VHCF Characteristics of A7075-T651 under Pressure Variation by Shot Peening Treatment

doi:2011.25.6.72

J. Ocean Eng. Technol. > Volume 25(6); 2011 > Article

J. Ocean Eng. Technol. 2011;25(6):72-79.
DOI: https://doi.org/10.5574/KSOE.2011.25.6.072

Suh Chang-Min,Kim Cheol,Kim Tae-Joon

School of Mechanical Engineering Kyungpook National University,School of Mechanical Engineering Kyungpook National University,Gyeongbuk Hybrid Technology Institute

쇼트 피닝의 압력변화에 따른 A7075-T651재의 VHCF 피로특성

서창민,김철,김태준

경북대학교 기계공학부,경북대학교 기계공학부,경북하이브리드부품연구원

Keywords: Shot peening, VHCF(Very high cycle fatigue), Fatigue characteristic

핵심용어: 쇼트 피닝, 기가 사이클 피로, 피로특성

Abstract

In this paper, the fatigue characteristics of shot peened A7075-T651 alloy were compared with those of the specimens without the shot peening. The multi-spindle and single-spindle rotating bending fatigue testing machines were employed for the evaluation. Shot peening (SP) with various pressure (5 psi, 10 psi, 15 psi, 25 psi and 35 psi) were used in this test. In order to investigate the effect of the applied pressure during the SP, we carried out the surface roughness test, compressive residual stress test, hardness test, tensile test, VHCF (Very high cycle fatigue) test and SEM observation. SP induced the formation of remarkable compressive residual stress from the surface to certain depth of sample by means of the plastic deformation. The surface hardness and the fatigue characteristics of the specimens were also modified by the SP. According to the S-N curves, fatigue lives of shot peended sample with 25 psi measures 50 times higher than that of the untreated sample. The fatigue lives of shot peened sample with 15 psi and 35 psi measure approximately 10 times higher than that of the untreated ones.