摘要
采用Al-Mg-Zn和Al-Mg-Zn-Sc-Zr合金焊丝为填充材料,对4 mm厚的7075-T651铝合金板材进行非熔化极惰性气体保护焊接(Tungsten inert gas welding,TIGW),并对焊接接头进行焊后热处理(Post-weld heat treatments,PWHT),研究焊接接头的显微组织和力学性能。结果表明,焊丝中添加微量Sc和Zr时,焊态下焊接接头的焊缝区晶粒明显得到细化,抗拉强度和硬度有明显提升;与未经PWHT的接头相比,经PWHT的接头弥散析出细小的η′(MgZn_2)亚稳定相,且并不影响二次Al_3(Sc,Zr)粒子的弥散分布,大幅度提高了焊接接头的抗拉强度和硬度。
7075 aluminium alloy sheets of 4 mm thickness were welded by manual TIG welding method with Al-Mg-Zn and Al-Mg-Zn-Sc-Zr welding wires as filler material. Welded joints were treated by post-weld heat treatment(PWHT) method. The microstructure and mechanical properties of welded joints with and without post-weld heat treatment were investigated. The results showed that the grains of weld metal zone were refined and mechanical property of TIGW joint welded by Al-Mg-Zn-Sc-Zr welding wire was improved obviously. Compared with joint without post-weld heat treatment, the PWHT joint dispersed and precipitated with fine η′(MgZn_2) substable phase, which have no effect on the dispersion distribution of secondary Al_3(Sc,Zr) particles, and greatly improved the tensile strength and microhardness of the welded joint.
引文
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