溶融PbおよびSn中における軟鋼,13Cr鋼および18-8鋼の高温疲労強度

There is extensive use of liquid metal at elevated temperatures as the coolant of heat exchanger, as the information and pressure medium, as the electro-magnetic fluid, as the lubricant and so on, for their excellent thermal and electrical characteristics. In using the liquid metal, however, there are many problems. One of them is that, in the case of structural materials, the metal weakened not only by the corrosion effect but also by combined effect of the alternating succesion of stress and the embrittlement by liquid metal. In the last mentioned respect, the present paper gives the fatigue tests of low carbon steel, 13Cr steel and 18Cr-8Ni steel in air and in contact with liquid tin and lead, in order to examine the fatigue resistance of various steels that were brought into contact with molten metals at elevated temperatures. The 18Cr-8Ni steel showed the smallest percentage decrease in fatigue limit of the three kinds of steels tested as the results. The discussion based on this experimental result has led to conclusion that the rich ductility of austenitic steel due to its having been employed in solution heat-treatment and the notch insensibility of 18Cr-8Ni steel for liquid metal embrittlement resist the fatigue damage.