Effect of surface pretreatment on corrosion resistance and bond strength of magnesium AZ31 alloy

► Phosphating process to AZ31 with additives of Na2MoO4 and NaF was developed. ► A coating that mainly contains Mg3(PO4)2, MgO, Mg (OH)2 was formed on the AZ31. ► Na2MoO4 and NaF improve the bond strength and corrosion resistance of the AZ31. ► A Model is used to optimize the content of Na2MoO4 and NaF in phosphate solution.