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반응석출법에 의해 피복된 TiC의 경화거동에 관한 연구
남기석,변응선,이구현,김도훈( K . S . Nam,E . S . Byon,G . H . Lee,D . H . Kim ) 한국열처리공학회 1994 熱處理工學會誌 Vol.7 No.4
In this study, lattice parameter, binding energy and microstructures of TiC layer according to the addition of Fe, Cr were investigated in the reactive deposition coating. From the results, the lattice parameters of the TiC layers by using ferro-titanium as a precursor were 4.329∼4.339A but the lattice parameters of the TiC layers formed by ferro-titanium and ferro-chromium decreased to 4.316∼4.330Å. The hardness of the former`s was HV(100g) 3,000∼3,400㎏/㎜ and the hardness of the latter`s was HV(100g) 3,800∼3,900. But, regardless of Cr and Fe, the binding energy of TiC layers were 454.75 eV for Ti2p_(3/2) and were 281.85 eV for Cls. Meanwhile, the TiC layers were densified by addition of Fe, Cr and internal defects were reduced Therefore, it can be concluded that the remarkable hardness increment was obtained by the improvement of microstructures of TiC rather than the increase of bond strength or Peierls stress.
레이저 빔을 이용한 철계 급랭 응고 재료의 표면 합금화
남기석,이구현 ( K . S . Nam,K . H . Lee ) 한국열처리공학회 1996 熱處理工學會誌 Vol.9 No.4
This work has been carried out to reduce the softening of heat affected zone on laser surface alloying. Iron based rapid solidification material with Cr_(5-10), V_(1-3), Mo_(3-7), W_(2-5), B_(7-8), C_(2-3), Si_(0.5-1)at% was alloyed on the surface of SM45C steel. The excellent softening resistance in alloyed and heat affected zone showed, which could be attributed to the formation of stable high temperature precipitates.
남기석,이구현 ( K . S . Nam,K . H . Lee ) 한국열처리공학회 1997 熱處理工學會誌 Vol.10 No.1
This work was to investigate suitable tool steels for hardening using laser beam, and was studied on carbon tool steels and alloyed tool steels such as STC3 steel, STS3 steel, STD11 steel and SKH51 steel. The surface hardness of HV700-1000 and the hardening depth of 2-2.5㎜ were obtained on STC3 steel and STS3 steel, and HV800-1000 was obtained on SKH51 steel. but STDll steel was not enough. Except STD11 steel, all steels used in this study can be hardened by laser quenching or laser rapid melting.
SCM440(H) 및 SNCM439 강의 열처리 특성에 미치는 질량효과
남기석 ( K. S. Nam ),현양기 ( Y. K. Hyun ),조창용 ( C. Y. Jo ),조유종 ( Y. H. Cho ) 한국열처리공학회 2011 熱處理工學會誌 Vol.24 No.1
Recently, renewable energy sources such as wind turbine, solar cell are interested in preventing global warming which is caused by the consumption of fossil fuel. SCM440H and SNCM439 have been used in the major components of the wind turbine gear because of excellent mechanical properties. In the present study, the heat treated mechanical properties of SCM440H and SNCM439 with 150mm diameter were compared with those with 25 mm diameter which is generally accepted material for structural application. Heat treated SCM440H showed better mechanical properties such as tensile strength, hardness and impact absorbed energy compared with those in SNCM439. Hardenss value between as-quenched and as-quenched followed by tempering showed big difference in SNCM439, however the difference in SCM440H was relatively small. Heat treated mechanical properties of the alloys with 25mm diameter were more uniform value than those with 150mm diameter. (Received November 3, 2010; Accepted November 29, 2010)