• 대한기계학회논문집A
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• 제40권12호
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• pp.1027-1035
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• 2016

내식성과 기계적 성능이 우수한 316L 스테인리스 강의 저주기 변형률제어 피로시험에서 3가지 변형률진폭과 3가지 변형률비의 조건이 피로수명에 미치는 효과를 분석하였다. 낮은 변형률범위에서 곡선이 거의 중첩되는 Masing 거동이 나타나고, 높은 변형률범위에서 비선형거동 응력범위가 서로 크게 벗어나는 non-Masing 거동과 함께 평균응력의 감소가 나타났다. 소성 변형률에너지를 이용하여 저주기 피로수명을 예측하고 non-Masing 거동을 고려한 수명예측 방법의 정확성 여부를 검토하였다. 각각의 변형률진폭과 변형률비의 조건에서 초기 수 사이클 동안 반복경화 현상 후 장시간동안 점진적으로 낮아져 연화하다가 파괴 되었다. 저사이클 피로수명을 정확히 예측하기 위해서는 변형률진폭에 따라 Masing 및 non-Masing 거동을 구분하고, 이를 반영한 수명예측식을 적용해야 함을 알았다.

• 대한기계학회논문집A
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• 제27권11호
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• pp.1856-1863
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• 2003

Overlay model had several advantages to describe hysteretic behavior of material and showed good capability for many engineering materials. However, this model is only applicable to material obeying Masing postulate. Some materials such as 316L stainless steel do not follow Masing postulate and show cyclic hardening(or softening) and strain range dependence. Low cycle fatigue tests of 316L stainless steel at 600$^{\circ}C$ were performed to investigate the characteristics of cyclic behavior of non-Masing material. From all tests cyclic softening was observed. There were differences in elastic limit of hysteresis loop according to applied strain range. To consider these features, modified overlay model was developed. Yield stresses of subelements were divided into isotropic and anisotropic part to describe the non-Masing behavior. The plastic strain range memorization was introduced to consider the strain range dependence. The prediction using modified overlay model showed a good accordance to actual hysteresis loops.

• 대한기계학회논문집A
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• 제28권4호
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• pp.333-342
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• 2004

Tensile and low cycle fatigue (LCF) tests on prior cold worked 316L stainless steel were carried out at various temperatures from room temperature to 650$^{\circ}C$. At all test temperatures, cold worked material showed the tendency of higher strength and lower ductility compared with those of solution treated material. The embrittlement of material occurred in the temperature region from 300$^{\circ}C$ to 600$^{\circ}C$ due to dynamic strain aging. Following initial cyclic hardening for a few cycles, cycling softening was observed to dominate until failure occurred during LCF deformation, and the cyclic softening behavior strongly depended on temperature and strain amplitude. Non-Masing behavior was observed at all test temperatures and hysteresis energy curve method was employed to describe the stress-strain hysteresis loops at half$.$life. The prediction shows a good agreement with the experimental results.