On the mechanical properties and microstructure of commercially pure Al fabricated by semi-constrained groove pressing

Commercially pure Al is severely deformed through semi-constrained groove pressing up to four passes. Mechanical properties and microstructure of the samples are studied using mechanical tests, transmission and scanning electron microscopy and X-ray line profile. The yield stress and tensile strength increase by a factor of 2.3 and 1.5, respectively, compared to the annealed state, after the third pass and decrease slightly afterward. The Hardness saturates at about 40 VHN at last stages of pressing. Fracture surface morphology demonstrates that the fracture mode is ductile even after four passes. Results show that finer and more dislocation free cells are observed after the fourth pass. An average grain size of about 300 nm is obtained after the final pressing. The results are compared with that of the previous works conducted on Al through fully or partially constraint groove pressing.

► The hardness saturates at a value of 40 VHN at final stages. ► The yield and tensile strength reach to their maximum values, after three passes. ► Four passes of semi-constrained groove pressing leads to grain size of about 300 nm. ► The fracture mode is ductile even after four passes. ► More dislocation free grains are observed at the final stages of pressing.