【摘要】 采用插销试验测试了20℃2、50℃、320℃和400℃预热温度下的焊接熔合区临界断裂应力,分析了插销试样断口和熔合区组织.结果表明:焊接熔合区断口为沿晶(IG)+准解理(QC)型,随着预热温度增加,QC比例增加;焊接熔合区组织为马氏体+下贝氏体+残余奥氏体;随着预热温度的升高,熔合区冷却速度降低,下贝氏体组织增加,引起晶内氢陷阱数量增加,从而导致熔合区的临界断裂应力提高,降低了冷裂纹敏感性.更多还原

【Abstract】 The critical fracture stress of preheated weld bonds at 20 ℃,250 ℃,320 ℃and 400 ℃,respectively was measured with implant test,and the fracture appearance of the implant samples and the microstructure of the bonds were analyzed.The results show that the fracture appearance of the bond is in the form of intergranular(IG) and quasicleavage(QC),and the proportion of QC increases with increasing preheating temperature.The microstructure of the weld bonds is a combination of martensite,lower bainite and retained austenite.The cooling rate of the bond decreases as preheating temperature increases,and the expanded region of lower bainite results in the increase of the number of hydrogen traps in grain to heighten the critical fracture stress and lower the sensitivity of the cold crack.更多还原