MONITORING THE BAINITE REACTION DURING AUSTEMPERING OF DUCTILE IRON AND HIGH SILICON CAST STEEL BY RESISTIVITY MEASUREMENT.

The accurate and rapid detection of austenite transformation (phase changes) during austempering of ductile iron and two high silicon cast alloy steels, by use of resistometry is described. The steels were alloyed with 1. 5% Ni and 0. 3% Mo. The resistometer is composed of a radiant heating furnace, a constant current source, a voltmeter, and the appropriate control and recording instruments. The results obtained by hardness measurements, x-ray measurements of austenite and metallography confirm that the resistometry technique is correctly detecting the critical stages of transformation occurring during austempering of ductile iron and high silicon cast steel.