INTERNAL FRICTION AND THE SPEED OF SOUND IN SINTERED HARD ALLOYS.

Development of new tools from powders of hard alloys for cutting of metals, as well as identification of the correct conditions for their application using existing methods of evaluation of cutting characteristics by mechanical testing, are very costly. Moreover, as was shown by analysis of the numerous experimental data, there is no strict correlation between service testing and laboratory methods for evaluation of mechanical properties in any testing temperature range. Because of this, the present work aims at the identification of those properties of tool materials which would permit correct forecasting of their behavior under stress at varying test temperatures. Internal friction is one of these properties. The experimental measurement of internal friction, absorption coefficient and the speed of sound as a function of temperature was carried out using the ultrasonic method.