焊接冷裂纹临界冷却时间判据t_（cr）的建立

Establishment of critical cooling time criterion t_(cr) of welding cold cracking

本文采用平板刚性拘束裂纹试验（ＰＲＲＣ）研究了四种国产低合金高强钢焊接冷裂纹敏感性，探讨了焊接接头扩散氢含量、焊接线能量、局部预热温度、拘束度的大小及由于局部预热产生附加应力等对钢材冷裂纹敏感性的影响。在上述试验研究的基础上，建立了国产低合金高强钢的临界冷却时间判据ｔ＿（ｃｒ）。并通过实例验证这一判据是可靠的，对于评定现行工艺条件下是否产生冷裂纹及确定合理焊接工艺都具有重要的指导意义。

The Plate Rigid Restraint Cracking tests(PRRC) have been used to study the welding cold cracking suseeptibilities of four kinds of domestic HSLA steels in this paper.And the effects of diffusive hydrogen content in welded joint,welding heat input,local preheat tempreture, restraint intensity and addional stress induced by local preheating on cold cracking susceptibility of steels have been discussed.On the basis of above research,the critical cooling time criterion t_(cr) of domestic HSLA steels is established.This criterion is proved to be reliable by real application,and hasimportant significance to assess if cold cracking occurs under conditions of weldingprocess in operation and to determine reasonable welding process.