Effect of cooling rate and austenitizing temperature on the mechanical properties of commercial steels

The effect of grain size and cooling rates on the mechanical properties of two grades of steels has been followed after heating to 910, 950 and 1000 deg. C. In rerrite/pearlite steels of carbon contents (0.21 % and 0.28%). Increasing austenitizing temperature and furnace cooling did not affect either the grain size or the mechanical properties. This has been mainly due to the pinning effect of Nb, Al and Mn contents. While the cooling rate of 25 C/min refines the grain size by 3 mm-1/2 for 0.21% 1.5 mm-1/2 for 0.28% carbon and improved the mechanical properties specially the strength up to 1.5 KN/mm2. (author)