Study on the Mechanical Response Behavior of X80 Pipeline Steel Welding Structure under Tensile Stress

Abstract The weld joint is composed of the weld area and the heat-affected area. The heterogeneity of the organizational structure will lead to local strain mismatch and affect its mechanical properties. This paper studies the strain distribution characteristics of the weld area and the heat-affected area under tensile stress, and reveals the respective strain response mechanism of the two regions. It is found that the weld area has lower yield strength and hardness, greater uniform elongation and strain hardening index. The plastic strain of the weld joint under tensile stress is highly heterogeneous, and the strain response mechanism is mainly based on the processing hardening effect. The strain response of the heat-affected area is weak and is affected by grain-oriented hardening. The research results provide a theoretical basis and experimental basis for the design of pipeline steel welding process and the safety evaluation under plastic deformation conditions.