| Title |
Effect of Heat Treatment on the Low Cycle Fatigue Behavior of a High Strength Spring Steel |
| Authors |
김광원(Kwang Won Kim); 유선준(Sun Jun Yoo); 남원종(Won Jong Nam); 이종수(Chong Soo Lee) |
| Keywords |
Low cycle fatigue; High-strength steel; Cyclic softening; Plastic energy density per cycle; Low-energy Dislocation substructures; Slip bands |
| 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. |