采用双光束激光辅助热丝工艺实现了16 mm厚11CrNi3MnMoV低合金高强钢的可靠连接,接头强度高于母材。在此基础上,重点研究了激光焊缝原始组织、激光二次重熔、经历热处理后的焊缝不同区域的组织变化规律。结果表明,双光束激光填丝焊的焊缝组织主要为贝氏体和针状铁素体,经历重熔与热处理后的焊缝组织发生明显细化,且经过热处理后的组织具有类似母材热影响区的分布规律,变化明显,主要为贝氏体正火组织和回火组织,且内层焊缝中的针状铁素体含量明显多于末层焊缝。同时在焊缝中存在大量的相互平行且紧密排列的铁素体束,有利于提高焊缝强韧性。

In present work,the 16 mm thick 11CrNi3MnMoV low alloy high strength steel plates are well joined by dual laser beams welding with hot filler wire,and the strength of joint is higher than parent metal. The microstructure characteristics of primary laser weld,the secondary remelting weld,heat treatment weld,and the effect of microstructure transformation on performances of weld are investigated. The results indicate that,in dual laser beams welding with filler wire,the microstructure of weld is mainly bainite and acicular ferrite,which should be refined by remelting and heat treatment. It’s distinct that the microstructure in reheated zone is similar to that of heat affected zone,and consists of normalized and tempered bainite. Moreover,the acicular ferrite in inner layer weld is much more than that in last layer weld. Meanwhile,a large number of parallel and compact ferrite exist in weld,which improve the tough of weld joint.