Fatigue life extension of notches in AISI 304L weldments using deep cryogenic treatment

The fatigue crack initiation lives of notches in AISI 304L austenitic stainless steel weldments were improved after the deep cryogenic treatment of specimens at liquid nitrogen temperature (−185 °C). During this treatment, a significant change in microstructure is developed. Strain induced martensitic transformation occurs. During this transformation, the weld metal expands. This expansion relieves the tensile residual stresses and induces compressive stresses around the welded part. However, it was observed that the fatigue crack propagation properties were not changed due to this treatment. Center crack tension type specimens were used in this investigation. Constant amplitude fatigue experiments with R = 0 were carried out with a frequency of 30 Hz.