Microstructural Studies of Nickel Free High Nitrogen Stainless Steel Produced Using Mechanical Alloying Under Nitrogen Atmosphere

Nickel free nano structure austenitic stainless steels(HNSS) have been extensively investigated lately due to their excellent properties. In particular, nitrogen as an alloying element improve mechanical and corrosion properties and nitrogen makes it possible to reduce the nickel content in stainless steels and as a result, offers additional advantages such as biomaterial application and cost savings. High pressure techniques have been developed for fabrication of high nitrogen stainless steel, but these procedures are typically very expensive. Alternatively, powder metallurgy can be employed in order to increase the nitrogen content in steels. Recently, it has been shown that nitrogen concentration in iron and steel powders results in a highly refined crystalline microstructure. The powder were characterized by means of X-ray diffraction(XRD) and scanning electrone microscop (SEM) with an energy dispersive X-ray microanalysis system(EDAX). The result showed that maximum nitrogen levels of 1.52 wt pct nitrogen were achieved after for 80 hours in addition, the grain size structure continually decreased and reached 10 nm.