A Fatigue Testing Machine of Rotary-Loading Type for Liquid Metal-Environment at High Temperature and its Application to Study of Fatigue Strength of Low Carbon Steel in Molten Lead and Zinc

Abstract

The more extensive application of liquid metal coolants to high temperature heat exchange systems today requires the estimation of fatigue properties and creep resistance of metals and alloys in liquid metal environment at elevated temperature. Only a limited amount of work on this subject, however, has hitherto been carried out. This investigation has been started to study the effect of liquid metal environment on the fatigue properties of steels. With a view to securing reliable contact of the specimen with liquid metal and the accuracy of temperature measurement, a fatigue testing machine has been developed of a vertical, cantilever-bending, rotary-loading and fixed specimen type. The molten metal held in a steel container with ceramic coating with the specimen suspended in it is heated in an electric resistance furnace.The preliminary results obtained on the low carbon steel in air, molten lead and zinc at 460°C and 550°C are summarized as follows;(1) The fatigue strength in molten lead of 460°C and 550°C is less than that in air and in higher temperature the difference increases.(2) The fatigue strength in molten zinc is extremely decreased in comparison with that in air because of embrittlement by liquid metal, dissolution of steel into molten zinc and repeated formation and cracking of brittle intermetallic compounds.