Effects of welding parameters and post-heat treatment on mechanical properties of friction stir welded AA2195-T8 Al-Li alloy

• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2018,（1）
• 页码范围: 219-227
• 页数: 9页
• 语种: 英文

摘要

In this study,the effects of main welding parameters (rotation speed (ω) and welding speed (ν)) on the microstructure,micro-hardness distribution and tensile properties of friction stir welded (FSW) 2195-T8 Al-Li alloy were investigated.The effects ofT6 post-treatments at different solution and aging conditions on the mechanical properties and microstructure characteristics of the FSW joints were also investigated.The results show that with increasing ω and v,both strength and elongation of the joints increase first,and then decrease with further increase of ω and v.All the joints under varied welding parameters show significant strength loss,and the strength reaches only 65％ of the base metal.The effect of T6 post-heat treatment on the mechanical properties of the joints depends on the solution and aging conditions.Two heat treatment processes (480℃ × 0.5 h quenching+ 180℃ × 12 h,520℃ × 0.5h quenching+180℃ × 12h aging) are found to increase the joint strength.Furthermore,low temperature quenching (480 ℃) is more beneficial to the joint strength.The joint strength can reach 85％ of the base metal.Whereas both low temperature aging (140℃ × 56h) and stepped aging (100 ℃ × 12 h + 180 ℃ × 3 h) processes decrease the joint strength.After heat treatment all the joints show decreased ductility due to the obvious grain coarsening in the nugget zone (NZ) and thermo-mechanically affected zone (TMAZ).