Hot workability of a high carbon high chromium tool steel

In this work, hot tension tests were conducted on as cast and wrought samples of a high carbon high chromium tool steel to study the hot workability under the rolling conditions. The flow curves illustrate the classical shape of dynamic recrystallization (DRX). It is observed that broken carbide nets in the wrought samples result in lower deformation activation energy 398 kJ/mol in comparison to the as cast samples 432 kJ/mol. Necking strains were calculated using the inflection point of the work-hardening (θ) vs. stress curves. Wrought samples show higher hot ductility and lower maximum stress than the as cast ones. It is shown that lower activation energy of deformation and lower stress concentration around the smaller carbides in the wrought samples is responsible for their higher hot workability.

► The threshold energy for initiation of DRX at wrought condition is 398 kJ/mol.
► The threshold energy for initiation of DRX at as cast condition is 432 kJ/mol.
► Hot ductility of the as cast samples is lower than the wrought ones.
► Necking and DRX times decrease with increase of strain rate or temperature.
► As cast samples have lower necking times in comparison to the wrought samples.