Modeling mechanical properties and plastic strain for hot forming-quenching AA6061 aluminum alloy parts

Abstract

The hot forming-quenching integrated process (HFQ) has proved to be an effective forming method, achieving good formability and excellent mechanical properties simultaneously for aluminum alloys parts. However, the relationship between the mechanical properties and plastic deformation in the part formed by the HFQ process remains unclear. An analytical model of mechanical properties and plastic strain for an HFQ-formed 6061 aluminum alloys part was established by curve fitting of experimental data. The mechanical properties were evaluated by tensile and micro-hardness tests, and the plastic strain distribution in the HFQ process was analyzed by an automatic strain measuring system. The tensile strength and Vickers hardness showed a linear function for the HFQ-formed 6061 aluminum alloys part, and the relationship between Vickers hardness and plastic strain also presented a linear mathematical function model. The proposed analytical model reveals the mechanical properties of the HFQ-formed 6061 aluminum alloys part quickly and accurately in a non-destructive way. Furthermore, the microstructural characteristics of the HFQ-formed aluminum alloys parts were observed by scanning electron microscopy and transmission electron microscopy to clarify the strengthening mechanism. Disperse and dense Mg2Si precipitates significantly increased with increasing plastic strain during hot forming. The results showed that the improvement in strength was mainly attributable to the increase in precipitates caused by dislocation tangle and lattice distortion after HFQ forming.