http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
산소와 철이 CP-Ti 의 고온 변형 거동에 미치는 효과
박중근,이강인,오민석,정종평,한종현 대한금속재료학회(대한금속학회) 2001 대한금속·재료학회지 Vol.39 No.11
Effect of oxygen and iron on the high temperature deformation behaviors of CP-Ti was studied at temperatures from 750 ℃ to 950 ℃ using compression test at various strain rates from 0.001s^(-1) to 10s^(-1). High temperature deformation efficiencies and flow instability conditions were, in particular, evaluated from their high temperature flow curves. The work hardening rates were always higher in the grade 1 than in the grade 4 CP-Ti. This was mainly attributed to the difference in the range of α+β two-phase field arising from the different Fe content. The optimum working condition was estimated to be the strain rate of 10s^(-1) at 850℃ and to be the strain rate of 10s^(-1) at 900℃ for grade 1 and grade 4 CP-Ti, respectively. The dynamic recrystallization mechanism was believed to be mainly responsible for the high deformation efficiency for both grades. The increase of oxygen content shifted the condition for the high deformation efficiency toward a higher temperature or lower strain rate condition, in a good agreement with the theoretical expectation for the shift direction of the condition for dynamic recrystallization. At the intermediate strain rates and at about 900℃, power dissipation efficiencies were very low in both specimens. This was believed to be closely related to the occurrence of α→β transformation during deformation.
Spray Forming 법으로 제조된 고속도강의 탄화물 조직과 기계적 성질에 미치는 carbon 의 영향
박중근,안상호,이언식,정재영,김관호,오민석 대한금속재료학회(대한금속학회) 2001 대한금속·재료학회지 Vol.39 No.8
Effect of carbon on the carbide microstructure of spray-formed high speed steels, Fe-xC-4.3Cr-6.5Mo-5.5W-5V-8.5Co, was investigated by calculating the phase equilibria via Thermo-Calc program and by analyzing their carbide micronstructure via transmission electron microscopy in particular. The calculation showed that the volume fraction of fine secondary carbides increases with carbon concentration and that fine secondary MC carbides become more prominent over M_6C carbides at larger carbon concentration. The result further showed that the driving force for the secondary MC carbides is distinctively larger than that for the secondary M_6C carbides. These results were in good agreement with the microstructural analysis using particularly TEM showing that the fine secondary carbides are mostly the MC carbides and that their volume fraction increases with carbon concentration. Tempering treatment results in a large increase of the hardness and bend strength of these steels. This is primarily because of the precipitation of fine secondary MC carbides during tempering treatment. This tempering effect was more pronounced at larger carbon content because of the larger amount of precipitation of fine secondary MC carbides. The bend deflection in as-rolled condition decreased with increasing carbon content. This appeared to be closely related to the variation of the amount of coarse primary carbides with carbon content.
Ti 미량합금강의 오스테나이트 결정립 성장 거동에 미치는 카본 함량변화의 영향
박중근,박지용,허태형,조웅용 대한금속재료학회(대한금속학회) 1997 대한금속·재료학회지 Vol.35 No.12
The influence of carbon content on the austenite grain growth of Ti-microalloyed C-Mn steels during reheating to the austenite region has been studied using optical microscope and transmission electron microscope. The austenite grain coarsening temperature(GCT) particulary at the center of slab decreases as the carbon content increases from 0.09wt% to near peritectic composition(0.16wt.%). This is believed to arise from the effect of carbon content as the segregation behavior of the interdendritic region! The degree of segregation is distinctively small in low carbon steel because of two simultaneous effects, namely the faster diffusion rate and shorter diffusion length. This is because of dendrite formation mechanism differs depending on the carbon content. The austenite grain size during reheating is observed to be distinctively small in the case of low carbon steel. This is due to the fact that the upper temperature for the austenite single phase region is comparatively low in the case of low carbon steel.
박중근 대한전기학회 1985 전기의 세계 Vol.34 No.5
수직전계 계산방법의 정밀도 및 근사과도의 평가의 기준이 되며 전하중첩법의 전위 및 전계 소계수식에 형태가 남아있다. 또한 영상전하가 전하중첩 및 표면전하법 등에서 이용되고 있는 것이 특징이다.