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서창민(Chang-Min Suh),허정훈(Jeong-Hoon Huh),이해무(Hae-Moo Lee),서덕영(Duck-Young Suh) 한국해양공학회 1996 韓國海洋工學會誌 Vol.10 No.2
The estimation of the remaining life for the aged components in power plant as well as chemical and petroleum plants has been recently concerned. The raw materials used in this study are the 1Cr-1Mo-0.25V rotor steel which intensified P and S compositions along with the nominal compositions of ASTM A470 standard. Five kinds of specimens with the different degradation levels were prepared by isothermal aging heat treatment at 630℃. The mechanical properties and fatigue strength of virgin and aged 1Cr-1Mo-0.25V rotor steel have been investigated through the hardness, tensile, fatigue test, SEM fractograph and EDS analysis at room temperature. Thus, the data of aged specimens were compared with those of virgin specimen to evaluate the aging effects.<br/> The main results obtained in this study are as follows; The decrease of the hardness due to degradation was distinguished until 50,000hrs simulated service time. And it was confirmed that the considerable amount of P, Mn, Cr and S was precipitated at the grain boundary of aged material through the SEM and EDS analysis. The fatigue strength of 25,000, 50,000, 75,000 and 100,000hrs aged material was decreased 29.5%, 24.4%, 28.6%, 35.7% than that of virgin material at 10<SUP>7</SUP> cycles of room temperature.<br/> The major cracks of virgin and aged materials initiated at the inclusions including Si, P and Mn compositions which were located at the outer periphery of the specimen.
균열 形狀比 變化에 따른 單一表面疲勞균열의 成長特性과 壽命豫測
徐昌敏(Chang-Min Suh),徐德榮(Duck-Young Suh),鄭正守(Jung-Soo Jung) 한국해양공학회 1993 韓國海洋工學會誌 Vol.7 No.2
This work has been investigated the relationship between single surface crack length and crack depth which have influence on the fatigue life. The simulation based on experimental results of 2.25 Cr-1Mo steel at various crack configuration ratios has enabled successful prediction of fatigue life at room temperature. The effect of crack depth should be considered for predicting fatigue crack growth rates as well as that of surface crack length. It is also shown that the crack growth mechanisms are in good agreement with experimental data according to the interaction of crack length and crack depth.
PEID를 利用한 中型 프레스의 設備總合效率 向上에 關한 硏究
徐昌敏,李文煥,徐德榮 경북대학교 산업기술연구소 1993 産業技術硏究誌 Vol.21 No.-
In recent years a serious interruption loss often occurs at highly expensive developed equipment. To maximize the total equipment efficiency of the Midium-Press it is essential to reveal and improve the potential loss of equipment based on these 6 kinds of chronic loss. Further, the way to minimize the investment in equipment has been presented by applying the PEID(Program for Equipment Improvement & Development).