+Effect of niobium on microstructure and properties of 6016 aluminum alloy

Abstract

6016 aluminum alloys with different niobium contents were prepared by smelting and casting. The alloys were rolled and heat treated, and the effect of niobium on microstructures and properties of the alloys were studied. The results show that the as-cast alloy consists of Mn-rich phases, Cu-rich phases, Mg-rich phases, Si-rich phases and small blocks of Zn-rich phases, and Nb element is solidly dissolved in these phases and matrix. After solution and pre-aging treatment, recrystallization occurs in the rolled alloy. The grain size of the rolled alloy is obviously smaller than that of the as-cast alloy, and the second phase precipitates dispersively. After solution treatment or solution treatment + pre-aging treatment, the tensile strength and plasticity of the alloy are significantly improved. With the increase of niobium content, the number and size of the second phase increase. The alloy with 1%Nb in T4P condition has the better comprehensive mechanical properties, and its elongation after fracture, tensile strength, yield strength, plastic strain ratio and strain hardening index are as following respectively: 34.20%, 372.77MPa, 208.54MPa, 0.82, 0.32.