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플라즈마질화처리에 의한 SM강의 미세조직 특성에 관한 연구
김무길(M. K. Kim),정병호(B. H. Jung),성해웅(H. W. Sung) 한국동력기계공학회 2005 한국동력기계공학회 학술대회 논문집 Vol.- No.-
Microstructural study of commercial medium/high carbon steels nitrided by plasma has been carried out, using Optical Microscope, Scanning Electron Microscope(SEM), Electron Probe Micro Analyzer(EPMA), Transmission Electron Microscope(TEM) and X-ray Diffraction (XRD). In the case of plasma nitriding, the mixed phases consisting of γ'-Fe₄N and ε-Fe₂.₃N were mainly observed in the nitrided layers near surface. But, the α"-Fe₁?N₂ phase was not observed. In the compound layer, high concentration of nitrogen was homogeneously distributed towards the parent steels. according to result that examine about nitrided layers near surface of samples, N, Fe and C ingredient using EPMA, could know that nitrogen is thickened from part that compound layer of near surface is formed, and area of compound layers showed that each ingredient composition is almost constant. In XRD observation, γ'-Fe₄N formed mainly in case that carbon content is less comparatively with SM20C. In TEM observation, γ'-Fe₄N were mainly observed in the nitrided layers especially in SM20C and SM40C. Also, the nitrided layers had submicron scale grains in all the samples investigated.
吳伊植,金武吉 釜山工業大學校 1980 論文集 Vol.21 No.-
鍛造硬化시킨 Cr-Mo강을 深冷處理하므로서 深冷處理하지 않은 것보다 여러 성질들이 向上되었다. 그 結果를 要約하면 다음과 같다. (1) 殘留 austenite를 martensite로 變態시켜 硬度를 增加시키고, 최대균열깊이를 減少시키 므로서 耐龜裂性이 向上된다. (2) 殘留 austenited量이 減少하여 同一한 硬度에서 殘留應力이 減少하여 硬化層이 增加한 다. As forging hardened Cr-Mo steel make Sub-Zero treatment, improved its properties than non Sub-Zero treatment. From above experiment, the following results were drawn. 1) As retained austenite transfered martensite, abtained to effect increase of hardness, decrease of depth in maximum cracks and improvement of crack-proof properties. 2) As retained austenite quantities decreased, retained stress decreased and hardened layer increased, at same hardness.
0.32%C-Ni-Cr-Mo鋼의 熱處理에 따른 强度와 延性變化에 關한 硏究
金雨烈,金武吉 釜山工業大學校 1980 論文集 Vol.21 No.-
The results to be investigated on strength and ductility in mixed structures (Martensite+Bainite) in 0.32% C-Ni-Cr-Mo steel are as follows; 1) The increase of volume fraction of upper bainit decreasese ductility and strength 2) Volume fraction of about 50% showed the positive deviation from mixture rule.
열처리 방법에 따른 2相 혼합조직강의 Martensite 분포형태와 경도에 관한 연구
김우열,김무길,김영환 釜山工業大學校 1985 論文集 Vol.27 No.-
The relationship between Martensitic morphology and hardness was examined under optical microscope with the process of heat treatment The results gained at the different methods were as follow: 1) DPⅠ and DPⅡ showed network structure and isolated island structurer in low volume fraction of the second phase, is martensite, respectively, but in high volume fraction its phenomenon was disappeared 2) DPⅡ showed fine grained structure and the hardness of this process was higher than that of DPⅢ, but lower than that of DPⅠ 3) In low volume fraction of the second phase, the hardness was increased by the formation of martensite-martensite interface in DPⅠ process than that of other processes.
플라즈마질화 및 침질탄화처리한 탄소강의 경도와 내마모특성
정병호,이재식,김무길,박화순,이병찬,신성하 한국열처리공학회 1999 熱處理工學會誌 Vol.12 No.2
Commercial carbon steels containing 0.2∼0.55wt.%C were plasma-nitrided or plasma nitrocarburized at 550℃ for 21.6Ks using H₂-N₂or H₂-N₂-CO mixed gas respectively. The characteristics of hardening and wear-resistance of each treatment were studied and compared. And also microstructure of nitrided layer and nitrides formed in compound layer near surface were studied. All plasma-nitrided steels investigated showed remarkable increase of surface hardness with the increase of carbon content. But nitrocarburized steels resulted in higher surface-hardness than plasma-nitrided steels, which means that nitrocarburized has higher surface-hardening effect. Plasma-nitrided steels showed hardness increase in through-thickness direction near surface. And also nitrocarburized steels showed similar hardness distribution in through-thickness direction to that of plasma-nitrided steel. However, nitrocarburized steels had higher cross-sectional maximum-hardness than plasma-nitrided steels as much as 100Hv. Wear test showed that the amount of specific wear was reduced by both plasma-nitriding and nitrocarburized, showing that the amount of specific wear was not related to the hardness. But non-treated specimen showed that the amount of specific wear was related to the hardness.