Experimental specimens prepared with stamped wrought Al 6451 alloy, which mainly contains 0.75 % Si and 0.58 % Mg and widely applied in automotive industries for body closure, were tested for tensile properties by comparing uncoated and plasma electrolytic oxidation coated specimens subjected to tensile tests. The properties including ultimate tensile strength (UTS), yield strength (YS), elongation (e f ) and elastic modulus (E) were evaluated by tensile tests. Following the coating layer built up to 3 μm and 10 μm, the ultimate tensile strength reduced from 161.5 MPa to 143.6 MPa, 137.0 MPa, the yield strength reduced from 86.8 MPa to 38.6 MPa and 38.0 MPa, the e f reduced from 16.2 % to 15.0 %, 15.3 %, the elastic modulus elevated from 62.9 GPa to 84.4 GPa, 79.0 GPa, respectively. The microstructure was analyzed by scanning electron microscope and energy dispersive spectroscopy, and the observations indicated that the coating layer provided initiation sites of cracking and consequently reduced the tensile strength and strength hardening rates of the alloy under tensile loading.
Zheng et al. (2026) studied this question.