Optimization of precipitate hardening parameters of 7075 aluminum alloy using response surface methodology

In the present research work, combination of artificial aging (pre and post) and natural aging was performed on 7075 Al alloy. Aging parameters were optimized using response surface methodology model to get the maximum value of Vickers micro-hardness, hardness value, and tensile strength. Three factors with five levels each were used to develop the center composite rotatable design (CCRD-approach). The three factors were pre-artificial aging temperature, natural aging time, and post-artificial aging temperature. The contour plots, surface plots, and mean effects plots were drawn to study the effect of individual factors and interactions of the factors on micro hardness. The coefficient of the regression R 2 was 0.9962 which shows the excellent accuracy of the developed model. One hundred and fifty-one percent increment in the micro hardness and 115% increment in the value of the ultimate tensile strength were observed in optimized sample compared to annealed sample. The Vickers micro-hardness, optical microstructural, tensile test, X-ray diffraction analysis, energy dispersive X-ray spectroscopy analysis, and fractography using scanning electron microscopy of fractured tensile specimen were conducted in this research work.