SCM 435 구조용강의 플라즈마 질화에 관한 연구

Abstract

본 연구는 SCM 435 구조용강을 450∼650℃의 온도범위에서 NH₃가스유량을 0.5∼2.1 l/min로 변화시키고, 20∼110분 동안 플라즈마 질화처리하여 강 표면에 생성된 경화층의 두께와 경도 및 조직을 조사하였다.

반응온도 550℃, NH₃1.65 l/min.에서 110분 동안 질화 하였을 경우 생성된 질화층의 두께는 260㎛으로써, 화합물층은 16㎛ 이며, 확산층은 224㎛로 이것이 최대의 질화층이었다. 한편, 반응온도 600℃, NH₃1.65 l/min. 가스유량에서 50분간 반응하였을때 24㎛의 최대 화합물층을 얻을 수 있었다.

또한 화합물층은 450℃와 500℃에서는 r'- Fe₄N-α-Fe로, 550℃에서는 r'-Fe₄N+ε- Fe₃N으로, 600℃이상에서는 r-Fe₄N+α-Fe로 구성되어있는 혼합상이었다.

550℃,NH₃1.65 l/min. 에서 80분 동안 질화처리하였을때 생성된 질화층의 최대 표면경도는 Hv 988이었다.

The plasma nitriding of SCM 435 structural steel has been studied at the temperature between 450℃ and 650℃ with gas flow rate of NH₃ 0.5 to 2.1 l/min. for 20 to 110 minutes.

The phases of compound layer formed below 500℃ and above 600℃ was mixture of r'-Fe₄N and ε- Fe₂₄N phases, while the phases formed 550 was r' - FeN and - Fe N phases.

The hardness of nitrided layer formed at 550℃ with gas flow rate of NH₃ 1.65 l/min. for 80minutes was Hv 988.

The thickness of nitrided layer formed at 550℃ with gas flow rate of NH 1.65 l/min. for 110minutes was 260㎛.

The nitriede layer was composed of 16㎛ compound layer and 244㎛ diffusion layer.

The plasma nitriding of SCM 435 structural steel has been studied at the temperature between 450℃ and 650℃ with gas flow rate of NH₃ 0.5 to 2.1 l/min. for 20 to 110 minutes.

The phases of compound layer formed below 500℃ and above 600℃ was mixture of r'-Fe₄N and ε- Fe₂₄N phases, while the phases formed 550 was r' - FeN and - Fe N phases.

The hardness of nitrided layer formed at 550℃ with gas flow rate of NH₃ 1.65 l/min. for 80minutes was Hv 988.

The thickness of nitrided layer formed at 550℃ with gas flow rate of NH 1.65 l/min. for 110minutes was 260㎛.

The nitriede layer was composed of 16㎛ compound layer and 244㎛ diffusion layer.