Q355/SKH9高速钢激光重频焊接接头冲击韧性分析

Impact toughness analysis of Q355/SKH9 HSS laser refrequency welded joint

文章采用激光焊接技术制造Q355/SKH9高速钢焊接接头,并开展V型缺口冲击韧性实验。研究结果表明:当试验温度下降后,接头受到了更小冲击吸收能量作用,焊接接头形成了明显梯度冲击韧性;在BM中存在大量回火板条型马氏体组织,HAZ热处理时内部形成了不同焊接热循环过程;在BM和HAZ断口部位形成了许多撕裂棱,表现为准解理断裂;断HAZ具备优异韧性,达到了比BM更优的韧性;经过回火处理后,板条马氏体与粒状贝氏体获得了更强冲击韧性;BM保持相对稳定的显微硬度与剪切强度,HAZ形成了大梯度变化的显微硬度与剪切强度;经过焊接热循环处理与之后回火过程,HAZ基体与晶界部位形成了更多碳化物,增大HAZ强度与硬度。

A new technology called Narrow-gap submerged arc welding was used to make a Q355/SKH9 high speed steel joint for fitness equipment,and an experiment on the impact toughness of a V-notch submerged Arc was conducted.The results show that when the test temperature drops,the joint is affected by less impact energy absorption,and the welded joint forms an obvious gradient impact toughness.There are a large number of tempered lath martensite structures in BM,and different welding thermal cycles are formed inside the HAZ heat treatment.Many tearing edges were formed at the BM and HAZ fracture sites,showing quasi-cleavage fracture.HAZ has excellent toughness,which is better than BM.After tempering,lath martensite and granular bainite obtained stronger impact toughness.BM maintains a relatively stable microhardness and shear strength,and HAZ forms a large gradient variation of microhardness and shear strength.After the welding thermal cycle treatment and later tempering process,more carbide is formed between HAZ matrix and grain boundary,which increases the strength and hardness of HAZ.