The effect of specimen thickness on low temperature gaseous carburization of 316L austenitic stainless steel

In this present paper, the effect of specimen thickness on carburized layer thickness and surface residual stress of low temperature gaseous carburized AISI316L austenitic stainless steel was investigated by using specimen with thicknesses from ~0.1 to ~3 mm. After 15 and 30 hrs Low Temperature Gaseous Carburization (LTGC) treatment, the carburized layer thickness, surface residual stress and surface morphology were studied by optical microscope (OM), X-ray residual stress analyzer and scanning electron microscope (SEM). The results show that the specimen original thickness has no effect on the thickness of carburized layer. Surface compressive residual stresses are constant as about -1.6 and -2.1 GPa when the specimen thicknesses are not less than 0.485 mm for 15 hrs and 0.926 mm for 30 hrs LTGC treatment respectively. With the reduction of specimen thicknesses from 0.485 to 0.081 mm for 15 hrs LTGC treatment and 0.926 to 0.082 mm for 30 hrs LTGC treatment, the compressive residual stresses declined and finally reached about +0.4 and +1.0 GPa, respectively. Surface inter-granular cracking occurred on 0.082 mm specimen after 30 hrs LTGC treatment.