热处理对喷射成形7xxx系铝合金TIG焊接头组织与性能的影响

Influence of heat treatment on microstructure and mechanical properties of spray formed 7xxx series aluminum alloy TIG weld joint

采用7055焊丝对喷射成形7xxx系铝合金进行TIG焊接,接头经450℃×1 h+475℃×1 h的双级固溶后水淬,再进行120℃×24 h的时效处理后,焊缝组织均匀、晶粒有所长大,但没有出现过烧现象.经复合固溶处理后合金元素充分溶入基体,使得基体中的合金元素含量高于固溶前的含量,而固溶之前分布在晶界的合金元素经固溶之后降低了,固溶过程使合金成分区域趋于均匀化,后续的时效过程中过饱和固溶体析出强化相,使得接头强度得到了显著提高7,055达到了母材强度的65%,7475达到了母材强度的91%.结果表明,试验拟定的热处理工艺是合理的.

Tungsten inert gas welding of spray formed 7xxx serial aluminum alloy was conducted with 7055 aluminum alloy as the filler wire.The resultant joints were solid solution treated at 450 ℃×1 h+475 ℃×1 h,and then water quenched and finally aged at 120 ℃×24 h.After solution,the microstructure of the weld was homogenous without overburning and the grain size slightly increased.The double-stage solution treatment dissolved the alloying elements in the base metal sufficiently,therefore the content of alloying elements increased in base metal but decreased in grain boundaries.Consequently,the alloying elements distributed more uniformly after the solid solution.In the subsequent aging treatment,strengthening phases precipitated from the oversaturated solid solutions,which improved the joint strength remarkably.The joint strength of 7055 and 7475 aluminum alloy reached 65% and 91% of the base metal,respectively,which indicated that the proposed heat treatment in this paper was suitable.