低炭素 -W-Ni-Cr-Mo 合金鋼의 表面 硬化處理에 關한 硏究 = Studies on the Surface Hardening Treatment in the Low Carbon, W, Ni,Cr,Mo Alloy Steel

국문 초록 (Abstract)

國內古鐵市場에서 比較的 低價로 쉽게 구입할 수 있는 兵器材 古鐵을 表面硬化 조작을 통하여 SKD-11銅으로 代置하며 使用할 수 있는가 여부를 검토하였다. 炭素함유량이 낮은 관계로 表面層의 高硬度値를 얻기 어려웠다. 表面의 炭素集中增加方法으로 고체침탄 및 액체침탄 방법을 실시한 결과 고체침탄처리온도 925℃ 침탄시간 10Hr이 가장 적당하였으며 이때 Case depth는 2.5mm이었고, 경도치는 HRc-64를 얻었다. 액체침탄처리로서는 Case depth가 0.5mm 이내이므로 工具銅으로 使用하는데 硏磨上의 문제점이 있다. 그러므로 0.12％ C, W, Ni, Cr, Mo 강은 고체침탄 및 담금질 처리하므로서 SKS, SKD와 같은 合金工具銅으로 代用하여 使用할 수 있다.

다국어 초록 (Multilingual Abstract)

Ordnance scrap materials such as tank body parts consisting of low carbon alloy steel(0.21%C, 0.8%W, 0.5%Cr, 1.3%Ni, 0.3%Mo) have great toughness and low hardness.
The maximum attainable hardness of any steel depends on carbon content.
Therefore the experiment has been carried out to study a hardening process of this alloy in application for manufacturing the high speed rotary shearing tool or similar tools.
The important results obtained from the study are summerized as follows.
1. Under the pack carburizing process at 925℃ for 10hrs. We could take the case depth 2.5mm. By the guenching process the hardness of this alloy steel has increased up to H?C 64.
2. The case depth and carbon content could be increased by the carburizing time. When the process time took over 10 hrs, the carbon content of the surface reached to that of the hypereutectoid steel(0.9%c).
In this case, the structure of case structure of case surface became a rough net work of brittle cementite.
3. The quenching process must be done by the two step quenching to control the rough austenite structure.
The optimum quenching condition was obtained with the first quenching temperature at 900℃ and the second quenching temperature at 770℃.

목차 (Table of Contents)

• Ⅰ. 序 論
• Ⅱ. 實驗方法
• Ⅲ. 實驗結果
• Ⅳ. 考 察
• Ⅴ. 結 論