열처리 기술의 현황과 전망

김한군(Han Goon Kim) 대한금속학회 1999 大韓金屬學會會報 Vol.12 No.6

Fe-Si-Mn-P강판의 초기조직변화가 잔류오스테나이트 형성 및 인장성질에 미치는 영향

문원진,강창용,김한군,김기돈,성장현 ( Won Jin Moon,Chang Yong Kang,Han Goon Kim,Ki Don Kim,Jang Hyun Sung ) 한국열처리공학회 1997 熱處理工學會誌 Vol.10 No.1

This study has been conducted to investigate the effects of initial structure on the microstructure and tensile properties of high strength trip steel sheet. The initial structure before austempering remarkably influenced the second phase. The specimen with normalized initial structure showed mainly bainitic ferrite and retained austenite, while the as rolled specimen and spherodized specimen showed martensite plus retained austenite and martensite plus bainitic ferrite with small retained austenite, respectively. Two type of retained austenite, film type and granual type were observed in all specimens. The as rolled specimen appeared the highest contents of retained austenite owing to the compressive stress by cold rolling. The contents of retained austenite increased with increasing intercritical annealing temperature and austempering time. Tensile strength showed the highest in the as rolled specimen, while the highest elongation were obtained in the normalized specimen. The maximum T.S.×El. Value showed in normalized initial structure and increased with increasing intercritical annealing and austempering time. The highest Value of T.S.×El. obtained at austempering temperature of 400℃ and retained austenite of 12%.

고강도 이온질화 기어의 개발

김영훈,선철곤,김한군 ( Young Hoon Kim,Cheol-Gon Sun,Han Goon Kim ) 한국열처리공학회 1994 熱處理工學會誌 Vol.7 No.3

The heat treatment charaterristic of SCM 440 and B 16 steels has been investigated in various condition(A, B and C) to the effect of heat treatment on mechanical properties, and the following results were obtained 1. We are obtained a good nitriding characteristic in bainitic structure than other heat treatment cycle in our experiment 2. Fatigue characteristic has shown in order of B>C>A condition as heat treatment cycle 3. The effective hardening depth and fatigue characteristic has been excellented in B 16 than SCM 440 after the nitriding and Q. T for B and C condition 4. Nitriding depth has been increased in addition of Cr, V and the nitriding efficiency is increased as easiness of banite formation to wide range of cooling rate by addition of Mo 5. The depth of compound layer in parallel surface, notched slop plane and notched bottom has been varied to the nitriding depth of 5, 4 and 3μ in relatively uniform pattern after 10h nitriding treatment for SCM 440 into A condition

스테인리스강의 기계적 성질에 미치는 저온 플라즈마 질화처리조건의 영향

빈정욱 ( Jeong Uk Bin ),김한군 ( Han Goon Kim ) 한국열처리공학회 2010 熱處理工學會誌 Vol.23 No.5

This study has been carried out to the low temperature plasma nitriding treatment on the mechanical properties of stainless steel at temperature range between 400˚C and 500°C. It was found that there was precipitated to free CrN matrix below 400˚C and there was precipitated S-phase of STS 316L, ε-phase of STS 409L and αN-phase of STS 420J2. STS 316L has formed relatively abundant CrN phase and γ`-Fe4N phase at 500˚C, alternatively STS 409L and STS 420J2 were more deeply nitrided than STS 316L at 500˚C.

진공침탄 열처리 기술개발에 관한 연구

이상길,강순배,정병호,김한군 ( Sang Gil Lee,Sun Bae Kang,Byong Ho Jung,Han Goon Kim ) 한국열처리공학회 1990 熱處理工學會誌 Vol.3 No.3

SCM 21 and D.P steel were carburized in vacuum using prophane at a temperature ranging from 1228k to 1308k under a gas pressure ranging from 21.3kpa to 61.8kpa, and the following results were obrained. 1) D.P. steel has considerable efficiency in depressing the grain growth during the high temperature carburizing and it has fine structure even at 1268k for 14.4ks when carburizied. Therefore this steel is expected to be suitable for vacuum carburizing at a high temperature. 2) Case depth was increased as the carburizing temperature increases and it was 3.2㎜ at max, temperature of 1308k, for max, time of 14.4ks and under max, pressure of 61.8kpa. Thus vacuum-carburizing was considered effective for the materials which need case depth, which is necessary for machine structure use. 3) The rate of case depth of SCM 21 was faster than D.P. steel under same carburizing conditions and the increasing rate of the case depth was constant. 4) Case depth was increased as the gas pressure becomes high under same carburizing temperature. 5) Case carbon concentration, C_s, of SCM 21 obeys to a formula, C_s=kt^½+C_0 Where k is 2.15×10^(-2)(wt%.S^(-1/2)) and this value is a little bit lower than that of SNCM 815.

진공침탄을 위한 처리조건 설정에 관한 연구

이상길,강순배,정병호,김한군 ( Sung Gill Lee,Sun Bae Kang,Byong Ho Jung,Han Goon Kim ) 한국열처리공학회 1992 熱處理工學會誌 Vol.5 No.4

SCM 415 has been vacuum carburized in the carburizing pressure of 60-65kpa and the carburizing temperature of 1233k and 1273k after varied to 0-20 in the ratio of N₂/C₃H_8 and then diffusion treated for various times at 1123k. The results obtained from the experiment are as follows. 1. With increasing from 0 to 20 in ratio of N₂/C₃H_8 the sooting formation of surface after carburizing considerably decreased. 2. The hardness control and surface carbon content of carburizing surface has been modified by the addition of nitrogen to the propan. 3. The appoximate value of k is indirectry calculated at 1123k which results are obtained to 0.58×10^(-2)(wt.%.s^(-1/2)). 4. A great deal of propan by addition of nitrogen gas in carburizing gas was possible to saving without considerable change in case hardening depth. 5. The effective carburizing depth range is obtained to 0.8-1.1㎜ by diffusion temperature of 1123k after carburization at 1273k-3.6ks, and the surface hardness is increased as the increasing of T_D/T_C in our experimental condition, and the maximum hardness as reachin distance from surface is decreased.

複合炭化物의 Growth Kinetics 및 强度에 관한 硏究

金漢軍 釜山工業大學校 1983 論文集 Vol.24 No.2

The growth kinetics and yield strength characteristics of complex carbides precipitated in Cr steels spheroidized after standardizing initial particle distributions were investigated by using various quantitative metallographic techniques. Most of the grain boundaries of ferrite matrix areoutlined by a string of complex carbide particles which are determined to be (Fe, Cr)₃C. The average values of activation energy have shown that the coarsening of complex carbide precipitates involves the coupled chromium-iron-carbon diffusion. The number of second phase particles pinning ferrite grain boundaries increases with increasing the chromium content, which results in a more decreasing growth rate of ferrite grains. During spheroidization hardness changes with the Hall-Patch type relation Hv=??. Yield strength is affected by parameters concerning both precipitate particles and ferrite grain boundaries and varies with the following Hall-Petch type equation ??.

0.45% 炭素鋼에서 析出된 시멘타이트 粒子의 Growth Kinetics에 관한 硏究

李相允,金漢軍,金榮熙 동아대학교 공과대학 부설 한국자원개발연구소 1984 硏究報告 Vol.8 No.2

This study has been carried out to invastigate into the Ostwald Ripering behavior of cementite particles precipitated in 0.45% carbon steel during spheroidizing treatment at a temperature range of from 650℃ to 710℃ after standarding the initial particle size distribution. The results obtained from the experiment are as follows. 1) Average particle size measurements have shown that the slopes of three straight lines obtained from the relation between the log of average particle radius and the log of spheroidizing time for three different temperatures 650℃, 680℃, and 710℃ approaches a value of 1/3 and that the growth of cementite particles occurs by diffusion controlling mechanism. 2) It has been found from the measurements of average radius and the number of particles per unit area that the average value of activation energy is obtained to be 47.1 ㎉/mole, which shows that coarsening of cementite particles is governed by the interdiffusion mechanism of iron and carbon atoms. 3) Cementite particle size distribution curves experimentally measured appears to approach the steady state distribution curve obtained for diffusion controlling mechanism and not to reach it within a spheroidizing time of 640 hours. The shapes of experimentally determined curves are rather broadened compared to that of steady state distribution curve.

강재의 조직과 파괴인성의 관계

김헌주,김한군 한국열처리공학회 2000 熱處理工學會誌 Vol.13 No.4

메조스코픽 구조를 가지는 급냉응고 Al-Nd-(Cu,Ag)합금의 기계적 성질

김영환,김한군,고근우 한국열처리공학회 1999 熱處理工學會誌 Vol.12 No.4

In rapidly solidified Al_(92-x)Nd_8(Cu,Ag)x (0≤X≤10at%) alloys, amorphous single phases were obtained in the ranges of Oat%≤X≤4at% for Al-Nd-Cu system and Oat%≤X≤6at% for Al-Nd-Ag system, respectively. Mesoscopic structures consisted of amorphous and crystalline phases were formed above solute ranges. It was founded that the mesoscopic structures were also formed near 1st exothermic peak on DSC curve by aging in amorphous single phase alloys. For example, amorphous Al_(92-x)Nd_8(Cu,Ag)x (X=2.4at%) alloys containing nanoscale Al particles and compounds, i.e., mesoscopic structure, exhibited higher tensile fracture strength(σ_f) than those of amorphous single phase alloys with the same composition. The σ_f showed a maximum value in the V_f ranges of 10∼15%. The reason is presumed that the nanoscale precipitates which have higher mechanical strength compared with the amorphous phase with the same composition act as an effective resistance to shear deformation of the amorphous matrix.