Assessing the Hardness of Quenched Medium Steel Using an Ultrasonic Nondestructive Method

Table 3

Relation of wave length and average grain size with different temperatures.

Temperature (°C)	760	800	840	880	920
Wave length (5 MHz, m)	1.174	1.178	1.179	1.182	1.176
Wave length (10 MHz, m)	0.589	0.588	0.590	0.588	0.588
Average grain size/wave length; (5 MHz, %)	1.5	1.9	1.6	0.9	0.9
Average grain size/wave length; (10 MHz, %)	3.0	3.7	3.1	1.8	1.8