Quenching and Aging Aluminum 6061

At Jones Metal, we form and heat treat metals and alloys of a variety of strengths and properties. To highlight our aluminum heat treating processes, we’ll walk through an example of our process with 6061 aluminum as our metal of choice. Here’s how we harden and soften aluminum alloy parts.

About 6061 Aluminum

6061 aluminum is a ductile metal that can be stamped, cut, deep drawn, drilled, tapped, bent, welded, hydroformed and more. Magnesium and silicon are the major alloying elements in this metal, and 6061 is generally strong and corrosion resistant. It is heat treatable and crack resistant when stress is removed.

When 6061 aluminum is brought to us off the shelf, it’s most often in O condition, which is its softest, most pliable state. During the forming process of some aluminum parts, our customers request heat treating processes to soften and remove stress from a part to avoid vibration issues and preserve the shape of the part. Because our in-house equipment covers a wide range of capabilities, we can take soft aluminum and treat it to the hardness that suits our customers’ needs.

The Quenching and Aging Heat Treatment Process

The process of taking a 6061 aluminum part in O condition to a stronger, more durable condition begins by heat treating the parts at 985 degrees Fahrenheit for an hour in a drop bottom furnace. At that point, the basket containing the parts is dropped into a quench tank. The quench liquid circulates to cool the parts rapidly. The key to this process is speed and even cooling; the parts are quenched within six seconds of the drop bottom furnace door opening.

With that process done, the quenched aluminum part is now in W condition. In this condition the material can be formed or straightened. Because time and room-temperature air can also have a hardening effect, setting these newly treated aluminum parts in the open on the workroom floor for 96 hours will bring the parts to T4 hardness. 6061-T4 aluminum is part way to the hardest that this aluminum alloy can be. The aluminum hardening process can be stopped by placing aluminum parts in a freezer until they’re ready to be hit on the press again.

After this secondary pressing, the parts go through an aging heat treatment process. Aging aluminum 6061 is done between 350 to 500 degrees Fahrenheit, and—depending on thickness and other factors—the parts stay in the oven for 12-24 hours.

Following this aging, the parts are now at a T6 condition. In general, T6 is the most common temper for aluminum, and because 6061 aluminum is often used in heavy-duty structures, the strength and limited formability of metal at that temper is important.

Aluminum Heat Treating at Jones Metal Products

At Jones, we’re proud to offer forming and heat-treating processes for both large and small orders, regardless of shape and material. Contact us online or call 888-479-9566 today to speak to an expert about which process is right for the parts you need. You can also send us your drawings online for a quote.

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