347奥氏体不锈钢阀门焊接壳体裂纹成因分析

Analysis on Cracks Forming of the Weled Valve Shell Made of 347 Stainless Steel

针对焊接后出现裂纹的347奥氏体不锈钢阀门壳体开展了失效分析,进行了宏观分析、化学成分和硬度测试、金相组织及能谱分析等,分析表明硼化物、硼碳化物与奥氏体形成了低熔共晶是导致开裂的冶金因素,热裂纹敏感性元素的偏析与富集、以及厚截面导致的拘束应力是导致阀门焊接壳体热影响区液化裂纹产生的原因。

Cracks appeared after welding of the valve shell made of 347 stainless steel,Measures such as macro analysis,chemical composition analysis,hardness tests,analysis on metallographic structure and energy spectrum were carried out in order to find the forming reason of cracks.The results show that boride,boron carbide and austenite form low melting eutectic,which is the metallurgical factor leading to cracking.The segregation and enrichment of heat crack sensitive elements and the restraint structure of thick section are the causes of liquefaction cracks in the heat affected zone of valve weld.