Effects of thermomechanical treatments on microstructure and mechanical behavior of HCS/LCS bimetal

A high carbon steel (HCS) and low carbon steel (LCS) bimetal was fabricated by centrifugal composite casting. Two different thermomechanical treatments (TMT1 and TMT2) were employed to improve the mechanical properties of the bimetal. TMT1 process includes 60% of overall reduction by hot compression with temperatures of 1100 and 800 °C, respectively. While TMT2 process involves 60% of overall reduction using the two-step deformation method, which is a combination of non-isothermal compression cooling from 1100 to 800 °C and isothermal compression at 800 °C. The flow stress behavior, microstructural evolution and microhardness variation were analysed. Experimental results show that both TMT processes contributed to the improvement in mechanical properties resulting from a refinement of the grain size and an increase of density of pearlitic lamella in HCS layer. However, TMT2 process gave a better efficiency and a more significance in improvement of properties with the evidence of the same overall reduction leading to a higher microhardness. © (2014) Trans Tech Publications, Switzerland