Nb-Mo系X80管线钢焊接冷裂纹敏感性的研究与预测

Research and prediction on cold cracking susceptibility of Nb-Mo X80 pipeline steel

通过插销试验获得Nb-Mo合金化的X80管线钢焊接冷裂纹下临界应力,分析发现Nb-Mo合金化的X80管线钢具有较小的冷裂敏感性.测量了不同焊接工艺条件下的焊接热循环参数、焊接热影响区最高硬度、熔敷金属初始扩散氢含量,和冷却到50℃时的残余扩散氢含量,建立了Nb-Mo合金化的X80管线钢冷裂纹判据公式,并对判据进行了分析.结果表明,在低氢条件下,钢的抗冷裂能力随着热影响区最高硬度的增大而提高;高氢条件下,钢的抗冷裂能力随着热影响区最高硬度的增大而降低;在试验硬度范围内冷裂倾向随残余扩散氢含量的增加而增大.

;The critical stresses of welding cold crack for Nb-Mo X80 pipeline steel was obtained by implant tests,it was found that its cold cracking susceptibility was low.The thermal cycle parameters,maximum hardness in HAZ and the original diffusible hydrogen content in deposited metal and diffusible hy-drogen content in deposited metal at 50℃ in different welding processes were measured,and the diffusible hydrogen content in deposited metal at 50℃ was calculated.The cold crack criterion equations of Nb-Mo X80 pipeline steel were established and ana-lyzed.The results show that the cold crack resistance of Nb-Mo X80 pipeline steel increases with the increase of maximum hard-ness in HAZ at the low diffusible hydrogen content,while it de-creases with the increase of maximum hardness in HAZ at the high diffusible hydrogen content.The cold crack sensitivity in-creases with the increase of the diffusible hydrogen content in the test maximum hardness scope.