Improving Intergranular Stress Corrosion Cracking Resistance in a Fe-18Cr-17Mn-2Mo-0.85N Austenitic Stainless Steel Through Grain Boundary Character Distribution Optimization

The grain boundary character distribution (GBCD) optimization and its effect on the intergranular stress corrosion cracking (IGSCC) resistance in a cold-rolled and subsequently annealed Fe-18Cr-17Mn-2Mo-0.85N high-nitrogen nickel-free austenitic stainless steel were systematically explored. The results show that stacking faults and planar slip bands appearing at the right amount of deformation (lower than 10%) are beneficial cold-rolled microstructures to the GBCD optimization. The proportion of special boundaries gradually increases in the subsequent stages of recrystallization and grain growth, accompanying with the growth of twin-related domain in the experimental steel. In this way, the fraction of low sigma coincidence site lattice (CSL) boundaries can reach as high as 82.85% for the specimen cold-rolled by 5% and then annealed at 1423 K for 72 h. After GBCD optimization, low sigma CSL boundaries and the special triple junctions (J2, J3) of high proportion can greatly hinder the nitride precipitation along grain boundaries and enhance the capability for intergranular crack arrest, thus improving the IGSCC resistance of the experimental steel.