Anisotropic Behaviors for X100 High Grade Pipeline Steel Under Stress Constraints

Because of the manufacture process of high grade pipeline steel, the anisotropic behaviors appeared in different directions, including both properties and microstructure. In this paper, mechanical properties and microstructures for X100 high grade pipeline steel were investigated with a series of tests, including not only experiments but also simulation. Tensile tests with DIC (Digital Image Correlation) method was used to get the stress-strain relationship, especially in the process of fracture. SENT (Single Edge Notch Tensile) tests with different notch sizes were used to characterize the fracture resistance anisotropies. The microstructure was characterized by both fracture analysis and inclusion characteristics to infer the relation between voids growth and crack propagation. Moreover, FE simulation of SENT was carried out by complete Gurson model. Finally, the results of tests and simulations were compared to study the effects of stress constraints on crack resistance in different directions.