MICROSTRUCTURE CONTROL OF FERRITE-PEARLITE HIGH-STRENGTH LOW-ALLOY STEELS UTILIZING MICROALLOYING ADDITIONS

The purpose of the paper was to summarize the role of microalloying ad ditions in the microstructure evolution control in ferrite-pearlite HS LA steels. The emphasis was placed upon employing high nitrogen conten t to increase grain refinement and precipitation strengthening in thes e steels. A complicated nature of the precipitation processes of carbo nitrides at different technological stages of steel processing, and it s relevance to the microstructure evolution and the mechanical propert ies of a final product was discussed. It was shown that increasing nit rogen content up to 150 - 200 ppm increased strength properties of ste els treated with V, Ti and Mb compared to the steels with low nitrogen contents.