Effect of Successive Annealing and Severe Plastic Deformation on Wear Characteristics of Aluminium Alloys

Abstract

Grain refinement by application of deformation involves creating new grain boundaries via interaction of dislocations themselves or with other structural defects. So in order to achieve fine grains one has to break the balance which is done either by enhancing grain boundary generation or by suppressing grain boundary annihilation. If we start with the crystal structure of AA2024 alloy it is face centered cubic (FCC) with high stacking fault energy of 200 mJ/m2. The grain refinement of such alloys is possible only by migration and multiplication newlineof crystal defects such as dislocations. This is possible by subjecting the alloy to straining by newlineusing various techniques which includes severe plastic deformation. Due to application of intense strain using SPD routes the dislocation density in the alloy increases and refine the microstructure. Repetitive corrugation and straightening (RCS) is a technique in which newlinecontamination free nanostructured materials can produced and it can be adapted for continuous production. The grain refinement in RCS is mainly due to dislocation interaction, accumulation and their spatial rearrangement. Repetitive corrugation and straightening (RCS) is one of least explored but potential severe plastic deformation technique for producing grain newlinerefinement in aluminium. The interest arises because of its simplicity and capability to newlineproduce the sheets in large scale by simple modification in existing rolling mills. The significance of work lies in the material selected for grain refinement using RCS and that newlinematerial is AA2024 alloy which at present is used in many aircraft applications. Improving the strength without deteriorating ductility is of prime importance for such applications and possibility of achieving using RCS is main objective of this work. Most important aspect of this work is utilization of design of experiments (Taguchi s L9 and L27 orthogonal array) in newlineoptimizing the RCS process parameters and annealing parameters to attain high strength and wear resistance. The work was div