Study On The Influence Of Polishing After Shot Peening On 300M Steel

300M steel is a kind of low alloy ultra-high strength steel, which is widely used in the manufacture of several key parts, for example, the aircraft landing gear. Based on the requirement of a domestic aviation enterprise, the influence of polishing after shot peening on 300M steel and its mechanism are studied in this paper.This paper's experiments include specimens' manufacture, shot peening and polishing, residual stress mensuration, surface roughness mensuration, fatigue tests and fracture surface analysis.First, the influence of shot peening on residual stress and fatigue performance on 300M steel was studied. By the way of X-ray stress measurement, the characteristics of residual stress distribution of specimens, which were shot peened at different intensities, were studied; and by the way of three-point bending fatigue test, the influence of shot peening intensity on 300M steel specimens' fatigue performance was studied. Studies show that the shot peening intensity is not always the higher the better.The focus of this paper is the study on the influence of polishing after shot peening on 300M steel. By the way of X-ray stress measurement and three-point bending fatigue test, the characteristics of residual stress distribution and fatigue performance of the specimens were studied, which were shot peened at the same intensities but polished at different depths. On this basis, the reason why Shot Peening Standards provide that the depth of metal removal does not exceed 10% of the specified arc height was analysed. Research shows that proper polishing after shot peening on 300M steel is good to increase its fatigue performance.