EVALUATION OF TEMPER EMBRITTLEMENT BY ULTRASONIC-ATTENUATION

Research conducted up to the present time indicates the possibility of predicting the toughness of a material by utilizing ultrasonic attenu ation characteristics. However, practically all of the cases concerned involve the investigation of changes in toughness brought about by ma king large changes in the microstructure of the material. However, the temper embrittlement encountered in Cr-Mo steels and the like are acc ompanied by large degradations in toughness with virtually no changes in microstructure and tensile strength. For this reason, it has been c onsidered difficult to evaluate temper embrittlement based on ultrason ic attenuation characteristics. In the research reported here, sensiti vity was enhanced by increasing the ultrasonic frequency (to 50 MHz) a nd the correlation between ultrasonic attenuation characteristics and temper embrittlement characteristics has been experimentally clarified .