| The steel for use as a Reactor Pressure Vessel(RPV) should have the high resistance to thermal fatigue, because it is run in high pressure water vapor of about 288℃ and exposed, in addition, to the irradiation of neutron constantly. In this work, low cycle fatigue characteristics of the three kinds of steels has been investigated, which are produced by different steel making processes, i.e. the conventional Vacuum Carbon Deoxidation(VCD) process, the method of adding Al to the former for the purpose of grain refining, and the method to use Si-killing process in place of VCD and also to add Al. The material made by VCD+Al and Sikilled+A1 process exhibited longer fatigue life than the specimen produced by VCD. This result is mainly caused by the difference in grain size, and the morphological difference at each specimen. The distribution of carbides in bainite structure is also thought to have an effect on their mechanical properties to some extent. |
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