The influence of welding heat input,preheat temperature and the deposited metal diffusible hydrogen content were considered,the HAZ critical stress of X80 pipeline steel was tested by implant test based on the orthogonal regression design.The significant factors on the critical stress were obtained by analysis of variance.By multiple linear regression,the critical stress equation and the cold cracking susceptibility criterion were established.The critical stress equation was analyzed.It was concluded that the initial diffusing hydrogen content had great influence on cold cracking susceptibility of X80 pipeline steel.When the initial diffusing hydrogen content is lower,the microstructure is found to be the most important factor on the critical stress.When the initial diffusing hydrogen content is higher,the residual hydrogen content has great influence on the critical stress as well as the microstructure.%采用一次正交回归设计,考察焊接热输入、预热温度和熔敷金属的扩散氢含量的影响,通过插销试验测定了X80管线钢焊接热影响区下临界应力,通过方差分析得到影响插销试验下临界应力的显著性因素,采用多元线性回归建立了下临界应力方程和冷裂纹判据,并对方程进行了分析;发现X80管线钢的冷裂倾向和初始扩散氢含量密切相关,当初始扩散氢含量较低时,组织形态对下临界应力的影响显著;当初始扩散氢含量较高时,下临界应力受到组织和残余扩散氢的共同作用.
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