Steels with a carbide-free bainitic matrix and retained austenite as second phase can provide excellent strength and ductility combination due to the transformation induced plasticity (TRIP) effect emanating from the retained austenite during deformation [1]. Such steels when hot rolled may be useful for making lightweight structural parts in heavy-duty vehicles as well as in passenger vehicles [2]. In this work, a few carbide-free bainitic steels (F1, F2, F3 and F4) with common alloying elements (C, Mn, Cr, Si, Mo) were theoretically designed conforming to the hot rolling practice and the design principles were validated in small-scale dilatometric specimens. Consequently, experiments on pilot-scale material were conducted and relevant mechanical properties (tensile, impact toughness and fracture toughness) and microstructures were characterised in detail to establish the structure-property correlations in these hot rolled steels