激光冲击处理对焊接接头力学性能的影响(Ⅱ)  

Effects of Laser Shock Processing on The Mechanical Properties of Welded Joints(Ⅱ)

作　　者：邹世坤[1] 王健[1] 王华明[2] 

机构地区：[1]北京航空工艺研究所,北京100024 [2]北京航空航天大学,北京100083

出　　处：《焊接学报》2001年第4期66-68,共3页Transactions of The China Welding Institution

基　　金：国防科技预研跨行业综合技术项目 ( 18.7.1.5 )

摘　　要：上文对GH3 0、1Cr18Ni9Ti焊缝进行了激光冲击处理 ,试验发现激光冲击处理提高GH3 0焊接接头强度 12 % ,但对疲劳寿命影响不明显 ;冲击提高 1Cr18Ni9Ti焊接接头强度仅为 5 % ,但提高疲劳寿命 3 0 0 %以上。为作进一步分析 ,本文测试了两种金属焊缝在有无激光冲击处理条件下的表面显微硬度分布和残余应力状态 ,并对GH3 0试件疲劳断口进行扫描电镜分析。经分析发现 ,激光冲击处理能明显提高GH3 0焊缝表层的显微硬度 ,也可以提高抗拉强度并获得较高的表面残余压应力 ,因此强化区域能抑制疲劳裂纹的萌生和扩展 ,降低裂纹扩展速率 ;但由于焊缝较宽 ,激光冲击光斑未能完全覆盖焊缝及热影响区 ,部分未冲击区域影响了疲劳寿命的提高。 1Cr18Ni9Ti在等离子焊接过程中产生相变马氏体 ,减弱了激光冲击处理产生形变马氏体对提高显微硬度的作用 ,因此对抗拉强度影响不大 ,但激光冲击处理可以使焊缝表面获得较高的表面残余压应力 ,因此能明显提高疲劳寿命。The welded zones of GH30 and 1Cr18Ni9Ti were shock processed by pulse laser in last paper,the results showed that the limit strength of GH30 welded joints was increased by 12% but the effect on fatigue life was not obvious,at the meantime,the limit tensile strength of 1Cr18Ni9Ti welded joints was increased by only 5% but the fatigue life was increased by more than 300%.For further investigations,the distribution of microhardness and residual stress of welded zones were measured and the fatigue fractures were analyzed by SEM. After laser shock processing,the limit strength of GH30 welded joints and the microhardness in the surface layer were increased,surface residual compress stress was improved.Fatigue initiation and crack growth were held back and crack growth rates were reduced in the strengthened zones,but the shock spot did not cover the welded joints or HAZ entirely,unshocked zones did harm to the fatigue properties; martensite phase was formed in plasma welding 1Cr18Ni9Ti,which reduced the effect of strain deformation martensite induced by laser shock processing on the microhardness,so laser shock processing had less effect on the strength of 1Cr18Ni9Ti welded joints,but the surface residual compress stress gained by laser shock processing could obviously improve the fatigue life of 1Cr18Ni9Ti welded joints.

关 键 词：激光冲击处理 焊接接头 显微硬度 残余应力 疲劳断口 力学性能 

分 类 号：TG407[金属学及工艺—焊接] TG441.8