International Journal of Engineering Research in Electronics and Communication Engineering

Correlations between Microstructure, Nitrogen Concentration and Micro Hardness of Nitrided Ferritic Stainless Steel

Author : Patthi Hussain ¹ Muhammad Azwam Ibrahim ²

Date of Publication :25th April 2018

Abstract: Gas Nitriding on Ferritic Stainless steels AISI 430 carried was out at 600 , for various period of nitriding process which were for 2 h, 8 h and 24 h. The effect of nitriding process period in term of microstructure, overall micro hardness, cross section hardness and nitrogen diffusion rate were investigated. The microstructures of the samples were carried out using Optical Microscope (OM) and Scanning Electron Microscope (SEM). The phase changes and Nitride precipitation formation were observed with respect to holding time of nitriding. Micro-analyses were also conducted on all samples using Energy Dispersive Spectroscope to investigate the effect of phase changes and it correlation toward the hardness of the materials. Unnitrided ferritic stainess steel was found having bigger grain size boundaries compare to nitride ferritic stainless steels. This is due to heat treatment during manufacturing process and concentration of nitrogen inside the steel. The size of grain boundaries reduces with nitriding time due to concertation of nitrogen inside the steels. The hardness value and concentration of nitrogen inside the steel reduce with the depth under the surface. The concentration of nitrogen in the steels increases with time of nitriding. Increasing in nitriding time increases the nitrogen composition inside the steel, thus reduce the grain size of the microstructure significantly and thus increase the hardness properties of the materials.

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