12Cr - 2Mo 2상 혼합강의 (混合鋼) 임계영역 ( α+γ ) 에서의 가열유지시간이 고온강화에 미치는 영향

곽사호,김문일 대한금속재료학회 1986 대한금속재료학회 학술대회 개요집 Vol.1986 No.0

大形鑄鋼의 燒着과 그 對策 : Chromite Sand를 中心으로

郭士濩,姜朝遠 조선대학교 생산기술연구소 1980 生産技術硏究 Vol.1980 No.-

chromite砂中의 不純物이 燒着現象에 미치는 영향을 調査하고 그 發生機構와 對策을 究明하기 위해 不純物 含量이 각각 틀린 3種의 實驗用 core를 製作하여 鑄入함으로써 core에의 溶鋼 浸透狀況을 調査하였다. 또 Table 5에 있는 化學成分으로 試片을 만들어 1000℃∼1400℃ 溫度 범위에서 그의 熱間壓縮强度를 測定했다. 實驗結果를 要約하면 다음과 같다. (1) chromite sand에는 SiO₂, MgO and FeO 系와 SiO₂,MgO, Al_(2)O_(3) 系의 2種類의 不純物이 있었다. (2) chromite sand中의 不純物含量이 많으면 많을수록 浸透는 깊어지고 chromite sands의 燒結은 심해졌다. (3) chromite sand中에 不純物이 많으면 chromite sand의 耐燒着性이 감소하고 燒着現象의 發生이 容易하였다. (4) 1100℃∼1300℃에서 chromite sand의 燒結은 砂粒間物質 때문이 아니고 chromite 粒子들끼리의 直接結合에 의해 發生한 것이다. In order to clarify the mechanism of metal penetration and prevent the defect for heavy section steel castings, 3 kinds of cores with each different amount of impurities were prepared and investigated. And that in the range of 1000℃ to 1400℃ the hot compressive strength of specimen of the chemical component in Table5 was measured. The results obtained are summarized as follows: 1) Two kinds of impurities were contained in chromite sands; one was largely composed of SiO₂, MgO and FeO, and the other largely of SiO₂,MgO and Al_(2)O_(3). 2) The more the content of impurities of chromite sands was, the deeper and severer the metal penetration was. 3) In case much impurities are contained in chromite sands, the resistance of chromite sand mold to metal penetration was reduced and metal penetration was liable to occur. 4) Impurity grains over 1200℃ lowered the hot compressive strength of chromite sands. 5) The sintering of chromite sand mold in the range of 1100℃∼1300℃ occurs, not because of the substance among the sand grains, but because of the direct bonding of chromite grains.

크로마이트 砂中의 不純物과 燒着과의 關係에 對하여

郭士濩 조선대학교 생산기술연구소 1978 生産技術硏究 Vol.1978 No.-

大型鑄鋼用 Chromite 砂中의 不純物과 燒着現象과의 關係를 究明하기 위해 不純物 含量이 각각 틀린 3種의實驗用 Core를 製作하여 鑄入함으로써 Core에의 溶鋼浸透狀況을 調査하였다. 또 Table 5에 있는 化學成分으로 試片을 만들어 1000℃ ∼ 1400℃ 溫度범위에서 그의 熱間壓縮强度를 測定했다. Setting Sand mold等 有機粘結劑를 使用하는 鑄型의 경우에는 그 效果가 현저하다. 이와 같이 燒着(metal penetration)과 Chromite Sands의 Sintering사이에는 重要한 相關性이 있음이 認定되고 있다. 그러나 Chromite Sands도 SiO₂를 中心으로 하는 不純物 含量에 따라 Chromite Sands의 燒結特性이 좌우되고 나아가서는 耐燒着性도 영향을 받게 된다. 따라서 Pouring(鑄入) 試驗을 通해 Chromite Sands의 Penetration mechanism(燒着機構)을 糾明하고 또 Chromite Sands의 耐燒着生을 低下시키는 不純物 含量의 영향을 檢討해 보았다. In order to clarify the relationship between the impurities of chromite sands for heavy section steel c astings and metal penetration, 3 kinds of cores with different impurities contentwere prepared and metal penetration into them was investigated. And that in the range of 1000℃ to 1400 ℃ the hot compressive strength of specimen of the chemical components in Table 5 was measured. The results obtained are summarized as follows: 1. Two kinds of impurities were contained in chromite sands; One was largely composed of SiO₂, MgO and FeO, and the other largely composed of SiO₂, MgO and Al_(2)O_(3). 2. The more the content of the impurities of chromite sands was, the deeper and severer the metal penetration and sintering, of chromite sands were respectively. 3. In case much impurities are contained in chromite sands, the resistance of chromite sands mold to metal penetration was reduced and metal penetration was liable to occur. 4. Impurity grains over 1200℃ lowered the hot compressive strength of chromite sands. 5. The sintering of chromite sand mold in the range of 1100℃∼1300℃ occurs, not because of the substance among the sand grains, but because of the direct bonding of chromite grains.

中크롬과 高크롬 페라이트系 耐熱鋼의 機械的 性質

곽사호 조선대학교 동력자원연구소 1986 動力資源硏究所誌 Vol.8 No.2

This study aims to contribute to the inprovement of ex-reactor components for nuclear generation, such as steam generators, superheater, tubing materials, turbine blades, etc.. And in this paper the duplex structure and mechanical properties, especially tensile strength, creep-rupture strength, hardness in the weld HAZ, weld cracking characteristics, etc. of middle Cr and high Cr ferritic heat resisting steels were investigated. Creep-rupture test was carried out in the air by the lever type single specimen equipment. Specimens for metallographic examination were etched with Vilella's reagent. The results obtained are summarized as follows : 1. The duplex structures of middle chromium and high chromium ferritic heat resisting steels exhibit beneficial mechanical properties, weldability and creep-rupture strength. 2. 12Cr-2Mo-V duplex steels are so good in weldability, elongation, elevated temperature formability and creep-rupture strength that they are anticipated to be suitable for boiler tubes, superheater, reheater, FBR steam generator, etc. in a nuclear power plant. 3. 12Cr-2Mo steels show better weldability and creep-rupture strength than full-martensitic 12Cr-1Mo steels. But the former exhibits lower tensile strength than the latter. 4. 0.09C-7Cr-3Mo steel gives better mechanical properties than 0.06C-7Cr-3Mo steel except for weldability.

폐 강판으로부터 철분말 제조 기술에 관한 연구(I)

곽사호,강조원 조선대학교 생산기술연구소 1999 生産技術硏究 Vol.21 No.1

This paper aims to study on manufacturing of steel powder and iron powder through carburizing and decarburizing the waste beverage steel cans of as-collected without melting. Metallographic characteristics were investigated by OM, SEM, EDS, XRD and emission spectrometer. The results obtained are as follows: 1. 2-piece and 3-piece waste beverage steel cans are mainly made of 99.5wt%Fe and 0.3wt%Mn, and their cover and tap are composed of AI-4.3wt%Mg. 2. The paints and Al alloy cover and tap of the waste beverage steel cans could be separated and removed by holding at 630℃ for 30min. in the rotary heat furnace and retort. 3. The waste beverage steel cans could be carburized in the atmosphere of air plus propane gas by holding at 930℃ for 60min. and decarburized in that of H20 plus H2 by 700℃ x 1hr treatment. 4. The apparent density, flow rate, green density.,and rattler value examined of the decarburized powder are 3.42g/㎤, 28.3s/50g, 6.67g/㎤ and 0.621, respectively.

純Titanium과 Titanium 合金鑄物의 機械的 性質에 關한 考察

郭士濩 朝鮮大學校 1975 綜合論文集 Vol.1975 No.-

高珪素球狀黑鉛鑄鐵에 있어서의 珪素의 役割

郭士濩,白勝男,姜朝遠 조선대학교 생산기술연구소 1981 生産技術硏究 Vol.1981 No.-

本 硏究는 高珪素球狀黑鉛濤鐵의 규소 含量에 따른 여러 種類의 試片을 만들어 그들의 高溫耐酸化性,機械的 性質의 特性을 比較,硏究함으로써 high Si―D.C.I. (高규소球狀黑鉛濤鐵)에 있어서의 Si의 영향을 고찰하여 보다 우수한 耐熱材料를 개발하는데 기여함을 목적으로 한다. 耐酸化性試驗은 kanthal 電氣爐에서 600∼950℃ 범위로 100時間 加熱後 酸化生成物量을 測定하였다. 850℃以上에서는 Si량이 3.5% 될 때까지는 酸化生成物量은 급격히 低下하고, 3.5%Si 以上에서는 減小率이 작아진다. 또 Si량의 增加는 界面에 擴散되는 C량을 많게 해주고 脫炭을 促進시켜 高溫에서의 耐酸化性을 向上시켰다. 機械的性質 試驗은 27℃(常週)∼700℃에서 했다. 다만 충격시험은 0℃∼200℃사이에서 실시했다. 溫度가 높을수록 引張强度에 대한 Si含量效果는 적어지고, 500℃ 以上에서는 Si量의 增加에도 불구하고 强度改善의 效果가 없었다. The study aims to investigate the roles or influences of silicon content in high silicon ductile cast iron with a good heat resistance and develop a ductile cast iron with better heat resistance and strength for automotive parts and industrial machinary by comparing and studying the characteristics of high temperature anti-oxidation and mechanical Properties-tensile strength, hardness, elongation, and impact value-of various specimens each different in silicon content from 3%, to 5%. The results obtained in this study are summarized as follows: ① Increasing Si-content in ductile cast iron contributes to the improvement of anti-oxidation. That is why Fe_(2)SiO_(4) content increases in the oxide layer, and decarburization reaction is accelerated. ② Adding silicon increases tensile strength in a straight line with silicon content, but over 500℃ it is not effective in improving the strength. The higher the temp, the smaller the effect of silicon content on the tensile strength is.

Al-Zn-Mg-Cu合金의 析出强化

郭士濩,白勝男,姜朝遠 조선대학교 생산기술연구소 1986 生産技術硏究 Vol.8 No.2

This paper aims to investigate the strengthening behavior by the age precipitation of Al-Zn-Mg-Cu alloy. This could be achieved by the comparison and analysis of the strengthening behaviors of Al-Zn-Mg alloy, Al-Zn-Mg-Cu alloy and the alloy adding Cr and Mn to the latter alloy. The close measurements of hardness, strength, electric resistivity were carried out after ageing and thermomechanical treatment at 90℃, 120℃ and 150℃. The results obtained are summarized as follows. 1) The complex pre-precipitation zones of G. P. and G. P. B. increase the 0.2% proof stress much more compared with single pre-precipitation zone of G. P .. From this result, it is possible to deduce that complex zone makes a more effective contribution to strengthening than single zone. 2) The complex metastable phases of η´ and S´ increase the rate of strengthening of alloys more than the single η´ metastable phase does. Fromthis result, it is possible to deduce that the metas table phases of η´ and S´ have more effective strengthening than the metastable phase of η´. 3) The combined structure of the complex zones (G. P. + G. P. B.) and the complex intermediate phases (η´ + S´ ) makes a more effective contribution to strengthening than that of G. P. zones and η´. 4) The combined addition of Cr and Mn delays the formation rates of pre-precipitation zone and accelerates the rate of growth of metastable phase. 5) So it is resonable to find out that the hardness is decreased, but the strength is remarkably increased by the combined addition of Cr and Mn in AI-Zn-Mg-Cu alloy.

18% Ni Maraging鋼에 있어서 逆變態 Austenite의 再結晶擧動에 關한 硏究

郭士濩,白勝男,姜朝遠 朝鮮大學校 動力資源硏究所 1982 動力資源硏究所誌 Vol.4 No.1

A recrystallized behaviour of austenite during heating at the temperature above Af was investigated in the solution-treated and the 50% rolled 18 Pct. Ni maraging steels. The characteristics of martensite structure formed from the unrecrystallized austenite were also studied. The results obtained in this study are as follows: 1) Just after the martensite-austenite transformation, the austenite structure is inherited into the reverted austenite in nondeformed and 50%. rolled specimens. The reverted austenite is recrystallized to a finer grain size by heating it for longer time or at higher temperature. 2) In the case of non-deformed materials, the reverted austenite grain boundary is the preferential nucleation site of recrystallization. On the other hand, in the 50% rolled materials, the recrystallization occurs finely and uniformly in the reverted austenite grain.

용강탈황시 황 이동기구에 미치는 슬래그 염기도의 영향

곽사호,고제만,임병모 대한금속재료학회(대한금속학회) 1994 대한금속·재료학회지 Vol.32 No.5

The mechanism of sulphur transport from steel bath into slag droplets produced during slag injection processes has been investigated by simulation experiments using the slags of different compositions. Powdered slags were introduced onto the surface of small steel melts in alumina crucibles at 1550℃ and the ensuing sulphur profiles in the steel and slag were determined by microprobe analysis. The results are as follows : 1) The desulphurization ability of molten steel appears to be best when the slag basicity is high. 2) The concentration and transport rate of sulphur within a slag is increased with high slag basicity; the mode of sulphur distribution is stepwise in basic slags while parabolic in acid. 3) Sulphur in the molten steel moved to the slag during the reaction and in the sulphur content in the steel at the interface was reached at the quasi-equilibrium state in a short reaction time. 4) The mechanism of sulphur transport seems to be controlled by a diffusion procsss in the slag side, which is in turn related to the viscosity of the slag.