Study on hot-working behavior of high carbon steel / low carbon steel composite material using processing map

The high carbon steel (HCS)/low carbon steel (LCS) laminated composite made by centrifugal casting technology was subjected to hot compression tests on Gleeble 3500 thermomechanical simulator in a range of temperatures (800-1100 oC) and strain rates (0.02-10 s-1). The hot-working behavior of the laminate was characterised by analysing the flow stress-strain curves and constructing the processing map based on dynamic materials model via superimposing efficiency of power dissipation and flow instability maps. The safe and unsafe processing conditions were identified in the processing map which was validated by microstructural examinations. Banded microstructure and micro-shear cracks occurred in the unsafe domains were responsible for the flow instability, while dynamic recrystallisation in stable domains with high efficiency of power dissipation imparted a good workability to the laminate. The optimum hot-working parameters were determined to be: (i) 800-1050 oC and 0.02-0.04 s-1, (ii) 800-1045 oC and 2.5-10 s-1 and (iii) 1050-1100 oC and 0.02-2.5 s-1.