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  • 6061-t6511

    I have a 3/4 square of alum stock labeled 6061-T6511. Could someone explain that T number. Never seen one that large.
    Gary Davison
    Tarkio, Mo.

  • #2

    T6 Solution heat-treated, and artificially aged.

    T_511 Applies to extruded products and to drawn tube when stress-relieved by stretching 1 to 3 % permanent set. Stretching is performed after solution heat treatment or after cooling from an elevated temperature shaping process. These products may receive minor straightening after stretching to comply with standard tolerances.
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    • #3
      6061-T6511 is pretty much "garden" variety aluminum.

      Interesting to note some of the bike makers have taken to listing their tubing with the complete "-T6511" heat treat spec. The implication being that they use exotic alloy in their frames.


      • #4
        Wrth noting that the stretch is commonly done just for straightening extruded products.... it ain't very special.

        Keep eye on ball.
        Hashim Khan


        • #5
          Additionally the "T6511" is what is generally referred to by its first two digits "T6" by manufacturers who don't know any better. I'm sure you've heard that several times, "T6 aluminum,T6 aluminum, T6 aluminum..." It's the same people who are pushing their product, "...And now the new RONCO Apple-peeler-corer-slicer. Made from T6 aircraft aluminum" & then it says somewhere else "T6 6061 aluminum". It's just the run of the mill, most common 6061 aluminum, and generally the best priced aluminum you come across as a machinist. However it is NOT the strongest aluminum.
          Last edited by YankeeMetallic; 09-06-2006, 05:20 PM.
          Duke Reno / Yankee Metallic Metalcraft


          • #6
            Not the strongest but i also wouldnt call 6061 T6 "garden variety" either, its still tough stuff, garden variety aluminum wont even take a heat treat.

            7000 series is suposed to be the bomb for bike frames now --- my cannondale is 6061 and is doing just fine (so far)


            • #7
              T6 isn't a particular alloy of aluminum, it's a heat treat identifier that is used to designate the condition of any heat treatable alloy. You can have 2024-T6, 6061-T6, 7075-T6 and any of the other members of those alloy families as well as the 4000 and 8000 series.

              If somebody is refering to aluminum as "T6" thinking that it means a specific alloy it simply shows that they have no idea what it means.
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              • #8

                Just a side note
                I see a lot of the term "6061 T6 aircraft aluminum" and the the phrase "billet aluminum" used on ebay.
                Items mainly for motorcycles,ATV's, etc.
                When I last checked aircraft aluminum was 7075, and billet means a semifinished section...

                Stupid people selling stupid things to people with an even lower IQ.
                please visit my webpage:


                • #9
                  Aircraft aluminum is usually 2XXX series and most commonly 2024-T4 for all the outer skins and most fabricated structural members like ribs and spars. It is a lot stronger than 6061-T6 which is used for some things but not nearly as much as 2024. Again, anybody referring to 6061-T6 as aircraft aluminum doesn't know much about aircraft and probably not aluminum either.

                  7075 is also used in aircraft but not much as it is too prone to stress corrosion cracking. When it is used it is normally for parts that don't undergo heavy cyclical loading but still need to be very strong. Seat belt brackets and seat frames are a good example.

                  All aluminum is made from billets so that makes all aluminum billet aluminum to start with.
                  Last edited by Evan; 09-06-2006, 05:53 PM.
                  Free software for calculating bolt circles and similar: Click Here


                  • #10
                    And the numbers behind the T6 are neccasary to take the wrinkles out of it.

                    You will not find any just "6061 T6". It is unusable, as the heat treat process warps it. You should see sheet and or plate as it leaves the solution furnace. And it gets worse as it cools. Yes it's T6 but it is ugly.

                    Stretching or leveling is the finale step to make it into a presentable and usable product. And is that finale "kiss" to further align its chemistry. Not it's hardness.

                    Whether you see it as the complete designator or not depends on the customers specifications for said designator.

                    Boeing has to have all the numbers on thier metal. Thus "aircraft" grade. Even the numbers of a labratory test are tracable in thier case.

                    "All aluminum is made from billets so that makes all aluminum billet aluminum to start with."

                    Extrusions are made from billets, the rest is made from ingots.
                    Last edited by topct; 09-06-2006, 05:55 PM.


                    • #11
                      And the term "billet" in those contexts is simply and indicator that it is machined to shape rather than extruded, pressed, or cast.
                      Master Floor Sweeper


                      • #12
                        There isn't any difference between billet and ingot except perhaps shape.
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                        • #13
                          A billet is simply a solid piece of material that is shaped into it's finished form by machining.
                          Most finished products are either cast or molded into shape. A billet is a raw block of material.

                          Ingot-A bar or wedge of steel, gold, or other malleable metal, cast in a mold; a mass of unwrought cast metal.


                          • #14
                            As a fork lift, crane, and machine operator for Kaiser Aluminum I cannot ever remember making "billets". The other plants had "billet" making machinery.

                            From the bottom, it started, hens, chicks, pigs, and ingots, all ingots. Any alloy on the list. Just different sizes. We did not make billets.

                            We made sheet and plate out of ingots.

                            There were billet makers however. They would take our ingots and make billets out of them.

                            They then could extrude or forge, from them. Thats what we were taught.

                            Machining is not done from billet. It is done from an extrusion or forging or a casting. The other is from plate. And that plate can be ten inches thick. But it was still called "plate", not billet.

                            And castings are not made from billet either.

                            Did we do this once before?


                            • #15
                              When a new customer tosses around the word billet, I see dollar signs$$$$$$