A Guide to Aluminum Heat Treatment Options: Achieving Optimized Materials for Fabrication
Different types of aluminum alloys exhibit unique physical properties that make them the ideal material for specific products and applications. For example, many applications call for maximum tensile strength, while others are a balancing act of strength, stiffness, and hardness.
Heat treatment is a tool that we can use to fine-tune those properties further, providing an even more optimized material solution for your custom fabrication project.
The Basics of Aluminum Heat Treatment Explained
Put simply, aluminum heat treatment carefully heats and cools the raw material which modifies the metal’s microstructure in a specific way, thus substantially modifying the mechanical properties. After heat treatment takes place, the aluminum is cooled slowly or rapidly quenched to essentially freeze the alloying elements in place.
Different quenching techniques and subsequent aging processes result in different thermal tempers such as T4, T6, T7, etc. For example, T6 treated aluminum involves quenching and then artificially aging the material in a process known as precipitation hardening. Below, we take a look at this and three other common aluminum heat treatment options.
The Four Main Types of Aluminum Heat Treating Compared:
Annealing – The annealing process involves heating the aluminum to a specific temperature (generally 570°F to 770°F) and then slowly cooling it, which sort of “resets” the grain structure of the metal. Annealing helps relieve internal stresses, often used to counteract the general effects of cold working. It can also be used to improve ductility, and/or soften the material. The “O” designation is used to classify annealed aluminum (e.g. aluminum 6061-O temper).
Homogenizing – Similar to annealing, homogenizing likewise involves the careful heating and cooling of aluminum material – though at much higher temperatures in the neighborhood of 1,000°F. The main goal with homogenizing is to redistribute the internal alloying elements and thus obtain a homogenous material chemistry. While annealing simply recrystallizes the microstructure through the movement of grain boundaries, the higher temperature of homogenizing allows for the migration of alloying elements too.
Solution Heat Treatment – Solution heat treatment involves heating the aluminum alloy to a high temperature, known as the solutionizing temperature, and then rapidly cooling it via quenching. This process is used to dissolve alloying elements into a solid solution. The “T” designation is followed by one or more digits indicating specific levels of solution heat treatment.
Precipitation Hardening (Artificial Aging) – Precipitation hardening, sometimes called artificial aging, involves reheating the aluminum to a lower temperature after performing solution heat treatment and quenching. This follow-up process facilitates the precipitation of finely dispersed particles throughout the material, which adds strength and uniformity. Like solution heat treatment, the “T” designation is used, followed by one or more digits to specify the particular temper – e.g. 6061-T651, a precipitation hardened form of the common 6061 aluminum.
Quality American Manufacturing and Custom Aluminum Fabrication Services
Alloy Fabrication is one of the Pennsylvania region’s leading fabricators specializing in custom aluminum fabrication projects. We offer full-service contract manufacturing solutions ranging from structural aluminum fabrication to custom tanks, tubular components, and other complex weldments.