Development of Cold-Rolled High-Strength Formable Steel for Automotive Applications

Higher fuel consumption and increased CO2 emission due to increasing number of automobiles are the global concern. Weight reduction of automobile is one of the ways to overcome this problem, and hence the automakers need a stronger and formable material for advanced vehicle applications. Interstitial free high strength (IFHS) steel has been developed with the addition of solid solution strengthening element, P and Mn, but it generally exhibits low [image omitted]-value 1.6. The present article deals with an effort in developing a new cold-rolled batch annealed high strength steel with improved drawability ([image omitted]). Reduction in P and B in Nb +Ti steel resulted in an improvement in [image omitted]-value to 1.8, but the strength becomes lower. A commercial trial with an optimum amount of P, Ti, Nb, and B in ultra low carbon steel resulted in excellent combination of strength (YS220MPa, UTS350MPa) and formability ([image omitted] and n=0.22). In addition, this steel showed lower planar anisotropy (r=0.14) as compared to conventional steels.