In this work an investigation was conducted into the tempering effects on mechanical properties of a carbon steel and a microalloyed steel, both with dual phase microstructure. The UTS and YS decreased and elongations increased with an increase of tempering temperature. However, the loss in UTS and YS at tempering temperatures of 100, 200, 300, 400, 500 and 600 degrees C was a minimum for microalloyed dual phase steel. This is thought to be due to tempering of the martensite and precipitation in the ferrite. (C) 2009 Elsevier B.V. All rights reserved.