Effect of Calcium and Magnesium Addition on the Cast Microstructure of HSLA Steel

Using the oxide of high melting-point and high stability to pin the grain boundaries is an effective method to improve the welding performance of the HSLA steel in this study. A kind of HSLA steel is designed in this experiment. The thermal stability second phase particles which would not be dissolved or aggregated at high temperature will be expected by means of adding calcium and magnesium simultaneously into the steel in the form of Si-Ca alloy and Mg-Zr alloy. The effect of calcium and magnesium addition on the cast microstructure and inclusions of HSLA steel were analyzed. The results show that the cast microstructure is mainly consist of lamellar and acicular ferrite, a small amount of pearlite and bainite. Compared with the original steel, there are bainites presenting in the experimental steel after adding 3 wt% Ca and 3 wt% Mg at the same time.