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반복하중을 받는 배관용 강재의 피로수명에 미치는 부식의 영향
박경동(Keyung-Dong Park),안재필(Jae-Pil An) 한국마린엔지니어링학회 2005 한국마린엔지니어링학회 학술대회 논문집 Vol.2005 No.-
The compressive residual stress, which is induced by shot peening process, has the effect of increasing the intrinsic fatigue strength of surface and therefore would be beneficial in reducing the probability of fatigue damage. However, it was not known that the effect of shot peening in corrosion environment. In this study, the effect of shot peening on corrosion fatigue crack growth of sping steel immersed in 6% FeCl₃ solution and corrosion characteristics with considering fracture mechanics. The results of the experimental study corrosion fatigue characteristics of spring steel are as follows; the fatigue crack growth rate of the shot peening material was lower than of the un peening material. And fatigue life shows more improvement in the shot peening material than un peening material. This is because the compressive residual stress of surface operate resistance of corrosion fatigue crack propagation. It is assumed that the shot peening process improve corrosive resistance and mechanical property.
박경동(Keyung-Dong Park),유형주(Hyoung-Ju Ryu) 한국마린엔지니어링학회 2005 한국마린엔지니어링학회 학술대회 논문집 Vol.2005 No.-
The lightness of components required on marine and shipbuilding industry is requiring high strength of components. In particular, fatigue failure phenomena, which happen in metal, bring on danger in human life and property. Therefore, antifatigue failure technology takes an important part of current industries. In this study, it was investigated about endurance and fatigue crack propagation rate of according to stress ratio of SMAW commonly using for welding structures in present. Fatigue crack propagation rate(da/dN) of low load(R=0.1) was lower than of high load(R=0.6) for piping weld. And in stage Ⅰ, △Kth, the threshold stress intensity factor of the weld under heavy load is higher than under small load. Fatigue life shows more improvement in the weld of stress ratio R=0.1 than in the weld of stress ratio R=0.6.
박경동(Keyung-Dong Park),김동욱(Dong-Uk Kim) 한국마린엔지니어링학회 2006 한국마린엔지니어링학회 학술대회 논문집 Vol.2006 No.-
Rupture by corrosion of pipe becomes the factor of supply water's pollution in waterworks and the factor of pollution of the soil and environment in drain pipe. Therefore, this research examined the weight reduction electric potential measure to measure the corrosion degree of piping materials after testing the corrosion of piping materials(Copper Pipe, Galvanized Steel Pipe, Stainless Steel Pipe) which is generally used at the moment in various corrosion environments(subterranean water, supply water, 3.5% NaCl, 3.5% HNO₃, 1% H₂SO₄). And let me show basic design data about problem occurrence such as leakage water, rust water, inside and outside corrosion from this.
박경동(Keyung-Dong Park),김동욱(Dong-Woog Kim) 한국마린엔지니어링학회 2005 한국마린엔지니어링학회 학술대회 논문집 Vol.2005 No.-
In this study, it was investigated about endurance and fatigue crack propagation rate of according to welding methods of SMAW and FCAW commonly using for welding structures in present. Endurance limits carried out highly in the order of SMAW, FACW and fatigue crack propagation rate out lowly in the order of SMAW, FCAW. By these results, it is needed to used SMAW welding methods for welding structures with small welding capacity and FACW methods for large welding structures after consideration about economic gains and operation efficiency of welding. Fatigue crack propagation rate is more effected by strength of welding materials than endurance limit of welding materials according to welding methods.
석유시추용 인코넬 625강의 FCAW 용접에 관한연구 ; 보호가스 변화가 기계적 성질에 미치는 영향
박경동(KEYUNG-DONG PARK),진영범(YOUNG-BEOM JIN),박형동(HYOUNG-DONG PARK) 한국해양공학회 2004 韓國海洋工學會誌 Vol.18 No.6
Inconel 625 is useful in a variety of industrial applications because of the resistance to attack in various corrosive media at temperatures from 200℃ to over 1090℃, in combination with good low and high temperature mechanical strength. Rencently this material has also been widely used in offshore processing piping in order to extend the maintenance term and improve the quality of anti-corrosion. In general, high quality weldings for this material are readily produced by commonly used processes. How, not all processes are applicable to this material group of Ni-alloys. Metallurgical or the unavailability of matching, position or suitable welding processes produce a lower quality. Nowadays, the flux cored wire is developed and applied for increased productivity in several welding positions, including the vertical position. In this study, the weldability and weldment characteristics(mechanical properties) of inconel 625 are considered in FCAW(Flux Core Arc Welding) associated with the several shielding gases(80%Ar+20%CO2, 50%Ar+50CO2, 100CO2) in view of welding productivity.
유형주,박경동,Ryu Hyung-Ju,Park Keyung-Dong 한국마린엔지니어링학회 2005 한국마린엔지니어링학회지 Vol.29 No.4
The lightness of components required in automobile and machinery industries is requiring high strength of components. Therefore this requirement is accomplished as the process of shot-peening method that the compressive residual stress is made on the metal surface as one of various improvement methods. Special research is, therefore, needed about compressive residual stress on the metal surface in the process of shot-peening method. Therefore, in this paper the effect of compressive residual stress of spring steel(JISG SUP-9) by shot-peening on fatigue crack growth characteristics in environmental condition(temperature) and mechanical condition(shot velocity, stress ratio) was investigated with considering fracture mechanics. By using the methods mentioned above, the following conclusions have been drawn. (1) The fatigue crack growth rate(da/dN) of the shot-peened material was lower than that of the un-peened one. In high temperature range. fatigue crack growth rate decreased with increasing temperature range, while fatigue crack growth rate increased by decreasing temperature in low temperature. (2) Fatigue life shows more improvement in the shot-peened material than in the un-peened material. And compressive residual stress of surface on the shot-peen processed operate resistance force of fatigue crack propagation.
선체 구조용 Alloy 625의 용접시 보호가스 조성비에 따른 부식특성에 관한 연구
안재필,박경동,An Jae-Pil,Park Keyung-Dong 한국마린엔지니어링학회 2005 한국마린엔지니어링학회지 Vol.29 No.4
Alloy 625 is used widely in industrial applications such as aeronautical aerospace, chemical, petrochemical and marine applications. Because of a good combination of yield strength. tensile strength, creep strength, excellent fabricability, weldability and good resistance to high temperature corrosion on prolonged exposure to aggressive environments. High qualify weldments for this material are readily produced by commonly used processes. But all of processes are not applicable to this material by reason of unavailability of matching, position or suitable welding filler metals and fluxes may limit the choice of welding processes. Recently, the flux cored wire is developed and applied for the better productivity in several welding position including the vortical position. In this study. the weldability and weldment characteristics of Alloy 625 are evaluated in FCAW weld associated with the several shielding gases($80\%Ar+20\%\;CO_2,\;50\%Ar+50\%\;CO_2.\;100\%\;CO_2$) in viewpoint of welding productivity. The results of the experimental study on corrosive characteristics of Alloy 625 are as follows; There is no remarkable difference among shielding gases. however they has a striking difference among corrosive solutions by results of distinguished density and time of corrosive solution. Generally, the shielding gases($80\%Ar+20\%\;CO_2$) was superior to the other gases on high temperature tensile and a low temperature impact. but all of the shield gases were making satisfactory results on corrosion test.
$3.5\%$ NaCl수용액에서 SAE 5155의 부식거동에 미치는 쇼트피닝의 영향
안재필,박경동,An Jae-Pil,Park Keyung-Dong 한국마린엔지니어링학회 2005 한국마린엔지니어링학회지 Vol.29 No.6
In this study. investigated the effect of shot peening on the corrosion of SAE 5155 steel immersed in $3.5\%$ NaCl solution and corrosion characteristics by the heat treatment during shot peening process. The immersion test was Performed on the four kinds of specimens. Corrosion Potential, polarization curve, residual stress etc. were investigated from experimental results. From these test results, the effect of shot peening on the corrosion was evaluated The important results of the experimental study on the effects of shot peened SAE 5155 on the corrosion are as follows; Shot peened specimens show the low of corrosion current as compared with un peened specimens. In the case of corrosion potential, shot Peened specimen shows more negative Potential as compared with that of parent metal Surface of specimen, which is treated with shot peening Process. is Placed as more activated state against inner parent metal. Corrosion rate is shown that shot Peened specimens have less corrode than un peened specimens. But non heat treated shot peened specimens show the biggest weight loss owing to variable compressive residual stress layer by shot ball.