Effect of pass strain on grain refinement in 7475 Al alloy during hot multidirectional forging

Abstract

Effect of pass strain (Δɛ) on grain refinement was studied in multidirectional forging (MDF) of a coarse-grained 7475 Al alloy at 490°C under a strain rate of 3 ×10⁻⁴s⁻¹. Results finally in formation of a finer grained structure with an average size of around 7.5 μm at strains of above 3.5, while, the processing with Δɛ = 0.4 develops a slightly coarser grain structure at higher strain of about 6. The effect of MDF on new grain evolution and the mechanisms of grain refinement are discussed in details