高張力鋼切り欠き底からの応力腐食割れ発生特性

概要

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Stress corrosion tests were conducted on the notched compact tension specimens of quenchedtempered SNCM 439 steel in three kinds of environmental solution : distilled water,3.5%NaCl, and 0.1N H_2SO_4 The crack nucleation behavior was analysed from a view point of fracture mechanics. The results obtained are summarized as follows. (1) Time to crack nucleation t_n of the notched specimens with various root notch radii was determined by a parameter of K_ρ/(ρ+ρ_0)^<1/2>, where K_ρ is the apparent stress intensity factor, ρ is the notch root radius and ρ_0 is the intrinsic notch root radius. The life got shorter as the hydrogen content became larger in the order of distilled water, 3.5%NaC1, and 0.1N H_2S0_4. (2) Stress corrosion cracks were formed from the notch on three different planes : the original notch plane and two inclined planes to the notch. The crack plane changed depending on environments, notch-root radrii and stress levels. Two inclined plarles of crack initiation from the notch agreed with the plane of the maximum shear stress.
社団法人日本材料学会の論文
1990-07-15