检索结果-南通市图书馆

Effect of post weld artificial aging and water cooling on microstructure and mechanical properties of friction stir welded 2198-T8 Al-Li joints

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第28期123卷 92-112页

作者： Y.Tao Z.Zhang p.xue D.R.Ni B.L.Xiao Z.Y.Ma Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

Friction stir welding(FSW)under both air cooling and water cooling conditions with welding parameters of 800-1200 rpm rotation rates and 50-200 mm/min welding speeds was carried out on 2198-T8 Al-Li alloys,and post weld artificial aging was performed on the air cooled *** welding defects other than lazy S were observed in the nugget zone(NZ)for all *** air cooling condition,the lowest hardness zone(LHZ)occurred in the heat affected zone(HAZ).FSW resulted in gradual dissolution of original T_(1),θ′andδ′/β′from the base material(BM)to the thermo-mechanically affected zone(TMAZ),and complete dissolution of all precipitates in the NZ withδ′/β′and Guinier-preston zones precipitating during *** air cooled joints exhibited no noticeable changes in intrinsic tensile strength with a joint strength reaching 81.3%of the BM,but varied elongation with welding parameters,which was closely related to failure in the NZ and fracture along lazy *** weld artificial aging led to the largest hardness recovery in the TMAZ but smaller hardness recovery in the initial LHZ and the *** aging kinetics across the joint was determined by volume fraction of both original precipitate dissolu-tion during welding and coarse particles formed during aging,and by dislocation density inherited from *** weld artificial aging greatly enhanced the joint strength with the ultimate tensile strength reaching 87.3%of the *** compared to air cooling condition,water cooling hardly affected the NZ hardness and did not improve the joint strength,and the reason was discussed in light of precipitates,hardness changes and fracture behavior.

关键词： Friction stir welding Aluminum-lithium alloys Microstructure Mechanical properties

Microstructure and Mechanical properties of X80 pipeline Steel Joints by Friction Stir Welding Under Various Cooling Conditions

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2020年第1期33卷 88-102页

作者： G.M.Xie R.H.Duan p.xue Z.Y.Ma H.L.Liu Z.A.Luo State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

X80 pipeline steel plates were friction stir welded(FSW)under air,water,liquid CO2+water,and liquid CO2 cooling conditions,producing defect-free *** microstructural evolution and mechanical properties of these FSW joints were *** granular bainite was observed in the nugget zone(NZ)under air cooling,and lath bainite and lath martensite increased signifi cantly as the cooling medium temperature *** particular,under the liquid CO2 cooling condition,a dual phase structure of lath martensite and fi ne ferrite appeared in the *** to the case under air cooling,a strong shear texture was identifi ed in the NZs under other rapid cooling conditions,because the partial deformation at elevated temperature was retained through higher cooling *** liquid CO2 cooling,the highest transverse tensile strength and elongation of the joint reached 92%and 82%of those of the basal metal(BM),respectively,due to the weak tempering softening.A maximum impact energy of up to 93%of that of the BM was obtained in the NZ under liquid CO2 cooling,which was attributed to the operation of the dual phase of lath martensite and fi ne ferrite.

关键词： Friction stir welding pipeline steel Microstructure Mechanical properties Cooling

Effect of static annealing on superplastic behavior of a friction stir welded Ti-6Al-4V alloy joint and microstructural evolution during deformation

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第35期130卷 112-123页

作者： C.L.Jia L.H.Wu p.xue D.R.Ni B.L.Xiao Z.Y.Ma Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

Structural integration is one of the most critical developing directions in the modern aerospace field,in which large-scale complex components of Ti alloys are proposed to be fabricated via the method of welding + superplastic ***,the undesired strain localization appeared during superplastic deformation of the entire joint has largely hindered the development of this *** our study,a combination process of friction stir welding(FSW) + static annealing+ superplastic deformation was first time proposed to eliminate severe local *** achieve this result,a fully fine lamellar structure was obtained in the nugget zone(NZ) via FSW,which was totally different from the mill-annealed structure in the base material(BM).After annealing at 900℃ for 180 min,the BM and NZ then exhibited the similar elongation of> 500% and similar flow stress at 900 ℃,3 × 10^(-3)s^(-1),which was the precondition for achieving uniform superplastic deformation in the entire ***,the different microstructures in the BM and NZ tended to become the similar equiaxed structure after deformation,which was the result of different microstructural evolution mechanisms in the NZ and *** the NZ,there was a static and dynamic spheroidization of the fully lamellar structure during the process,which could largely reduce the flow softening of the fully lamellar *** the BM,a new view of "Langdon-CRSS theory"(CRSS,critical resolved shear stress) was proposed to describe the fragmentation of the coarse equiaxed structure,which established the relationship between grain boundary sliding and intragranular deformation during deformation.

关键词： Friction stir welding Titanium alloys Superplasticity Static annealing Microstructure

Enhanced Mechanical properties of Friction Stir Welded 5083Al-H19 Joints with Additional Water Cooling

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2017年第9期33卷 1009-1014页

作者： B.B.Wang F.F.Chen F.Liu W.G.Wang p.xue Z.Y.Ma School of Mechanical Engineering Liaoning Shihua University Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

3-mm-thick 5083Al-H19 rolled plates were friction stir welded(FSW) at tool rotation rates of 800 and200 rpm with and without additional water cooling. With decreasing the rotation rate and applying water cooling, softening in the FSW joint was significantly reduced. At a low rotation rate of 200 rpm with additional water cooling, almost no obvious softening was observed in the FSW joint, and therefore a FSW5083Al-H19 joint with nearly equal strength to the base material(BM) was obtained. Furthermore, the grains in the nugget zone were considerably refined with reducing the heat input and ultrafine equiaxed grains of about 800 nm were obtained in the lowest heat input condition. This work provides an effective method to achieve high property FSW joints of precipitate-hardened and work-hardened Al alloys.

关键词： Friction stir welding Aluminum alloy Water cooling Microstructure Mechanical property

Fabrication of large-bulk ultrafine grained 6061 aluminum alloy by rolling and low-heat-input friction stir welding

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2018年第1期34卷 112-118页

作者： C.Y.Liu B.Qu p.xue Z.Y.Ma K.Luo M.Z.Ma R.p.Liu Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Key Laboratory of New processing Technology for Nonferrous Metal & Materials Ministry of Education Guilin University of Technology Guangxi Key Laboratory of Universities for Clean Metallurgy and Comprehensive Utilization of Nonferrous Metal Resources Guilin University of Technology State Key Laboratory of Metastable Materials Science and Technology Yanshan University

In this study, the ultrafine grained （UFG） 6061 Al alloys fabricated by cold rolling were friction stir welded （FSW） with different rotation rates under both air cooling and rapid cooling in water. Low-heat-input parameters of 400 rpm rotation rate in water （400-Water） could effectively inhibit the coarsening of recrystallized grains, reduce the precipitation rate, and retain more dislocations of the UFG 6061 Al parent metal. 400-Water joint showed high lowest-hardness value, narrow low-hardness zone, and high tensile strength, attributing to the effect of dislocation, grain boundary, solid-solution, and precipitation hardening. This work provides an effective strategy to fabricate large-sized bulk UFG AI alloy by cold rolling with large deformation and low-heat-input FSW.

关键词： Aluminum alloys Ultrafine grained materia Friction stir welding Mechanical properties

Static spheroidization and its effect on superplasticity of fine lamellae in nugget of a friction stir welded Ti-6Al-4V joint

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第24期119卷 1-10页

作者： C.L.Jia L.H.Wu p.xue H.Zhang D.R.Ni B.L.Xiao Z.Y.Ma Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The spheroidization of the lamellar structure can greatly contribute to the superplasticity of the nugget zone(NZ)of Ti alloy welds,which is the key to achieve the integral superplastic forming of welds for the fabrication of large-scale complex ***,the spheroidization process is complex and costly since it cannot be obtained generally,unless the lamellae suffers from a large *** this study,the static spheroidization was achieved for the fine lamellae structure in the nugget of a friction stir welded(FSW)Ti-6Al-4V joint,particularly by the annealing without any *** specialα/βinterface obeying a Burgers orientation relationship(BOR)after FSW was first time directly observed,whose effect on the spheroidization was discussed.A new static spheroidization mechanism with the gradual coalescence of the adjacent lamellae was discovered,which we named as“termination coalescence”.There was a slower coarsening rate in the lamellar structure than in the classical equiaxed one,due to the BOR in the lamellae,although both of them exhibited a volume diffusion character during ***,the similar superplasticity can be achieved for the base material and NZ after *** study can provide a new way to the spheroidization and a theoretical basis for the integral superplastic forming of welds during production.

关键词： Friction stir welding Titanium alloys Spheroidization mechanism Coalescence Superplasticity Static annealing

Effect of heat-input on pitting corrosion behavior of friction stir welded high nitrogen stainless steel

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2019年第7期35卷 1278-1283页

作者： H.Zhang p.xue D.Wang L.H.Wu D.R.Ni B.L.Xiao Z.Y.Ma Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences

In this study, different welding param eters were selected to investigate the effects of heat-in put on the microstructure and corrosion resistance of the friction stir welded high nitrogen stainless steel joints. The results show ed that, the welding speed had major influence on the duration at elevated tem perature rather than the peak tem perature. The hardness distribution and tensile properties of the nugget zones (NZs) for various joints were very similar while the pitting corrosion behavior of various NZs showed major differences. Large heat-input resulted in the ferrite bands being the pitting location, while tool wear bands were sensitive to pitting corrosion in the low heat-input joints. Cr diffusion and tool wear were the main reasons for pitting. The mechanisms of pitting corrosion in the NZs were analyzed in detail.

关键词： High nitrogen stainless steel Friction stir welding Mechanical properties Corrosion resistance Heat-input

Achieving ultra-high strength friction stir welded joints of high nitrogen stainless steel by forced water cooling

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2018年第11期34卷 2183-2188页

作者： H.Zhang D.Wang p.xue L.H.Wu D.R.N B.L.Xiao Z.Y.Ma Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China University of Chinese Academy of Sciences 19 Yuquan RoadBeijing 100049China

The microstructure and properties of water-cooled and air-cooled friction stir welded（FSW） ultra-high strength high nitrogen stainless steel joints were comparatively studied. With additional rapid cooling by flowing water, the peak temperature and duration at elevated temperature during FSW were significantly reduced. Compared to those in the air-cooled joint, nugget zone with finer grains（900 nm） and heat affected zone with higher dislocation density were successfully obtained in the water-cooled joint,leading to significantly improved mechanical properties. The wear of the welding tool was significantly reduced with water cooling, resulting in better corrosion resistance during the immersion corrosion test.

关键词： Friction stir welding Stainless steels Mechanical properties Corrosion

Microstructural refinement mechanism and its effect on toughness in the nugget zone of high-strength pipeline steel by friction stir welding

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第34期93卷 221-231页

作者： R.H.Duan G.M.Xie p.xue Z.Y.Ma Z.A.Luo C.Wang R.D.K.Misra State Key Laboratory of Rolling and Automation Northeastern UniversityNo.3 Wenhua RoadShenyang 110819China Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China School of Metallurgy Northeastern UniversityNo.3 Wenhua RoadShenyang 110819China Department of Metallurgical Materialsand Biomedical EngineeringUniversity of Texas at El PasoTX 79968USA

High-strength pipeline steel was subjected to friction stir welding(FSW)at rotation rates of 400-700 rpm,and the grain refinement mechanism of the nugget zone(NZ)was *** thermomechanical process during FSW in the NZ was simulated by multi-pass thermal compression,thereby achieving the austenitic non-recrystallization temperature(T_(nr)).The austenitic non-recrystallization in the NZ at the lowest rotation rate of 400 rpm caused a significant grain ***,the reduced rotation rate also resulted in the formation of a high ratio of island-like martensite-austenite(M-A)*** toughness of the NZs was enhanced as the rotation rate decreased,which is attributed to the fine effective grains and homogeneously distributed fine M-A constituents dramatically inhibiting crack initiation and propagation.

关键词： pipeline steel Friction stir welding Grain refinement M-A constituent Toughness