Optimization of Heat Treatment Aging Process Parameters for 7050 and 7075 Aluminum Alloys

Abstract

Abstract Among the different commercially used Al alloys, the 7000 series offers some of the highest mechanical properties making them the material of choice for several critical engineering applications. These Al alloys often required to undergo a heat treatment process to enhance its mechanical properties to the desired levels. This process, known as Heat Treatment (HT) is a multi-step procedure which involves heating of the alloy to a set temperature followed by rapid quenching in a solution consisting of either water or glycol. Finally, the quenched alloys are subject to aging at near room or elevated temperatures which results in achieving the desired temper that has the mechanical and metallurgical properties that are needed for the application. Achieving the desired results in the HT process is extremely challenging and time-consuming. The most common industry practice is to rely on both metallurgical and manufacturing experts and resort to the costly trial-and-error approach which results in lower productivity, poor quality, and a massive waste of time, money, and energy. While there exist standard industrial specifications on the range of values to be used for heat temperatures, age soak times, and quench rates, the range is often too broad to be of any practical significance. The operators have to resort to a stop/restart approach while intermittently evaluating and testing the mechanical properties until the desired level is reached. Currently, there is a growing need to know the optimal operating parameters for the HT process. This study uses commercially available software to optimize the results for the heat treatment aging parameters using mechanical testing data such as hardness, yield strength, and electrical conductivity. Aging is the final step, and most of the time the longest step, in the HT process and therefore it is vital that the values such as age soak time are dialed in as much as possible to achieve the desired properties as soon as possible without wasting time, effort and energy.