An improved steel substrate for preparing chromized steel, the substrate consisting essentially of a flat rolled plain low carbon columbium treated steel initially having a total carbon content of at least 0.03% and containing about 0.03-0.15% columbium. The steel substrate is the flat rolled product of the solidification of molten steel having the above composition. The carbon content of the steel substrate is partially stabilized whereby a controlled portion of the carbon is free to diffuse upon heating to an elevated chromizing temperature. The carbon content which is free to diffuse, the columbium content, and the thickness of the substrate are carefully correlated whereby the overall quality of the chromized product prepared therefrom may be controlled and maintained at optimum levels. The invention further provides the improved chromized steel products prepared thereby.