【摘要】 神头二电厂过热器异种钢接头高温运行约 4× 10 4 h后 ,沿耐热钢HAZ发生了裂纹 .经手弧焊修补 ,运行一段时间后再次出现裂纹 .本文通过断口及金相分析表明 ,接头前期失效为蠕变失效 ,这可由耐热钢HAZ珠光体球化 ,碳化物聚集和碳迁移说明 ;接头后期失效为应力腐蚀失效 ,这可由存在的应力和含有Cl-的水蒸气共同作用导致 .另外 ,接头焊接缺陷引起应力集中 ,也加速了SCC的产生 .改进焊接工艺 ,采用镍基焊丝TIG焊的过渡接头可有效提高其蠕变强度和服役寿命 .更多还原

【Abstract】 The dissimilar metal joints of superheater tubes cracked along the heat resistant steel HAZ after operating at high temperature for 4×10 4 hours at shen Tou ⅡPower Plant, and they cracked once again after being mended by arc welding and operating for a period of time. By means of fracture morphology and microstructure analysis, it is proved that the former failure is induced by creep damage, and can be explained by carbide concentration and carbon migration while the later failure is induced by SCC and it can be explained by stress and steam containing Cl -. Furthermore, the defects cause stress concentration and may induce SCC. Improving the welding process and using nickel based weld transition joint can improve creep strength and service life of A/F dissimilar metal joints.更多还原