HR3C钢焊接接头700℃的蠕变组织演变

Microstructure evolution of HR3C steel welded joint during creep at 700 ℃

利用光学显微镜和扫描电子显微镜,通过高温持久试验分析了700℃试验中HR3C钢焊接接头蠕变组织。结果表明,高温持久拉伸的HR3C钢接头组织中析出大量粗大的M23C6沿奥氏体晶界连续分布是促使蠕变裂纹产生的原因;在焊缝胞状树枝晶内的M23C6以针状形态几乎布满整个组织,加速了裂纹扩展,致使接头的蠕变断裂强度降低。

Microstructure evolution of HR3 C steel welded joint obtained from creep rupture test at 700 ℃ was investigated by optical microscopy and scanning electron microscopy. The results show that large amount of M23C6 precipitates in the welded joint during the high temperature creep process. Coarse M23C6 particles are continously distributed along the austenite grain boundaries,inducing the initation of creep cracks. The cellular dendrite welded seam abounds with acicular M23C6,which accelerates the crack propagation and results in the decrease of creep rupture strength.