1Cr18Mn8Ni5N不锈钢筒形结构件环形接头微裂纹工艺研究

Study on process for ring joint of 1Cr18Mn8Ni5N stainless steel

文中采用光学显微镜、扫描电镜、XRD等方法对1Cr18Mn8Ni5N不锈钢某筒形结构件环形接头微裂纹进行了研究,并利用显微硬度压痕法评估了接头粗晶区的焊接应力。结果表明:当热输入为250~300 J/mm时,该结构件接头出现微小裂纹,裂纹主要分布于接头粗晶区。裂纹呈密集型分布,自熔合区靠近粗晶区的一侧启裂,随后沿晶界扩展,甚至在紧邻粗晶区的母材中也分布着裂纹。进一步提高热输入至397 J/mm后,接头则无裂纹。粗晶区晶粒粗大和尺寸均匀性差以及焊接应力是裂纹形成的主要原因。

In the paper,the process of microcrack in ring joints of 1Cr18Mn8Ni5N stainless steel was studied by using OM,SEM and XRD.The results showed that when the heat input was 250~300 J/mm,there were microcrack in joints,which were mainly distributed on the upper and lower surfaces of joints and located in coarse-grained zone.The crack initiated on the side near the coarse-grained zone,then propagated along the coarse grain boundary,even in the base metal adjacent to the coarse-grained zone.The cracks were densely distributed,and there were also secondary cracks near the main crack.However,there was no crack in joint when the heat input was 397 J/mm.These cracks were mainly due to the austenite grain growing up to coarse grain,the poor size uniformity and the welding residual stress.