30 CrMo &40 CrNi 钢焊接冷裂纹敏感性研究

STUDY ON THE SUSCEPTIVITY TO WELDING COLD CRACK OF 30CrMo AND 40CrNi STEEL

对３０ＣｒＭｏ＆４０ＣｒＮｉ钢的焊接冷裂敏感性进行了研究，确定了采用手工电弧焊焊接３０ＣｒＭｏ＆４０ＣｒＮｉ钢的焊接材料。用透射电镜观察了ＨＡＺ组织的精细结构。结果表明，１００℃预热、２５０℃×２ｈ紧急后热热影响区粗晶区可得到对防止冷裂纹有利的、以位错板条马氏体和下贝氏体为主、带有少量孪晶片状马氏体的显微组织。这不仅为评定３０ＣｒＭｏ和４０ＣｒＮｉ的抗裂性能提供了理论依据，而且对实际焊接生产具有重要的指导意义。

The susceptivity to welding cold crack of 30CrMo and 40CrNi steel has been studied,and the welding materials for covered arc welding were selected.The results obtained by making use of TEM show that there are mainly the dislocated lath martensite,lower bainite and some twining martensite in the microstructures of HAZ with the preheating at 100 ℃ and postheating at 250℃×2 h.The results can be of not only theoretical basis for evaluating the crack resistance ability of 30CrMo and 40CrNi steel,but also of momentous directive significance to the welding production in practice.