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Evaluation of Mechanical Properties and Fatigue Behavior of STS 304L due to Plastic Working

소성가공에 따른 STS 304L 재료의 기계적 특성 및 피로평가

  • 심현보 (영남대학교 기계공학부) ;
  • 김영균 (한국가스공사) ;
  • 서창민 (경북대학교 기계공학부, 대구기계부품연구원)
  • Received : 2017.02.03
  • Accepted : 2017.02.20
  • Published : 2017.07.01

Abstract

The purpose of this study is to investigate the influence of the cold reduction rate and an ultrasonic fatigue test (UFT) on the fatigue behaviors of STS 304L. The tensile strength, yield strength, hardness value and fatigue limit in the UFT fatigue test linearly increased as thickness decreased from 1.5 mm to 1.1 mm, as the cold reduction rate of STS 304L increased. As a result of the UFT fatigue test (R = -1) of four specimens, the fatigue limit of the S-N curve formed a knee point in the region of $10^6$, and the 2nd fatigue limit caused by giga cycle fatigue did not appeared. In the case of t = 1.1 mm, the highest fatigue limit was 345 MPa, which was 64.3% higher than the original material (t = 1.5 mm). As a result of the UFT fatigue test of STS 304L, many small surface cracks occurred, grown, coalesced while tearing.

Keywords

Surface Cracks;STS 304L;Ultrasonic Fatigue Test;Rotary Bending Fatigue Test;Cold Reduction;LNG(Liquid Nitrogen Gas);Fatigue Limit

Acknowledgement

Supported by : 한국가스공사

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