Abstract
Controlling the chilling tendency of molten iron is essential for the production of high quality thin wall spheroidal graphite iron castings. The chilling tendency is usually evaluated with the cooling curves of CE meter specimens and the structures of standard chill specimens. However, these methods have the following drawbacks : The cooling velocity of very thin wall castings is considerably higher than that of CE meter specimens, and it takes a relatively longer time to assess the chill amount for standard chill specimens. The applicability of the ultrasonic test was thus examined as a nondestructive rapid evaluation method. 2.5mm wall spheroidal graphite cast iron specimens with 0 to 100% ledeburite were prepared. Ultrasonic absorption was evaluated in water. The results showed that damping capacity increased linearly with the increase in the fractional area of the ledeburite.
