Abstract: Corrosion rate and corrosion behavior of four cold rolled carbon steel used for radiator manufacture have been studied in different dissolved oxygen and chloric ion concentration by weight loss test and electrochemical measurement.The structure and composition of the rust layer were examined by X-ray diffraction and scanning electron microscopy.The results shown that corrosion rate is mainly dependent on oxygen concentration in heating water system,after oxygen in solution has been removed,the rust consists of magnetite Fe₃O₄ and chloric ion increases corrosion of material.Corrosion resistance decreases with residual/stress.