预热温度对12Cr10Co3W2Mo耐热钢焊接冷裂纹敏感性的影响

采用插销试验进行了12Cr10Co3W2Mo耐热钢在室温以及预热100,200和300℃条件下焊接接头粗晶区临界断裂应力试验研究,测试了热影响区最高硬度,观察了粗晶区微观组织,并对插销试样断口进行了扫描电镜观察.结果表明,随着预热温度升高,临界断裂应力呈线性增加趋势;热影响区最高硬度出现在粗晶区,该区域组织为板条马氏体,随着预热温度升高,粗晶区硬度呈小幅下降趋势;在各预热温度下,插销试样起裂区断口均呈解理+准解理氢致开裂特征,随着预热温度提高,氢致开裂的断口特征逐步消失.

Influence of preheating temperature on cold cracking sensitivity of 12Cr10Co3W2Mo heat resistant steel

The critical fracture stress of coarse grain heat-affected zone (CGHAZ) of 12Cr10Co3W2Mo heat resistant steel weld was investigated by implant test when the preheating temperature was room temperature, 100℃, 200℃ and 300℃, respectively. The highest microhardness in heat-affected zone was measured; the microstructure in the CGHAZ was observed; and the fracture surface of implant samples was detected with scanning electron microscopy (SEM). The results indicate that the critical fracture stress increased linearly with the increase of preheating temperature. The microstructure in CGHAZ was lath martensite and the microhardness was highest. The microhardness of CGHAZ decreased slowly as the preheating temperature increased. Under different preheating temperatures, the crack initiation zone in implant samples was mixed cleavage and quasi-cleavage hydrogen-induced cracking (HIC) morphology. And with the increase of preheating temperature, the HIC features disappeared gradually.