This paper focuses on the effect of welding parameters on microstructure and tensile strength of joints welded by friction-stir welding(FSW).The effects of pin profile(threaded conical,non-threaded conical and triangu...This paper focuses on the effect of welding parameters on microstructure and tensile strength of joints welded by friction-stir welding(FSW).The effects of pin profile(threaded conical,non-threaded conical and triangular pin),tool rotational speed(800,1000,1250 and 1600 r·min^(-1))and welding speed(63,80,100 and 125 mm·min^(-1))on the mechanical and microstructural properties of joints welded in 5-mm 7075-T6 were investigated.The results depict that the pin profile has a major role in the shape and grain size of the weld nugget zone(WNZ).In other words,a wider weld nugget and a finer grain size by threaded conical pin are obtained in WNZ.The attained data of tensile tests show that the maximum ultimate tensile strength(UTS)belongs to the threaded conical pin which is attributed to a finer grain size generated in the weld nugget zone.Additionally,it is found that the tensile strength increases with the welding speed increasing,whereas rotational speed has a bilateral effect on the tensile strength.The microhardness tests show that the minimum hardness is obtained in the heat-affected zone(HAZ).展开更多
It is common for the rotating pin largely plunging into lower sheet to break up lap interface of Friction Stir Lap Welding(FSLW)joint,but the unavoidable up-bending morphology of hook outside Nugget Zone(NZ)largely re...It is common for the rotating pin largely plunging into lower sheet to break up lap interface of Friction Stir Lap Welding(FSLW)joint,but the unavoidable up-bending morphology of hook outside Nugget Zone(NZ)largely reduces the joint bearing ability.Based on the novel Opposite-directions Flowing FSLW(OF-FSLW)by the self-developed rotating tool with an Xshaped right-left thread pin,the 2024 aluminum alloys lap joint was successfully welded in this study.The migration law of lap interface during welding was investigated by the experimental and numerical methods,and then how the rotating pin and its rotating velocity affect the formation and strength of OF-FSLW joint was further analyzed.The results show that the Material Concentrated Zone(MCZ)which formed above the original lap interface made the hook bend downward,the NZ greatly enlarged and the beginning part of cold lap compressed and thickened,thereby heightening the joint bearing ability.For the OF-FSLW joint,its maximum tensile strength was403 MPa,and the corresponding joint efficiency of 90.8%was an incredible and superb value for the 2000 series heat-treatment strengthened aluminum alloys friction stir welded joint.The OF-FSLW technology by the rotating tool with an X-shaped right-left thread pin is proven to be a greatly effective approach for manufacturing the aluminum alloys lap joint with superb strength.展开更多
文摘This paper focuses on the effect of welding parameters on microstructure and tensile strength of joints welded by friction-stir welding(FSW).The effects of pin profile(threaded conical,non-threaded conical and triangular pin),tool rotational speed(800,1000,1250 and 1600 r·min^(-1))and welding speed(63,80,100 and 125 mm·min^(-1))on the mechanical and microstructural properties of joints welded in 5-mm 7075-T6 were investigated.The results depict that the pin profile has a major role in the shape and grain size of the weld nugget zone(WNZ).In other words,a wider weld nugget and a finer grain size by threaded conical pin are obtained in WNZ.The attained data of tensile tests show that the maximum ultimate tensile strength(UTS)belongs to the threaded conical pin which is attributed to a finer grain size generated in the weld nugget zone.Additionally,it is found that the tensile strength increases with the welding speed increasing,whereas rotational speed has a bilateral effect on the tensile strength.The microhardness tests show that the minimum hardness is obtained in the heat-affected zone(HAZ).
基金supported by the National Natural Science Foundation of China(Nos.51874201 and 52074184)Natural Science Foundation project of Liaoning Province(2023-MS238)+1 种基金Liaoning Revitalization talents program(XLYC2203009)the Fundamental Research Funds for the Universities of Liaoning Province。
文摘It is common for the rotating pin largely plunging into lower sheet to break up lap interface of Friction Stir Lap Welding(FSLW)joint,but the unavoidable up-bending morphology of hook outside Nugget Zone(NZ)largely reduces the joint bearing ability.Based on the novel Opposite-directions Flowing FSLW(OF-FSLW)by the self-developed rotating tool with an Xshaped right-left thread pin,the 2024 aluminum alloys lap joint was successfully welded in this study.The migration law of lap interface during welding was investigated by the experimental and numerical methods,and then how the rotating pin and its rotating velocity affect the formation and strength of OF-FSLW joint was further analyzed.The results show that the Material Concentrated Zone(MCZ)which formed above the original lap interface made the hook bend downward,the NZ greatly enlarged and the beginning part of cold lap compressed and thickened,thereby heightening the joint bearing ability.For the OF-FSLW joint,its maximum tensile strength was403 MPa,and the corresponding joint efficiency of 90.8%was an incredible and superb value for the 2000 series heat-treatment strengthened aluminum alloys friction stir welded joint.The OF-FSLW technology by the rotating tool with an X-shaped right-left thread pin is proven to be a greatly effective approach for manufacturing the aluminum alloys lap joint with superb strength.
