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As is well accepted, any heavy duty parts of a vehicle, such as suspension and transmission systems, should be made of
special grades of microalloyed steels. In addition the experience shows that the temperature of these parts may locally rise up to about 200 °C. In the present work, relying on the in-house steel making potential, a series of vanadium microalloyed steels were prepared and successively heat treated to obtain different desired multi-phase microstructures. The related fatigue properties were then examined to investigate the effects of material and process variables. The results indicate that the increase of temperature would result in strain aging phenomena and this, in turn, may lead to higher fatigue life in ferrite-martensite dual phase microstructure.