Research and development at National Research Institute for Metals on structural materials for cryogenic use are described. The R & D are made up of development of new structural materials, testing technology at cryogenic temperatures and production and evaluation of materials data. Newly developed ferrous materials are 13% Nickel ferritic iron alloys and precipitation strengthened austenitic iron alloys. The strength of these materials is higher than that of the usual ones at lower temperatures. Several suitable materials are also found among titanium alloys. A simplified method for Charpy impact testing near liquid helium temperature was devised. At present, fatigue test facilities at liquid helium temperature are under construction and in the near future, the evaluation of life of materials will be started. Materials data base is regarded as a key for cryogenic technology and the study is recently undertaken as one of important projects. These basic research on structural materials are carried out comprehensively in order to make extensive contribution to cryogenic science the technology.
The correlation presented by Nishikawa and Fujita has been well known as a useful equation for the prediction of nucleate boiling heat transfer to room temperature fluids. This report describes a trial to apply this correlation to cryogenic fluids (He, H2, Ne, N2, Ar and O2). The original equation requires large values of the nucleation factor for the cryogenic fluids. However, using the modified pressure factor, a good coincidence is obtained between the correlation with reasonable values of the nucleation factor and the experimental data appearing in literatures.
A temperature-variable sample rotating cryostat has been developed in order to measure the angular and temperature dependence of the upper critical field in several single crystal Chevrel phase superconductors. In the cryostat, the temperature of the sample can be varied from 2 to 15K within an accuracy of ±10mK. The sample can be rotated with an accuracy of ±1°. in an adiabatic vacuum can around a horizontal axis at the center of our superconducting magnets which are able to generate magnetic fields up to 16.5T