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Thread: Heat treating 6061 or Fortal

  1. #1

    Post Heat treating 6061 or Fortal

    Hello everyone,
    I seem to recall that 6061 aluminum can be hardened, is this correct? I have also seen an aluminum alloy on the market that is called Fortal. Can it be heat treated also?
    The question arises from the need to custom build rifle sights and scope mounting bases. Most Weaver style bases that I have modified appear to be slightly more stiff then off the shelf 6061 raw stock. The commercial produced bases also are not as "stringy" when machining.
    If 6061 and/or Fortal is capable of being hardened, how would a HSM do it?

  2. #2
    Join Date
    Apr 2001


    I don't think there is a practical way to heat-treat aluminum at home. I think you need a pretty fancy (i.e. expensive) computer-controlled heat-treat oven.

    I don't see any particular reason to do it, anyway. Buy the aluminum alloy with the properties you want to begin with. (6061 is probably not it. 2024 is fairly common, and harder.) The only reason we don't do that with steel is because hardened steel is too hard to machine readily...unless you're grinding it. But that's not a problem with aluminum.

    Also, the stiffness of all aluminum alloys is probably about the same, give or take a little.

    Check some of the websites of aluminum manufacturers (Alcoa, Kenametal, etc.) They probably have specs and application data online.

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  3. #3
    Join Date
    Feb 2003


    6061(-T5) is already "hardened". The meanings of the terms are different for ferrous and non-ferrous materials as are the effects of heat treatment. If memory serves, 6061 is chemically hardened. Hardened aluminum is not like hardened steel, it's not going to produce a hard edge but it will produce a material resistant to penetration. Aluminum can also be physically hardened through deformation like CRS and work hardening. Heat treatment of aluminum is done to anneal work hardening and to stress relive.

    So if you need "hardened" aluminum, 6061-T5 is the stuff to use, as is.

    Oh yea, there is a weird aluminum/aluminum-oxide ceramic matrix developed by Specialized bicycles for use in some high end frame sets that got sold to (I believe) GM to be developed into transmission and engine components. Stuff is basically small ceramic particles mixed in to metallic aluminum.

  4. #4



    I have made many scope bases and a few rings using 6061. No problems with any of them. I mostly make mounts for Ruger style rings.

    Paul G.
    Paul G.

  5. #5


    The most common of the 6061 alloys is T6 which is a hard aluminum. A soft 6061 would be the 6061-0 which is dead soft and usually comes in sheets for forming. The T6 series comes in either sheet, plate or bar form. 2024-T3 is a good aluminum in bar form to machine. 5052-H32 or H34 is a good sheet aluminum to work with. It is fairly hard and has a nice sheen to it for different projects witout having to do anything to the finish. For machining, stay away from the 1100 / 3000 series sheet as it is a dead soft and machines like bubble gum. These are normally reserved for punching, forming, and can be polished for reflectors. 7075 aluminum is real nice to machine but is expensive. If I had my choice I would make all my aluminum projects out of the 7075.

    If it's not good enough for you, it's sure not good enough for anyone else.

  6. #6
    Join Date
    Jan 2003
    On the Oil Coast,USA


    I have the heat treat instructions for 7075 t-6 from Alcoa if you are interested I can post them.I have done it the only trick to it is that the saturation temperature has to be held +/-50*f and you need lots of cold water we used a 30 gallon drum of water with about three bags of ice floating in it and got excellent reasults.
    I just need one more tool,just one!

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