Study of Thickness Effect on Fracture Toughness of High Grade Pipeline Steel

Abstract

The critical fracture toughness decreases when thickness of specimens increases and stress-strain field in crack tip start changing to plane strain state from plane stress state. In this paper, fracture toughness tests were carried. Based on the analysis of stress-strain field in crack tip and fracture toughness test results, a fracture toughness-thickness empirical model was established and the plane strain fracture toughness and critical thickness of X80/X100 were calculated. Then the validity of the empirical model was discussed and verified. The analytical results indicate that the safety of thick wall pipelines is worth of attention.