摘要
应用光学显微镜、扫描电镜等手段,对奥氏体焊条焊接HK—40炉管和1Cr5Mo法兰的异种焊接接头在长期高温服役期间开裂泄漏的失效原因进行了分析,结果表明在长期高温服役中碳扩散迁移,在熔合区邻近1Cr5Mo钢母材侧形成脱碳层;其基体因贫碳软化,强度降低,加上1Cr5Mo钢和奥氏体焊缝金属的线膨胀系数有较大差异.高温下变形不协调,熔合区存在应力集中,导致在脱碳层这个薄弱部位萌生裂纹并沿其扩展,穿透内外壁,造成泄漏。
The failure reason of leakage for a dissimilar metal weldment joinning a HK-40 tube and a ICr5Mo flange at a hydrogen reformer during long-time high temperature service was analyzed by means of optical microscope and scanning electron microscope. The results show that the migration of carbon takes place during long -time high temperature seruice, and a decarbonization layer is formed in the fusion region adjacent to ICr5Mo parent metal, at which strength of the material degrades due to the absence of carbon. In the other hand. stress concentration is caused in the fusion region due to difference of thermal expansion cofficient of ICr5Mo steel and Austenitic weld metal. Finally, a crack produces at the weaker decarbonization layer, propagates along the layer, and results in leak.
出处
《压力容器》
1996年第2期145-150,共6页
Pressure Vessel Technology
