炭素鋼の高温純水中における時間依存形き裂進展挙動

概要

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Subcritical-crack growth rates for carbon steels in high-temperature pure water are obtained from fatigue and constant load tests. The test specimens, made of STS 42 and 49 carbon steel pipes are CT type and surface-cracked flat plate-type. The experimental environment is saturated pure water at 288℃ and 7.8 MPa pressure. The subcritical-crack growth rates are influenced by several factors; the fatigue crack growth rate, da/dN in water is accelerated by low frequency and high stress ratio. The da/dN in water from a trapezoial load wave and for welded metal is less than from a triangular wave and for base metal. In addition, the da/dN in water at 150℃ and in a steam environment is lower than in water at 288℃. The growth rate, da/dN, in the thickness and the width directions is almost equivalent to the results of the surface-cracked flat plate specimens. The curve of the crack growth rate, da/dt, is obtained from the constant load test. The threshold value of the stress intensity factor for stress corrosion cracking for STS base and welded metal of carbon steels is relatively large when compared with the sensitized Type 304 stainless steel and other carbon steels.
社団法人日本機械学会の論文
1990-03-25