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구양모,이성학,Golkovskii, M,서동우,정병일 대한금속재료학회(대한금속학회) 1995 대한금속·재료학회지 Vol.33 No.8
The present study is concerned with microstructural analyses of the surface layer of a high speed steel (HSS) roll modified by irradiation of accelerated electron beam. HSS roll specimens were irradiated using an electron accelerator, and the microstructures of the irradiated surface layers were examined. Upon irradiation, the irradiated surface layer was melted because of the large heat input, resulting in microstructural change from coarse cell structure of primary carbides to a mixture of fine carbide cell and retained austenite. This microstructural modification might improve fracture or fatigue properties of the irradiated surface layer, although its hardness was decreased and quench cracks were found occasionally in the heat affected region. In order to solve the problems for applying the accelerated electron beam technique to HSS rolls, appropriate processing methods such as pre-or post-irradiation were suggested.
1.0- 2.5MeV 전자가속기를 이용한 대기 중에서 전자빔에 의한 탄소강의 표면경화
박성민,장창환,구랑모,Golkovskii, M,Korchagin, A,Kuksanov, P 대한금속재료학회(대한금속학회) 1993 대한금속·재료학회지 Vol.31 No.7
Surface hardening of carbon steel by electron beam in the atmosphere was carried out using an 1.0∼2.5MeV electron accelerator. The electron beam energy used was 1.4MeV, and the power density of the beam was about 10⁴kW/㎠. The sample piece was rotated and translated during irradiation, so that the point of irridation on the steel surface changed continuously. When the electron beam impinged on the surface, the irradiated area melted very quickly and cooled rapidly owing to the large heat sink provided by the bulk of the steel material. The cooling rate was so fast that the melted area was mostly transformed into martensite phase(or a bainite phase in a limited part) during the self-cooling. The surface hardness of the carbon steel changed from approximately 250Hv to 700Hv, on the Vickers scale. The maximum hardened depth was l.6mm. The melting and cooling times were so fast that oxidation of the steel surface was almost negligible, even though the sample was always in the atmosphere. This method can be applied to heat treatment of steel surfaces for many industrial purposes, owing to its high treatment rate and simplicity.