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Flat friction stir spot welding of low carbon steel by double side adjustable tools

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Journal of Materials Science & Technology 2021年第7期66卷 1-9页

作者： Xiaopei Wang Yoshiaki Morisada Hidetoshi Fujii Joining and welding Research Institute Osaka University11-1 MihogaokaIbarakiOsaka 567-0047Japan

2 mm low carbon steel plates were successfully welded by the flat friction stir spot welding(FSSW) using double side adjustable tools, by which the keyhole formed in the conventional FSSW was eliminated and a flat surface on both the top and bottom sides of the welded joints was obtained. In addition, the hook shape usually generated in the conventional FSSW was eliminated by this technique, and the unbonded interface was parallel to the surface of the sheets. Owing to the enlarged bonded interface width by eliminating the keyhole and the intermixed interface by the adjustable probe, the plug fracture occurred under all the welding conditions in the present study. Due to the suppression of the thickness thinning and elimination of the hook shape, the joint performance was improved in the plug fracture mode. The shear tensile performance was considered to strongly depend on the microstructure in the tip area of the unbonded interface and the maximum shear fracture load of 23.0 kN was achieved in this study.

关键词： friction stir spot welding Interface structure Low carbon steel Mechanical properties Microstructure

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Defence Technology（防务技术） 2021年第2期17卷 531-544页

作者： Gui-ju Zhang Cai-yuan Xiao Olatunj Oladimeji Ojo Key Laboratory of Hunan Province for Efficient Power System and Intelligent Manufacturing Shaoyang422000HunanChina College of Mechanical and Energy Engineering Shaoyang UniversityShaoyang422000HunanChina Department of Industrial and Production Engineering Federal University of Technology AkureAkureNigeria

This paper studies the friction stir spot welding of AA2024-T3/AA7075-T6 Al alloys in the ambient and underwater environments by clarifying the nugget features,microstructure,fracture and mechanical properties of the *** results show that the water-cooling medium exhibits a significant heat absorption capacity in the AA2024-T3/AA7075-T6 welded *** features such as stir zone width,circular imprints,average grain sizes,and angular inter-material hooking are reduced by the watercooling effect in the *** whitish(intercalated structures)bands are formed in the underwater joints while Mg2Si and Al2CuMg precipitates are formed in the ambient and the underwater welded joints *** increase in tool rotational speed(600e1400 rpm)and plunge depth(0.1 e0.5 mm)increases the tensile-shear force of the welded AA2024-T3/AA7075-T6 joints in both the ambient and underwater *** maximum tensile-shear forces of 5900 N and 6700 N were obtained in the ambient and the underwater welds respectively.

关键词： friction stir spot welding Underwater friction stir spot welding Nugget characterization Microstructure Mechanical properties Fracture

Interface strengthening in dissimilar double-sided friction stir spot welding of AZ31/ZK60 magnesium alloys by adjustable probes

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Journal of Materials Science & Technology 2021年第26期85卷 158-168页

作者： Xiaopei Wang Yoshiaki Morisada Hidetoshi Fujii Joining and welding Research Institute Osaka University11-1 MihogaokaIbarakiOsaka 567-0047Japan

Dissimilar welding of AZ31/ZK60 magnesium alloys with a thickness of 2 mm was successfully carried out by the double-sided friction stir spot welding with adjustable probes.A dissimilar joint bearing flat surfaces on both sides without a keyhole was obtained and the shear failure load of 8.7±0.5 kN was *** role of the adjustable probes has been revealed in *** the center of the stir zone,the welding interface structure was heterogeneous around which some distinct oxides still remained,leading to a weak interface *** the contrary,the welding interface structure around the shoulder/probe interface was homogeneous with no oxides giving rise to a strong interface strength,which is attributed to the severe material flow introduced by the adjustable *** addition,the vicinity outside the shoulder/probe interface,where the fracture occurred during the shear tensile tests,was also strengthened owing to the shearing and torsion by the adju stable ***,a stable plug failure can be obtained and the joint properties can be improved.

关键词： friction stir spot welding Dissimilar welding Interface strengthening Microstructure Magnesium alloys

Effect of rotary direction and speed on mechanical properties in friction stir spot welding of A6061 sheets e

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China welding 2013年第3期22卷 18-24页

作者：宋骁邢丽卜文德刘奋成黄春平柯黎明 School of Aeronautical Manufacturing Engineering Nanchang Hangkong University Nanchang 330063

friction stir spot welding of A6061 sheets was conducted using a tool with thread pin. The hook geometries, hook formation and mechanical properties of the joints welded with different rotary directions and speeds were investigated. The results show that the hook in the joint welded in clockwise was curved upwards and that in anticlockwise was curved downwards. The hook formation was related to the plastic material flow in the joint. With increasing the rotary speed in clockwise direction, the hook moved upwards and far way from the center of the keyhole, resulting in an increase in the effective weld width and a decrease in the effective sheet thickness. Three types of fractuces were observed and they were affected by the hook geometries. The tensile shear load increased firstly and then decreased when the rotary speed increased in clockwise direction, which was related to the hook geometries.

关键词： friction stir spot welding rotary direction rotary speed hook geometries mechanical properties

Filling technique for keyhole of friction stir spot welding based on the principles of resistance spot welding

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China welding 2019年第3期28卷 34-41页

作者： Deng Lipeng Ke Liming Liu Jinhe School of Material Science and Engineering Northwestern Polytechnical UniversityXi’an 710072China School of Aeronautical Manufacturing and Engineering Nanchang Hangkong UniversityNanchang 330063China

Keyhole at the end of a weld prepared by friction stir welding(FSW)is one of the major issues that impede the application of *** address this issue,a keyhole filling technique was proposed in this paper,which is based on the principles of resistance spot welding(RSW).A three-phase secondary rectifier resistance spot welder was applied as the experimental instrument for filling the keyhole in the center of friction stir spot weld(FSSW).The test sheet is a 2024-T4 aluminium alloy with a thickness of *** experiments results show that the filled joint strength is improved by 26.12%since the area is increased for the plug in the *** there are two kinds of dimples in the tensile fracture-equiaxial dimples and long *** filled joint involves the fusion welding zone(FWZ),pressure welding zone(PWZ),melted plug zone(MPZ),and plastic deformation zone(PDZ).The FWZ and the PWZ is the melting bond and diffusion bond between the plug and keyhole,*** MPZ is the center part and the PDZ is upper or lower part of the plug.

关键词： friction stir spot welding resistance spot welding keyhole aluminum alloy

Development of processing windows for friction stir spot welding of aluminium Al5052/copper C27200 dissimilar materials

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Transactions of Nonferrous Metals Society of China 2017年第6期27卷 1273-1284页

作者： S. SIDDHARTH T.SENTHILKUMAR M.CHANDRASEKAR Department of Mechanical Engineering University College of EngineeringAnna University-Tiruchirappalli Tiruchirappalli 620 024 India

friction stir spot welding technique was used to join dissimilar combinations of aluminium alloy(Al5052)with copperalloy(C27200)and friction stir spot welding windows such as tool rotational speed–dwell time and tool rotational speed?plungedepth diagrams for effective joining of these materials were *** a central composite design model,empirical relationswere developed to predict the changes in tensile shear failure load values and interface hardness of the joints with three processparameters such as tool rotational speed,plunge depth and dwell *** adequacy of the developed model was verified usingANOVA analysis at95%confidence *** surface methodology was used to optimize the developed model to maximizetensile strength and minimize interface hardness.A high tensile shear failure load value of3850N and low interface hardness valueof HV81was observed for joints made under optimum conditions,and validation experiments confirmed the high predictability ofthe developed model with error less than2%.The operating windows developed shall act as reference maps for future designengineers in choosing appropriate friction stir spot welding process parameter values to obtain good joints.

关键词： friction stir spot welding dissimilar materials aluminium copper processing windows response surface methodology

Clarifying effect of welding conditions on microstructure and mechanical properties of friction stir spot-welded DH590 automotive high-strength steel plates

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Journal of Iron and Steel Research International 2021年第2期28卷 232-243页

作者： Ya-peng Zhao Lian-feng Chen Shi-jie Zhu Yu-feng Sun Shao-kang Guan School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001HenanChina Henan Key Laboratory of Advanced Magnesium Alloys Zhengzhou UniversityZhengzhou 450001HenanChina Beijing Shougang Co. Ltd.Beijing 100041China

friction stir spot welding was successfully applied to the 1.2-mm-thick DH590 dual-phase steel plates by using a polycrystalline cubic boron nitride rotating *** welding,the rotation speed ranged from 600 to 1000 r/min and the penetration depth ranged from 0.1 to 0.3 *** the spot joints,the size of the stir zone increased with the increase in rotation speed as well as the penetration depth of the *** with the banded ferrite and martensite structure of the base metal,a mixed microstructure of ferrite and tempered martensite,refined bainite structure and coarse martensite structure were found in the heat-affected zone,thermomechanically affected zone and stir zone of the joints,*** kinds of interfacial shapes were formed between the upper and lower steel plates,and the formation of the bonded interface was dominated mainly by the penetration depth of the rotating tool rather than the rotation *** was revealed that the joints with straight interfaces showed higher shear tensile loads comparing with those with hook-like *** tensile tests showed that the maximum shear tensile load reached about 15.56 kN when the rotation speed and penetration depth were set as 800 r/min and 0.3 mm,*** specimen was fractured through plug failure mode with a total elongation of about 5.6 mm.

关键词： friction stir spot welding DH590 dual-phase steel Microstructure Joint strength Microhardness

Influencing mechanism of pre-existing nanoscale Al5Fe2 phase on Mg-Fe interface in friction stir spot welded Al-free ZK60-Q235 joint

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Journal of Materials Science & Technology 2020年第7期42卷 220-228页

作者： R.Z.Xu Q.Yang D.R.Ni B.L.Xiao C.Z.Liu Z.Y.Ma Institute of Metal Research Chinese Academy of SciencesShenyang110016China College of Material Science and Engineering Shenyang Aerospace UniversityShenyang110136China Department of Materials Science and Engineering University of Illinois at Urbana-Champaign1304 W Green StUrbanaIL61801United States Fredrick Seitz Materials Research Laboratory University of Illinois at Urbana-Champaign104 S Goodwin AveUrbanaIL61801United States

Al-free ZK60 magnesium (Mg) alloy sheet was selected as substrate material of Mg-steel pinless friction stir spot welding (FSSW), avoiding the effect of the Al element in the substrate on the alloying reaction of Mg-iron (Fe) interface. The sound FSSW joint of ZK60 Mg alloy and Q235 steel with a hot-dipped aluminum (Al)-containing zinc (Zn) coating was successfully realized. The detailed microstructural examinations proved that Al5Fe2 phase at the Mg-Fe interface came from the pre-existing Al5Fe2 phase in the coating and acted as the transition layer for promoting the metallurgical bonding of Mg and Fe. The interfaces with well-matched lattice sites among Fe, Al5Fe2 and Mg were formed during FSSW. A low energy interface with good match of lattice sites ((002)Al5Fe2//(110)Fe, [110]Al5Fe2//[113]Fe) between Al5Fe2 and Fe was identified. For the interface between Al5Fe2 and Mg, an orientation relationship of (622)Al5Fe2//(3112)Mgand[158]Al5Fe2//[2423]Mg was observed. The tensile-shear load of the ZK60-steel joint could reach 4.6 kN. Moreover, the joint fracture occurred at the interface between the Al5Fe2 layer and the Mg alloy substrate, suggesting the brittle fracture characteristic.

关键词： Dissimilar welding friction stir spot welding Magnesium alloys Steels Zinc coating

Effects of pin geometry on the material flow behavior of friction stir spot welded 2A12 aluminum alloy

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China welding 2015年第2期24卷 25-29页

作者：李政玮岳玉梅马琳姬书得柴鹏 Faculty of Aerospace Engineering Shenyang Aerospace University Shenyang110136. Beijing Aeronautical Manufacturing Technology Research Institute Beijing 100024.

A three-dimensional finite volume model was established by the ANSYS FLUENT software to simulate the material flow behavior during the friction stir spot welding （FSSW） process. Effects of the full-threaded pin and the reverse-threaded pin on the material flow behavior were mainly discussed. Results showed that the biggest material flow velocity appeared at the outer edge of the tool shoulder. The velocity value became smaller with the increase of the distance away from the tool surface. In general, material flows downwards along the pin thread when the full-threaded pin is used. Meanwhile, both the materials of the upper and the lower plates flow towards the lap interface along the pin thread when the reverse-threaded pin is used. The numerical simulation results were investigated by experiment, in which 2A12 aluminum alloy was used as the research object. The effective sheet thickness （EST） and stir zone （SZ） width of the joint by the reverse-threaded pin were much bigger than those by the full-threaded pin. Accordingly, cross tension failure load of the joint by the reverse-threaded pin is 23% bigger than the joint by the full-threaded pin.

关键词： friction stir spot welding pin geometry material flow behavior numerical simulation