MECHANICAL BEHAVIOUR OF ULTRA-FINE GRAIN ED Al-6063 ALLOY PROCESSED BY SEVERE PLASTIC DEFORMATION

Abstract

6063 Aluminum alloys offer excellent strength, formability, corrosion resistance and also good weldabilty. Hence, these alloys are widely used in automotive, structural and aerospace applications. In today's world to meet the upcoming challenges, we need to make an option for new materials that consume less energy but perform huge task, so that we can save some amount of energy resources that are being degraded day-by-day. Since few decades many researches have been successfully held on new class of materials having high strength which are nothing but ultra-fine grained (UFG) materials according to these research a bulk of literature on its W. mechanical properties of aluminium alloys and not enough literature have been provided on plastic deformation mechanisms and fracture and fatigue behaviour of aluminum alloys. 1-lence the main objective of this project is to deliver further work done on strain rate sensitivity which is key parameter for revealing plastic deformation mechanisms assessed through tensile and compression test at different strain rates. and also determination of fracture toughness in terms of J (area under the curve in the presence of pre-crack done by wire Electrical Discharge Machining (EDM)) through three-point bend test on severely deformed 6063 Al alloys which are produced through SPD process of Will axial forging at liquid nitrogen temperature. Enhanced mechanical properties like hardness, tensile strength and increased strain rate sensitivity (SRS) cryoforged 6063 Al alloy is observed. And decrement in ductility, fracture toughness and strain hardening coefficient values of deformed Al 6063 alloy. After annealing for 1 hour at 155°C little improvement in fracture toughness values and ductility in highly deformed Al 6063 alloy and decrement in low deformed Al 6063 alloy. EBSD results shows that increasing forging passes leads to increase in dislocation density and highly deformed materials confirms that formation ultrafine grains due to increased strain leads to decrease in low angle boundaries and increase in high angle boundaries. The deformed samples followed by annealing shows decrease in dislocation density. Finally SEM images of fracture surfaces of deformed Al 6063 alloy shows decreasing dimple sizes as strain is increased and small sized dimples observed in highly deformed Al 6063 alloy.