Study of structural changes for STS 316L using the positron annihilation lifetime spectroscopy

The defects due to extrusion strengths and the temperature dependent deformities for low carbon stainless steel (STS 316L) were investigated using positron annihilation spectroscopy. The defects were restored after tempering at 700 °C. The gradients of the peak on the positron annihilation lifetime spectrum for a sample annealed at 700 °C is increased compared to the as extruded sample. In addition, we calculated the trapping rate and bulk lifetime based on the theoretical model. Both values are decreased, as the extrusion strengths are reduced. All annealed samples showed reduced trapping rate and bulk lifetime, comparing with as extruded samples.