Factors affecting reheat cracking in the HAZ of austenitic steel weldments

Effect of pre-strain on creep of three AISI 316 austenitic stainless steels in relation to reheat cracking of weld-affected zones

“…Thickness, notches and weld defects are deleterious because ductility sharply decreases as stress triaxiality increases [11][12][13][14][15][16][17]. Following the results of the present study, thickness has an additional effect: welding thick components requires numerous welding passes which leads to a high level of pre-strain in the weld-affected zone, which impairs ductility.…”

“…14 illustrates such slip bands, which developed at the surface of an annealed 316L(N) flat specimen during plastic tensile strain of approximately 4% at 600°C in vacuum. Skelton et al [12] reported similar slip bands and grain boundary steps developed during mock-up welding thermo-mechanical cycles. The lower the stacking fault energy, the more planar the dislocation distribution and the higher the local stress concentration.…”

“…Even pre-strained 316H -the most brittle stainless steel studied here -should therefore sustain this strain without cracking. However, creep ductility is known to decrease drastically when stress triaxiality increases [11][12][13][14][15][16][17]. In order to assess the reheat-cracking sensitivity of the studied materials with more realistic mechanical loading conditions, dedicated mechanical tests with high local stress triaxiality were therefore carried out.…”

“…Such a mechanism is consistent with the reheat-cracking sensitivity of unstabilised stainless steels with a high solute content such as AISI 316H or 316L(N). It also suggests that AISI 316L would be less prone to cracking.Recent work on reheat cracking of unstabilised austenitic stainless steels [11][12][13][14][15][16][17] mostly focused on the influence of stress triaxiality on intergranular damage and on the influence of pre-strain on creep ductility. However, these studies did not mention the role of solute atoms in the cracking mechanism.…”

Effect of heat treatment on fatigue crack initiation of laser powder bed fusion stainless steel 316L

“…For welded austenitic stainless steel structures containing heat affected zones (HAZ), reheating is known to produce intergranular cracking [33,34]. The relaxation of residual stress is opposed by the bulk of the grains, leading to the accumulation of intense plastic strain at the grain.…”