前期工艺状态对不锈钢油管的疲劳影响研究

对3种不同成型工艺制得的304不锈钢油管进行了压力脉动实验,在油管失效破裂后通过金相分析、扫描电子显微镜(SEM)能谱仪(EDS)分析和X射线显微镜分析等手段对关键破裂部位进行了微观组织分析,并确定了失效原因。结果表明,3个样品失效形式均为疲劳断裂,但裂纹源产生原因不同,样品1断裂处存在氧化铝夹杂,断裂源是由夹杂物引起的;样品2断裂面为典型穿晶型形貌,裂纹拓展较快,断裂可能是由于晶粒粗大,样品3断裂面存在直径10μm左右的“陨坑”,断裂源可能是由疏松等材料缺陷产生。

Study on fatigue effect of prophase process status on stainless oil tube

The pressure pulsation experiment of 304 stainless steel tubing produced by three different forming processes was carried out.After the failure happened,the microstructure of the key fracture area was observed by and the failure cause was determined.The failure modes of those three samples were all fatigue fracture,meanwhile the origins of the fatigue crack nucleation were different.Alumina inclusions was found in the first sample,the fracture source was caused by those inclusions.A typical transgranular morphology was observed in the second sample,which indicates a high a high speed in crack expanding.The large grain size may be the reason for this fracture.There are several“crater”with a diameter of 10μm exist on the surface of the third fracture plane.Material defects such as porosity reasonable for the fracture.