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발전기용 18Cr-18Mn-N 오스테나이트계 스테인리스강의 기계적 특성에 미치는 냉간가공과 응력완화 처리의 영향
황병철(B. Hwang),배종인(J-I. Bae),하헌영(H-Y. Ha),이태호(T-H. Lee),신종호(J-H. Shin),이종욱(J-W. Lee) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.5
High-nitrogen 18Cr-18Mn austenitic steels have been recently developed and used for generator retaining rings which require to have non-magnetic, high strength, high ductility and good corrosion resistance. The ring materials shall be expanded by an appropriate method such as segmented dies, tapered plug and etc. in the temperature range 15 to 200℃, and stress-relief annealed at around 400℃ to achieve the required mechanical properties. This study is concerned with the effect of cold working and stress relief treatment on the mechanical properties of high-nitrogen 18Cr-18Mn austenitic steel with different N content. Although the yield and tensile strength usually increased with N content and cold working ratio, an increase in strength by cold working was dependent on the N content. The strengths also increased after stress relief treatment, which was affected by the amount of cold working. On the other hand, the ductility and impact toughness steadily decreased with cold working ratio, irrespective ofN content and stress relief treatment.
베이나이트계 고강도강의 미세조직과 기계적 특성에 미치는 B 및Cu 첨가의 영향
임현석 ( H S Yim ),이승용 ( S Y Lee ),황병철 ( B Hwang ) 한국열처리공학회 2015 熱處理工學會誌 Vol.28 No.2
Effects of B and Cu additions on the microstructure and mechanical properties of high-strength bainitic steels were investigated in this study. Six kinds of high-strength bainitic steels with different B and Cu contents were fabricated by thermo-mechanical control process composed of controlled rolling and accelerated cooling. The microstructures of the steels were analyzed using optical and transmission microscopy, and the tensile and impact tests were conducted on them in order to investigate the correlation of microstructure with mechanical properties. Depending on the addition of B and Cu, various low-temperature transformation products such as GB (granular bainite), DUB (degenerated upper bainite), LB (lower bainite), and LM (lath martensite) were formed in the steels. The addition of B and Cu increased the yield and tensile strengths because of improved hardenability and solid solution strengthening, but decreased the ductility and low-temperature toughness. The steels containing both B and Cu had a very high strength above 1.0 GPa, but showed a worse lowtemperature toughness of higher DBTT (ductile-to-brittle transition temperature) and lower absorbed energy. On the other hand, the steels having GB and DUB showed a good combination of tensile and impact properties in terms of strength, ductility, yield ratio, absorbed energy, and DBTT. Received March 2, 2015; Revised march 9, 2015; Accepted March 20, 2015)
UV - excited chlorine radical을 이용한 실리콘 웨이퍼상의 금속 오염물의 건식세정에 관한 연구
손동수(D. S. Son),황병철(B. C. Hwang),조동율(T. Y. Cho),천희곤(H. G. Chun),김경중(K. J. Kim),문대원(D. W. Moon),구경완(K. W. Koo) 한국진공학회(ASCT) 1997 Applied Science and Convergence Technology Vol.6 No.1
본 연구에서는 실리콘 웨이퍼 표면에 존재하는 미량의 Zn, Fe, Ti 금속 오염물들이 UV-excited chlorine radical을 이용한 건식세정 방법으로 제거되는 반응과정을 찾아내고자 하였다. 실리콘 웨이퍼 상에 진공증착법으로 원형패턴이 있는 Zn, Fe, Ti 박막을 증착시켜 상온 및 200℃에서 UV/Cl₂ 세정하였을 때, 염소 래디컬 (Cl*)이 Fe, Zn, Ti와 반응하여 제거되는 것을 반응 전후 광학현미경과 SEM을 통해 표면 형상 변화을 관찰하였고, in-line으로 연결된 XPS를 통해서 반응 후 웨이퍼 표면에 남아있는 화합물의 화학적 결합상태를 관찰하였으며, UV/Cl₂ 세정 후 실리콘 기판이 손상받는 정도를 알기 위해 AFM으로 표면 거칠기를 측정하였다. 광학현미경과 SEM의 분석 결과에 의하면 Zn와 Fe는 쉽게 제기되는 반면 염화물을 형성하기 보다는 휘발성이 적은 산화물을 형성하는 경향이 강한 Ti은 약간만 제거되는 것을 확인하였다. XPS 분석을 통해서 이들 금속 오염물들이 chlorine radical과 반응하여 웨이퍼 표면에 금속 염화물을 형성하고 있는 것을 확인하였고, UV/Cl₂ 세정처리를 하였을 때 실리콘 웨이퍼의 표면 거칠기가 약간 증가하는 것을 알 수 있었다. 지금까지의 결과를 통해 볼 때, 습식세정과 UV/Cl₂ 건식세정을 병행하면 플라즈마 및 레이저를 사용하는 다른 건식세정 방법에 비하여 보다 저온에서 실리콘 기판의 큰 손상 없이 비교적 용이하게 금속 오염물을 제거할 수 있음을 제안하였다. The reaction mechanisms of dry cleaning with UV-excited chlorine radical for Zn, Fe and Ti trace contaminants on the Si wafer have been studied by SEM, AFM and XPS analyses in this work. The patterned Zn, Fe and Ti films were deposited on the Si wafer surface by thermal evaporation and changes in the surface morphology after dry cleaning with Cl₂ and UV/Cl₂ at 200℃ were studied by optical mocroscopy and SEM. In addition, changes in the surface roughness of Si wafer with the cleaning was observed by AFM. The chemical bonding states of the Zn, Fe and Ti deposited silicon surface were observed with in-line XPS analysis. Zn and Fe were easily cleaned in the form of volatile zinc-chloride and iron-chloride as verified by the surface morphology changes. Ti which forms involatile oxides was not easily removed at room temperature but was slightly removed by UV/Cl₂ at elevated temperature of 200℃. It was also found that the surface roughness of the Si wafer increased after Cl₂ and UV/Cl₂ cleaning. Therefore, the metallic contaminants on the Si wafer can be easily removed at lower temperature without surface damage by a continuous process using wet cleaning followed by UV/Cl₂ dry cleaning.
in - line XPS와 AFM을 이용한 유기물의 UV / ozone 건식세정과정 연구
이경우(K. W. Lee),황병철(B. C. Hwang),손동수(D. S. Son),천희곤(H. G. Chun),김경중(K. J. Kim),문대원(D. W. Moon),안강호(K. H. Ahn) 한국진공학회(ASCT) 1995 Applied Science and Convergence Technology Vol.4 No.3
본 실험에서는 실리콘 웨이퍼 위에 photoresist(PR)와 octadecyltrichlorosilane(OTS, CH₃(CH₂)_l7SiCl₃)를 입혀서 UV/ozone 처리를 하였을 때 어떻게 유기물질들이 UV/ozone과 반응하여, 어떻게 표면에서 제거되는지를 in-line으로 연결된 XPS로 분석하고 반응시킨 표면들의 거칠기(roughness)를 AFM을 이용하여 관찰하였다. 실험결과 상온에서 UV/ozone 처리를 했을 경우, PR과 OTS같은 유기물질이 표면에서 산화되는 것을 알 수 있었으나 이들이 제거되지 않고 표면에 그대로 남아있음을 알 수 있었다. 그러나 가열하면서(PR : 250℃, ORS : 100℃) UV/ozone 처리를 하였을 경우 표면에서 산화됨과 동시에 이들 산화물들이 표면에서 제거됨을 알 수 있었다. XPS 분석으로부터 이들의 산화 반응물은 PR과 OTS 모두 -CH₂- , -CH₂O- , =C=O, -COO-를 가지는 것으로 나타났으며, 열에너지에 의해서 이들이 표면에서 제거되는 것으로 나타났다. AFM 분석결과는 상온에서 UV/ozone 처리를 하였을 경우에 표면의 거칠기가 적은 반면, 가열하면서 UV/ozone 처리를 하였을 경우에는 표면의 거칠기가 다소 증가하였다. In this work, photoresist (PR) and octadecyltrichlorosilane (OTS, CH₃(CH₂)_17SiCl₃) on Si were removed by the UV/ozone cleaning method and the surfaces were analyzed byin-line XPS to study mechanisms how the organic films react with UV/ozone and removed from the surface. The surface topographic changes were also observed by AFM. UV/ozone treatments of PR and OTS films at room temperature resulted in the oxidation of the organic surface contaminants, which remained on the surface of the silicon substrates at room temperature. The PR and OTS were oxidized and desorbed very rapidly by UV/ozone treatment at 100℃ and 200~250℃, respectively. From the XPS analyses, it was found that PR and OTS were oxidized to compounds having -CH₂-, -CH₂O-, =C=O, -COO- and desorbed from the surface upon heating. Thd AFM results showed that the UV/ozone treatments of PR and OTS at room temperature did not increase the surface roughness, but the surface roughness was increased at the higher temperature(PR : 250℃, OTS : 100℃).
고변형능 라인파이프강의 미세조직과 기계적 특성에 미치는 압연 및냉각 조건의 영향
이상인 ( S I Lee ),황병철 ( B Hwang ) 한국열처리공학회 2014 熱處理工學會誌 Vol.27 No.5
Effects of rolling and cooling conditions on microstructures and mechanical properties of high-deform-able pipeline steels were investigated in this study. Six kinds of pipeline steels were fabricated by varying rolling and cooling conditions, and their microstructures were analyzed by scanning electron microscopy, electron back-scattered diffraction, and transmission electron microscopy. Tensile and Charpy impact tests were conducted on the steels in order to examine the mechanical properties. The steels rolled in the two-phase region showed better low-temperature toughness than those in the single-phase region due to the larger amount of ferrites having high-angle boundaries, although they have lower strength and absorbed energy. The steel rolled in single-phase and finish-cooled at higher temperature showed a good combination of high strength and good low-temperature toughness as well as excellent deformability of the lowest yield ratio and the highest uniform elongation because of the presence of fine ferrite and a mixture of various low-temperature transformation phases.
질소와 탄소가 복합 첨가된 두 오스테나이트계 Fe-18Cr-10Mn 합금의 연성-취성 천이 거동
이승용 ( S Y Lee ),김보영 ( B Y Kim ),황병철 ( B Hwang ) 한국열처리공학회 2015 熱處理工學會誌 Vol.28 No.1
The ductile-to-brittle transition behavior of two austenitic Fe-18Cr-10Mn alloys with the combined addition of nitrogen and carbon was investigated in this study. The alloys exhibited a ductile-to-brittle transition behavior because of unusual brittle fracture at low temperatures unlike conventional austenitic alloys. The alloy with higher carbon content had higher yield and tensile strengths than that with lower carbon content due to the solid solution strengthening effect resulting from carbon addition. However, the increase in carbon content promoted the occurrence of intergranular fracture, and thus deteriorated the impact toughness. In order to develop successfully the austenitic Fe-18Cr-10Mn alloys with the excellent combination of strength and toughness in the future, therefore, more systematic studies are required to find the appropriate amount and ratio of nitrogen and carbon.
배종인(J. I. Bae),하헌영(H. Y. Ha),강전연(J. Y. Kang),황병철(B. Hwang),이태호(T. H. Lee) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.5
Duplex stainless steels (DSS) composed of ferrite and austenite have an attractive combination of mechanical and corrosion properties. Commercial DSS contain a considerable amount of Ni ranging from 4 to 7 wt.%. In recent years, efforts have been made to develop lean DSS with reduce Ni which can provide substantial economical savings and improve mechanical properties due to transformation-induced plasticity. In the present study, several kinds of lean DSS with unique chemical composition were fabricated, and the mechanical and corrosion properties were investigated with precipitation behavior. Based on the results, the lean DSS developed in KIMS showed an excellent combination of strength-elongation and good corrosion resistance.