高温水中におけるSUS 304の低サイクル疲労強度と破面

概要

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The low-cycle fatigue tests at various strain rates and strain wave forms were conducted on sensitized and solution treated 304 S.S. in 573K water with 8ppm dissolved oxygen. The results based on the fractographical study are as follows:(1) The low cycle fatigue life of 304 S.S. in high temperature water was shorter than that in air and affected by sensitization, strain rate and strain wafe form.(2) In the sensitized 304 S.S., cracks initiated in intergranular mode, while in the solution treated one they initiated in transgranular mode.(3) In the sensitized 304 S.S., the fracture mode changed from the intergranular type to the transgranular type when the crack propagation rate (da/dt)T reached to about 1×10-8m/sec.(4) When cracks propagated in transgranular mode, the crack propagation rate was affected by the tension going frequency, not by sensitization.