In the present study HSLA steels of varying carbon concentrations, alloyed with Mn, Ni, Cr, Mo, Cu and micro-alloyed with Nb and Ti were subjected to different finish rolling temperatures from 850°C to 750°C in steps of 50°C. The microstructure of the steel predominantly shows martensite. Fine twins, strain induced precipitates in the martensite lath along with ε-Cu precipitates are observed in the microstructure. With an increase in carbon content the strength value increases from 1200MPa UTS to 1700MPa UTS with a negligible reduction in elongation. Impact toughness values of 20-26 joules at room temperature and -40°C were obtained in sub-size samples.
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