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Journal of Materials Science & Technology 2018年第9期34卷 1628-1637页

作者： l.h.wu K.Nagatsuka K.Nakata Joining and Welding Research Institute Osaka University

It is a challenge to achieve a sound welded metal/carbon-fiber-reinforced thermoplastic（CFRTP） joint with high strength and few bubbles. In this study, sound lap joints of Cu and CFRTP were obtained by friction lap joining（FlJ） directly at rotation rates of 600-2000 rpm, with the welding tool at the joint center and offsetting the tool 7 mm away from the center toward the retreating side, respectively. Tool offsetting reduced the non-uniform temperature distribution in the lap joints resulting from the high conductivity of Cu, which not only enhanced the tensile shear force from 0.89-2.25 kN to 1.71-3.54 kN,with the maximum increasing rate of 135%, but also reduced the bubble area to only 19% of the original level of 2000 rpm. It is the first time to report a high-quality Cu/CFRTP joint with a high strength and few bubbles. The large increase of the strength after tool offsetting was attributed to the increase of the joining area, the decrease of bubbles and the decrease of the CFRTP degradation. The details on the generation,quantitative distribution and expulsion of the bubbles in the FlJ joints were discussed.

关键词： hybrid joining Plastic Metal Carbon-fiber-reinforced plastic Properties

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

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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

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

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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

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

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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

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

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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

Evolution mechanisms of microstructure and mechanical properties in a friction stir welded ultrahigh-strength quenching and partitioning steel

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Journal of Materials Science & Technology 2022年第7期102卷 213-223页

作者： Z.W.Wang J.F.Zhang G.M.Xie l.h.wu h.Zhang 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 State Key laboratory of Rolling and Automation Northeastern UniversityShenyang110819China

Ultrahigh-strength quenching and partitioning(Q&P) steels have attracted strong interests in the auto manufactory,while the comprehensive understanding in the microstructure and mechanical behavior of their welded joints is highly needed to enrich their *** the present work,it is designed to make an insight into these imperative *** strength Q&P 1180 steel joints to parent metal were successfully fabricated via friction stir welding(FSW) technique under different parameters. Apparent hardening and softening were observed in stir zone(SZ) and heat-affected zone(hAZ) respectively,whose microstructures strongly depended on the peak temperature and cooling rate during *** formation of fresh martensite was the main mechanism for the SZ hardening,while the decomposition of metastable phases played key roles in the microhardness drop of the hAZ.A heat source zone-isothermal phase transition layer model was proposed to clarify the impregnability of the joint strength under parameter *** dual-phase structure,nano-carbide particles,tempered initial martensite,and ultrafine-grained ferrite synergistically improved the strain hardening ability of the hAZ,which eventually resulted in the equal strength FSW joints.

关键词： Ultrahigh-strength Q&P steel Friction stir welding Microstructure Mechanical property Strain hardening

Effects of welding speed on the multiscale residual stresses in frictionstir welded metal matrix composites

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Journal of Materials Science & Technology 2019年第5期35卷 824-832页

作者： X.X.Zhang l.h.wu h.ANDra W.M.Gan M.hofmann D.Wang D.R.Ni B.l.Xiao Z.Y.Ma Shenyang National laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Fraunhofer Institute for Industrial Mathematics Fraunhofer-Platz 1 Kaiserslautern 67663 Germany German Engineering Materials Science Centre Helmholtz-Zentrum Geesthacht D-21502 Geesthacht Germany heinz Maier-leibnitz Zentrum (MlZ) Technische Universitat Munchen D-85747 Garching Germany

The effects of welding speed on the macroscopic and microscopic residual stresses(RSes) in friction stir welded 17 vol.% SiCp/2009 Al-T4 composite plates were studied via neutron diffraction and an improved decoupled hierarchical multiscale modeling methods. Measurements showed that the macroscopic and total RSes had the largest variations in the longitudinal direction(lD). Increasing the welding speed led to higher values of measured lD macroscopic and total RSes in the matrix. The welding speed also significantly influenced the distributions and magnitudes of the microscopic RSes. The RSes were predicted via an improved hierarchical multiscale model, which includes a constant coefficient of friction based thermal model. The RSes in the composite plates before friction stir welding(FSW) were computed and then set as the initial states of the FSW process during modeling. This improved decoupled multiscale model provided improved predictions of the temperature and RSes compared with our previous model.

关键词： Metal-matrix composites (MMCs) Friction stir welding Residual/internal stress Neutron diffraction Finite element analysis (FEA) Multiscale simulation

Achieving a strong polypropylene/aluminum alloy friction spot joint via a surface laser processing pretreatment

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Journal of Materials Science & Technology 2020年第15期47卷 103-114页

作者： S.C.han l.h.wu C.Y.Jiang N.li C.l.Jia P.Xue h.Zhang h.B.Zhao D.R.Ni B.l.Xiao Z.Y.Ma Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang110016China Department of Materials Science and Engineering Guilin University of TechnologyGuilin541006China

Strong metal/non-polar plastic dissimilar joints are highly demanded for the lightweight design in many fields,which,however,are rather challenging to achieve directly via *** this study,we designed a laser processing pretreatment on the Al alloy to create a deep porous Al surface structure,which was successfully joined to the polypropylene(PP) via friction spot welding.A maximum joint strength of29 MPa was achieved,the same as that of the base PP(*** joint efficiency reached 100%),much larger than ever *** joining mechanism of the Al alloy and the PP was mainly attributed to the large mechanical interlocking effect between the laser processed Al porous structure and the re-solidified PP and the formation of chemical bond at the *** deep porous Al surface structure modified by laser processing largely changed the Al-PP reaction *** evidence of the C-O-Al chemical bond was first time found at the non-polar plastic/Al joint interface,which was the reaction result between the oxide on the Al alloy surface and thermal oxidization products of the PP during *** study provides a new way for enhancing metal-plastic joints via surface laser treatment techniques.

关键词： Friction stir welding hybrid joint Metal Polymer Surface treatment Interface

Microstructure and mechanical properties of double-side friction stir welded 6082Al ultra-thick plates

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Journal of Materials Science & Technology 2020年第6期41卷 105-116页

作者： C.Yang J.F.Zhang G.N.Ma l.h.wu X.M.Zhang G.Z.he P.Xue D.R.Ni B.l.Xiao K.S.Wang Z.Y.Ma Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China CRRC Changchun Railway Vehicles Co. Ltd.Changchun 130062China School of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an 710055China

In the present work,80 mm thick 6082Al alloy plates were successfully double-side welded by friction stir welding(FSW).The relationship between the microstructures and mechanical properties was built for the double-side FSW butt joint with more attention paid to the local characteristic *** was shown that a phenomenon of microstructural inhomogeneity existed in the nugget zone(NZ)through the thickness *** grain size presented an obvious gradient distribution from the top to the bottom for each single-pass weld,and the microhardness values decreased from both surfaces to the middle of the *** lowest hardness zone(lhZ)exhibited a"hyperbolical"-shaped distribution extending to the middle of the *** tensile properties were obtained in the three sliced specimens of the FSW joint,and the joint coefficient reached about 70%which achieved the same level as the conventional FSW Al alloy *** element modeling proved that the"hyperbolical"-shaped heat affected zone(hAZ)was beneficial to resisting the strain concentration in the middle layer specimen which helped to increase the tensile *** on the analysis of the hardness contour map,tensile property and microstructural evolution of the joints,an Isothermal Softening layer(ISl)model was proposed and established,which may have a helpful guidance for the optimization on the FSW of ultra-thick Al alloy plates.

关键词： Ultra-thick aluminum alloy plates Double-side friction stir welding Finite element model Microstructural inhomogeneity Mechanical properties

Distributions and risk assessment of heavy metals in solid waste in lead-zinc mining areas and across the soil, water body, sediment and agricultural product ecosystem in their surrounding areas

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China Geology 2025年第1期8卷 92-106页

作者： Zhi-qiang wu hai-ying li liu-yan lü Guo-jun liang Ting-ting wu Jiang-xia Zhu No.117 Geological Team Bureau of Geology and Mineral Exploration and Development of Guizhou ProvinceGuiyang 550023China Ecological Environment Monitoring Center of Guizhou Province Guiyang 550023China Guizhou Institute of Geological Survey Guiyang 550081China Environmental Engineering Assessment Center of Anshun City Anshun 561000China Environmental Emergency Center of Anshun City Anshun 561000China

To identify the root causes of heavy metal contamination in soils as well as prevent and control such contamination from its sources,this study explored the accumulation patterns and ecological risks of heavy metals like Cd and Pb in solid waste in mining areas and across the water body,sediment,soil and agricultural product ecosystem surrounding the mining *** on the residual solid waste samples in lead-zinc deposits in a certain area of Guizhou Province,along with samples of topsoils,irrigation water,river sediments,and crops from surrounding *** study analyzed the distributions of eight heavy metals,i.e.,Cd,As,Cr,hg,Pb,Zn,Cu,and Ni,in the samples through field surveys and sample ***,this study assessed the contamination levels and ecological risks of heavy metals in soils,sediments,and agricultural products using methods such as the single-factor index,Nemerow composite index,and potential ecological risk *** results indicate that heavy metals in the solid waste samples all exhibited concentrations exceeding their risk screening values,with 60%greater than their risk intervention *** soils and sediments demonstrate slight and moderate comprehensive ecological risks of heavy *** single-factor potential ecological risks of heavy metals in both the soil and sediment samples decreased in the order of hg,Cd,Pb,As,Cu,Zn,Cr,and Ni,suggesting the same sources of heavy metals in the soils and *** of the agricultural product samples exhibited over-limit concentrations of heavy metals dominated by Cd,Pb,Ni,and Cr,excluding hg and *** agricultural product assessment using the Nemerow composite index reveals that 35%of the agricultural product samples reached the heavy metal contamination level,implying that the agricultural products from farmland around the solid waste dumps have been contaminated with heavy *** eight heavy metals in the soil,sediment,and agricultural product samples manifested hig

关键词： lead-zinc mining area Solid waste Soil Water body Sediment Agricultural product Nemerow composite index Cd,Pb,Ni,Cr elements heavy metal contamination Ecological risk assessment Coefficients of variation(CVs) Environmental restoration engineering