Question

Question 2 (40 Marks) a) A hot aluminium (grade 2014) frame produced by extrusion is quenched. After quenching, the frames are kept at room temperature. The hardness of the frame is 140 HV. (1) Describe the microstructure of the aluminium frame. (5 marks) (ii) An engineer would like to increase the hardness of the frame. Explain the heat treatment to increase the hardness of the frame and the microstructure produced by this heat treatment process. (5 marks)

Answer 1

Q2(9 (1) Describe the microstructure page- of the aluminium frame Aus The extrusion is in the ) aluminium frame is produced by extrusion and then êt is quenched, During when performed during the formation of aluminium frame. Then recrystallization occurs microstructure and it curls in some local part of the structure and also during extrusion the structure suffered large amount of strains, when quenching takes place in that aluminium frame they influenced their microstructure in recrystallisation duurs during extrusion does not have Unsform reer Istallized grains but after quenching grains are developed in mature and they are uniform and that make aluminium frame aud devens to this thter mechanical propertiel changes as well. Various ways e the а. Substantial change in microstructure

209) page-2 the Heat Treatment to increase hardness of aluminium frame and microstructure produced Age hardening is the heat treatment process that should be applied to increase the hardness frame. The of the the aluminium process takes place in three age hardening heat treatment stages first stage is that aluminium frome will be taken to the solution of high temperature and that cause all the solute porticles or atom dissolved in it. then rapid cooling is done to increase the solubility is the second stage and in third stage the Solution is heated to temperature intermediate for precipitation. Microstructure produced after age hardening have uniformly dispersed grains ared they have a Jurform grain Structure and there is no Strain and dislocation and interaction between strain in structure and their dislocations. that is formed