鋳造合金鋼に対する熱き裂性の測定結果

抄録

  The life of tools for hot work is influenced not only by wear but also by hot check caused due to repetition of heating and cooling. In order to investigate the hot check phenomena occurring on cast tools for hot work the authors built a testing machine which was useful to reproduce hot check on a laboratory scale. The machine has an advantage that hot check can be easily produced by such a way that a number of test pieces are simultaneously subjected to a repetition of thermal shock under the same condition. Experimental results were:
  1) Accuracy and reproducibility of the measurement was established by using a method in which a thermocouple was buried at a point of 0.5mm below the surface of specimen.
  2) The roughness of the surface of specimens had no effect upon the accuracy and reproducibility of measurement, unless the roughness was too great.
  3) As a result of experiments, it was known that cast steel was higher in the resistance to hot check than cast iron or cobalt base alloys.
  4) Experimental results thus obtained seem to be useful for developing the production of cast tools in practice.