Journal of Ocean Engineering and Technology (한국해양공학회지)

Korean Society of Ocean Engineers (한국해양공학회)
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The Effects of the Microstructural Change of Dual Phase Steel on Fatigue Fracture Propagation

복합조직강의 미시조직변화가 피로파괴전파에 미치는 영향

  • Oh, Sae-Wook (Engineering College, Donga University) ;
  • Kim, Ung-Jip (Dept.of Mechanicals Engineering, Graduate School of Donga University)
  • 오세욱 (동아대학교 공과대학) ;
  • 김웅집 (동아대학교 대학원 기계공학과)
  • Published : 1991.12.01

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Abstract

Not only difference of fatigue crack growth and propagation behavior resulted from the grain size, the hardness ratio and volume fraction in M.E.F. dual phase steel composed of martensite in hard phase and ferrite in soft phase, but also the effects of the plastic constraint were investigated by fracture mechanics and microstructural method. The main results obtained are as follows: 1) The fatigue endurance of M.E.F. steel increases with decreasing the grain size, increasing the ratio of hardness and volume fraction. 2) The initiation of slip and crack occures faster as the stress level goes higher. These phenomena result from the plastic constraint effect of the second phase. 3) The crack propagation rate in the constant stress level is faster as the grain size gets larger, the ratio of hardness lower and volume fraction smaller.

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