Nitriding of A316 Stainless Steel Pipe with Improvement of Corrosion Resistance

Nitriding process is a process that can enhance mechanical properties as well as the
corrosion rate of steels. Hence due to this reason, nitriding had become one of the desirable
method used for surface treatment in producing material with high quality of performance.
The main purpose of this project is to enhance the corrosion resistance of austenitic
stainless steel which used normally in oil and gas industry. This project is mostly
concentrating on conducting the gas nitriding process and investigation is made to define
the effect of nitriding process on the pipe in terms of corrosion resistance and
microstructure. The high temperature gas nitriding process was subjected on A316L
austenitic stainless steel at the temperature of 1200°C for 8 hours holding time. The
samples were undergoing the metallography process to see and compare of the
microstructure of treated and untreated AISI 316. The microstructures of the nitrided
stainless steel were found they are twin formation which can be can divided into two
patterns which is suspended twin and transgranular twin. Besides that, the samples
undergo Energy Dispersive Spectrometer (EDS) test in order to check the nitrogen content
after the stainless steel was nitrided. The nitrogen content is expressed in duration curve
which shows that the diffusion of the nitrogen throughout the whole pipe after nitriding
process are uniformed. Moreover, the immersion test was carried out to compare the
corrosion rate before and after nitriding.