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tensile properties and deformation behavior of an extra-low interstitial fine-grained powder metallurgy near alpha titanium alloy by recycling coarse pre-alloyed powder

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Journal of Materials Science & Technology 2022年第34期129卷 96-107页

作者： H.R.Zhang H.Z.Niu M.C.Zang Y.H.Zhang S.Liu D.L.Zhang School of Materials Science and Engineering Northeastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

An extra-low interstitial near alpha alloy Ti-3Al-2Zr-2Mo(wt%) was fabricated by hydrogenation and thermomechanical consolidation(TMC) of the coarse and spherical pre-alloyed powder with particle sizes of 60 to 270 μm. The coarse powder is a byproduct of pre-alloyed powder produced for selective laser and electron beam additive manufacturing. The TMC process involves powder compaction, fast sintering,in-situ dehydrogenation and an immediate hot extrusion to form a fully dense and fine-grained martensitic microstructure. Further dehydrogenation in vaccum at 700 °C converted the martensitic microstructure into an interwoven α/β microstructure which exhibited an improved yield strength, apparent necking and premature cracking at grain boundary α(α_(GB)) ribbons. A further annealing of 880 ℃/1 h/AC led to the formation of a fine-grained α/β_(t)composite structure, which achieved an enhance ultimate tensile strength of 835 MPa and excellent tensile ductility of 16.0%. Analysis of the deformation behavior of the alloy in different states revealed that the α/β_(t)composite structures brought about an enhanced strain hardening capability by heterogeneous deformation effect of hard β_(t)and soft α-laths, which inhibited the formation of microcracks and consequently improved the coordinated deformation.

关键词： Nearα-Ti alloy Coarse pre-alloyed powder Hydrogenation tensile properties Deformation behaviour

tensile properties analysis of CFRP-titanium plate multi-bolt hybrid joints

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Chinese Journal of Aeronautics 2022年第3期35卷 464-474页

作者： Yanping ZHENG Chaoyu ZHANG Ying TIE Xu WANG Mingkun LI School of Mechanical and Power Engineering Zhengzhou UniversityZhengzhou 450001China

Hybrid joints have better tensile properties than pure bonded and bolted bolts,and are increasingly used in the aerospace *** tests are carried out for the Hybrid Bonded/Bolted(HBB)joints of Carbon Fiber Reinforced Polymer(CFRP)laminate and titanium alloy plate under different bolt numbers,and the corresponding load–displacement curves are *** the same time,based on Continuum Damage Mechanics(CDM)theory,which is derived from 3D Hashin failure criteria,and a Cohesive Zone Model(CZM),the tensile strength prediction model of the composite laminate-titanium alloy plate multi-bolted HBB joint was established,and the numerical simulation results were in good agreement with the experimental height,which validate the feasibility of the *** difference in the bearing capacity of HBB joints under different numbers of bolts is compared and *** this basis,the influence of inter-bolt distance on the tensile properties of the HBB joints is *** results show that the double-nail HBB joints can effectively improve the end warpage and low bearing capacity of the single-nail HBB *** tensile failure load of the double-nail HBB joints under the standard lap width(30 mm)is 82.6%higher than that of the single nail,the tensile failure load of the three-bolt HBB joints is 34.1%higher than that of the double *** the three-bolt HBB joint,the joint strength is controlled by the adhesive and the external bolt,while the internal bolt is redundant,the hybrid joint can be simplified by reducing the middle *** inter-bolt distance has a great influence on the failure load of the hybrid *** the inter-bolt distance can effectively improve the bearing capacity of the structure.

关键词： CFRP laminate Finite element model Hybrid(bonded/bolted)joint Multi-bolt tensile properties

tensile properties and fractographs of Ti–2.5Al–1.5Mn foils at different temperatures

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Rare Metals 2017年第4期36卷 247-255页

作者： Zhen-Wu Ma Guo-Quan Tong Feng Chen College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016China

The tensile properties and fractographs of Ti- 2.5Al-1.5Mn foils at different temperatures were investi- gated. It is observed that material properties closely cor- relate with the thickness （T） to grain size （d） ratio and deformation temperature. tensile analysis shows that local deformation is the main deformation feature in foils forming at room temperature, which may lead to premature fracture. The causes of inhomogeneous deformation behavior are the limited number of deformable grains contained in deformation zone and the weak transferability of hardening among different grains. Fracture analysis reveals that the size of dimples can represent the ductility of foils at room temperature. With the further increase of deformation temperature, the main plastic deformation mode of foils is transformed from intragranular disloca- tions and twin crystal to grain-boundary gliding and roll- ing. In conclusion, foil forming at elevated temperature can increase the hardening transferability and the number of deformable grains in deformation zone, which is an effective method to improve the formability and reduce the scatter of material properties.

关键词： Size effects Titanium foils tensile properties Homogeneous deformation Elevated temperature

tensile properties of a composite–metal single-lap hybrid bonded/bolted joint

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Chinese Journal of Aeronautics 2021年第2期34卷 629-640页

作者： Xiaoqi LI Xiaoquan CHENG Yujia CHENG Zhiyong WANG Wenjun HUANG School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China Istar-space Technology Co. Ltd.Tianjin 300304China AVIC China Helicopter Research ami Development Institute Jingdezhen 333001China

Hybrid bonded/bolted(HBB) joint has been widely used in engineering practice because it can overcome the potential weakness of pure bonded and pure bolted joints. However, studies on HBB joint are still at the initial stage. In this paper, tensile properties of a composite–metal singlelap HBB joint was investigated experimentally. And a detailed finite element model(FEM) was established to simulate the tensile behavior of the joint. The model was verified by the experimental results. Then the damage propagation and load transfer mechanism were explored based on the FEM. The results show that the HBB joint can provide multi-load transmission paths and resist damage propagation in the adhesive. The HBB joint has higher strength and energy absorption capacity than the pure bonded joint. And the HBB joint has greater initial damage load and tensile stiffness than pure bolted joint. Adhesive fillets can obviously improve the tensile performances of the HBB joint. Lateral stiffness of the joint boundary and testing machine show obvious effects on tensile performances of single-lap hybrid joints.

关键词： Experimental tests Failure mechanism Finite element model Hybrid(bonded/bolted)joint tensile properties

tensile properties of Surface-Treated Glass Fiber Reinforced PTFE Composite with Rare Earth Elements

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Journal of Rare Earths 2003年第3期21卷 364-367页

作者：薛玉君程先华 School of Mechanical Engineering Shanghai Jiaotong University

The optimum amount of rare earth elements (RE) for treating glass fiber surface and its effect on the tensile properties of glass fiber reinforced polytetrafluoroethylene (GF/PTFE) composites were investigated. The tensile properties of GF/PTFE composites with different surface treatment conditions were measured. The fracture surface morphologies were observed and analyzed by SEM. The results indicate that rare earth elements can effectively promote the interfacial adhesion between the glass fiber and PTFE, owing to the effects of rare earth elements on the compatibility. The tensile properties of GF/PTFE composites can be improved considerably when the content of RE in surface modifier is 0.2%～0 4%, and the optimum performance of GF/PTFE composites is obtained at 0.3%RE content.

关键词： GF/PTFE composites tensile properties rare earths

tensile properties and microstructure of rheo-diecast 7075 alloy prepared by serpentine channel process

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China Foundry 2019年第3期16卷 161-167页

作者： Wei-min Mao Wen-zhi Zhu School of Materials Science and Engineering University of Science & Technology Beijing Beijing 100083 China State Key Laboratory of Materials Processing and Die & Mould Technology Huazhong University of Science & Technology Wuhan 430074 China

A semisolid slurry of 7075 aluminum alloy was prepared by means of a serpentine channel process(SCP) and rheo-diecasting. The influences of pouring temperature during slurry preparation,the injection pressure and die preheat temperature on the mechanical properties and microstructure of a rheo-diecast 7075 aluminum alloy were investigated. The results show that the as-cast strength and elongation of the tensile samples were 210-260 MPa and 0.2%-1.7%,respectively,with an injection pressure of 130 MPa,a pouring temperature of 700-720 oC,a preheat temperature of 280-350 oC,and a plunger speed of 0.5 m·s-1. The results also show that the aged strength and elongation of the tensile samples were 420-453 MPa and 1.0%-1.4%,respectively,when the alloy solution was treated at 470 oC for 12 h and aged at 120 oC for 24 h. The substantial shrinkage porosity in the 7075 aluminum alloy tensile samples was the main cause of low elongation.

关键词： serpentine channel rheo-die casting 7075 aluminum alloy microstructure tensile properties

tensile properties and fracture surface of 07MnNiCrMoVDR steel welded joint at low temperature

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China Welding 2009年第2期18卷 62-64页

作者：张丽红陈芙蓉解瑞军 College of Materials Science and Engineering Inner Mongolia University of Technology Huhhot 010051

The tensile properties and fracture surface of 07MnNiCrMoVDR steel welded joint at low temperature have been studied by universal testing machine and scanning electron microscope. The results show that the tensile properties of 07MnNiCrMoVDR steel welded joint are greatly affected by temperature. tensile strength and yield strength of 07MnNiCrMoVDR steel welded joint increase, but elongation and reduction of area decrease with temperature decreasing. The macro-fracture of 07 MnNiCrMoVDR steel welded joint exhibits that the shear lip is not significant and micro-fracture makes up of dimpled fracture and tear fracture, and dimple becomes tiny and uniform with temperature decreasing.

关键词： low temperature tensile properties fracture surface 07MnNiCrMoVDR steel welded joint

tensile properties and fracture characteristics of spray cast alloy IC6 (Ni-7.8Al-14Mo-0.05B)

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China Foundry 2007年第1期4卷 10-12页

作者： MI Guo-fa WANG Hong-wei TIAN Shi-fan LI Zhou ZENG Song-yan Henan Polytechnic Institute Jiaozuo 454000 China Harbin Institute of Technology Harbin 150001 China Institute of Aeronautical Materials Beijing 100095 China

tensile testing results of spray cast Ni3Al-based superalloy indicated that the yield strength and tensile strength increase with the increasing of temperature and reached maximum at around 760℃, then decrease with the increasing of temperature. After high temperature isostatic pressing (HIP), yield strength decreased and ductility and tensile strength increased. Stereographic projection showed that no matter at room temperature, medium temperature or high temperature, cracks extend along (111).

关键词： spray casting Ni3Al-based superalloy tensile properties fracture characteristics

Fluidity, Microstructure, and tensile properties of Sub-rapidly Solidified Mg-6Al-4Zn-xSn(x=0,0.6,1.2,1.8) Alloy

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Acta Metallurgica Sinica(English Letters) 2021年第9期34卷 1265-1276页

作者： Jie Cui Tianjiao Luo Yingju Li Xiaohui Feng Qiuyan Huang Yuansheng Yang School of Materials Science and Engineering Northeastern UniversityShenyang 110819China Institute of Metal Research Chinese Academy of ScienceShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China

In this paper, the infl uence of the Sn element on the melt viscosity, grain size, shrinkage, and tensile properties of the subrapidly solidified Mg-6Al-4Zn alloy was studied. The results showed that the melt viscosity of the Mg-6Al-4Zn alloy was greatly decreased because of the addition of Sn. As the content of Sn increased from 0 to 1.8 wt.%, the grain size of the alloy was refined, and the dendrite microstructure was changed to rose-shaped ones simultaneously. The decreased melt viscosity and refined microstructure were conductive to the feeding of melt, which contributed to the reduction in volume fraction of shrinkage. The volume fraction of shrinkage of the Mg-6Al-4Zn-1.2 Sn alloy was reduced by 30.8%, compared with that of the alloy without Sn addition. tensile properties of the Mg-6Al-4Zn-x Sn alloys were increased firstly and then decreased with the augmented Sn content. The yield strength, ultimate tensile strength, and elongation of the alloy containing 1.2 wt.% Sn were 21.4%, 39.5%, and 259.0% higher than those of the alloy without Sn addition, respectively. The addition of Sn was considered to reduce the shrinkage of the sub-rapidly solidified Mg-6Al-4Zn magnesium alloy and thus improved its tensile properties. To identify the mechanism, the effect of Sn on the volume fraction of shrinkage was discussed from three aspects of melt viscosity, grain refinement, and volume fraction of eutectic phases.

关键词： Magnesium alloy Melt viscosity Grain size Shrinkage tensile properties