检索结果-内蒙古大学图书馆

SSRN 2023年

作者： Fu, Hao Zhang, Fei Zhang, Wen Zhang, Tianyi Huang, Xiedong Chen, Peng Wu, Hong Li, Zulai Shan, Quan School of Material Science and Engineering Kunming University of Science and Technology Kunming650093 China National & Local Joint Engineering Laboratory for Technology of Advanced Metallic Solidification Forming and Equipment Kunming650093 China Yunnan Kungang Wear Resistant Material Science Co. Ltd. Kunming650093 China State Key Laboratory of Powder Metallurgy Central South University Changsha410083 China

Precipitation could be a considerable factor in strengthening and improving wear resistance in Ti, V, Nb alloyed high manganese steel. In this work, nitrogen is introduced to promote the precipitation of M (Ti, V, Nb) C, and the influences on mechanical and frictional wear properties are investigated. The submicron and micron(≤2μm) precipitates are increased in volume obviously, meanwhile the tensile strength, from 594MPa to 685MPa, and yield strength, from 362MPa to 433MPa, of the nitrogenous steel are enhanced respectively, and the Vickers hardness is elevated slightly. Then the weight loss of nonnitrogenous and nitrogenous both increase linearly with the load increasing, under frictional wear, the wear resistance of nitrogenous steel remains higher than the nonnitrogenous. This study provides relevant guidance on how the nitrogen addition affect the mechanical and wear properties. © 2023, The Authors. All rights reserved.

关键词： Nitrogen

The Effect of Rra Treatment on Mechanical Properties and Wear Behavior in Vanadium Micro-Alloyed Hadfield's Steel

学校读者我要写书评

暂无评论

SSRN 2023年

作者： Wang, Rui Zhang, Wen Zhang, Fei Fu, Hao Huang, Qinyuan Wu, Hong Li, Zulai Shan, Quan School of Material Science and Engineering Kunming University of Science and Technology Kunming650093 China National & Local Joint Engineering Laboratory for Technology of Advanced Metallic Solidification Forming and Equipment Kunming650093 China Yunnan Kungang Wear Resistant Material Science Co. Ltd. Kunming650093 China State Key Laboratory of Powder Metallurgy Central South University Changsha410083 China

To solve the ongoing problems of micro-alloyed Hadfield’s steel, insufficient hardness and excessive deformation in the early working period, expensive alloying elements like Ti, Nb, and V have been utilized. However, traditional long-time, single-stage aging exacer-bates vanadium to assemble at the edge of initial precipitates, which diminishes estimated effects. For this, here we report the tremendous impact of retrogression and re-aging process(RRA) in this steel by booming the V (C, N) mean sized in 11nm. The procedure enhances the micro-hardness, yielding strength, tensile strength, and impact-wear resistance for more than 27.4%, 29.5%, 22.2%, and 51.5%, respectively. Moreover, the wear mechanism of RRA samples has been investigated in that micro-sized precipitates surrounded by numerous nano V(C, N) stick in the matrix and hinder the abrasive embedding consistently, thus decreasing the micro-cutting and micro-plowing. This new process maximizes the utilization of costly and nonrenewable vanadium and magnifies the impact-wear resistance under either medium or high-intensity working conditions. © 2023, The Authors. All rights reserved.

关键词： Wear resistance

Abnormal grain growth mechanism and inhibiting strategy by a tailored two-step solution treatment of ZK60 Mg alloy

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2025年

作者： Dang, Guanghan Chen, Liang Tang, Jianwei Zhao, Yuhui Zhang, Cunsheng Kong, Xiangshan State Key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Shandong Jinan250061 China Shandong University Shandong Jinan250061 China

Mg profiles extruded through porthole die inherently contain longitudinal welds, which can readily induce the abnormal grain growth (AGG) in solution treatment at elevated temperature. Here, a strategy of two-step (primary and secondary) solution is tailored to inhibit AGG. The results indicate that AGG during primary solution can only be suppressed when the temperature drops below 300 °C, while these samples experienced AGG during secondary solution. It is interesting that the width of abnormal grain after secondary solution significantly decreases from 1,473 to 71 µm with increasing the holding time of primary solution from 3 to 84 h. This inhibiting effect results in notable enhancements in mechanical properties, where the elongation, initial fracture points, and maximum bending force are improved by 88.58 %, 32.63 %, and 128.50 %, respectively. The dislocation density and types of the precipitated phases after primary solution are the main factors for inhibiting AGG. First, the dislocation density decreases with increasing the time of primary solution, reducing the stored energy in grain interior. Second, as the primary solution time is extended, MgZn2 phases greatly become coarsening, accompanied by a transition in their relationship with α-Mg from coherent to semi-coherent. Moreover, the quantities of Mg4Zn7 (non-coherent with α-Mg) and Mg2Zn3 (semi-coherent with α-Mg) undergo a substantial increase, contributing to a high interfacial energy that effectively inhibits the grain boundary migration during secondary solution. © 2025

关键词： Zinc alloys

Effect Mechanism of Paramagnetic Element Cu In-Situ Alloying on the Microstructure and Magnetic Properties of Slm-Formed Nifemo Alloys

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Xiong, Falin Yang, Jiaoxi Guo, Donghai Liu, Wenfu Du, Zhicheng Yang, Feng Li, Ran Ge, Xueyuan Wang, Miaohui Xu, Hongchao Zhou, Zheng Institute of Laser Engineering Faculty of Material and Manufacturing Beijing University of Technology Beijing100124 China Central Iron and Steel Research Institute Beijing100081 China State Key Laboratory for Advanced Forming Technology and Equipment China Academy of Machinery and Technology Beijing100083 China Beijing National Innovation Institute of Light weight Ltd. Beijing100083 China Beijing Tieke Shougang Railway-Tech Co. Ltd Beijing100083 China

NiFeMo alloy possesses exceptional soft magnetic properties, and suffers significantly from the SLM process. The major objective of this study is to explore the relationship between microstructure and magnetic properties of SLM formed (NiFeMo)100-xCux alloy (x=0 wt.%, 0.5 wt.%, 0.8 wt.%, 1.1 wt.%, 1.4 wt.%, 1.7 wt.%, and 2.0 wt.%) by adding Cu in-situ alloying, and develop a new method to adjust the magnetic properties of SLM molding materials. The structure and magnetic properties of the alloy samples were characterized using scanning electron microscopy (SEM), X-ray diffraction, electron backscattering diffraction (EBSD), DC B-H hysteresis map, and transmission electron microscopy (Titan-G2) techniques. The results show that (NiFeMo)100-xCux alloy exhibits FCC γ-(Ni, Fe) solid solution structure within the range of added Cu content in this study. In the central region of the melt pool, columnar crystals grow in the direction of the temperature gradient, and the average grain size (D) gradually decreases with the increase of the Cu content of in situ alloying, while the content of low-angle grain boundaries (LAGS) decreases. Cu atoms exist in γ-(Ni, Fe) solid solution by replacement solid solution, changing the crystal structure and leading to lattice distortion. The (NiFeMo)98Cu2 alloy has an average crystal plane spacing d of about 0.2261 nm along the (1[[EQUATION]]) γ-(Ni, Fe) direction, and a lattice distortion ∆Ε of about 1.09%. The saturation magnetic induction (BS) increases and then decreases with increasing Cu additions, with BS > 0.7 T for NiFeMo alloys with Cu additions of 0.8 wt.%, 1.1 wt.%, and 1.4 wt.%. The coercivity (HC) generally decreased with the increase of Cu content, and HC © 2024, The Authors. All rights reserved.

关键词： Alloying

The Microstructure Effect on Fatigue and Dwell-Fatigue in a Nickel-Based Superalloys

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Peng, Zichao Zheng, Zebang Wang, Xuqing Zou, Jinwen Science and Technology on Advanced High Temperature Structural Materials Laboratory Beijing Institute of Aeronautical Materials AECC Beijing100095 China State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of High-Performance Precision Forming Technology and Equipment School of Materials Science and Engineering Northwestern Polytechnical University P.O. Box 542 Xi’an710072 China

In this study, the fatigue behaviors of a nickel-based superalloys FGH96 with different microstructural morphologies generated from different heat-treatment processes were investigated. The fatigue and dwell-fatigue tests with the same maximum stress of 1200 MPa were conducted at 650°C. The relationship between the γ’ morphology and the fatigue properties was established. The results indicate that the critical shearing stress of dislocation movement played a key role in affecting the fatigue life. No apparent difference can be observed from the fracture morphology at the macroscopic scale for normal fatigue and dwell-fatigue tests. However, in the crack initiation region, the crack was observed to grow along the grain boundary for the dwell-fatigue condition and resulting in the intergranular fracture, which was similar to creep failure. The introduction of dwell time in the fatigue loading brings larger cyclic strain deformation originates from massive dislocation slip. The dwell debit for the considered loading condition is about 100 times. © 2022, The Authors. All rights reserved.

关键词： Fatigue of materials

Core@Shell Ti3c2tx@Ni Particles with Enhanced Microwave Absorption Properties and Prolonged Stability

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Xu, Weimin Li, Shibo Hu, Shujun Zhang, Weiwei Yu, Wenbo Zhou, Yang Center of Materials Science and Engineering School of Mechanical and Electronic Control Engineering Beijing Jiaotong University Beijing100044 China State Key Laboratory of Advanced Forming Technology and Equipment Beijing National Innovation Institute of Lightweight Ltd. Beijing100083 China

2D Ti 3 C 2 T x MXene with a multi-layered structure and surface functional groups exhibits an ability to attenuate electromagnetic energy through the dielectric loss mechanism. However, the absence of magnetic properties causes its unmatched impedance and poor MA performance. In addition, as exposed to air, oxidization of Ti 3 C 2 T x generally starts from its nanosheet edges and gradually expands to the inside, causing severe oxidative degradation within days and thus restricting its industrial applications. Here, core@shell structured Ti 3 C 2 T x @Ni particles were prepared by electroless plating. The plated thinner Ni(P) shell endows the modified Ti 3 C 2 T x particles with good impedance matching with microwaves. A minimum reflection loss (RL min ) value of -48.34 dB was achieved in the Ti 3 C 2 T x @Ni particles, better than the RL min of -11 dB for the pristine Ti 3 C 2 T x . The core@shell Ti 3 C 2 T x @Ni particles are particularly attractive in its storage stability. As compared with the fast and oxidation of Ti 3 C 2 T x within 12 weeks, the as-prepared Ti 3 C 2 T x @Ni particles are stable up to a year in air because the Ni shell prevents Ti 3 C 2 T x nanosheets from oxidative degradation. © 2022, The Authors. All rights reserved.

关键词： Nanosheets

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

学校读者我要写书评

暂无评论

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

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

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

学校读者我要写书评

暂无评论

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

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

学校读者我要写书评

暂无评论

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

Modulating dislocation reactions through preferential hydrogen segregation in bcc metals

学校读者我要写书评

暂无评论

arXiv

arXiv 2024年

作者： Hou, Jie Peng, Ducheng Kong, Xiang-Shan Deng, Huiqiu Hu, Wangyu Chen, Cheng Song, Jun College of Materials Science and Engineering Hunan University Changsha410082 China State key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Shandong Jinan250061 China School of Physics and Electronics Hunan University Changsha410082 China School of Aeronautics Northwestern Polytechnical University Shaanxi Xi’an710072 China Department of Mining and Materials Engineering McGill University MontrealQCH3A 0C5 Canada

The interaction between dislocations is fundamental to plastic deformation, work hardening, and defect accumulation. While extensive research has focused on the impact of solutes on individual dislocations, how solutes affect dislocation-dislocation reactions remains largely unexplored. Here, using atomistic simulations of iron as a model bcc system, we demonstrate that hydrogen solutes enable two /2 screw dislocations to react and form a edge dislocation junction, a process that is otherwise unfavorable in hydrogen-free environments. This phenomenon arises from the preferential segregation of hydrogen around the dislocation, which reduces the energy of the reaction product. The resulting dislocation demonstrates remarkable stability and transforms into a vacancy-type dislocation loop under strain. These vacancy-type dislocation loops can accumulate during continuous deformation and dislocation reactions, serving as precursors for the initiation of structural damage, such as cracking and blistering. Our findings highlight the pivotal role of hydrogen in dislocation reactions, uncover a novel defect accumulation mechanism crucial for interpreting recent experimental observations, and represent a significant advance in understanding hydrogen-induced damage in bcc metals. Copyright © 2024, The Authors. All rights reserved.

关键词： Screw dislocations