Improving tensile properties of a room-temperature formable and heat-treatable Mg–6Zn-0.2Ca (wt.%) alloy sheet via micro-alloying of Al and Mn

Abstract

We have developed a strong Mg–6Zn-0.2Ca (wt.%) based alloy sheet with good room-temperature formability via micro-alloying of Al and Mn. The Al and Mn micro-alloyed Mg–6Zn-0.2Ca-0.1Al-0.1Mn (wt.%, ZXAM6000) alloy sheet forms fine grain structure with an average grain size of 15 μm and weakened basal texture, in which (0001) planes of most grains split to both rolling and transverse directions, leading to a good Index Erichsen value of 7.2 mm along with moderate 0.2% proof stresses of 155 MPa (rolling direction) and 120 MPa (transverse direction). After an aging treatment, the alloy sheet shows notable increase in the strengths; the peak-aged ZXAM6000 alloy sheet exhibits high 0.2% proof stresses of 264 MPa and 209 MPa along the rolling and transverse directions. The balance of the 0.2% proof stresses and the Index Erichsen value of the developed alloy sheet is comparable to that of Al–Mg–Si based 6xxx alloy sheets; hence, the developed alloy sheet may broaden the application of wrought Mg alloys in automotive industries.