Enhanced plasma nitriding efficiency and properties by severe plastic deformation pretreatment for 316L austenitic stainless steel

In order to enhance the plasma nitriding efficiency and improve the hardness and wear resistance of 316L austenitic stainless steel, severe plastic deformation was adopted prior to plasma nitriding. The microstructure, phase constituents, hardness and wear resistance samples after plasma nitriding were determined by metallographic microscope, X-ray diffractometer, microhardness tester and universal friction and wear tester. The results showed that severe plastic deformation had significant enhancement effect on plasma nitriding efficiency. Under the same plasma nitriding parameters of 420 °C and 4 h, the thickness of nitriding layer was increased from 6.36 μm to 14.10 μm, more than twice thicker enhanced by severe plastic deformation. XRD confirmed that the nitriding layer is consisted of S phase. Meanwhile, the surface hardness was improved from 990HV to 1110 HV and with moderated gradient of cross sectional hardness; more valuably, the wear resistance was greatly enhanced by severe plastic deformation.