Microstructural and mechanical properties of wire-arc additively manufactured Al-Zn-Mg aluminum alloy: The comparison of as-deposited and heat-treated samples

In this study, a thin-wall sample is built with a homemade Al-6.2Zn-2.2 Mg aluminum alloy welding wire using a gas welding arc as a heat source, then the deposit is subjected to the T6 heat treatment (HT). There are many second phases appeared in the as-deposited sample. Chemical analysis revealed an uneven distribution of Zn and Mg. The T6 HT processing reduced the amount and size of the second phase in the deposit, and Zn and Mg atoms are dissolved in the Al matrix, improving the elemental distribution in the sample. After T6 HT, properties of the deposits significantly changed: the average tensile strength (TITS) increased from 299 - 324 MPa to 389-402 MPa, the elongation decreased from 8.98%-9.66% to 4.18%-5.57%, and the microhardness is increased from 113 HV to 150 HV.