1966 年 15 巻 154 号 p. 507-511
This report is to present data for the effects of low temperature on the fatigue behaviors of welded joints of killed steel SM41, high tension steel HT50 and austenite stainless steel SUS27. Fatigue tests were carried out on plain and V-notched specimens having theoretical stress concentration factor 2 under direct cyclic stress in the temperature range of room temperature to -55°C.
The results obtained are summarized as follows:
(1) The fatigue strength of welded joints of various steels increases with the decrease of testing temperature: the increasing ratio of fatigue strength in SM41 is larger in plain specimens than that in notched specimens, on the contrary the ratio in SUS27 is larger in notched specimens than that in plain specimens and that in HT50 is nearly equal in both specimens.
(2) The fatigue strength of joints welded with different kind of steel is nearly equal to that of weaker joints welded with the same kind of steel, because the fatigue failure occurred at the heat affected zone of steel having lower fatigue strength.
(3) The fatigue strength reduction factor of SM41 increases with the decrease of temperature and that of HT50 scarcely varies. On the contrary the factor of SUS27 decreases with the decrease of temperature and SUS27 steel has the smallest reduction factor.
(4) The variation of fatigue strength reduction factor seems to be affected by the variation of yield ratio with the decrease of testing temperature.
(5) The variation of fatigue ratio with the decrease of temperature is different in various steels: the ratio in SM41 increases with the decrease of temperature, but that in SUS27 decreases. In HT50 the fatigue ratio is scarcely affected by the testing temperature.