주철에 있어서 구상화원소가 흑연화현상에 미치는 영향

홍종미 대한금속재료학회(대한금속학회) 1971 대한금속·재료학회지 Vol.8 No.4

可鍛鑄鐵의 機械的性質 改量 및 燒鈍時間의 短縮에 關해서는 많은 硏究가 되어 있으나 球狀化元素添加한 球狀黑鉛 可鍛鑄鐵의 黑鉛化現象 및 그 機構에 對해서는 그다지 發表된 바 없다. 따라서 本硏究에서는 球狀化元素로서 Mg, Ca, Ce, Zr, Bi를 添加한 白銑을 燒鈍하였을 적에 黑鉛化速度와 黑鉛核生成率 및 黑鉛核成長速度를 示差熱膨脹計와 金屬顯微鏡으로서 測定하고 球狀化元素에 따라서 核生成과 擴散 어느 쪽에 依해 더욱 支配的인가를 調査檢討하였다.

비철금속재료의 진보

홍종미 대한금속재료학회(대한금속학회) 1977 대한금속·재료학회지 Vol.15 No.1

고탄소강의 경화능에 미치는 Cr 의 영향에 관하여

홍종미,김완철 대한금속재료학회(대한금속학회) 1972 대한금속·재료학회지 Vol.10 No.4

高炭素低크롬鋼의 硬化能에 미치는 크롬의 影響과 燒入時 發生하는 變形 및 cracking에 미치는 Ms點과 硬化能間의 關係를 考察하였다. 크롬添加時의 Austenite 結晶粒子成長에 要하는 活性化에너지는 다음과 같다. Q_c=23,000 ㎈/㏖ Q_(0.3Cr)=32,000 ㎈/㏖ Q_(0.5Cr)=36,800 ㎈/㏖ 硬化能은 熱處理條件이 同一할적에는 燒入前의 Austenite 粒度보다는 Austenite에 溶解된 炭化物의 量과 Austenite로부터의 炭化物析出速度에 依해서 支配된다. 또 燒入할때 나타나는 變形 및 cracking은 硬化能이 一定할 때는 直徑減少와 Cr量減少로서 防止될수 있으며 硬化能이 작을수록 直徑減少에 對한 Cr減量率은 커야 cracking이 防止된다. The effect of chromium on hardenability in high carbon steel was studied by U-curve method at quenching temperature of 800℃. The relation among the cracking induced by quenching, Ms temperature and hardenability was also studied. The activation energies for growth of austenite grain were as follows. Q_c=23,000 ㎈/㏖ Q_(0.3Cr)=32,000 ㎈/㏖ Q_(0.5Cr)=36,800 ㎈/㏖ Hardenability was dominated under constant heat-treatment condition by amounts of dissolved carbide and the precipitating velocity of carbide from austenite rather than austenite grain size before quenching. At constant hardenability, the cracking induced by quenching was prevented by reducing diameter of specimen and chromium amount. As the hardenability was smaller, the chromium reduction rate for reducing diameter of specimen must be bigger to prevent cracking induced by quenching.

주철의 강도에 대한 소고

홍종미 대한금속재료학회(대한금속학회) 1974 대한금속·재료학회지 Vol.12 No.3

내식성청동 Valve 에 대한 소고

홍종미 대한금속재료학회(대한금속학회) 1974 대한금속·재료학회지 Vol.12 No.1

주철에 있어서 흑연화현상에 미치는 구상화원소의 영향

홍종미 대한금속재료학회(대한금속학회) 1971 대한금속·재료학회지 Vol.9 No.3

球狀黑鉛鑄鐵에 있어서 黑鉛化速度, 黑鉛核生成速度 및 黑鉛核成長速度에 미치는 지르코늄, 칼슘 및 세륨의 影響을 調査하였다. 黑鉛核生成 및 成長에 要하는 活性化에너지를 測定하고 相互關係를 檢討하였다. 球狀化元素에 따라서 黑鉛核生成에 要하는 浩性化에너지는 22,000∼35,000 ㎈/㏖이고, 黑鉛核成長에 要하는 活性化에너지는 25,000∼35,000 ㎈/㏖였다. 또 黑鉛化에 미치는 각원소의 影響은 다음과 같았다. (1) 지르코늄 處里한 鑄鐵의 黑鉛化는 黑鉛核生成과 成長이 同等하게 作用하여 促進된다. (2) 칼슘 處理한 鑄鐵의 黑鉛化는 黑鉛核生成보다 黑鉛核成長에 의해 促進된다. (3) 세륨 處理한 鑄鐵의 黑鉛化는 黑鉛核成長보다 黑鉛核生成에 의해 促進된다. The effects of Zr, Ca and Ce on the rate of first stage graphitization, nucleation and growth of graphite particles in nodular cast iron were studied. Activation energies of nucleation and growth were measured and their interrelation was discussed. The activation energies of nucleation and growth of graphite were ranged from 22,000 to 35,000 ㎈/㏖., from 25,000 to 35,000 ㎈/㏖, depending on the nodulizing elements, respectively. The effects on graphitization were as follows. ① The graphitization of Zr-treated cast iron was accelerated by both nucleation and growth of graphite. ② The graphitization of Ca-treated cast iron was accelerated by growth of graphite than nucleation of graphite. ③ The graphitization of Ce-treated cast iron was accelerated by nucleation of graphite than growth of graphite.

축수강에서의 기계적 성질에 미치는 탄화물의 거동에 관한 연구

홍종미,이룡호,허무영 대한금속재료학회(대한금속학회) 1979 대한금속·재료학회지 Vol.17 No.6

炭化物이 球狀化된 從來의 軸受鑛을 熱處理 한것과 球狀化 된것을 S-curve의 nose溫度에서 恒溫 變態시켜 微細한 層狀 pearlite 組織을 만든後 熱處理 한것을 機械的性質, 加工硬化 및 未溶解炭化物等에 미치는 影響을 檢討한 바 다음과 같았다. 1. 微細한 層狀 pearlite의 組織을 갖는 便이 從來의 球狀化된 것 보다 溶體化 速度가 增加함을 보여주었다. 2. 微細한 層狀 pearlite便이 從來의 球狀化된 것보다 溶體化後에 燒入하면 보다 微細하고 少量의 未溶解炭化物을 만들었다. 3. 微細한 層狀 pearlite組織을 갖는 것은 此後 溶體化 後에 높은 引張强度와 加工硬化率을 보여주었다. 4. 燒入後 深冷處理 한것 보다는 austenite가 少量殘留하는 便이 引張强度가 크다. In order to study the effect of carbide behavior on mechanical properties in bearing steel, the responses of two different microstructure to subsequent heat treatment were investigated. One microstructure was a fine lamellae pearlite prepared by the isothermal transformation at the nose temperature, and the other microstructure was that of a commercial bearing steel, ie, coarse spheroidized carbide dispersed in ferrite matrix. The results obtained in this experiment were summarized as follolws. 1. The fine lamellae pearlite structure showed faster carbide dissolving rate than the spheroidized carbide in the commercial steel. 2. The fine lamellae pearlite structure resulted in finer and smallor amount of undissolved carbide in the martensite matrix than the spheroidized carbide. 3. The fine lamellae pearlite structure showed higher flow stress and work hardening exponent after subsequent austenitizing for hardening. 4. The martensite with retained austenite showed higher tensile strength than the one without it because of better ductility.

Al-Bronze 에서 기계적 성질에 미치는 Ni 와 Fe 의 영향

조성석,홍종미 대한금속재료학회(대한금속학회) 1975 대한금속·재료학회지 Vol.13 No.4

Al을 8∼8.5%, Fe와 Ni를 各各 2∼6% 範圍內로 變化시킨 Al靑銅의 組織과 機械的 性質에 미치는 影響을 檢討한 結果는 다음과 같다. 1. 鑄放品의 機械的性質은 Fe/Ni 比가 增加할수록 向上된다. 2. 析出硬化에 要하는 活性化에너지는 Ni 및 Fe가 增加할수록 減少하며 Ni 添加때는 26,000∼35,000 ㎈/㏖의 範圍이고 Fe 添加때는 24,000∼28,000 ㎈/㏖이였다. 3. 溫度 873°K, 應力 2.3 ㎏/㎟의 creep條件下에서 creep速度는 Ni 增加와 더불어 增加하고 Fe 增加와 더불어 減少하였다. 이때의 範圍는 Ni 添加時가 1.0×10^(-4)∼1.20×10^(-4)/min이고 Fe 添加時는 0.33×10^(-4)∼0.73×10^(-4)/min이다. 따라서 熱間强度는 Fe에 의해서 增加되고 Ni에 의해서 減少된다. A study has been made of the structure and properties of complex aluminum bronzes containing 8-8.5% Al and 2-6% of Ni and Fe respectively. The relation among Fe/Ni ratio, and mechanical property has been also studied. The results were as follows. 1. Mechanical properties of castings was increased as Fe/Ni ratio increases. 2. Activation energy for precipitation hardening was decreased as Ni and Fe increases. It's range of specimen added Ni was from 26,000 to 35,000 ㎈/㏖, and by adding Fe from 24,000 to 28,000 ㎈/㏖. 3. The creep rate under the condition as T=873°K, σ=2.3 ㎏/㎟ was increased with the increasing Ni content and was decreased with the increasing Fe content. The creep rate by adding Ni was 1.0×10^(-4)∼1.20×10^(-4)/min, by adding Fe was 0.33×10^(-4)∼0.73×10^(-4)/min. Hot strength was increased by adding Fe and decreased by adding Ni

중탄소강의 경화능에 미치는 응력의 영향

조성석,홍종미,최재하 대한금속재료학회(대한금속학회) 1977 대한금속·재료학회지 Vol.16 No.2

중 탄소 강에서 경화능 및 입자성장에 미치는 static stress와 dynamic stress의 영향을 조사하였다. 탄소강 봉은 용질 원자의 편석 및 잔류 응력을 제거하기 위해 925℃에서 1hr. 소준되었다. 그 후 0∼3.3% 범위내로 pre-strain을 주었다. Jominy end-quenching test는 일정한 냉각속도에서 하였으며 경화능은 static stress가 증가함에 따라 증가되었다. 입자 성장지수, n이 static stress와 dynamic stress에서 서로 비교되었다. 거기서 n값은 dynamic stress에서가 static stress에서 보다 훨씬 더 컸다. The effects of static stress and dynamic stress on hardenabilty and grain growth in medium carbon steel were investigated. Carbon steel bars were normalized at 925℃-1hr in order to eliminate the segregation of solute atoms and to relieve the residual stress, and then pre-strained in the range of 0 to 3.3%. Jominy bars were prepared for ø l"×L4". In order to observe pre-structure before quenching, grain growth with time was investigated at 800℃, 850℃, 900℃. Jominy end-quenching test was undertaken at constant cooling velocity. Hardenability was enhanced with increasing static stress. Activation energy for grain growth with static stress and dynamic stress was investigated. Austenite grain growth was much more accelerated with increasing static stress and dynamic stress. Grain growth exponent, n was compared with static stress and dynamic stress. That value under dynamic stress was much more bigger than that under static stress.

Al-Zn 공정합금의 일방향성응고에 의한 Cellular Structure

신명철,맹선재,홍종미 대한금속재료학회(대한금속학회) 1973 대한금속·재료학회지 Vol.11 No.4

이 硏究에서는 一方向으로 凝固시킨 Al-Zn 共晶合金의 cell 形成過程과 cell morphology를 調査하였다. Cell은 grain boundary와 growth induced boundary 및 fault line 等에서 부터 優先的으로 形成되기 시작했다. Cell의 模樣은 固溶體合金에서처럼 規則的인 形은 아니었으나 代表的인 形으로 마름모形이 나타났고 菊花狀形 및 hexagonal cell이 不規則하게 變形된 것 같은 形態도 나타났다. 不純物로서 Cd의 濃度를 0.52%로 增加했을때는 cellular dendrite 가 形成되었다. In this work the stage of cell development and the cell morphology in the Al-Zn eutectic have been studied by solidifying the alloy unidirectionally. Cells are shown to develop preferertially from grain boundaries, growth induced boundaries and fault lines. In the Al-Zn eutectic alloy, well developed regular cell shape as in solid solution has not been found, but its typical sharp is rhombic. Besides, chrysanthemum-like shape and some other shape, which seems likely deformed from any hexagonal form irregulary, has been found. At high impurity concentration. 0.52% of Cd, cellular dendrite has been produced.