플라즈마 질화법에 의한 SKD 11 공구강의 표면 경화에 관한 연구

Abstract

본 연구는 온도범위 450 - 650℃, NH₃ 가스유량 0.5 - 2.1 l/min., 처리시간 20 - 110분의 조건에서 SKD 11 냉간 금형용 공구강을 플라즈마 질화처리하여 강 표면에 생성된 경화층(화합물층 및 확산층)의 조성 및 두께와 각각의 경도값을 조사하여 질화의 최적조건을 찾고자 하였다. 반응온도 550℃, NH₃2.1 l/min., 반응시간 110분일 경우 14㎛의 최대 화합물층을 얻었으며, 반응온도 550℃, NH₃1.65 l/min.로 110분간 반응시켰을 때 생성된 확산층은 210㎛였으며, 최대 질화층은 220㎛이었다.

또한, 플라즈마 질화처리한 SKD 11 냉간 금형용 공구강 표면과 화합물층을 XRD로 분석한 결과 450℃와 500℃에서는 r' - Fe₄N + α - Fe로, 550℃에서는 r' - Fe₄N - ε -Fe₂₃N, 그리고 600℃ 이상에서는 r' - Fe₄N + α + Fe로 구성되어 있는 혼합상이었다. 550℃, NH₃1.65l/min., 80분간 질화처리 하였을 때 생성된 질화층의 최대표면경도는 Hv 1100이었다.

The plasma nitriding of SKD 11 tool 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 mixtures of r'-Fe₄N and α- Fe phases, while the phases formed at 550℃ was r'-Fe₄N and ε-Fe₂₄N phases.

The thichness of compound layer formed at 550℃ with gas flow of NH₃2.1 l/min. for 110 minutes was 14㎛.

The thickness fo nitrided layer formed at 550℃ with gas flow rate of NH₃1.65 l/min. for 110 minutes was 220㎛.

The nitrided layer was composed of 10㎛ compound layer and 210㎛ diffusion layer.

The hardness of nitrided layer formed at 550℃ with gas flow rate of NH₃ 1.65 l/min. for 80minutes was Hv 1100.

The plasma nitriding of SKD 11 tool 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 mixtures of r'-Fe₄N and α- Fe phases, while the phases formed at 550℃ was r'-Fe₄N and ε-Fe₂₄N phases.

The thichness of compound layer formed at 550℃ with gas flow of NH₃2.1 l/min. for 110 minutes was 14㎛.

The thickness fo nitrided layer formed at 550℃ with gas flow rate of NH₃1.65 l/min. for 110 minutes was 220㎛.

The nitrided layer was composed of 10㎛ compound layer and 210㎛ diffusion layer.

The hardness of nitrided layer formed at 550℃ with gas flow rate of NH₃ 1.65 l/min. for 80minutes was Hv 1100.