Research on Hydrogen Induced Cracking Mechanism of Ferritic Steel in Welding Process Based on I₁ Fracture Criterion

Based on I₁ fracture criterion, hydrogen induced cracking mechanism of ferritic steel in welding process is proposed.Material begins to fracture when first stress invariant I₁ taken shape by hydrogen pressure, interior stress and applied load reaches fracture strength I_b. The hydrogen induced cracking mechanism was verified by hydrogen charging tensile test of two materials.