Analysis of Heat Treatment Response for Cryorolled AA2219 Alloy

AA2219 sheets used in space applications need a combination of properties as strength and ductility for its enhanced usage. For this purpose, the heat treatment parameters were optimized to bring out the better strength in these alloys. AA2219 sheets were rolled at a cryogenic liquid nitrogen temperature at - 196 degrees C and room temperature for 50% and 75% reduction. DSC analysis was done to relate the effect of the precipitation kinetics to the strength of the material. The rolled samples were subjected to annealing at different temperatures for shorter periods. The annealing parameter was optimized by using mean results from the full factorial design based on the microhardness values obtained. Using the optimized annealing parameter, artificial ageing was performed at temperatures ranging from 75 to 125 degrees C for 30 h. The uni-directional rolled samples showed maximum strength after ageing at 125 degrees C for 24 h and cross-rolled sample at 100 degrees C for 18 h. A predictive model using regression and ANFIS were designed to determine the responses for the various input parameter settings for both the annealing and ageing and was validated. Analysis of variance was used to determine the significance of the ageing process parameters proving reduction percentage and ageing time having more effect on the heat treatment process.