강의 Martensite 중의 잔류 Austenite 에 관한 X-선적 연구 = A Study on Retained Austenite in Martensitic Steel using X-ray Diffraction

국문 초록 (Abstract)

두 種類의 martensite合金, 즉 Fe-C基 martensite鋼(Fe-1.7%C)과 Fe-Ni基 martensite合金(Fe-27% Ni-0.14%C)을 마련해서, 이 두 martensite 조직 중에 含有된 잔류 austenite의 tempering 擧動을 X-線的으로 調査하여 다음과 같은 結論을 얻었다.
1. Fe-1.7%C martensite 鋼의 잔류 austenite는 約 150℃×1hr tempering에서 分解하기 시작하였으며 280℃×1hr tempering에서는 거의 大部分 分解하였다.
2. Fe-1.7%C martensite 鋼中의 殘留 austenite의 (111)γ 回折線의 積分幅은 tempering 溫度와 더불어 增加하였다.
3. Fe-27% Ni-0.14%C martensite 鋼은 430℃까지 tempering하여도 殘留 austenite가 分解하지 않았다.
4. Fe-27% Ni-0.14%C martensite 鋼에 있어서 austenite의 積分幅은 360℃ tempering 까지는 거의 一定한 값을 나타내다가 그 以上 溫度가 增加함에 따라 減少하였다.

다국어 초록 (Multilingual Abstract)

Two types of martensitic alloy, Fe-C based martensitic steel (Fe-1.7%C) and Fe-Ni based martensitic alloy (Fe-27% Ni-0.14%C), were prepared and then the retained austenite decomposition behaviors of these alloys were investigated during tempering.
The results obtained in this study are as follows.
(1) The retained austenite of Fe-1.7%C martensitic alloy begins to decompose into bainite when tempered at 150℃ for one hour. On tempering at 280℃ for one hour, most amount of retained austenite contained in the alloy is transformed to bainite.
(2) The integral breadth of retained austenite diffraction line increases as tempering temperature is increased up to about 280℃. This is because volume expansion occurs when the retained austenite is transformed to bainite.
(3) In the case of Fe-27% Ni-0.14%C martensitic alloy, the retained austenite does not decompose although tempering is done up to higher temperature such as 430℃.
(4) The line broading of retained austenite in the Fe-27% Ni-0.14%C martensitic alloy maintains a nearly constant value during tempering up to about 360℃, and then shows a decreasing value on further tempering at higher temperature than the point.