X100管线钢焊接接头组织及力学性能分析

Analysis on Microstructure and Mechanical Properties of Welded Joint of X100 Pipeline Steel

采用埋弧焊对X100管线钢板施焊,分析焊接接头组织及力学性能。结果表明:X100管线钢埋弧焊焊接接头焊缝区组织为针状铁素体(AF)、先共析铁素体(PF)、粒状贝氏体和部分镐牙状侧板板条铁素体(FSP);HAZ组织为粒状贝氏体和铁素体;焊接接头平均抗拉强度为796.3 MPa,与母材组织达到了等强匹配;冲击功平均为133 J,剪切面积百分比平均为72%。焊缝冲击断口为脆性断裂,河流状花样明显。Mg O、Al2O3夹杂物呈树枝状析出,引起了多个二次裂纹,降低了韧性。

Submerged arc was used to weld X100 pipeline steel plate, the microstructure and mechanical properties of the welded joint was analyzed. The results show that： the microstructure of weld zone is acicular ferrite（AF）, proeutectoid ferrite（PF）, granular bainite and ferrite side-plate（FSP）. The microstructure of HAZ is granular bainite and ferrite. The average tensile strength of the welded joint is 796.3 MPa and the average percentage of shear area is 72%, which matches the basic metal. The SEM shows that the fracture of the welded joint is brittle, with obviously river pattern. Mg O, Al2O3 which separate out in arborescent crystal can cause much secondary crack, thus reducing toughness.