哈氏合金薄板激光填丝焊接接头高周疲劳性能

High cycle fatigue strength of laser welding Hastelloy C-276 with filler wire

为了评价激光薄板填丝焊接接头的高周疲劳性能,利用升降试验法评价了指定2×10~6周次寿命的0.7 mm厚激光填丝焊接接头样件高周疲劳强度,借助扫描电子显微镜分析了断口及断裂位置。结果显示,激光填丝焊接接头的高周疲劳强度为396.6 MPa,断口形貌显示近无夹杂物,裂纹源区呈解理特征,裂纹主要为沿晶扩展,在裂纹扩展区呈现典型的疲劳条纹特征,且条纹间距随裂纹扩展长度的延长而加宽,瞬断区主要呈现与拉伸断口一致的韧窝形貌。观察断口截貌可知,裂纹主要在焊缝上表面焊趾附近萌生,并沿板厚方向扩展,在沿焊接方向扩展过程中会跨越熔合线,在焊缝区内和相邻母材区内扩展。

In order to evaluate the high cycle fatigue performance of laser weld joint with filler wire,the 2×106 high cycle fatigue strength of 0.7 mm thick laser weld joint with filler wire is evaluated by up and down method. SEM is used to analysis the fracture surface and fracture position. The results showed that the fatigue strength was 396.6 MPa. The fracture surface showed no precipitated phase. The crack source zone showed cleavage features,which mean the crack prolonged along the grain boundaries at early stage. The crack developing zone showed fatigue striations which became sparse with crack prolonging. Fracture zone feature was same with the tensile fracture surface which showed dimples and micro-holes features. The crack was originated from weld toe region on the top surface and prolonged along the thickness direction. During the propagation along the weld direction,the crack spread across the fusion line and in the weld zone and the adjacent base metal zone.