Terry found a typo - it should be about 960F instead of 96F...I was thinking
faster than I type.
Sorry
Scott
-----Original Message-----
From: Terry [mailto:terry@kk6t.com]
Sent: Tuesday, March 24, 2009 8:20 PM
To: Scott MacKenzie
Subject: Re: [TowerTalk] 6061 vs 6063
Heated to 96F.......is that a typo?
73 de Terry KK6T
Scott MacKenzie wrote:
> As with all things - there is a lot of myth, mis-information and
> fallacy about heat treating. Since I do this for a living I might as
> well join the fray.
>
> 6061 and 6063 are hardenable, heat treatable alloys. They are heated
> to approximately 96F, then cooled rapidly using water, water sprays,
> poly alkalyene glycols and oil (very rare), they are then aged to
> obtain final properties (the -T tempers). The properties of a part
> vary widely depending on the temper.
>
> The first digit after the T indicates the sequence of operations. T 6
> indicates solution heat treatment, quenched and artificially peak aged.
>
> T8 indicates solution heat treat, quenched, cold worked (typically
> stretched) and artificially aged.
>
> The second digit indicates variation in basic heat treatment.
>
> Both alloys are readily formable in the O condition. As a general
> rule you need 1.5T to form in the O (annealed condition) - with larger
> allowances as the part is formed in various heat treated conditions.
> The exception is the AQ condition - where parts can be readily formed,
> then aged to the final heat treated condition. This is different from
> steel where the parts are hard and brittle when quenched.
>
> Because of alloying content - in the T6 condition, the 6061 will have
> better properties than 6063.
>
> Both are quenched in water. The difference is the alloy content and
> the process sequence. The T8 parts are typically drawn over a mandrel
> to stretch them prior to final aged.
>
> In the T8 condition, it is likely that the 6063-T832 will have similar
> properties to 6061-T6.
>
> If you have any other questions regarding heat treatment - and the
> proper way to do it, please contact me via this thread or off-line
>
> D. Scott MacKenzie, PhD Met Eng, FASM
>
> Aka KB0FHP
>
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of Roger (K8RI)
> Sent: Tuesday, March 24, 2009 6:49 PM
> To: TexasRF@aol.com
> Cc: towertalk@contesting.com
> Subject: Re: [TowerTalk] 6061 vs 6063
>
>
>
> TexasRF@aol.com wrote:
>
>> Most antenna manufacturers are using 6063-T832 alloy tubing. The T832
>> is very important and I have seen no one refer to this in these
>> tubing discussions.
>>
>> The yield strength of 6061-T6 and 6063-T832 is the same; typically
>> 38,000 to 40,000 psi. I have tested both types of tubing by hanging
>> weights on the end of six ft pieces until a permanent change in
>> straightness occurred. Both types showed a slight bend with the same
>> weight on them.
>>
>> Plain 6063, like you would find in a hardware store has a typical
>> yield strength of about 27,000 psi, demonstrating the importance of
>> the T (for temper) numbers.
>>
>> 6061-T6 is manufactured with an oil quenching process (what ever that
>> is)
>>
> I'd like to enlarge on that a bit if I may and I'm no expert.
>
> Quenching is the rapid, but controlled cooling of a material in some
medium.
> That medium may vary from water to oil, to even liquid Nitrogen. The
> cooling medium used controls the rate at which the metal is cooled and
> thus the hardness. The faster it's cooled the harder the result. The
> effects also vary. In the case of quenching a piece of steel, which
> which I'm quite familiar, water will result in a very hard and
> *brittle* piece. Quenching the same piece in oil will slow the cooling
> process substantially. It will also add carbon into the surface
> *layer*, not just on the surface. In this case you end up with a very
> hard surface with an underlying support layer that is very tough.
> Under that, depending on the size of the piece will be a core of the
> native material. That surface layer has the carbon diffused down into
> it which also adds to the hardness and durability essentially turning that
layer into a hardened high carbon steel.
>
> The Quenching of Aluminum is similar, but I have no experience with it
> so lack the details .
>
>> and usually has a dull to ugly dark finish. 6063-T832 is manufactured
>> with a completely different process that reduces manufacturing costs
>> and leaves the material with a shiny bright finish.
>>
>> As far as bending and welding characteristics, I have not studied
>> that and leave it to others to complete the story.
>>
>>
> As a rough comparison, the springy Aluminum alloys are much like a
> steel spring. They can be bent, but exceeding the minimum bend radius
> (which can be quite large) will end up fracturing the material just
> like bending a flat coiled spring too far will cause it to break or
shatter at the bend.
>
> With the advent of TIG welding, the ability to weld Aluminum has
> become far easier. Oxyacetylene welding of Aluminum can be done, but
> takes practice (One that I never managed to master). Even then it's
> easy to get a "granular" weld which is not all that uncommon on
> Aluminum tower cross braces. The reason "Torch welding" is so difficult
with Aluminum
> is the ability of Aluminum to transfer heat. TIG welding creates a lot
> of heat concentrated in a small area from an electric arc. The
> welding rod is fed into this arc with the two making the weld
> relatively easy to control.
>
> The differences I've seen are with welding steel the weld is usually
> the strongest point where in Aluminum it is the softest and usually
> the weakest point. Although due more to technique, or the lack there
> of, you'll see Aluminum welds break at the edge which is "usually" due
> to lack of penetration and is much like a cold solder joint.
>
> That's welding and quenching Aluminum...more or less.
>
>> 73,
>> Gerald Williamson, K5GW, General Manager Texas Towers (we do have
>> 6063-T832 tubing)
>>
>>
>>
>> In a message dated 3/24/2009 4:03:31 P.M. Central Daylight Time,
>> K8RI-on-TowerTalk@tm.net writes:
>>
>>
>>
>> jim Jarvis wrote:
>> > Dave,
>> >
>> > I haven't looked in a materials handbook to see the spec, so I'm
>> only
>> > repeating what Bethlehem Aluminum and Wikipedia said. But I
>> think you
>> > misread my comment.
>> >
>> > 6061 will spring.... it can be bent and NOT take a set. Up to
>> the
>> > point of breaking.
>> >
>> 6061 is much harder than 6063. It's what we use for aircraft skin,
>> cowls, wheel pants... etc. so 6061 can be bent, it can be shaped
>> into
>> rather complex shapes using an English Wheel, as well as panishing to
>> stretch or shrink the material. OTOH not all 6061 is created
>> equal. It
>> comes in a wide variety of hardness. I think that may be where at
>> least
>> some of the confusion over 6061 comes from. As was mentioned
>> earlier in
>> this thread, 6061-T6 can be bent and formed into complex shapes.
>>
>> There are several sites on the web devoted to metal working.
>> http://www.metalmeet.com/ and http://www.metalshapers.org/ are two I
>> know of.
>> > 6063, on the other hand, can be bent into a curved shape and
>> stay there.
>> >
>> >
>> 6061 can be bent, be it tube or sheet, but it takes more care (and
>> work)
>> to do so than with 6063.
>> > If you use a bending brake to bend 6061, it's likely to fracture
>> or
>> > surface distort,
>> >
>> 6061 can be bent to 90 degrees using a brake, BUT there are
>> limitations.The radius of the bend needs to be at least 1.5 times the
>> thickness and it depends on the hardness of the particular sheet.
>> > rk it as well as you can 6063.
>> >
>> > One argument in favor of 6063 may be that being less brittle, it
>> may
>> > withstand
>> > vibration better, over time.
>> >
>>
>> I think you will find the softer alloys will work harden quicker than
>> those that are springy.
>>
>> 73
>>
>> Roger (K8RI)
>> > Perhaps I'm wrong. Check with the Alcoa Aluminum spec sheets,
>> which
>> > can be
>> > linked to from Wikipedia.
>> >
>> > Jim
>> >
>> >
>> >
>> >
>> > On Mar 24, 2009, at 1:37 PM, Dave Johnson wrote:
>> >
>> >
>> >> Sorry Jim but who ever told you this is full of it. 6061-T6 is a
>> >> alloy that is designed to be bent a long way and not take a set.
>> >> It will not crack or orange peel.
>> >>
>> >> Dave - K4SSU
>> >>
>> >>
>> >>
>> >> ----- Original Message ----- From: "jim Jarvis"
>> >> <jimjarvis@optonline.net>
>> >> To: <towertalk@contesting.com>
>> >> Sent: Tuesday, March 24, 2009 10:40 AM
>> >> Subject: Re: [TowerTalk] 6061 vs 6063
>> >>
>> >>
>> >>
>> >>> I verified with the Al tube vendor the 6061/6063 question.
>> >>>
>> >>> They're both the same price.
>> >>>
>> >>> 6061 is stronger. but if you need to put a bend in the
material,
>> >>> 6063 is what you want.
>> >>> 6061 will crack or orange peel if you try to bend it. 6063
>> will
>> >>> not.
>> >>>
>> >>> N2EA
>> >>>
>> >>>
>> >>> _______________________________________________
>> >>>
>> >>>
>> >>>
>> >>> _______________________________________________
>> >>> TowerTalk mailing list
>> >>> TowerTalk@contesting.com
>> >>> http://lists.contesting.com/mailman/listinfo/towertalk
>> >>>
>> >
>> > _______________________________________________
>> >
>> >
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