Development of corrosion-resistant Mg-Al-Ca-Mn-Zn alloy sheet with good tensile properties and stretch formability

To develop high-performance magnesium alloy sheets for sheet applications in the automotive industry, we investigated the effects of the Al content on the tensile properties, stretch formability, and corrosion re-sistances of Mg-xAl-0.5Ca-0.4Mn-0.8Zn (mass%, x = 2, 5, 8, AXMZx101) alloy sheets. The addition of 5% Al led to the highest limiting dome height of 6.4 mm. The AXMZ5101 alloy sheet also exhibited a good combination of in-plane isotropic strength and ductility. The 0.2% proof stress and elongation to failure were 193 MPa and 24.2% for the rolling direction and 188 MPa and 23.1% for the transverse direction, respectively. Such moderate Al addition resulted in a significantly improved corrosion resistance with a corrosion rate of 0.18 mm/y after immersion in a 3.5% NaCl solution for 7 days, which was approximately 1/ 4 lower than that of a commercial Mg-Al-Zn alloy sheet. An in-depth characterization revealed that such a good combination of tensile properties and stretch formability is associated with the small grain size, weak basal texture, high work hardenability, and activation of nonbasal slips and that a high corrosion resistance should be achieved by the formation of a dense oxide-rich layer. (c) 2022 Published by Elsevier B.V.

Automated summary

By investigating the effects of Al content on the mechanical properties, formability, and corrosion resistance of magnesium alloy sheets, it was found that moderate Al addition significantly improves these properties, resulting in good overall performance of the alloy sheets.