高强度钢差厚板激光拼焊焊缝成形及组织分析

Analysis about formation and microstructure of laser-welding-tailored-blanks with unequal thickness of high strength steels

选取2.0mm,1.5mm厚的HSA340板材和0.7mm厚的H340LAD+Z板材,按强度相近厚度不同原则两两搭配进行激光拼焊。焊后选取具有代表性的焊缝横截面进行金相组织检验,并对焊缝接头各区域进行硬度测量,分析了激光焊缝接头各区域金相组织及其硬度的变化。结果表明,差厚板激光拼焊过程中,母材散热情况不同,会造成焊缝金相组织在各自靠近母材的局部区域有很大差异;激光拼焊板的热影响区宽度窄,与母材及焊缝间有明显的界线,生成的组织细密;焊缝及热影响区的硬度值均大于母材;合理调整激光光束的入射位置和入射角度,可以显著改善焊缝成形,提高拼焊板的接头质量。

Two kinds of high-strength-steel sheets, HSA340(2.0 mm, 1.5 mm) and H340LAD+Z(0.7 mm), were introduced. They were arranged in pairs and welded together by laser welding on principle of similar strength but unequal thickness. The special cross-section of welded joints was chosen for metallographic examination and hardness measurement. The results show, in the welding process, the microstructure of the weld will have great diversity at local region closing each parent metal because of the different cooling condition of each parent metal. The width of heat affected zone(HAZ) in laser-welding-tailored-blanks is narrow, the remarkable boundary divides the HAZ with the parent meal and weld, and not only the grain size but also the microstructure in the HAZ are also fine. And the hardness of the weld and the HAZ are higher than that of parent metal. The joints of tailored blanks will be obviously improved when the incident position and incident angle of laser beam were set rationally.