Property prediction and residual stresses in aluminium alloy 7010

This project investigates the development of C-curves for aluminium alloy 7010 under various tempers and processing conditions and the subsequent use of quench factor analysis (OF A) for property prediction. Statistical evaluation and comparison of both the isokinetic (classical Quench Factor Analysis) and the nonisokinetic property prediction models using both fixed and variable values for the minimum property values was carried out. It was concluded that the nonisokinetic property prediction model with a variable minimum property value provided the most accurate method for property prediction of the techniques evaluated for aluminium 7010 alloy in an overaged temper. C-curves were then successfully developed for 0.2% proof stress, Vickers hardness and electrical conductivity. The validity of these C-eurves was proved using multiple isothermal holds and multiple quenchants demonstrating the effectiveness of the models at up to 67% strength loss with a recorded error of only 4.6%. The use of the Jorniny end quench method to provide a relatively quick source of continuous cooled data for C-curve construction for aluminium alloy 701O in the peak aged, overaged and a cold compressed+overaged condition was demonstrated. It was shown that that the method provides a good indicator of alloy quench sensitivity. The method also revealed that in the cold compressed+overaged condition, that 7010 cold compressed prior before artificial aging demonstrates greater quench sensitivity than the alloy in the peak aged and overaged conditions. The influence of post-quench delay prior to cold compression on residual stress was evaluated using x-ray diffraction and was found to be non-conclusive.