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Effects of the Reversely Rotating Assisted Shoulder on Microstructures During the Reverse Dual-rotation Friction Stir Welding 被引量:3
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作者 J.Q.Li H.J.Liu 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2015年第4期375-383,共9页
The reverse dual-rotation friction stir welding(RDR-FSW) has the capability to adjust the heat generation because of the separately designed tool shoulder and tool pin.The welding torque exerted on the workpiece by th... The reverse dual-rotation friction stir welding(RDR-FSW) has the capability to adjust the heat generation because of the separately designed tool shoulder and tool pin.The welding torque exerted on the workpiece by the reversely rotating shoulder is opposite to that exerted by the rotating tool pin,so the total welding torque is reduced,which is beneficial to reducing the clamping requirement of workpieces.In the present paper,a RDR-FSW joint was welded in a condition similar to the optimal welding condition of conventional FSW,and microstructures in various zones were investigated by comparison,aiming to highlight effects of the reversely rotating assisted shoulder.Due to the heat conduction of the middle cylinder and the bottom end cover on which the assisted shoulder was machined,the thermal effect of RDR-FSW was smaller than that of the conventional FSW.Moreover,the effect of assisted shoulder on the plastic flow or deformation of material or was constrained in a thin layer near the weld top surface,and thus the flow of material especially along the thickness direction was clearly decreased in the RDR-FSW.In the heat-affected zone(HAZ),the precipitate coarsening was the main evolution and was completed through the dissolution of small precipitates and the continuous growth of large precipitates.By contrast,the dissolution degree of precipitates increased significantly in the thermomechanically affected zone(TMAZ),and a small amount of original meta-stable precipitates transformed to block-shaped stable precipitates.Precipitate evolutions in the shoulder affected zone(SAZ)and the weld nugget zone were similar,i.e.the majority of original meta-stable precipitates dissolved into the matrix and the remainder transformed to stable precipitates,though the dissolution degree was greater in the SAZ.Compared with the conventional FSW joint,the coarsening degrees of precipitates in the HAZ and TMAZ of RDR-FSW joint were much smaller,as well as the dissolution degrees of precipitates in all four specified zones. 展开更多
关键词 friction stir welding Reverse dual-rotation fricti
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纳米二氧化锆添加剂对润滑脂摩擦学性能影响的研究 被引量:3
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作者 贾其苏 许世鹏 赵杰鸽 《材料保护》 CAS CSCD 2021年第2期13-20,54,共9页
为研究纳米二氧化锆作为添加剂对润滑脂摩擦性能的影响,制备了不同比例纳米二氧化锆的润滑脂,采用四球摩擦试验机以及高温往复式摩擦磨损试验机研究了纳米二氧化锆对润滑脂摩擦学性能的影响。利用激光粒度分析仪、粉末X射线衍射仪、傅... 为研究纳米二氧化锆作为添加剂对润滑脂摩擦性能的影响,制备了不同比例纳米二氧化锆的润滑脂,采用四球摩擦试验机以及高温往复式摩擦磨损试验机研究了纳米二氧化锆对润滑脂摩擦学性能的影响。利用激光粒度分析仪、粉末X射线衍射仪、傅立叶变换红外光谱仪对纳米二氧化锆进行表征,利用金相显微镜、三维形貌仪对磨损表面的三维形貌进行了表征。结果表明:添加纳米二氧化锆可以优化润滑脂性能,其最佳的添加比例为0.3%,最优的工作温度为50℃,平均摩擦系数比原始脂低16.87%,钢球磨斑直径较原始脂相比低11.48%,钢球的质量损失与原始脂质量低74.72%,钢球的磨斑平均高度比原始值低33.16%。 展开更多
关键词 润滑脂 纳米二氧化锆 摩擦系数 四球试验 高温往复 摩擦磨损试验
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