An investigation on the usability and corrosion resistance of the dual-phase steel in the reinforced concrete structures

In this dissertation study, SAE1010 structural carbon steel, which is the fundamental construction material of construction industry and wide range of product in our country, has been studied as dual phase steel by applying appropriate heat treatment and its mechanical properties and corrosion behavior in the concrete have been investigated for various tempering conditions.Dual-phase steel having different martensite volume ratio has been obtained by applying different quenching conditions; its (?+?) structure, which is obtained over A1 temperature by heating, is immersed into the ice+water medium and then it is annealed for various duration; 20, 40 and 60 minutes. Additionally, these dual-phase steels have been tempered at 200, 300 and 400 oC for 45 minutes and then cooled to the room temperature. Mechanical properties such as tensile strength, yielding strength, reduction of cross sectional area, total elongation, resilience modulus and toughness have been determined and metallographic examination of the steels has been done. In addition, fractographic examination has been studied with Scanning Electron Microscope (SEM) as well as their corrosion behavior in concrete.It is observed that mechanical properties of dual-phase steel have changed according to the hardness and ratios of martensite phases. Tensile strength, yield strength and resilience modulus of the steels have reduced, the total elongation, reduction of the cross sectional area and toughness have been increased upon to the tempering heat treatment. However, corrosion resistance of dual-phase steel in concrete decreases comparing to that of ferritic-perlitic structure and corrosion resistance have reduced with tempering heat treatment.