Achieving a high corrosion resistant and high strength magnesium alloy using multi directional forging

Highlights: • A new magnesium alloy was prepared by melting, then extrusion and finally MDF at different temperatures. • MDF improved the corrosion rate significantly where at the optimized condition, an ultra-low corrosion rate alloy was achieved where the corrosion rate was even less than that of high purity Mg and equal to ultra-purity Mg which is the lowest corrosion rate according to the reviewed literature, due to no micro-galvanic corrosion by impurities. • The optimized corrosion rate was obtained via MDF at 300 oC. • Corrosion rate reduction after MDF was due to removal of elongated grains with prismatic orientation, uniform distribution of grains size and secondary phase. • The present research suggests a new method to produce ultra-low corrosion rate, high strength light Mg alloy. -- Abstract: An attempt was made to develop a corrosion-resistant, high-strength Mg alloy using multi-directional forging (MDF). An extruded alloy as well as pure Mg was MDFed at temperatures between 220 and 340 °C with 40 °C intervals. Grains, second phase distribution, and Volta-potential difference between second phases and matrix were measured. Moreover, tensile and compression tests were used to assess mechanical properties. The corrosion behavior was characterized using electrochemical, hydrogen evolution, and mass loss techniques. A corrosion-resistant Mg alloy with a corrosion rate less than even high purity Mg obtained which has not been previously reported for a light Mg alloy. It was found that the lowest corrosion rate can be obtained for the alloy MDFed at 300 °C.