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압축잔류응력이 차량용 스프링강(SUP-9)의 파괴인성에 미치는 영향
박원조(WonJo Park),김추용(ChoYong Kim),허선철(SunChul Huh),이광영(KwangYoung Lee) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Recently, many components used in machinery industry demand lightness and high strength. The shot-peening method is used in order to improve fatigue life of spring steel(SUP-9) which is used in suspension of automobile. The compressive residual is induced in shot-peening process. This paper investigated the effect of the compressive residual stress on the fracture toughness. The test of Fracture toughness had been conducted at room temperature, high temperature(100℃, 200℃) and low temperature(-60℃, -100℃) from SUP-9 Steel was process by shot-peening. so we survey fractography of SUP-9 Steel by SEM.
쇼트피닝 투사 속도에 따른 Al6061-T651의 압축잔류응력 및 피로특성에 관한 연구
박성호(SungHo Park),허선철(SunChul Huh),박원조(WonJo Park) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.3
Recently, the steel parts used for automobiles and trains are required to be used under higher stress than ever before in need of the weight down. To achieve this requirement of a high strength steel, it must be necessary to decrease the inclusion contents and surface defects such as decarburization, surface roughness etc. In this study, the results of observation on the arc height, surface roughness, hardness, residual stress and fatigue life of a Al6061-T651 shot peened were obtained. Experimental results show that the increase of arc height is tremendous by shot velocity. Also shows that increase of surface roughness, hardness and compressive residual stress, fatigue life of Al6061- T651 by shot velocity.
쇼트피닝에 의한 알루미늄합금의 피로균열진전 거동에 관한 연구
박성호(SungHo Park),박원조(WonJo Park),허선철(SunChul Huh) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
Nowadays, many components used in aerospace and automobile industry were required lightness and high strength. The shot peening process is most often used to improve fatigue properties of metal part. The shot peening method is in used in order to improve the fatigue life of Aluminum alloy which is used in aerospace and automobile industries. The compressive residual stress is induced in this shot peening process. This paper is investigated the effect of the compressive residual stress on the fatigue crack growth characteristics and we found the optimum shot peening condition. Test results show the fatigue characteristics were increased by optimum peening condition. But the fatigue characteristics were decreased by under peening or over peening condition. The fatigue life and fatigue strength of shot peened specimens are higher than those of unpeened specimens. Fatigue crack growth tests on compact tension specimen of width 12.5㎜ were conducted by using sinusoidal waveform and used the Servo hydraulic fatigue testing machine (MTS 810). 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. Shot peening was performed on velocity of 40㎧, 50㎧, 70㎧ by impeller type shot peening machine, and used compact tension specimen are Al7075-T6 and Al6061-T651.
소결온도 및 SiO₂첨가량에 따른 탄화규소의 마모 특성
박성호(SungHo Park),박원조(WonJo Park),윤한기(HanKi Yoon) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
In this study, monolithic liquid phase sintered SiC (LPS-SiC) was made by hot pressing method with nano-SiC powder whose a particle size is 30㎚ and less on the average. Alumina (Al₂O₃), yttria (Y₂O₃) and silica (SiO₂) were used for sintering additives. To investigate effects of SiO₂, Al₂O₃/Y₂O₃ composition was fixed and then ratios of SiO₂ were changed as seven kinds. Materials have been sintered for 1 hour at 1760℃, 1780℃ and 1800℃ under the pressure of 20㎫. The system of sintering additives which affects a property of sintering as well as the influence depending on compositions of sintering additives were investigated by measurement of density, mechanical properties such as flexural strength, vickers hardness and sliding wear resistance were investigated to make sure of the optimum condition which is about matrix of SiC<SUB>f</SUB>/SiC composites. The abrasion test condition apply to load of 20N at 100RPM for 20min. Sintered density, flexural strength of fabricated LPS - SiC increased with increasing the sintering temperature. And in case of LPS-SiC with low SiO₂, has very excellent wear resistance.
소결온도 및 SiO₂ 첨가량에 따른 탄화규소의 마모 특성
박성호(SungHo Park),박원조(WonJo Park),윤한기(HanKi Yoon) 대한기계학회 2008 大韓機械學會論文集A Vol.32 No.11
In this study, liquid phase sintered SiC (LPS-SiC) materials were made by hot pressing method. The particle size of nano-SiC powder was 30㎚. Alumina (Al₂O₃), yttria (Y₂O₃) and silica (SiO₂) were used for sintering additives. To investigate effects of SiO₂, ratios of SiO₂ contents were changed by five kinds. Materials have been sintered for 1 hour at 1760℃, 1780℃ and 1800℃ under the pressure of 20㎫. The system of sintering additives which affects a property of sintering as well as the influence depending on compositions of sintering additives were investigated by measurement of density, mechanical properties such as flexural strength, vickers hardness and sliding wear resistance were investigated to make sure of the optimum condition which is about matrix of SiCf/SiC composites. The abrasion test condition apply to load of 20N at 100RPM for 20min. Sintered density, flexural strength of fabricated LPS - SiC increased with increasing the sintering temperature. And in case of LPS-SiC with low SiO₂, sliding wear resistance has very excellent. Monolithic SiC 1800℃ sintering temperatures and 3wt% have excellent wear resistance.
박성호(SungHo Park),박원조(WonJo Park),허선철(SunChul Huh),이광영(KwangYoung Lee) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
Recently, the steel material part used at the automobile and aerospace industries are require to be used lightweight parts. therefore, used material steel have to be a high stress and light, which is an indispensable condition in this field. aluminum alloy is very light and high stress. but many industries are require to more mechanical characteristic. so we need to development research about the aluminum alloy. there are many way for enhance mechanical characteristic of the aluminum alloy. we used the shot peening as way of the enhance mechanical characteristic. The wear test is one of important factors which evaluate the life of the machine. the surface conditions are measured to know the influence wear characteristics by shot peening and influence on material durability wear and friction by shot velocity. test result show the wear characteristics were increased by optimum peening condition. but the wear characteristic were decreased by under peening or overpeening condition. In this study, used a ball on disk type experiment to measure wear less and friction . shot velocity are 40㎧,50㎧ 70㎧ and used specimen are Al7075-T6 and Al6061-T651.
쇼트피닝에 의한 레이저 용접의 피로 수명 지연 효과에 관한 연구
박성호(SungHo Park),이현준(HyunJun Lee),Jiang Jun,허선철(SunChul Huh),박원조(WonJo Park) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.10
At present, welding technology is not only emphasized in the development of manufacturing technology but also application is expanding. In these systems, application of SUS as high-temperature material which is used for special purposes is attempted, and improvement of manufacturing technologies bear watching together with increase of using rate. Specifically, Wings with surface of three-dimensional shape usually applied to Fastener with purpose of lightweight. However, due to development of welding technology, methods of existing assembly tend to be replaced by welding, recently. Specifically, if laser welding techniques is applied, it minimizes heat-affected zone than other welding techniques. However, in the case of these special welding, residual stress is raised, and it fatally affects fatigue life. In order to remove residual stress and delay effect of fatigue life, shot-peening is executed; it executes shot-peening and verifies delayed effects of fatigue life. The intention of this study is to obtain the optimal conditions of shot-peening.
MoSi₂기 복합재료의 제조과정에 따른 트라이볼로지 특성
박성호(Sungho Park),박원조(Wonjo Park),허선철(Sunchul Huh),이광영(Kwangyoung Lee),윤한기(Hanki Yoon) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In this study, monolithic MoSi₂, 20 vol.% SiC particles-reinforced MoS₂ matrix, SiC/MoSi<br/> composite and 20 vol.% ZrO₂ panicles-reinforced MoSi₂ matrix, ZrO₂/MoSi₂ composite was fabricated by hot pressed sintering at 1350℃ under 30 ㎫ during 60 min. Vickers hardness and sliding wear resistance of the monolithic MoSi₂, ZrO₂/MoSi₂ and SiC/MoSi₂ composite was investigated at room temperature. Abrasion tester used a pin-on-disk type and a Si3N4 ceramic ball which used as machine structural materials. The test condition apply to load of 8kgf a 7.5rpm for 6 hours and the effect of hardness is also discussed The ZrO₂/MoSi₂ composite has shown the very excellent wear resistance compared with monolithic MoSi₂ and SiC/MoSi composite at room temperature.<br/>
쇼트피닝에 의한 고강도 알루미늄 합금의 피로균열진전에 관한 연구
전현배(HyunBae Jeon),박원조(WonJo Park),박성호(SungHo Park) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
Nowadays, many components used in aerospace and automobile industry were required lightness and high strength. The shot peening process is most often used to improve fatigue properties of metal patio The compressive residual stress is induced in this shot peening process. This paper is investigated the effect of the compressive residual stress on the fatigue crack growth characteristics and we found the optimum shot peening condition. Test results show the fatigue characteristics were increased by optimum peening condition. The fatigue life and fatigue strength of shot peened specimens are higher than those of un-peened specimens. Fatigue crack growth tests on compact tension specimen of width 12.5㎜ were conducted by using sinusoidal waveform and used the Servo hydraulic fatigue testing machine (MTS 810). 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. Shot peening was performed on velocity of 40m/s, 50m/s, 70m/s by impeller type shot peening machine, and used compact tension specimen are A1707S-T6 and A16061-T651.