fissuration différée au réchauffage

OBS: [Delayed re-heat cracking] only occurs with certain materials such as 321 type stainless steel, as it is caused by hardening of the steel due to fine precipitations of titanium carbide inside the crystalline structure. The hardening causes the plastic deformation capacity to be transferred to the periphery of the grains. For this to happen, the following conditions have to be met: a high operating temperature ([higher than] 475°C for 321 steel), a geometrical discontinuity at the weld root, strain hardening at the weld root showing significant shrinkage, heavy local load, which may be due to welding stresses, a defect in the weld root (e.g. a small shrinkage crack).