溶融すず, 鉛および亜鉛中における軟鋼の疲労強度

切欠き材の場合

抄録

The increasing use of liquid metal coolants for compact heat exchanger demands the basic knowledge of the fatigue properties of solid metals when brought in contact with liquid metals. In the present paper, the fatigue test of notched specimens made of low carbon steel was carried out in molten tin, lead and zinc at elevated temperature with the fatigue testing machine of the rotating loading and fixed-specimen type. The results obtained are summarized as follows;
(1) The fatigue strength of a notched specimen in molten tin is lower in the higher stress with a smaller number of cycle range at the test temperature of 250∼550°C than that in air, but higher by 13∼34% in the lower stress with a larger number of cycle fatigue.
(2) The fatigue strength of a notched specimen in molten lead compared with that in air is considerably reduced at every test temperature over the whole range of number of stress cycles.
(3) In molten zinc the fatigue strength of a notched specimen is not so extremely reduced as in the case of an unnotched specimen in the lower stress with a larger number of cycle range because of mechanical strengthening by intermetallic compounds at the root of the notch.
As mentioned above, the fatigue strength in molten metal depends upon the kind of molten metal, the shape of the specimen, test temperature, the number of stress cycles and so on. In order to arrange the effects of environment on the fatigue strength, fatigue-environmental factor, f_env, was newly introduced, which is the ratio of fatigue strength in a liquid metal environment to that in air. Consequently, it is considered that the factor is adequate in estimating the fatigue strength in various environments qualitatively and quantitatively.