EPR法评价HR3C钢焊接接头的晶间腐蚀敏感性

Evaluation of susceptibility to ingtergranular corrosion of HR3C steel welded joint by EPR method

关键词:  HR3C钢  电化学动电位再活化法  焊接接头  晶间腐蚀

Key words:  HR3C steel  double-loop electrochemical potentiokinetic reactivation  welded joint  intergranular corrosion

摘要:

利用电化学动电位再活化法研究了HR3C钢焊接接头的晶间腐蚀敏感性，并通过金相显微镜、X-射线衍射仪、扫描电子显微镜及能谱仪研究了HR3C钢焊接接头的微观组织.结果表明,HR3C钢焊缝金属和焊接热影响区均为奥氏体+析出相组成，焊接接头具有较低的晶间腐蚀倾向.由于焊缝金属中Cr和Nb等元素含量高及晶界和枝晶界铌、铬元素偏析等原因提高了晶界耐腐蚀性，使其具有优异的抗晶间腐蚀性能；而热影响区由于受焊接热循环作用晶界析出M23C6引起晶界贫铬，具有一定的晶间腐蚀敏感性.

Abstract:

Susceptibility to intergranular corrosion of HR3C steel welded joint was investigated by double loop electrochemical potentiokinetic reactivation (DL-EPR) method. The microstructure of HR3C steel welded joint was examined with optical microscopy, X-ray diffractometer, scanning electron microscopy and energy dispersive spectrometer. The results show that the weld metal and heat affected zone of HR3C steel joint consisted of γ-phase and precipitates. The welded joint exhibited low susceptibility to intergranular corrosion. Intergranular corrsion resistance of the weld metal was improved due to the high content of Cr and Nb in the weld metal and the segragation of Nb and Cr near the grain and dendrite boundaries. However, the heat-affected zone was susceptible to intergranular corrosion owing to the depletion of Cr near the region of grain boundaries where M23C6 precipitates formed during welding.