Effect of Cooling Rate on The Plasma Nitriding Process of 304 Austenitic Stainless Steel
Abstract
Abstract: The aim of this work is to study the influence of the cooling rate on the properties of the modified
surface layer of AISI 304 steel after rf plasma nitriding. The nitride samples were characterized by glow
discharge optical spectroscopy, x-ray diffraction, optical microscopy, scanning electron microscopy and
Vickers microhardness measurements. The results revealed that microstructure, nitriding rate and surface
microhardness values were found to be cooling rate dependent. The treated layer is mainly composed of
nitrogen expanded austenite (γN), iron nitride (γ‘-Fe4
N) and chromium nitride (Corn). A maximum thickness
of treated layer (19.9 µm) is achieved for sample treated at medium cooling rate of 900 Cm3
/min. It has a
maximum surface hardness and nitriding rate of 1402 HV0.1 and 0.66 μm2
/s, respectively.
