Microstructure and Corrosion Behaviour of the Car Steels in Chloride Contained Environments

The DP۹۸۰, DP۵۹۰, and IF steels are used in the construction of car bodies due to their unique mechanical properties. In this paper, the corrosion behavior and microstructure of the DP۹۸۰, DP۵۹۰, and IF steels which are used in the automotive industry are investigated and evaluated. In order to evaluate the corrosion behavior of all three alloys, the electrochemical impedance spectroscopy and potentiodynamic polarization were evaluated in ۰.۱ M NaCl + ۰.۱ M H۲SO۴ and ۰.۱ M NaCl + ۰.۱ M NaOH environments. The corrosion evaluations of all three alloys show much better corrosion behavior in the alkaline environment than in the acidic environment due to the formation of the passive layer. While these alloys show much less corrosion resistance in the ۰.۱ M NaCl + ۰.۱ M H۲SO۴ environment, the uniform corrosion occurs while there is no evidence of the passive layer formation. The DP۹۸۰ and DP۵۹۰ dual-phase steels show lower corrosion resistance than the IF steel due to the presence of the ferrite and martensite phases and the possibility of galvanic cell formation at the interface between the two phases. The DP۹۸۰ dual-phase steel has a better corrosion behavior than the DP۵۹۰ due to the lower martensite content in both acidic and alkaline solutions, but the corrosion behavior of these two sheets of steel is very close to each other

Keywords:

Corrosion , Microstructure , Chloride contained environments , Electrochemical impedance spectroscopy , Potentiodynamic polarization , خوردگی , ریزساختار , محیط های کلریدی , فولاد خودرو , طیف سنجی امپدانس الکتروشیمیایی , پلاریزاسیون پتانسیودینامیک