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TP304계 고질소 스테인레스강의 단조특성과 냉간압연 모사
이명열(M. R. Lee),이종욱(J. W. Lee),김병구(B. K. Kim),김영득(Y. D. Kim),신종호(J. H. Shin) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.5
오스테나이트계 고질소 스테인레스간 4가지 후보강종인 HNS C1, C2, C3, C4에 대해 질소함량, 가압조건 따른 단조재와 온도 및 동일한 가압조건에서 Ni 합금원소 첨가유무에 따른 용체화 처리재(HNS C1, C3)의 물성평가와 실제 냉연 공정의 pass schedule 검증을 위한 모사실험을 통해 다음과 같이 요약 하였다. 1) 가압증가에 따른 질소함량의 증가로 강도 및 경도가 동시 상승하며, 결정립의 미세화 및 기계적 쌍정 발생이 많았다. 동일한 가압조건에서 Ni 첨가된 HNS C3가 Ni 미첨가한 HNS C1보다 강도-연성 조합평가에서 열/냉간 가공성 등의 특성이 우수하였다. 2)고칠소강 스테인레스강의 적정한 용체와 처리온도 범위는 상요화된 AISI304와 유사한 1050~1100℃이며, 용체화처리 후 냉각방법의 변경(수냉과 공냉)에 따른 경도의 편차는 없었다. 3)냉연 pass schedule 검증을 위한 모사실험에서 초기 압연의 최적조건은 roll속도 5mpm, pass당 압연율 15~17%였다. Several high nitrogen stainless steel ingots(100kg) were fabricated with changing Ni and [N]₂ contents by Pressurized Vacuum Induction Melting(P_VIM). After free forging process, chemical compositions, microstructure and mechanical properties were estimate. Hardness was increased with the increase of [N]₂ content. Furthermore, microstructure including a lot of tempering twins was observed with optical microscope. Mechanical properties were estimates as function of solution treatment temperature and cooling method(air/water) under duration time of lhr on sample that were fabricated with Ni content under the atmospheric [N]₂ pressure. At solution treatment range of 1050~1100℃, hardness was decreased with the increase of solution temperature and there were little discrepancy of microstructure and hardness with cooling method. Computer simulation was carried out in order to inspect pass schedule in cold rolling process. When the condition of simulation was roll speed of 2.5mpm, rolling rate 15~17% per pass, it was ascertained that the formation such as deformation by sticking and lamellar sliver etc. was restricted from a simulation.
Urea-SCR 시스템에서 유동혼합 개선을 위한 혼합기 형상에 관한 수치적 연구
이종욱(J.W. Lee),최훈기(H.K. Choi),유근종(G.J. Yoo) 한국전산유체공학회 2010 한국전산유체공학회지 Vol.15 No.4
To alleviate NOx emission, a variety of approaches has been applied. In marine diesels, the application of SCR systems has been considered an effective exhaust aftertreatment method for NOx emission control. Most current SCR systems use a various catalyst for the reaction of ammonia with NOx to form nitrogen and water. In theory, it is possible to achieve 100% NOx if the NH₃-to-NOx ratio is 1:1. However, the reaction has a limited non-uniformity of the exhaust gas flow and ammonia concentration distribution. Therefore, it is necessary to investigate the optimum flow conditions. In order to achieve uniform flow at monolith Front face, we are equipped with a various mixed devices. In this paper, it is presented that the mixed devices play an important role improvement of flow patterns and particle distributions of NH₃ by numerical simulation.
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.
이명열(M. R. Lee),이종욱(J. W. Lee),김영득(Y. D. Kim),신종호(J. H. Shin) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
The purposes of this study investigate effect of forging and hot and cold rolling on mechanical properties in austenitic high nitrogen steel(HNS) containing Cu and Ni. The 100㎏ HNS ingots manufactured by Pressurized Vacuum Induction Melting(PVIM) were forged and followed hot and cold rolling. Peak stress(σp) decreased with strain increase. Tensile and yield stress strength were decreased with addition of Cu and Ni, while enlongation was increased slightly. There was no difference in nitrogen contents with addition of Cu and Ni.
Urea-SCR 시스템의 유동혼합 개선을 위한 혼합기 형상에 관한 수치적 연구
이종욱(J.W. Lee),최훈기(H.K. Choi),유근종(G.J. Yoo),김원석(W.S. Kim) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.5
To alleviate NOx emission, a variety of approaches has been applied. In marine diesels, the application of SCR systems has been considered an effective exhaust aftertreatment method for NOx emission control. Most current SCR systems use a various catalyst for the reaction of ammonia with NOx to form nitrogen and water. In theory, it is possible to achieve 100% NOx if the NH3-to-NOx ratio is 1:1. However, the reaction has a limited non-uniformity of the exhaust gas flow and ammonia concentration distribution. Therefore, it is necessary to investigate the optimum flow conditions. In order to achieve uniform flow at monolith front face, we are equipped with a various mixed device. In this paper, it is presented that the mixed devices play an important role improvement of flow patterns and particle distributions of NH3 by numerical simulation.
설계인자 변경에 따른 버터플라이 밸브 유동 특성에 관한 연구
이종욱(J.W. Lee),최훈기(H.K. Choi),유근종(G.J. Yoo) 한국전산유체공학회 2009 한국전산유체공학회 학술대회논문집 Vol.2009 No.11
Flow control butterfly valve(FCBV) is known to have difficulty in controlling flow rate along valve opening due to its high flow rate. In low opening condition, the butterfly valve also has some shortcomings such as noise, vibration and erosion which are mostly caused by cavitation effects. Therefore, the FCBV requires proper remedies to reduce cavitation effects and to improve .flow control performance. Numerical analysis is applied to FCBV flow to find effects of design factors such as seat diameter and valve opening rate. Cases with 3 different sizes of seat diameter and various valve opening rate are selected for the numerical analysis. From the analysis results, it is found that the FCBV with small seat diameter shows better pressure loss performance and reduced cavitation effects.