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3% NaCl 수용액중에서 복합조직강의 부식피로 파괴거동에 미치는 주파수변화의 영향
오세욱(S.W. Oh),신규동(K.D. Shin),김웅집(W.J. Kim) 한국해양공학회 1995 韓國海洋工學會誌 Vol.9 No.2
Fatigue tests were carried out by a rotary bending testing machine of cantilever type. M.E.F(ferrite encapsulated islands of martensite) materials were made by a series of heat treatment from a low carbon steel(SM 20 C). The fatigue tests were conducted at stress levels of 302 MPa and 137 MPa with frequencies of 25 ㎐, 2.5 ㎐ and 0.5 ㎐ in 3% NaCl solution.<br/> The fatigue strength increased with frequency got higher. The microcracks and corrosion pits were generated at the boundary between the matrix and the 2nd phase. The cracks generated by the corrosion pits were coalesced with the pits around the notch and became the initial crack. The Ni/Nf ratio increased as the frequency and stress level decreased. The interference phenomenon increased with stress level and frequency gots higher. The crack propagation rate was delayed as the stress level lowers and the frequency gets higher, however, the range of the stress intensity factor depended only on a stress level.