진동기구의 SAE 5155강재 부식에 따른 압축 잔류응력의 영향

The Effects of Compressive Residual Stress by Corrosion a SAE5155 Steel Vibrating Apparatus

A study of corrosive environment under shot peening processing, compressive residual stress formed within materials interacts with growth stress due to corrosion progress. This causes long time of protective coating formation and subsequent higher resistance of corrosion than un peening materials. Corrosion fatigue crack growth rate in each corrosive solution as a whole was lower for shot peening than un peening. This is regarded that the compressive residual stress acts as harness and slows down fatigue crack growth rate. Threshold stress intensity factor in the corrosive environment was lower under corrosive environment than at room temperature. This is regarded that in the range of low frequency stress intensity factor at the crack tip acts as a partial electrochemical corrosion and the growth of fatigue crack progress rate shows a low value. Fatigue life at room temperature is 453 percent higher for shot peening specimen than un peening specimen. The percentage was 294, 488 366 higher under corrosive environment of 6% FeCl3 solution, 10% HNO3 + 3% HF solution, 3.5% NaCl in aqueous solution respectively. The results indicate shot peening effects is high for critical corrosion.