• Title/Summary/Keyword: 시간의존형균열성장

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A Study on Transition From Cycle-dependent to Time-dependent Crack Growth in SUS304 Stainless Steel (SUS304강의 사이클의존형에서 시간의존형균열성장으로의 천이에 관한 연구)

  • 주원식;조석수
    • Journal of Welding and Joining
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    • v.14 no.1
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    • pp.38-46
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    • 1996
  • High temperature low cycle fatigue crack growth behavior is investigated over a range of two temperatures and various frequencies in SUS 304 stainless steel. It is found that low frequency and temperature can enhance time-dependent crack growth. With high temperature, low frequency and long crack length, ${\Delta}J_c/{\Delta}J_ f$, the ratio of creep J integral range to fatigue J integral range is increased and time-dependent crack growth is accelerated. Interaction between ${\Delta}J_f$ and ${\Delta}J_c$ is occured at high frequency and low temparature and ${\Delta}J_c$, creep J integral range is fracture mechanical parameter on transition from cycle-dependent to time dependent crack growth in creep temperature region.

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A Study on Prediction of Crack growth Rate Under Creep-Fatigue Interaction (크리이프-피로 상호작용하의 균열성장속도 예측에 관한 연구)

  • Joo, Won-Sik;Cho, Seok-Swoo
    • Journal of Ocean Engineering and Technology
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    • v.9 no.2
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    • pp.98-111
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    • 1995
  • High temperature low cycle fatigue shows that cycle-dependent crack growth owing to cyclic plastic deformation occurred simultaneosly with time-dependent crack growth owing to intergranular deformation. Consequently, to estimate crack growth rate uniquely, many to investigators have proposed various kinds of parameters and theories but these could not produce satisfactory results. Therefore the goal of this study is focused on prediction of crack growth rate using predominant damage rule, linear cumulative damage rule and transitional parameter ${\Delta}J_c/{\Delta}J_f$. On the basis of these sinusoidal loading waveform at 600$^{\circ}C$ and 700$^{\circ}C$.

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A Study on Fatigue Crack Growth Behavior at a Creep Temperature Region in SUS 304 Stainless Steel (SUS 304 강의 크리프 온도역에 있어서 피로균열성장거동에 관한 연구)

  • 주원식;오세욱;조석수
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.3
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    • pp.548-554
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    • 1994
  • The high temperature fatigue crack growth behavior of SUS 304 stainless steel at $550^{\circ}C$ and $650^{\circ}C$ was investigated under various kinds of stress ratio and frequency in sinusoidal waveform on the basis of the non-linear fracture mechanics. The result arranging crack growth rate by modified J-integral J' showed influence of stress ratio and frequency. All the data obtained under the test at $550^{\circ}C$ were plotted within data band of da/dN-${\triangle}J_f$ relationship for cycle-dependent crack growth. On the basis of static creep and cycle-dependent data band; both time- and cycle-dependent crack growth behavior was observed under loading conditions at $650^{\circ}C$, but cycle-dependent crack growth behavior predominantly appeared and time-dependent crack growth behaviour was little observed under loading conditions at $550^{\circ}C$. Fractographic examinations for fracture surface indicated that the fracture mode was generally transgranular. The stripes were found on fracture surface and each stripe was accompanied by a crack tip blunting and an abrupt increase in the load-point displacement. The $J'_{an}$ had a validity in case of $650^{\circ}C, but scarcely had it in case of $550^{\circ}C$.