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저방사화강(JLF-1)의 고온 피로균열진전거동에 관한 연구
박원조,정재욱,허선철,허정원 경상대학교 해양산업연구소 2002 해양산업연구소보 Vol.15 No.-
The objective of this study is to investigate life and fatigue crack propagation in the Reduced Activation Ferritic steel(RAFs) JLF-1. Crack growth rate tests on compact tension specimen of thickness 12mm were conducted by using sinusoidal waveform. Compact tension specimens were used and crack growth rate da/dN and stress intensity factor range ΔK were analyzed concerning to the R value of 0.1, 0.3 and 0.5 In order to find out the value of ΔK, load amplitude constant method was applied by the standard fatigue testing method describes in ASTM E647-95a. The effects of stress ratio and specimen size on the fatigue crack growth propagation for JLF-1 steel were discussed within the Paris law. As the result of this study, fatigue crack growth rate increased with in creasing the load ratio, Consequently, fatigue crack propagation of half size specimen was similar to those of full size specimen at room temperature. Also, there was no difference between base metal and weld metal at room temperature and high temperature.(400℃)
$9Al_2\;.\;2B_2O_4$/ AC4CH 금속기 복합재료의 피로강도 특성
박원조,이광영,허선철,Park, Won-Jo,Lee, Kwang-Young,Huh, Sun-Chul 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.10
Metal matrix composites with whisker reinforcements have significant potentials for demanding mechanical applications including defense, aerospace, and automotive industries. Especially metal matrix composites, which are reinforced with aluminum borate whisker, have been used leer the part of piston head in automobile because of good specific strength and wear resistance. In this study, AC4CH-based metal matrix composites with $Al_{18}$B$_{4}$ $O_{33}$ reinforcement have been produced using squeeze casting method, after T6 heat treatment, we evaluated fatigue life property of matrix and MMC composite and investigated fracture mechanism.m.
박원조,Md. Anowar Hossian,Yong-Bum Choi,Sung-Ho Park,허선철 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.10
Metal fiber preform reinforced aluminum alloy composite as made by the infiltration of molten metal under low pressure casting process. The infiltration behavior of filling pattern and the velocity profile with low-pressure casting process was investigated. The thermocouple was inserted into the preform in order to observe the infiltration behavior. The infiltration of applied pressure time, 1, 2 and 5 s under constant pressure of 0.4 MPa was completely filled during 0.4 s. In these conditions, molten aluminum alloy has successfully infiltrated to FeCrSi metal fiber preform by low-pressure casting process. It was observed the porosity of composites for reliability of composites. The automobile piston was developed with FeCrSi reinforced aluminum alloy that is 0% porosity by the optimal applied pressure and applied pressure time.
박원조,허선철,신동인 경상대학교 해양산업연구소 2002 해양산업연구소보 Vol.15 No.-
STS 304 has been developed with Nickel and Chromium containing about 8% Nickel and 18% Chromium. In case of STS 304 could be apply to ship hull and ship materials as well as various industries because it has a specific strength, high tensile strength and heat resistant. The experiments of mechanical properties and plain stress fracture toughness(J_IC) were carried out to obtain the characteristics of STS 304. Fracture strength tests were performed in accordance with the ASTM standard test method Standard Test Method for Plane-Strain Fracture Toughness of Metallic Materials (ASTM E8l3). The influence of thickness on the plane strain fracture toughness of this STS 304 steel was also investigated. The fractured specimens were examined by SEM.
Microstructure and wear characteristics on Al alloy matrix composite reinforced with Ni perform
박원조,김형진,허선철 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.6
Al based composite reinforced with Nickel is used for diesel engine piston, because the thermal properties, strength and corrosion resistant are for better than Al alloy alone. For processing, the intermetallic compounds of Ni and Al improves wear resistance due to its high hardness. Existing process methods for MMC (metal matrix composite) using preform were manufactured under high-pressure. However, this causes deformation of the preform or weaknesses in the completed MMC. Low-pressure infiltration can prevent these problems, and there is an advantage of cost reduction in of production with small-scale of production equipment. In this study, the microstructure and wear characteristics of Al-based composite with Ni preform as reinforcement with low-pressure infiltration was analyzed.
온도 변화에 따른 DW-100 용접재의 기계적특성에 관한 연구
박원조,정재욱,변상열,허선철,유재환 경상대학교 해양산업연구소 2002 해양산업연구소보 Vol.15 No.-
In recent years, the studies of mechanical property of weld materials were one of the most important basic test of our welding indursty. The used specimen in this study is weld metal of DW-100 flux cored wire which is using for flux cored are welding and one type of flux cored wires were used in this test. This paper is based on the quality of the mechanical property of welding material under the different temperture, test temperature of each weld metal is from RT to 900℃ and temperature gap is 100℃ for each weld metal. It is particularly important to assess tensile properties and each specimen was examined using by the following methods; Reduction of area rate, Tensile strength test, and observation of SEM. All tensile tests were performed in accordance with the ASTM standard test method, tension testing of metallic materials (ASTM I-8). This study proves that the mechanical properties of until 400℃ were good as the increasing temperature compare with mechanical properties of RT. As the results of this study, the tensile strength of 300℃ was higher than other weld metals. Also the reduction of area rate was the lowest at 300℃ according to the previous test results. Consequently, this weld metal is a good substitute for the existing welding materials until 400℃ which is used in the development of welding industries today.