• Processing of bimodal ultrafine grained microalloyed dual phase steel sheet, the said steel sheet

(i) Normalization

• Normalization of a hot rolled microalloyed steel plate of 6 mm thickness at 930°C for 30 minutes to remove the pearlite banding

(ii) Warm rolling

• Warm rolling of normalized steel to a true strain of 2.4 in thickness

(iii) Intercritical annealing

• Intercritical annealing of warm rolled sheet at 700 – 800°C for 2 – 3 minutes in salt bath furnace followed by water quenching to room temperature,
• steel sheet is characterized by a heterogeneous grains of fine and ultrafine ferrite microstructure and
• Martensite dual phase steel, comprising a mixture of 50 vol. % to 85 vol. % of polygonal ferrite dispersed with 15 vol. % to 50 vol. % of colonies of lath martensite and 2-4 nm niobium carbonitrides (Nb(C, N)) and vanadium carbonitrides (V(C, N)) precipitates,
• where the chemical composition of the microalloyed steel in wt% is C (0.12 – 0.20), Si (0.2 – 0.45), Mn (1.0 -2.0), Nb (0.015 -0.03), V (0.05 – 0.08), S (0.006 – 0.008), P (0.009 – 0.013), N (0.009 – 0.012) and the remaining is Fe.