BEHAVIOR OF STEELS NEAR THE INCIPIENT MELTING TEMPERATURE

A new method of incipient melting temperature (IMT) detection has been developed in which a constant-strain-rate tensile deformation is appl ied to a specimen whose temperature is simultaneously increasing. The IMT is determined in a single test, and any phase transformations befo re the IMT will also be detected by the effects on the stress vs strai n behavior in the same experiment. By means of such tests, the incipie nt melting behavior of a series of steels with carbon levels from 0.03 1 to 0.45 wt pct was examined. For the steels containing 0.08 to 0.097 pct C and about 1.5 pct Mn, it was found that incipient melting occur s in the two-phase (gamma + delta) region in the temperature range fro m 1470-degrees-C to 1480-degrees-C and is significantly influenced by microalloying elements. In the ultralow-carbon steel (0.031 pct C), th e IMT is in the single-phase delta region, and for the medium-carbon s teel containing 0.42 pct C (hyperperitectic) it is in the gamma single phase.