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

Abstract: 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.

Author(s): Translated by SUN Hong

CNPC Bohai Equipment North China Petroleum Steel Pipe Co., Ltd., Qingxian 062658, Hebei, China