A common process of auto-parts production consists of forging, normalizing, quench and tempering. Normalizing treatment is usually employed to improve machinability of steel, and to homogenize and refine the microstructure. For simple parts, production cost would reduce if normalizing stage were eliminated. In this paper, effects of normalizing on properties of a carbon steel has been studied. Experiments have been carried out at industrial conditions on forged, quenched and tempered parts. Results show minor effect of normalizing on microstructure, hardness and tensile properties. However, specimens normalized after forging indicate improved fatigue life at different stress amplitudes. Forty samples were tested for each heat treatment at three different stress amplitudes. Statistical analysis of the results proves meaningful reduction in number of cycles to failure for specimens without normalizing treatment. It is believed that more number of cracks in these specimens and more coalescence of cracks cause the early failure of specimens. Disperse ferrite areas in microstructure seem to be the preferred initiation sites and different distribution of ferrite in the microstructure of samples leads to different fatigue lives.

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