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420J1 마르텐사이트계 스네인리스강의 오스테나이트화 조곤이 기계적 성질에 미치는 영향
김영주,주동원,박성훈,김기돈,성장현 ( Y . J . Kim,D . W . Joo,S . H . Park,G . D . Kim,J . H . Sung ) 한국열처리공학회 1994 熱處理工學會誌 Vol.7 No.1
To investigate the effect of austenitizing tempratures on the mechanical properties and corrosion resistance of 0.19%C-13.6%Cr martensitic stainless steel, the changes in martensitic trasformation temperatures, mechanical properties and anodic polarization curve were examined after changing the sustenitizing temperatures and tempering temperatures. On increasing heating rate at the same austenitizing temperatures, A_s, A_r and M_s increased. And the M_s temperature showed to be decreased with increasing austenitizing temperature. With increasing tempering temperature up to 500℃, strength, hardness and impact value were not changed remarkably, on the other hand the tensile strength and hardness decreased and impact value increased after tempering above 550℃ owing to the M_(23)C_6 carbide precipitation. The abrupt decrease in elongation at the tempering temperture of 500℃ proved to the precipitation of M_7C₃carbide. The effect of austenitizing temperature on the mechanical properties of the tempered specimen showed to be decreased in impact value and elongation at the austenitizing temperature of 1150℃. At low tempering temperatures the corrosion resistance of the tempered specimen was not changed obviously with increasing tempering temperature. On the other hand, the resistance decreased above the tempering temperature of 600℃ due to the precipitation of M_(23)C_6 carbides. The corrosion resistance showed to be improved with increasing the austenitizing temperature owing to the dissolution of carbides.
25Cr - 7Ni - 3Mo 2 상 스테인리스강의 미세조직과 기계적성질
강창룡,김효정,김창규,김익수,주동원,성장현 ( C . Y . Kang,H . J . Kim,C . G . Kim,I . S . Kim,D . W . Joo,J . H . Seong ) 한국열처리공학회 1998 熱處理工學會誌 Vol.11 No.3
N/A This study was carried out to investigate the influence of variations in the temperature and time of isothermal heat treatment, applied stresses and prestrain on the isothermal transformation behavior of γ and σ phases and mechanical properties of 25Cr-7Ni-3Mo duplex stainless steel. The precipitation of γ and σ phases through isothermal heat treatment showed the type curves with a certain incubation period, the curve migrated to in a short period of time and the amount of precipitation increased with decreasing isothermal heat treatment temperature. Under the state of isothermal transformation, the precipitation of γ and σ phases was stimulated by applied stress, with increasing applied stress, the curves migrated to in a short period of time and also observed that the application of stress has a greater influence on the amount of σ precipitation than that of γ precipitation. The precipitation of γ and σ phases was stimulated by cold and warm rolling before isothermal heat treatment and precipitation of γ and σ phases has a greater influence on the warm rolling than cold rolling. The tensile strength and hardness increased with increasing cold and warm rooling reduction ratio.
Al 함유 13%Cr 스테인리스강의 표면 질소침투 열처리에 미치는 첨가원소 탄소의 영향 : 13%Cr 스테인리스강의 고질소 표면침투 열처리
성장현,주동원,김기돈,유대경,박진욱 한국열처리공학회 2000 熱處理工學會誌 Vol.13 No.3
This study aims to investigate the effect of carbon content on the surface nitrogen permeation of 13%Cr-1.8%Al alloyed stainless steels. The surface nitrogen permeation was performed at 1050℃-1200℃ in the 1㎏/㎠ nitrogen gas atmosphere. The nitrogen permeated surface layer of the specimen containing 0.03%C consists of AlN, martensite and retained austenite phases, while the surface layer of the specimen containing 0.14%C appears the AlFe₃C_x phase including former three phases. The specimen containing 0.14%C shows lower total case depth than that containing 0.03%C at the nitrogen permeation temperatures of 1050℃ and 1100℃, while the total case depth of the specimen containing 0.14%C is remarkably increased at the temperature of 1150℃ and 1200℃ due to the increase in the retained austenite content. Martensitic phase, AlN and AlFe₃C_x precipitate of the nitrogen permeated surface layer cause to increase the surface hardness of 550∼600Hv.
5083 Al 합금 용접재의 조직 및 저온 인장성질에 미치는 시효처리의 영향
성장현,이해우,주동원,이준희,이태청 한국열처리공학회 2000 熱處理工學會誌 Vol.13 No.1
The microstructural characteristics and low temperature tensile properties between 25℃ and -196℃ for as-welded and age hardened specimen by using Al 5083-H321 for base metal, 5083-5356 and 5083-4043 weldments have been investigated. The hardness of 5083-5356 weldment decreases with aging treatment, whereas the weld region of 5083-4043 weldment shows remarkable increase in hardness after aging due to the precipitation of fine Si particle at the grain boundaries and interiors. Low temperature tensile properties of 5083 Al base metal, 5083-5356 and 5083-4043 weldments appear to be the increment of tensile strengths and elongations at the room temperature and -196℃, while the decrement of tensile properties around -50℃ is shown. Through the observation of fine serration to fracture in the stress-strain curve and tensile fractography, the increment of localized deformation leading to promote the neck initiation and the increment of the dimple size cause to decrease in tensile strengths and elongations around -50℃. For the tensile specimen of the 5083 base metal, 5083-5356 and 5083-4043 weldments, the reason to increase in elongation after solution and aging treatment is the diminishment of fine pit, the resolution of Mg into the matrix and the spheridization of the eutectic Si.
사출성형한 AISI T15 계 고속도공구강분말의 소결조건 변화가 탄소함량 및 소결밀도에 미치는 영향
김순호,성장현,정은,양형도,주동원 대한금속재료학회(대한금속학회) 1995 대한금속·재료학회지 Vol.33 No.12
For the purpose of investigating the applicalibity of AISI TI5 grade high speed steel for metal injection molding. The mixed elemental and prealloyed powders were sintered in a vacuum and N₂-20%H₂ atmosphere. The debinding rates of the prealloyed and the mixed elementa powder were 92.5% and 105.3%, respectively. It is considered that the fine pores existed on the surface of the prealloyed powder caused the binder to remain in the powder by a capillary action during the debinding process. The carbon contents of the prealloyed and mixed powder were 2.01wt.% and 1.79Wt.%, respectively, after debinding. When sintered at an optimum temperature in a vacuum, the rate of carbon loss after the sintering for the prealloyed and mixed elemental powder showed a little difference of 19.5% and 17.9%, respectively. When sintered in N₂-20%H₂ atmosphere the carbon loss for the mixed elemental powder was found too high, over 86%, to effectively control the carbon content. The maximum sintered densities after the vacuum sintering were above 97% for both mixed and prealloyed powder whereas the sintered densities of the mixed and prealloyed powder after N₂-20%H₂ sintering were 94% and 77.1%, respectively. Therefore it was difficult to apply the prealloyed powder into the metal injection molding process in the atmosphere of N₂-20%H₂gas.