• Title/Summary/Keyword: Double Shot Peening

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Evaluation of Harmless Crack Size of SCM822H Steel by Double Shot Peening (이중 쇼트 피닝에 의한 SCM822H 강의 무해화 균열 크기 평가)

  • Jin-Woo Choi;Seo-Hyun Yun;Yung-Kug Kwon;Gum-Hwa Lee;Ki-Woo, Nam
    • Journal of the Korean Society of Industry Convergence
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    • v.26 no.6_2
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    • pp.1011-1017
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    • 2023
  • In this study, the harmless crack size (ahml) by double shot peening (DSP) using shot balls with different diameters was evaluated on carburized, quenched-tempered SCM822H steel. The minimum crack size (aNDI) detectable by non-destructive inspection was also evaluated. The relationship between the crack size (a25,50) that reduces the fatigue limit by 25% and 50% and ahml was evaluated. The residual stress of DSP was greater in SP(0.6+0.08) than SP(0.8+0.08) and appeared deeper in the depth direction. In addition, the hardness below the surface appeared larger. The fatigue limit of DSP increased 2.07 times and 1.95 times compared to non-SP. All ahml of the DSP specimen was determined at the depth (a). The compressive residual stress distribution affects ahml, and the ahml of SP(0.6+0.08), which has a large compressive residual stress and a high fatigue limit, appeared large. ahml of SP(0.6+0.08) introduced deeper than the residual stress of SP(0.8+0.08) is larger in the range of As=1.0-0.3. Since the residual stress in the thickness direction has a greater effect on ahml than the residual stress at the surface, it is necessary to introduce it more deeply. The relation of ahml, a25,50, and aNDI were evaluated in the point for safety and reliability.