Abstract: The progress in deformation mechanics of alloy with two ductile phases widely used in the industrial production is reviewed in the paper. Developments and applications of mixture law describing strength of fibre composite materials in the dual phase steels are introduced, Mileiko's theory based on assuming equal strain in both phases, model for stress-distribution in both phases, continuum model based on assuming strain-distribution in both phases and micfo-mechanics model based dislocation theory as well a...