通过宏观形貌和微观形貌观察、硬度测试、测量腐蚀失重等方法对高速列车用A7N01S-T5激光-MIG复合焊接头进行了晶间腐蚀性能研究。结果表明:腐蚀会降低焊接接头的硬度;在含Cl-的腐蚀介质中,焊接接头的腐蚀程度大于母材,接头热影响区是腐蚀最严重的区域。这是由于焊接热作用的影响导致热影响区晶粒粗化和强化相在晶界富集,削弱了晶界的结合能,腐蚀最先从晶界开始发生所致。 The intergranular corrosion behavior of A7N01S-T5 laser-MIG composite welding head for high-speed train was studied by macroscopic and microscopic observation, hardness test and measurement of corrosion loss. The results show that corrosion reduces the hardness of the welded joint. In the corrosion medium containing Cl-, the welded joint is more corroded than the base metal, and the joint HAZ is the most corroded area. This is due to the influence of the heat of welding, which leads to the coarsening of grain coarsening in the heat-affected zone and the strengthening phase in the grain boundary, weakening the binding energy of the grain boundary, and the corrosion starts from the grain boundary first.