Effect of Stress Ratio on Fatigue Fracture of a Shot Peening Marine Structural Steel

J. Ocean Eng. Technol. 2004;18(5):43-49.

PARK KYOUNG-DONG,JIN YOUNG-BEOM,PARK HYOUNG-DONG

쇼트피닝 가공된 해양구조용강의 피로파괴에 미치는 응력비의 영향

박경동,진영범,박형동

부경대학교 기계공학부,부경대학교 기계공학부 대학원,부경대학교 기계공학부 대학원

Keywords: Marine Structural Steel, Shot Peening, Crack Growth, Stress Ratio, Threshold Stress Intensity Factor, Fatigue Crack Growth, Stress Intensity Factor

핵심용어: 해양구조용강, 쇼트피닝, 균열성장, 응력비, 하한계 응력확대계수, 피로균열성장, 응력확대계수

Abstract

The lightness of components required in the automobile and machine industry necessitates the use of high strength components. In particular, the fatigue failure phenomena, which occurs when using metal, increases the danger to human life and property. Therefore, antifatigue failure technology is an integral part of current industries. Currently, the shot peening is used for removing the defect from the surface of steel, while improving the fatigue strength on surface. 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 a stress ratio(R=0.1, R=0.3, R=0.6) was investigated, giving consideration to fracture mechanics. By using the methods mentioned above, following conclusions are drawn: (1) The fatigue crack growth rate(da/dN) of the shot-peening material was lower than that of the un-peening material and in stage I,