620℃超超临界机组用9Cr-Mo-Co-B钢（CB2）焊接接头性能退化机制研究

摘要

The creep rupture property of welded joint of advanced 9%Cr-Mo-Co-B steel (CB2)used for 620 ℃ USC steam turbine was studied. The welded joint was prepared by shielded metal arc welding(SMAW)with matching electrodes of MTS 5Co1 and MTS-616 respectively. The result indicated that the creep strength of welded joint was weaker than that of the base material. The fracture usually occured in the intercritical heat affected zone (HAZ)of the welded joint and demonstrated a typical IV cracking. The mi-crostructure of the welded joint was investigated by using optical microscopy OM and scanning electron microscopy (SEM). The degradation mechanism of welded joint of the 9%Cr-Mo-Co-B steel was explored by analysing phases of precipitates.%文章研究了620℃超超临界机组9%Cr-Mo-Co-B 钢(CB2)焊接接头的持久性能，焊接接头采用 SMAW 方法进行焊接，焊材分别选用 MTS 5Co1和 MTS-616。持久性能实验表明焊接接头的持久强度低于母材，断裂位置发生在焊接接头的热影响区临界区(ICHAZ)，为典型的 IV 型裂纹。文章采用光学显微镜 OM 及扫描电镜 SEM 观察焊接接头的微观组织及析出相，通过对析出相的分析研究了9%Cr-Mo-Co-B 钢焊接接头的性能退化机制的成因。