On the stress corrosion crack growth behaviour in high temperature water of 316L stainless steel made by laser powder bed fusion additive manufacturing

Highlights: •Stress-relieved AM 316L SS has an anisotropic non-equilibrium microstructure and preferred SCC path in the build direction. •Fully-annealed AM 316L shows equiaxed coarse grains and similar SCC growth rate as wrought material. •Retained unrecrystallized grains in the high-temperature annealed AM part poses minimal impact on the SCC crack growth. •Increasing porosity and pore size in AM 316L stainless steel may enhance its SCC growth rate. •For nuclear applications, high temperature recrystallization annealing is necessary for AM stainless steel part. -- Abstract: This paper reports a comprehensive study of the stress corrosion crack growth behaviour of laser additively-manufactured (AM) 316L stainless steel in high temperature water. A wide range of parameters and their effects were evaluated, including microstructure, heat treatment, stress intensity factor, cold work, crack orientation, oxidizing vs. reducing conditions, and porosity. Stress-relieved material exhibits anisotropic microstructure and preferred crack path along material's build direction. With high-temperature annealing, the material recrystallizes to equiaxed structure and behaves like wrought material. The retained unrecrystallized grains in an annealed AM part may not affect the cracking. Increased porosity may enhance the crack growth rate.