双相钢激光焊管的焊缝组织演变及扩口性能研究

介绍了马氏体含量不同的双相钢(DP590和DP780)激光焊管的焊缝组织演变,研究了焊缝硬度分布特征及其对扩口性能的影响。结果表明:激光焊缝的熔合区存在明显硬化,组织为单一的马氏体,DP780钢热影响区出现了显著的软化,DP590钢无软化区存在,造成这一差别的原因在于两者马氏体含量不同;软化区的存在导致DP780钢激光焊管的扩口率急剧下降,仅为DP590钢的10%左右;建立了焊管扩口的数值模型,模拟结果与试验结果相吻合。

STUDY ABOUT WELDING SEAM STRUCTURE DEVELOPMENT AND TUBE END EXPANSION PERFOR-MANCE FOR DUAL PHASE STEEL LASER -WELDING PIPE

It is introduced the welding seam structure development of laser-welding pipe of dual phase steel（DP590 and DP780） with different content of martensite,studied the hardness distributing feature of welding seam and its influence on tube end expansion performance.It is showed from the result that the fusion zone of melting seam is obviously hardened,the structure is pure martensite;and the heat affected zone of DP780 steel is remarkably softened whereas the DP590 steel not,and the reason for that is the different martersite content;the softened zone makes the tube end expansion rate of laser-welding pipe of DP780 steel going down rapidly and being only about 10 percent of that of DP590 steel.It is constructed the numerical model for tube end expansion of welding pipe.The simulating result is identical with the test.