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Vol.36, No.6, 823 ~ 831, 1998
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| Title |
| Effect of Heat Treatment on the Low Cycle Fatigue Behavior of a High Strength Spring Steel |
| 김광원 Kwang Won Kim , 유선준 Sun Jun Yoo , 남원종 Won Jong Nam , 이종수 Chong Soo Lee |
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| Abstract |
| In the present investigation, the low cycle fatigue(LCF) behavior of a high-strength steel heat-treated to different strength levels has been studied using the cylindrical smooth specimens under strain-controlled fully reversed pull-push condition: During the strain-controlled cycling the steel exhibits continuous softening behavior independent of the applied strain levels and heat-treatment. It has been found that the saturation of the plastic energy density per cycle(△W) proves to be a valid criterion to determine the stable hysteresis loops for establishing the cyclic stress strain(CSS) curve. The strain-life curve calculated on the basis of the CSS relationship is in good agreement with the experimental result, indicating a fine consistency between data from the CSS approach and from the strain-life approach. Then, the LCF properties are discussed with regard to their dependence on the heat treatments or strength levels of the steel investigated. Finally, the low-energy dislocation substructures during LCF have been identified using transmission electron microscopy. |
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| Key Words |
| Low cycle fatigue, High-strength steel, Cyclic softening, Plastic energy density per cycle, Low-energy Dislocation substructures, Slip bands |
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