Ultrasonic inspection of heat-treatment quality for large press forgings

1.The basic reason for total or partial nonsounding for large forgings during ultrasonic inspection is the presence of coarse grains grown during heating castings after forging (reheated structure) which is not refined due to improper heat treatment.2.After carrying out normalization and tempering properly, large forgings have a fine-grained microstructure (grain size Nos. 5–8) with good sounding (not less than four bottom echo signals).