Laboratory-scale experiments were carried out to improve the strength of the pre-stressed steel by combination of the Cr-Ti addition and heat treatment. A predetermined amount of the scrap and some ferrous alloys (such as FeMn, FeSi, FeCr and FeTi) was melted in the induction furnace. The molten steel was casted into the 45 mm ingot which was then hot forged into the 25 mm, subsequently prepared the tensile specimens that were heat-treated by quenching and tempering. After that, the hot forged and heat-treated specimens were subjected to the composition analysis, the tensile test and microstructural observation by optical and scanning electron microscopy. It has been concluded that the strengths of the prestressed steel strongly increased when the martensitic microstructure was obtained through the proper heat treatment. All the prepared steel exhibited a high strength and adequate elongation, especially the ultimate tensile strengths of the Cr-Ti added steel had reached the values of 961 and 1611 MPa corresponding to the hot-forged and heat-treated steel. This increase was attributed to the hardenability of the Cr element as well as the formation of the fine Ti precipitates which hindered the movement of the dislocation. The results suggested that further research must be conducted for the practical production of pre-stressed steel that is used in the constructional applications.
