A study of the mechanical properties and chemical composition of some HYS 12 concrete reinforcement steel rods produced in Nigeria

Abstract

‘A Study of the Mechanical Properties and Composition of Some HYS 12 Concrete Reinforcement Steel Rods Produced in Nigeria’ has been carried out. The work started with the collection of samples from four different mini mills in Nigeria. These samples were prepared into standard test specimens for the various tests according to the standard specifications for those tests, which included hardness test, impact strength test, tensile test and chemical composition test using Spectro-lab metal analyzer (Fe-01-F). From the results obtained; the study has shown that the value of the mechanical properties that were investigated, which included; hardness, impact strength, yield strength, ultimate tensile strength, and % elongation at failure were all determined by their chemical compositions; particularly, carbon, silicon, and phosphorus. Specimen G4 has the highest mechanical properties of all the mechanical properties tested. It has a hardness value of 34.4BHN, impact strength of 275.0J, yield strength of 526.13 N/mm2, and ultimate tensile strength of 610.01N/mm2. Specimen F3 has the highest % elongation at failure of 15.67%. Specimen A1 has the least % elongation at failure of 8.57%. The higher the value of the strain hardening rate the better for HYS 12 concrete reinforcement steel rods, since this will allow sufficient time for occupants of the building to escape before final failure. In conclusion the work has clearly shown that the mechanical properties of the HYS 12 rolled steel rods studied were dictated by the size, amount, and distribution of the Carbon / cementite phase and on the structure of the metal matrix. This in turn depended on the chemical composition of the specimens, in particular their carbon and Silicon content, and also on processing variables such as method of melting, inoculation practice and the cooling rate of the rolled steel bars. The three constituents of steel, which most affect strength and hardness, they are; total carbon, silicon, and phosphorus.