Effect of cooling rates in a hypoeutectoid steel under forced convection conditions.

A physical model was developed to estimate the thermal history in hypoeutectoid steel under continuous cooling and forced-convection conditions. The thermal histories were acquired at different cooling rates to emulate the forced-convection conditions in a controlled cooling conveyor and compared in every cooling condition with the microstructural evolution of the pearlite. Through Scanning Electron Microscopy (SEM) the pearlite interlamellar spacing was determined, as well as Vickers hardness mechanical tests, validated the effect on the cooling rate on microstructural parameters such as transformation temperature and pearlite interlamellar spacing. It was found that air velocity increased the undercooling rate and decreased the pearlite interlamellar spacing.