X100钢级埋弧焊管焊缝局部拉伸强度和延性研究

Investigation of Local Tensile Strength and Ductility Properties of X100 Submerged Arc Seam Weld

为了研究X100钢级埋弧焊焊管不同区域的局部和整体拉伸行为的差异,通过拉伸试验比较了焊管不同区域的强度和延性性能,分析了其断裂行为及马氏体-奥氏体(M-A)对局部拉伸性能的影响,并结合显微组织、硬度试验及拉伸试验,分析焊后及再加热后热影响区的性能。结果表明,相比埋弧焊第2道焊道,焊道重叠区的热影响区表现出更高的屈服强度、抗拉强度、硬度、应变硬化和整体延性;焊道2和热影响区重叠区的断裂均发生在细晶热影响区(FGHAZ)处,重叠区FGHAZ中较高的M-A分数和较小颗粒间距促进了弥散强化,从而使该区域的强度更高;尽管重叠区试样的FGHAZ表现出比焊道2 FGHAZ高的整体应变,但其局部应变相对更低。

In order to study the difference of local and global tensile behavior in different areas of X100 submerged arc welded pipe, the strength and ductility of different areas of welded pipe were compared through tensile test, and the fracture behavior and the effect of martensite-austenite(M-A) on local tensile properties were analyzed. Combined with microstructure, hardness test and tensile test, the properties of heat affected zone after welding and reheating are analyzed. The results show that compared with pass 2 of submerged arc welding, the heat affected zone in the overlap zone shows higher yield strength, tensile strength, hardness, strain hardening and overall ductility. The fracture of pass 2 and the overlapping area of heat affected zone occurs in the fine grain heat affected zone(FGHAZ). The higher M-A fraction and smaller particle spacing in the overlapping FGHAZ promote dispersion strengthening, resulting in higher strength in this area. Although the FGHAZ of the overlap sample shows a higher overall strain than pass 2 FGHAZ, the FGHAZ of the overlap sample shows a lower local strain than pass 2 FGHAZ.