Influence of Stress Corrosion Cracking on Crack Tip Creep and Crack Propagation Rate in Welded Joints

Crack tip creep is a key parameter affecting the stress corrosion cracking (SCC) growth rate of nickel base alloy structural materials, significantly impacting the stress corrosion cracking rate of austenitic stainless steel and other materials. To explore the variation law of the crack tip creep field at different positions from the weld-seam of the welded joint, a numerical calculation model of the welded joint under different crack initiation positions was established based on alloy 600, and the crack tip stress field and creep were analyzed in detail. Results show that the unevenness of the material will cause obvious stress discontinuity at the crack tip of the material boundary; as the distance between the crack position and the weld interface increases, the stress of the crack tip before creep is affected by the mechanical properties of the base metal decreases. The creep rate of the weld side cracks gradually increases with the distance from the material interface. The minimum crack growth rate appears when the crack is located at the interface between the Ni-based alloy and base metal. The increased distance from the material interface increases the crack growth rate gradually. When the distance from the interface \(d>\) 0.1mm, the influence of mechanical properties on the growth rate is weakened.