1885

ABSTRACT The present investigation concerns the influence of Cu on the ageing behavior of the Cu -added Ti, B microalloyed steels subjected to air cooling and water quenching after hot rolling. The microstructural evolution and mechanical properties achieved in the cases of Cu -added and Cu -less steels has unveiled the favorable role of Cu in forming the ferrite -martensite dual phase structure after air cooling and bainitic structure after water quenching of the hot rolled steel. The Cu -added samples after hot rolling followed by air cooling and water quenching are subjected to the isochronal ageing at appropriate temperatures with and without 15% cold deformation prior to the ageing. After carrying out ageing treatment of the hot rolled samples without any cold deformation, nominal improvement in the hardness value has been recorded at the peak ageing temperatures. Air cooled and water quenched samples after 15% cold deformation have yielded significant improvement in hardness by subsequent ageing treatment. It has also been demonstrated that a suitable amount of cold deformation prior to the ageing treatment aids in lowering the peak ageing temperature in comparison to the samples aged without any prior cold deformation