Cu-Cr-Zr合金搅拌摩擦焊接接头的组织和力学性能

Microstructure and mechanical properties of friction stir welding joint of Cu-Cr-Zr alloy

采用旋转速度为750和1500 r/min,焊接速度为23.5 mm/min的焊接参数分别对时效态和固溶态的3 mm厚的Cu-Cr-Zr合金板进行搅拌摩擦焊接,研究转速及母材区(BM)初始状态对搅拌摩擦焊(FSW)接头的微观组织与力学性能的影响,并对接头的力学性能进行模型化定量分析。结果表明:FSW后,接头晶粒显著细化,沉淀相在搅拌头的高温热作用下固溶在基体中。当BM的初始状态为时效态时,与1500 r/min样品相比,750 r/min样品晶粒尺寸较小且存在沉淀相,750 r/min样品力学性能较高,主要是晶界强化和沉淀强化的作用。当BM的初始状态为固溶态时,与1500 r/min样品相比,750 r/min样品晶粒尺寸较小,力学性能较高,主要是晶界强化的作用。当FSW转速相同时,时效态接头的晶粒尺寸小于固溶态接头,而力学性能高于固溶态接头,主要是由于BM的初始组织状态不同导致的。综合分析表明:FSW过程中选用低转速焊接,可以获得性能较优的接头。

Friction stir welding(FSW)was conducted on Cu-Cr-Zr alloy plates with 3 mm thickness by using rotation speed of 750 and1500 r/min and welding speed of 23.5 mm/min,in the state of aged and solid solution treated respectively.The effects of rotation speed and base metal(BM)initial state on the microstructure and mechanical properties of the FSW joints were studied,and the mechanical properties of joints were modeled and quantitatively analyzed.The results show that the grain size of the FSW joint significantly refines,and the precipitated phase is dissolved in the matrix under the high-temperature effect of the stir-welding head.When the initial state of BM is aged state,compared with the specimens of 1500 r/min,the grain size of the 750 r/min specimens is smaller,and there exists precipitate phase in the matrix,so that the 750 r/min specimens have higher mechanical properties mainly due to the comprehensive effect of grain boundary strengthening and precipitation strengthening.When the initial state of BM is solid solution state,compared with the specimens of 1500 r/min,the 750 r/min specimens have smaller grain size and high mechanical properties mainly due to grain boundary strengthening effect.When the FSW speed is the same,the welding joint grain size of the aged state is smaller than that of solid solution state,but the mechanical properties of the aged state is higher than that of solid solution state,which is mainly due to the difference of the initial state microstructures.The comprehensive analysis shows that a welding joint with better performance can be obtained by the FSW process with a lower welding speed.