials especially titanium alloys. Previous studies on EBSM process were focused on the manufacturing of one single material. In this study, a novel EBSM process capable of building gradient structures with dual metal materials was developed. Ti6Al4V powders and Ti47Al2Cr2Nb powders were used to fabricate Ti3Al/TiAl and Ti6Al4V/Ti3Al dual metal structures. The chemical compositions, microstructure and micro-hardness of the dual material samples were investigated employing Optical Microscope (OM), Scanning Electronic Microscope (SEM), Electron Probe Micro-Analyzer (EPMA). Results showed that the thickness of the transition zone was about 300μm. The transition zone was free of cracks, and the chemical compositions exhibited a staircase-like change. The microstructure and chemical compositions in different regions were studied. Micro-hardness was affected by the microstructure. The microstructures turned out to be full lamellar at the TiAl region and basket-weave structure at the Ti3Al and Ti6Al4V region. © SFF *** rights reserved.

关键词： Fabrication

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In-Situ Investigation On Tensile Deformation and Fracture Behaviors of Ti60 Alloy Rolled Sheet with Equiaxed Microstructure

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SSRN 2022年

作者： Wang, Boning Zeng, Weidong Zhao, Zibo Jia, Runchen Xu, Jianwei Wang, Qingjiang State Key Laboratory of Solidification Processing School of Materials Science and Engineering Northwestern Polytechnical University Xi’an710072 China Institute of Metal Research Chinese Academy of Sciences Shenyang110016 China Defense Technologies Innovation Center of precision forging and ring rolling School of Materials Science and Engineering Northwestern Polytechnical University Xi’an710072 China Shaanxi Key Laboratory of High-Performance Precision Forming Technology and Equipment Northwestern Polytechnical University Xi’an710072 China

In this work, the deformation mechanism and fracture behavior of Ti60 alloy sheet with equiaxed microstructure (the volume fraction of equiaxed α grains is 68%) using the in-situ tensile test were studied by in-situ scanning electron microscope (SEM) and electron backscattering diffraction (EBSD). The results show that equiaxed α grains activate three coordinated deformation mechanisms, mainly single slip mode, supplemented by slip transfer and grain rotation. The alloy is mainly coordinated by equiaxed α grain deformation, dominated by prismatic and basal slip, and prismatic slip in (10 0) plane and [1 10] direction as the most active slip system. With the increase of deformation, the soft oriented equiaxed α grains preferentially occur prismatic slip, while some hard oriented grains rotate in the direction favorable to slip. When there is no slip transfer between adjacent grains, dislocation pile-up at the grain boundary and causes stress concentration, which makes the grain boundary easy to become the crack nucleation point. In SEM and EBSD studies, lamellar α grains have no obvious deformation characteristics. However, TEM study found that some lamellar α grains were kinked, which led to lamellar fracture and the formation of high-density dislocation areas around them. Meanwhile, due to the large difference in coordinated deformation ability between equiaxed α grains and lamellar α grains and between equiaxed α hard and soft oriented grains. Therefore, cracks are initiated, propagated and fractured mainly at the junction of the α colony composed of lamellar α grains and at the equiaxed α grain boundary. © 2022, The Authors. All rights reserved.

关键词： Deformation

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Dynamic Modeling of Over-Constrained Parallel Driving Mechanism with Planar Sub-Closed-Chains

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SSRN 2022年

作者： Huang, Yangyang Zhang, Jinzhu Xiong, Xiaoyan Wang, Rui Liu, Hongfei College of Mechanical and Vehicle Engineering Taiyuan University of Technology Taiyuan030024 China Department of Mechanical Engineering The State Key Laboratory of Tribology Institute of Manufacturing Engineering Tsinghua University Beijing100084 China Engineering Research Center of Advanced Metal Composites Forming Technology and Equipment Ministry of Education Taiyuan030024 China

This paper proposes a novel 4-degree-of-freedom (DOF) parallel driving mechanism (PDM) with sub closed-chains. PDM consists of operating mechanisms, driving mechanisms and connecting joints. First, displacement, velocity and acceleration models of the PDM are established. Then, the Newton-Euler approach is taken to deduce the kinematic formula of each link and the formula of inertial force at the center of mass. At the same time, it remains difficult to solve the equation since the number of equations is less than the number of unknowns. To solve this problem, the decoupling principle of PDM is proposed in this paper. The operating mechanism is decoupled from the driving mechanism at the connecting joints. Further, the screw theory is applied to analyze the cause of over-constraints problems, and 9 deformation coordination equations are introduced. Moreover, a complete dynamic model of the mechanism is obtained. According to the co-simulation with Matlab, Adams and Abaqus, the method is correct and reasonable. At last, a physical prototype is developed to verify the correctness of the dynamics. © 2022, The Authors. All rights reserved.

关键词： Dynamics

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Mold Wear During Die forging Based on Variance Analysis and Prediction of Die Life

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Transactions of Nanjing University of Aeronautics and Astronautics 2020年第6期37卷 872-883页

作者： CAI Ligang LIU Haidong PAN Junjie CHENG Qiang CHU Hongyan Beijing Key Laboratory of Advanced Manufacturing Technology Beijing University of TechnologyBeijing 100124P.R.China Guizhou Anda Aviation Forging Co Ltd Anshun 561005P.R.China

A process parameter optimization method for mold wear during die forging process is proposed and a mold life prediction method based on polynomial fitting is presented,by combining the variance analysis method in the orthogonal test with the finite element simulation test in the forging *** process parameters with the greatest influence on the mold wear during the die forging process and the optimal solution of the process parameters to minimize the wear depth of the mold are *** hot die forging process is taken as an example,and a mold wear correction model for hot forging processes is derived based on the Archard wear *** element simulation analysis of die wear process in hot die forging based on deform software is performed to study the relationship between the wear depth of the mold working surface and the die forging process parameters during hot forging *** optimized process parameters suitable for hot forging are derived by orthogonal experimental design and analysis of *** average wear amount of the mold during the die forging process is derived by calculating the wear depth of a plurality of key nodes on the mold *** life for the entire production process is predicted based on average mold wear depth and polynomial fitting.

关键词： die forging process Deform analysis of variance mold wear die life prediction

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Research on active pressurized forced lubrication deep drawing process and evaluation of lubrication effect

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Research Square 2021年

作者： Chen, Duan Zhao, Changcai Chen, Xiaoyi Li, Haoyang Zhang, Xin Key Laboratory of Advanced Forging & Stamping Technology and Science Yanshan University Ministry of Education of China Qinhuangdao Hebei066004 China College of Mechanical Engineering Yanshan University Qinhuangdao Hebei066004 China

Friction and lubrication are important parameters that affect the quality of sheet metal forming, excellent lubrication condition and less harmful friction can reduce local thinning of sheet metal, delay fracture and improve surface quality. Aiming at the poor friction conditions and difficult lubrication in the flange area during deep drawing, an active pressurized forced lubrication deep drawing(FLDD) process was proposed in this paper. A hydraulic system was employed to flush high pressure lubricating oil into the contact gap between die and sheet in the flange area. The high pressure hydrostatic oil film in the contact gap can reduce the real contact area and improve the lubrication condition effectively. The equipment is simple, the cost is low, and lubricating oil pressure can be measured and controlled. Under the conditions of 20kN, 35kN and 50kN blank holder force(BHF), FLDD test of box parts was carried out with 5MPa and 9MPa pressure water-based lubricating oil. The horizontal comparison experiment was conducted with common lubricating media such as polyethylene film(PE film), high-purity molybdenum disulfide particles, vegetable oil and water-based lubricating oil under the same process conditions. Lubrication effect was evaluated by obtaining test data. Test results illustrated that the lubrication effect of high-purity molybdenum disulfide particles was the best and that of vegetable oil was the worst. The lubrication effect of water-based mineral lubricant was significantly improved after pressurization. The maximum forming height was increased by 17.97%, the maximum forming force was reduced by 8.9%, the maximum wall thickness thinning rate was reduced by 7%, and the lubrication effect of 9MPa pressure was superior to that of 5MPa. Although there is still a certain shortfall with special lubricating media such as high-purity molybdenum disulfide, FLDD process has definite application value in improving production environment, pollution control and aut

关键词： Sulfur compounds

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Insights into Laser Powder Bed Fused Β-Type Titanium Alloy: Investigating Corrosion Behavior and Wear Properties after Post-Heat Treatment

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SSRN 2025年

作者： Luo, Xuan Li, Yuhao Yang, Chao Zhao, Chao Ma, Hongwei Song, Tao Sun, Minghan Liu, Xiaotao Li, Dongdong Li, Ning State Key Laboratory of Materials Processing and Die & Mould Technology Huazhong University of Science and Technology Wuhan430074 China National Engineering Research Center of Near-net-shape Forming for Metallic Materials Guangdong Provincial Key Laboratory for Processing Forming of Advanced Metallic Materials South China University of Technology Guangzhou510640 China Ningbo University China School of Materials Science and Engineering

The systematic evaluation of corrosion resistance and wear behavior represents a critical imperative for advancing biomedical titanium alloys in implant applications. This study systematically examines the corrosion-wear characteristics of laser powder bed fusion (LPBF)-fabricated β-type Ti-34.5Nb-6.9Zr-4.9Ta-1.4Si (TNZTS) alloy after post heat treatment, comparing with LPBF-processed Ti-35Nb-7Zr-5Ta (TNZT) and Ti-6Al-4V counterparts. Electrochemical analysis reveals the TNZTS system's excellent corrosion resistance, stemming primarily from reduced porosity and stabilized passivation film formation. The incorporation of Si effectively addressed the inherent limitation of TNZT alloy in forming defective passivation films under high-potential conditions, thereby enhancing their corrosion resistance. In addition, the TNZTS alloy with hard S2 phase also showed a significant improvement in wear resistance, as manifested by shallower and narrower wear tracks and a lower specific wear rate. This study provides foundational insights into the novel β-type Ti-Nb-Zr-Ta-Si alloy with excellent corrosion resistance and wear properties, positioning it as a promising candidate for load-bearing orthopedic implant applications. © 2025, The Authors. All rights reserved.

关键词： Passivation

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The effect of aging treatment on microstructure and corrosion resistance of 7××× series aluminum alloy

The effect of aging treatment on microstructure and corrosio...

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2020 International Conference on Artificial Intelligence and Electromechanical Automation, AIEA 2020

作者： Li, Chunming Zhang, Feng Yang, Yong Chen, Yunbo Zuo, Lingli Zhang, Yang Chen, Lin State Key Laboratory of Advanced Forming Technology and Equipment Beijing National Innovation Institute of Lightweight Ltd Beijing100083 China Anhui Fenghui Metal Co. Ltd. Fuyang236500 China

ISBN: (纸本)9781728182889

the influence of aging treatment on the microstructure and corrosion resistance of 7××× series aluminum alloy was studied by means of microstructure analysis, energy spectrum analysis, tensile test and intergranular corrosion test. The results show that the tensile strength, yield strength and elongation of alloy after peak-aging (121°C / 24 h) treatment are 605.3 MPa, 501.9 MPa and 8.6%, respectively, but which corrosion resistance is the worst;the strength of over-aged (121°C / 6 h + 177°C / 8 h) is significantly lower than that of peak-aging, but it has highest elongation, reaching 11.9%, besides, its corrosion resistance is the best;the strength of interrupted ageing (121°C / 0.5 h (water cooling) + 65°C / 240 h + 121°C / 24 h) alloy is the highest, and the corrosion resistance is better than those of peak-aging. © 2020 IEEE.

关键词： Corrosion resistance

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Minor pre-tension and aging-induced fine dispersion of precipitates for strength-ductility coordination in Mg-Y-Nd alloys

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Journal of Rare Earths 2025年

作者： Yanan Yu Luyi Han Ximan Sun Xiangjian Zhu Dejin Wei Guangchun Wang Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education) School of Materials Science and Engineering Shandong University Jinan 250061 China State key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Jinan 250061 China

Increasing the number density of precipitates is a critical factor in enhancing the strength-ductility balance of metallic materials. This study investigates the precipitation behavior of dislocation-induced precipitates and its impact on the strength-ductility coordination through minor pre-tension applied before aging. Statistical analysis of precipitate size reveals that pre-tension-induced dislocations provide additional nucleation sites, resulting in β′ phase refinement and a more dispersed distribution, which effectively alleviates stress concentration. In contrast, non-pre-tensioned samples exhibit increased grain boundary precipitates and larger PFZs, leading to extensive intergranular fracture. The pre-tension treatment accelerates aging kinetics, significantly reducing prismatic dislocation density after aging. This reduction facilitates β 1 phase nucleation and its linear arrangement along specific prismatic planes. This work systematically examined intra-granular precipitation strengthening induced by minor pre-tension, along with the interaction mechanisms between grain boundary precipitates and PFZs, providing crucial insights for developing high-performance magnesium alloys.

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