Effect of hot rolling history and cooling rate on the phase transformation of plain carbon steel

Bars from plain carbon steel were hot rolled in the new laboratory semi-continuous mill with the application of various total deformation. The phase transformation temperatures were determined from the surface temperature-time curves registered in the course of free cooling of the rolled products. The A(r3) temperature was influenced by the total amount of the previous deformation, and it increased with the descending rolling temperature. The obtained results were verified by metallographic analyses, and they were compared with the CCT and DCCT diagrams, constructed from the results of dilatometric tests. The performed experiments illustrate the useful cooperation of plastometric and laboratory hot rolling experiments, as well as the potentiality of a simple study of the non-isothermal decomposition of austenite using analysis of the cooling curves.