균열이 있는 STS316L 용접시편에 대한 초음파 핀 피닝 적용 시 피로수명 향상에 관한 연구

초록

Because cracks in a structure significantly shorten its fatigue life, ultrasonic pin peening was applied to improve the fatigue life of a structure with cracks. Fatigue specimens were fabricated via tungsten inert gas welding using stainless 316L, and microcracks with a width and depth of 0.2 ㎜ were machined along the weld toe. The test pieces were pin-peened using an ultrasonic pin-peening device. The effects of peening on the microstructure and hardness were investigated. Fatigue tests were performed on cracked specimens using a 20 ㎑ ultrasonic resonance fatigue tester. The peened and nonpeened test pieces showed a fatigue limit close to 2×106 cycles. The fatigue limits of the nonpeened and peened specimens were 55 and 140 ㎫, respectively. Peening increased the fatigue limit of the test specimen by 150%.

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