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ALBC3 합금의 쇼트피닝 분사거리에 따른 해수 내 캐비테이션 손상 평가
한민수· ( Min Su Han ),장석기 ( Seok Ki Jang ),김종신 ( Jong Sin Kim ),김성종 ( Seong Jong Kim ) 한국부식방식학회(구 한국부식학회) 2013 Corrosion Science and Technology Vol.12 No.5
Marine equipment exposed to harsh environments requires not only excellent corrosion resistance but also improvement of physical characteristics against natural material degradation. With growing interests in ocean energy resources, the higher reliability for marine equipment has become more important in terms of material characteristics. ALBC3 alloy represents excellent corrosion resistance and is widely used in corrosive environments. However, cavitation damage occurs frequently due to its poor durability in high flow rate of marine environment. In this research, shot peening technology was employed as a surface modification with shot peening stand-off distance to mitigate cavitation damage. The effects of shot peening on extent of cavitation damage and weight loss were evaluated for both shot peened and non-peened specimens. The results revealed that the application of shot peeing decreased cavitation damage for all experimental conditions in comparison with the non-peened specimens. The optimum stand-off distance was determined to be 10 cm, since more than 35 % of cavitation damage reduction was observed.
Al 7075-T651의 마찰교반 용접에 대한 회전속도와 이송속도의 영향
한민수,전정일,장석기,Han, Min-Su,Jeon, Jeong-Il,Jang, Seok-Gi 대한기계학회 2007 大韓機械學會論文集A Vol.31 No.4
The 7075-T651 Al alloy was welded by friction stir welding. Microstructure, macro behaviors and fracture type in the nugget, thermo-mechanically affected zone(TMAZ) and heat affected zone(HAZ) of the welded part were compared to base metal. The microsturctures of nugget zone were compared with tool rotation speeds and various tool transition speed. When the rotation speeds were decreased and transition speeds were increased, the hardness of nugget zone were decreased. Also, the optimal microstructure was observed at the low rotation speed of 800rpm and the high transition speed of 124mm/min. The transgranular dimple and quasi-cleavage at fractured part of nugget zone were investigated.