I.v. Singh

Mechanical and Fracture Behaviour of Ultra Fine Grained 7075 Al Alloy I.v. Singh

The present work speaks about experimental evaluation of Mechanical and Fracture properties and simulation studies (by FEM and XFEM) to analyse fracture behaviour of ultra fine grained 7075 Al alloy produced by cryorolling technique. The precipitation hardenable Al 7075 alloy (Al-Mg-Zn-Cu) plates were solutionised and then cryorolling (rolling at liquid nitrogen temperature) done to achieve different thickness reductions (40%, 70% and 90%). It was observed that at 70% thickness reduction fully formed UFG (Ultra Fine Grained) structure produced for the 7075 alloy. Some of the specimens were then artificially aged after giving short annealing treatment for a while at different temperatures to optimize the peak ageing condition. The effect of cryorolling and cryorolling + peak ageing conditions on mechanical properties and fracture characteristics under different loads were investigated. Microstructural characterization done using SEM and FESEM. FEM and XFEM simulations were carried out to show improved fracture behaviour and crack arrest capabilities of the UFG alloy. Fracture surface morphology of the UFG alloy confirms the simulation findings.