Experimentally based study on the effect of initial grain size for characterization of the grain coarsening phenomenon during hot rolling of a mediumcarbon steel

Laboratory experiments using a hot deformation simulator were carried out t o clarify the effect of initial grain size on the grain coarsening phenomen on in hot metal working with light reduction. As an example of medium carbo n steel, AISI1045 was adopted and specimens to various grain sizes were pre pared by changing the thermo-mechanical histories. They were subjected to a hot deformation testing by the simulator. The threshold grain size to caus e the grain coarsening phenomenon was then determined and a criterion was p resented to ensure a fine grain after hot rolling. The validity of the new criterion was checked through hot rolling of bars by a prototype mill in a laboratory.