Correlation between microstructure and micro-hardness of 316L nitrided austenitic stainless steel

Abstract

This paper presents the effect of duration of solution nitriding towards microstructure and microhardness of AISI 316L stainless steel. The AISI 316L stainless steel was exposed to high temperature gas nitriding process at 1200 °C by using 50% ammonia gas and 50% nitrogen gas for different durations of 8, 15 and 20 hours. The nitrided austenitic stainless steel then underwent several analyses and tests to find the effect of different durations of nitriding towards its microstructures and microhardness. From the experiments conducted to the nitrided samples, it was found that the higher duration of nitriding resulted in the increase of microhardness of the samples due to the increase of nitrogen content in the stainless steel. However, there was no effect found on the microstructure of the nitrided samples. It was noted that the highest hardness was obtained from the nitrided sample of 20 hours that has 245.1 HV which is about 70% higher than the as-received sample.

Laser Surface Alloying of Austenitic 316L Steel with Boron and Some Metallic Elements: Properties

“…The similar tests were also carried out after low-pressure and low-temperature gas nitriding (LTGN) of high-velocity oxy-fuel (HVOF) sprayed 316L coating [ 45 ] in order to investigate the wear resistance of the layers produced. The nitrided layers, produced by high-temperature gas nitriding (HTGN) [ 46 , 47 ] as well as by nitriding in liquid media [ 48 , 49 ] were not subjected to wear tests. The wear behavior of powder-pack carburized austenitic steel was not provided [ 50 , 51 ].…”

“…Among these processes, the most important are: low-temperature plasma gas nitriding (LTPGN), high-temperature plasma gas nitriding (HTPGN), low-temperature plasma gas carburizing (LTPGC), low-temperature plasma gas nitrocarburizing (LTPGNC), cathodic plasma electrolytic nitriding (CPEN) or plasma paste boriding (PPB). The conventional thermo-chemical treatment, i.e., boriding [ 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ], nitriding [ 44 , 45 , 46 , 47 , 48 , 49 ] or carburizing [ 50 , 51 , 52 ] as well as producing the TiN coatings by physical vapor deposition (PVD) [ 53 , 54 ], requires the mechanical or chemical removing these oxides before these processes. It is relatively difficult due to the susceptibility of austenitic steel to re-passivation.…”