奥氏体不锈钢油管开裂原因分析

Cause analysis of cracking of austenitic stainless steel tubing

对某电厂汽轮机EH油管开裂管进行了宏观形貌检查、材质分析、硬度检测、显微组织分析、扫描电镜和能谱分析等。结果显示,材质为1Cr18Ni9Ti不锈钢的EH油管存在带状夹杂物超标和热影响区缺陷等产品质量问题。分析认为,带状非金属夹杂物破坏了基体组织连续性,降低了材料的表面成型质量、材质质量,并降低韧性和抗疲劳性能。热影响区存在焊接缺陷,EH油管在高周振动运行环境下,易在缺陷位置优先开裂,并逐渐扩展。

The cracked EH tubing of steam turbine in a power plant was examined by macro morphology,material analysis,hardness test,microstructure analysis,scanning electron microscope and energy spectrum analysis.The results show that the EH tubing made of 1Cr18Ni9Ti stainless steel has some product quality problems such as excessive band-shaped inclusions and defects in the heat-affected zone.The analysis shows that banded non-metallic inclusions destroy the continuity of matrix structure and reduce the surface forming quality,material quality,toughness and fatigue resistance of the material.There are welding defects in the heat affected zone.Under the high cycle vibration operation environment,EH tubing is easy to crack preferentially at the defect position and expand gradually.