X90高强度管线钢预精焊冷裂纹形貌及成因

发布时间：2018-04-27 19:13

本文选题：X管线钢 + 高强度　；参考：《焊接学报》2017年07期

【摘要】：采用力学测试、组织分析、扫描电镜和能谱分析的方法,研究了X90高强度管线钢预精焊的焊接裂纹形貌,并分析了裂纹形成原因.结果表明,X90螺旋焊钢管内焊缝上的横向裂纹为冷裂纹,裂纹在焊缝组织中呈穿晶扩展或沿晶界扩展.X90含有较多的Mn,Cr,Mo,Ni,Cu等合金元素,强度高,导致内焊缝的焊接残余应力高于裂纹的临界应力.内焊道维氏硬度比外焊道的高,且焊缝两侧的硬度分布极不对称,造成了内焊道附近的应力集中和分布不平衡.内外焊缝重合区域的扩散氢不易逸出,其含量较高,在气孔、夹渣等"陷阱"处聚集,导致裂纹产生和断口上大量氢白点形成.焊缝一次结晶所形成的连续细长的树枝晶晶界为裂纹扩展提供了"通道".
[Abstract]:By means of mechanical test, microstructure analysis, scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS), the weld crack morphology of X90 high strength pipeline steel was studied, and the causes of crack formation were analyzed. The results show that the transverse crack in the weld of HX90 helical welded steel pipe is cold crack, and the crack is transgranular or propagate along grain boundary. X90 contains more alloy elements such as MnCrCrOMO-NiONI-Cu, and the strength of the crack is high. The welding residual stress of the inner weld is higher than the critical stress of the crack. The Vickers hardness of the inner weld is higher than that of the outer weld, and the hardness distribution on both sides of the weld is very asymmetric, which results in the stress concentration and distribution unbalance near the inner weld. The diffusion hydrogen in the overlap zone of internal and external welds is not easy to escape, and its content is high, which accumulates at the "traps" such as pores and slag, resulting in the formation of cracks and a large number of hydrogen white spots on the fracture surface. The continuous thin dendritic boundary formed by the primary crystallization of the weld provides a "channel" for crack growth.
【作者单位】：中国石油集团石油管工程技术研究院;
【基金】：陕西省自然科学基金资助项目(2011JQ6017)
【分类号】：TE973.3;TG441.7

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