Al-Mg-Zn铝合金焊接接头力学性能研究

摘要

7XXX Al-Mg-Zn alloy was widely used in high-speed train manufacture In this paper,the aluminum alloy was heat treated by artificial aging process after extrusion processin~ During the welding process,the heat-treated condition of aluminum alloy would be transformed by the welding heat source,resulting in the weakening of the mechanical properties of weldment.The thermal cycling curve was collected during welding procedure test.Subsequently,the temperature evolution in HAZ was analyzed,and HAZ was subdivided into two sections of solid-solution area and aging area by peak temperature.Furthermore,the microstructure evolution and hardness distribution of two kinds of HAZ was concluded.After pulsed-MIG welding and laser-MIG hybrid welding procedure tests,appeared softening in the over aging region of the joint.%高温挤压后经过人工时效处理的热处理强化型材是广泛应用于高速列车车体的结构材料.在列车车体的焊接制造过程中,由于焊接热源作用改变了型材的热处理状态,导致接头区域的力学性能弱化.通过采集焊接试验过程的热循环曲线,研究7系铝合金接头热影响区的温度变化过程,根据热循环曲线特征将热影响区划分为固溶区和过时效区,并分析热影响区的组织演变和硬度分布规律.脉冲MIG和激光-MIG复合焊两种焊接方法在接头的过时效区域都出现软化.