Mechanical Properties and Microstructural Evolution of Bulk UFG Al 2014 Alloy Processed Through Cryorolling and Warm Rolling

Abstract

Tensile properties, microstructural evolution and fracture toughness of Al 2014 alloy subjected to cryorolling followed by warm rolling (CR + WR) have been investigated in the present study. The solution-treated (ST) Al 2014 alloy is cryorolled followed by warm rolling process at different temperatures (110, 170 and 210 °C). The mechanical properties and microstructural features of deformed and undeformed Al 2014 alloys were characterised by optical microscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The CR + WR samples at 170 °C showed an improved hardness (179 HV), tensile (UTS 499 MPa, YS 457 MPa) and fracture toughness (K_Q = 37.49 MPa $\sqrt {\text{m}}$, K_ee = 37.39 MPa $\sqrt {\text{m}}$ and J integral = 33.25 kJ/mm²) with respect to ST alloy as measured from the tensile and fracture toughness test. The improved mechanical properties of CR + WR alloy are attributed to grain boundary strengthening, combined recovery and recrystallisation, precipitation hardening and dynamic ageing effect during the deformation. The precipitation of metastable spherical phase Al₂Cu was responsible for the improved tensile and fracture properties of fine-grained Al 2014 alloy observed in the present work.