The sample is quickly taken out to room temperature from the furnace adjusted to each temperature, cooled at room temperature, and quickly inserted into the furnace again. This cycle is repeated for 5 cycles.
The temperature is raised in increments of 50℃ if one sample does not crack, and the maximum value of the temperature range where cracking does not occur is the spall resistance temperature.

A heated load jig is placed in the center of the plate sample placed at room temperature to apply a thermal shock to the sample. A set of 5 samples per sample is performed in increments of 50℃ until all samples are cracked.The average temperature at which the sample cracks is taken as the thermal shock limit temperature.

After the heating test with a load applied at each temperature, the amount of sagging downward from the horizontal surface of the sample is measured with a dial gauge as the "deflection amount". The average value of the amount of deflection of the five sheets is taken as the result of that temperature.