X100管线钢焊接冷裂纹敏感性

Investigation on cold cracking susceptibility of X100 pipeline steel

关键词:  X100管线钢  冷裂纹敏感性  应力  应变

Key words:  X100 pipeline steel  cold cracking susceptibility  stress  strain

摘要:

采用E10018焊条进行了斜Y形坡口焊接裂纹试验，结合数值模拟方法对X100管线钢焊接冷裂纹敏感性进行了研究，分析了预热温度对热影响区显微组织、接头硬度分布、应力应变状态的影响规律. 结果表明，X100管线钢具有一定的焊接冷裂纹敏感性，采用不高于100℃预热可以降低冷裂纹敏感性；100℃预热时裂纹率为0，此时粗晶区显微组织不是很粗大、M-A组元数量最少、硬度较低，且残余应力和应变水平都较低；但预热温度大于150℃时，粗晶区晶粒粗大、M-A组元数量增加，且接头中等效残余应力、应变水平升高，导致冷裂纹敏感性增加. 建议采用100℃进行预热.

Abstract:

The Tekken test using E10018 electrode and finite element (FE) simulation to evaluate the cold cracking susceptibility of X100 pipeline steel has been performed. The impact of preheating condition on the HAZ microstructures, distribution of hardness, and the stress-strain state in the welded joint was analyzed. The experimental results showed that X100 pipeline steel reveals certain susceptibility to cold cracking without preheating. It was found that preheating temperature below 100℃ resulted in a lower cold cracking susceptibility. Preheating temperature of 100℃ is most effective with zero cracking ratios due to a relative fine CGHAZ microstructure and low M-A constituent amount, a low hardenability, low level stress and strain level. However, excessive preheating temperature of 150℃ and 200℃ can lead to higher cold cracking susceptibility due to an increase in CGHAZ grain size, M-A constituent amount, equivalent stress level and strain level in the Tekken specimens. Preheating temperature of 100℃ is recommended to reduce cold cracking.