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피닝 처리에 따른 304 스테인레스 강의 마모 특성 평가 및 미세구조 분석
정진성(Jine-Sung Jung),이한상(Han-Sang Lee),신기삼(Kee-Sam Shin),김선진(Sun-Jin Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
In most case of materials damages were happened at the surface. The various methods for increasing the fatigue life were existed like as the diffusion coating process, flame hardening, surface rolling and shot peening. The peening of these techniques was applied to the various industries during long times. We investigated on the wear properties and micro-structure before and after shot peening. The 304 stainless steel was used as the test materials. Firstly, the optimum peening condition was determined by the Almen intensity and rotary bending fatigue test. Secondly, the surface roughness and residual compressive stresses were evaluated with the stylus and X-ray diffraction equipment. And then, the wear tests were performed on abrasion and solid particle erosion. Finally, the micro-structure of tested specimens was analyzed using by X-ray diffraction, scanning electron microscope and transmission electron microscope. The residual compressive stress was existed to about 70㎛ depth, the wear properties also was increased and the twins were found in micro-structure.
이한상 ( Han Sang Lee ),정진성 ( Jine Sung Jung ),유근봉 ( Keun Bong Yoo ),김의현 ( Eui Hyun Kim ) 대한금속재료학회 ( 구 대한금속학회 ) 2010 대한금속·재료학회지 Vol.48 No.4
The hot corrosion properties of heat-resistant steels were investigated in an oxidation atmosphere including artificial ash and sulfur dioxide. The heat-resistant steels of T22, T92, T122, T347HFG, Super304H and HR3C were evaluated at 620, 670 and 720℃ for 400 hours. The relationship between the corrosion rate and the temperature followed a bell-shaped curve with a peak rate at around 670℃. The corrosion rates showed a decreasing tendency as the chrome contents of these steels increased from 2.l5 wt.% to 24.5 wt.%, and austenitic steels had a lower corrosion rate than ferritic steels. Sulfidation by SO2 as well as molten salt corrosion also had an effect on the total corrosion rate, especially showing an increase in the corrosion rate in ferritic steels. Regardless of the chrome content in the steels and irrespective of the test temperature, the corrosion scale was composed of an outer oxide and an artificial ash mixed layer, a middle oxide layer andinner sulfide, and amixed oxide layer. As the chrome content increased, the proportion of chrome oxide in the corrosion scale increased. Before spalling of the corrosion scale, voids and cracks were initiated in the sulfide and the mixed oxide layer or at the interface with the substrate. (Received December 16, 2009)
강명수(Myung Soo kang),정진성(Jine Sung Jung),하정수(Jung Soo Ha) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
In this study the life assessment of low cycle fatigue for 12Cr steel at high temperature arc described. Secondly, comparisons between predicted lives and experimental lives are made for the several sample life prediction models. Two minute hold lime in either tension or compression reduce the number of cycles to failure by about a factor of two. Twenty minute hold time in compression lead to shorter lives than 2 minute hold time in compression. Experiments showed that life predictions from cIassical phenomenological models have limitations. More low cycle fatigue experiments should be pursued to gain understanding of the physical damage mechanisms and to allow the development of physically-based models which can enhance the accuracy of the predictions of components. From a design point-of-view, life prediction has been judged acceptable for these particular loading conditions but extrapolations to thermo-mechanical fatigue loading, for example, require more sophisticated models including physical damage mechanisms.
IN 738LC 합금의 미세조직 열화와 물성의 상관성 연구
유정훈,주성욱,신기삼,허성강,이재현,김의현,정진성,장성호,송기욱,하정수,Yoo Junghoon,Jo Sungwook,Shin Keesam,Hur Sungkang,Lee Je-Hyun,Kim Eui-Hyun,Jung Jine-sung,Chang Sungho,Song Geewook,Ha Jeongsoo 한국재료학회 2004 한국재료학회지 Vol.14 No.1
IN 738LC, the major material for gas-turbine for power generation, was heat treated at $750^{\circ}C$, $850^{\circ}C$, $950^{\circ}C$ for 1000, 2000, and 4000 hrs and the microstructural evolution and mechanical properties were examined using optical microscope, XRD, SEM/EDS. The results showed ${\gamma}$', the main strengthening elements in this alloy, was about 300 nm in size and was about 56% by area fraction in as-cast samples. The area fraction of ${\gamma}$' peaked at 2000 hours at $750^{\circ}C$. The average diameter of the ${\gamma}$' which was about 300 nm at ascast specimen increased to about 1 $\mu\textrm{m}$ after heat treatment at $950^{\circ}C$ for 4000 hrs. Carbides were formed at dendrite, cell or grain boundaries which was ascribed to the segregation caused by solute redistribution during solidification. It was found that MC type carbides formed at low temperature, whereas carbides of $M_{23}$ /$C_{ 6}$/ type formed at higher temperature or at longer degradation. The hardness and impact energy decreased as the heat treatment temperature or time of retention increased, which was inaccrodance with the area fraction of ${\gamma}$'.
장동식(Jang Dong-sik),김의현(Kim Eui-hyun),정진성(Jung Jine-sung),김민태(Kim Min-tae),김종영(Kim Chong-young) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.3
Features of the materials database system for the plant facilities management are discussed based on the WWW on the Internet which is being developed at Korea Electric Power Research Institute(KEPRI). KEPRI has developed the web-based materials database for Flue Gas Desulfurization(FGD) systems operated at Korea Electric Power Corporation(KEPCO)'s fossil power plants. It is composed of materials data search engine, FGD's utilities data search module, maintenance history search module, dictionary of materials engineering and etc. Web-based materials database for fossil power plants is being developed. Using XML(eXtensible Markup Language) technology new database system is designed to share its data with others systems.
XML을 이용한 플랜트 재료 데이터베이스 개발 및 활용
장동식(Jang Dong-sik),김의현(Kim Eui-hyun),정진성(Jung Jine-sung),공희경(Kong Hee-kyung) 한국정보과학회 2004 한국정보과학회 학술발표논문집 Vol.31 No.1B
산업설비 현장에서는 설비 운영과 관련하여 재료 관련 정보에 대한 요구가 비교적 빈번하게 발생하고 있으나 필요한 기술 자료의 확보, 검토 등에 많은 어려움을 겪고 있다. 따라서 산업설비에 적용되는 재료들을 종합하여 비교, 검토할 수 있는 시스템을 개발하여 인터넷을 통해 제공할 경우 산업설비의 운영효율 향상, 신뢰도 향상에 기여할 수 있을 것으로 기대된다. 재료 데이터베이스 시스템은 재료가 사용되는 설비의 운영과 관련한 각종 데이터와 상호 연계되어야 할 필요가 있다. 손상해석, 재료선정 등은 인장시험 등 각종 시험 데이터와 더불어 재료가 사용되는 실제 설비의 응력, 온도 등 운전환경, 사용이력 등이 중요한 판단 자료가 되기 때문이다. 또한 재료 데이터는 플랜트 운영시스템, 자재구매/관리시스템 등 다양한 시스템의 기본 마스터데이터로 이용될 수 있다. 따라서 재료 데이터가 갖는 이러한 특성을 충족시키기 위해서는 확장성과 이식성이 뛰어난 XML을 기반으로 재료 데이터베이스를 개발하는 것이 바람직할 것으로 판단된다. XML을 기반으로 개발된 재료 데이터베이스는 20,000건의 방대한 재료 규격정보를 담고 있으며 규격검색, 이름검색, 화학성분 검색, 기계적 특성 검색 등 다양한 검색 기능을 제공한다. 또한 대표적인 종합플랜트인 화력발전소의 설비데이터와 통합 연동되어 재료의 적용현황 및 환경 등을 통합적으로 검색할 수 있다. XML을 이용한 본 개발시스템은 향후 상용 ERP 패키지 다양한 시스템의 기본 데이터베이스로 활용될 수 있을 것으로 기대된다.
가스터빈용 소재 IN 738LC 합금의 미세조직 열화거동
유정훈,주성욱,신기삼,김의현,정진성,장성호,송기욱,하정수 국립7개대학공동논문집간행위원회 2002 공업기술연구 Vol.2 No.-
IN 738LC, used as gas-turbine for power generation, was heat treated at 750℃, 850℃, 950℃ for 1000, 2000, and 4000 hrs. and the microstructural evolution are examined using optical microscope, XRD, SEM/EDS. For comparison, part of gas turbine used for 18439 hours for power generation was also examined. The results showed γ´, the main strengthening elements in this alloy, was about 300 nm and was about 56% in as-cast samples. The volume fraction of γ´peaked at 2000 hours at 750℃ and then decreased at further or longer heat treatment. The average diameter of the γ´ which was about 200 nm increased to about 1㎛. Carbides were formed at dendrite, cell, or grain boundaries which was ascribed to the segregation caused by solute redistribution during solidification. It was found that the at low temperature, M_6C type carbides formed, whereas carbides of M_23C_6 type formed at higher temperature, or at longer degradation.