오스테나이트계 스테인리스강의 플라즈마 질화특성에 미치는 열처리 조건의 영향

Abstract

Because Austenitic Stainless Steels have high hardness and wear resistance, They have been used in a range of commercial area. As regards Plasma Treatment, There have been many studies about time, temperature, pressure, etc. of Corrosion resistance of Austenitic Stainless Steels that have efficient Nitriding effect and the studies have resulted many consequences.

Plasma Nitriding is known for general way to develop wear resistance, hardness, corrosion resistance. traditional nitriding treatment that is carried at relatively high temperature can increase wear resistance and hardness. But, corrosion resistance is being decreased while traditional nitriding procedure because of the precipitation of CrN. In Austenitic matrix, the decline of CrN is even and it is hard to form stable passivity layer. So the active corrosion can be problem on the surface of steel.

This study focused on effects of time and temperature of STS 316L that is austenitic stainless steel and that has a wide range of using area. during the plazma nitriding, diffusion layers are increased prorate to the growth of the nitriding layer, also plazma nitriding effect brought formation of nitriding layers and diffusion layers. surface hardness have been increased to the level of more than 1000Hv. Otherwise some place which have low temperature have lower surface hardness. In this sense, The effect of time and temperature can be important matter in plazma nitriding. In 15 hours of plazma nitriding, In the result of the electrokinetic potential test, the specimen which have been treated at 400℃ have same figure of Un-treated specimen's corrosion resistance figure. the specimen which have been treated at 420℃ have decreased corrosion resistance figure. In addition, the corrosion resistance of the specimen which have been treated at 500℃ was highly decleased. In these sense, The increase of the temperature of the plazma treatment at 15 hours treatment reduces corrosion resistance figures.