2091Al-Li合金TIG焊焊接接头组织与强度

Strength and Microstructure of TIG Welded Joints 2091 Al-Li Alloy

关键词:  2091Al-Li合金  拉伸性能  显微组织  TIG焊

Key words:  2091Al-Li alloy  strength  microstructure  TIG

摘要:

研究了2091Al-Li合金TIG焊焊接接头焊态及不同热处理状态下的显微组织和拉伸性能。结果表明:在焊态焊缝区已存在少量细小的沉淀强化相δ'相,但由于其体积分数小,沉淀强化作用弱,此时固溶强化为主要强化机制,接头强度较低,接头强度系数为64%。焊后经人工时效处理,由于有大量的沉淀强化相δ'和s'相析出,沉淀强化作用强,接头强度有明显提高,接头强度系数可达89%。焊后经固溶处理加人工时效,沉淀强化相分布均匀,尺寸适中,接头强度大大提高,接头强度系数高达98%。

Abstract:

The microstructure and tensile properties of TIG welded joints of Al-Li alloy were investigated both in as-welded and different postweld heat treatment conditions.The results show that solid solotion strengthening played an important role in the as-welded condition,though the precipitation strengthening δ' phase formed already in the as-welded weld metal,but its effect was not apparent due to the lower volume fraction of δ' phase.So the strength ration of the welded joint/base metal (φ) was 64%.After artificially aging heat treatment,the precipitation strengthening effect increaced much due to the formation of more δ' phase and s' phase.Its φ value was increased up to 89%.The highest stength of the welded joints was obtained after solid solution and then artificially aged heat treatment.Due to the proper size of recipitation strengthening phases and their well distribution,the φ value was increased up to 98%.