# What is T6?



## Mac66 (10 Mar 2008)

In adverts for aluminium bike frames I often see something like "7005-T6" frame.

I think the T6 bit is about a heat treatment process, but can anyone explain what it actually involves. Is there a T scale?

Thanks


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## alecstilleyedye (10 Mar 2008)

t6 is indeed another way of saying heat treated. i've seen it on 6061 alu (my bike is that, but it says heat-treated, rather than t6). afaik t6 is not part of a scale, just another name for the process.


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## Elmer Fudd (10 Mar 2008)

T0 is as extruded.
T4 is solution treated and naturally aged.
T6 is solution treated and artificially aged.
Solution treated is where the alloy is extruded and cooled either by air or water to give a rapid temperature drop, this changes the grain structure to give a harder alloy.
Alloy gets "harder" the older it gets (ageing) so by cooking the alloy in ovens for a predetermined time (different temps and times for different alloys) you can make the alloy even stiffer.
1050 / 1070 is virtually pure alloy and as soft as poop.
6063 is the standard stuff you tend to see everywhere.
6061 is a slightly harder mix than 6063
7005 we are now getting into aerospace alloys.
3X04 A company specific alloy that is tough as old boots.


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## LLB (10 Mar 2008)

Elmer Fudd said:


> T0 is as extruded.
> T4 is solution treated and naturally aged.
> T6 is solution treated and artificially aged.
> Solution treated is where the alloy is extruded and cooled either by air or water to give a rapid temperature drop, this changes the grain structure to give a harder alloy.
> ...



You forgot 6082. Most extruders in the UK use either 6063 or 6082


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## Elmer Fudd (10 Mar 2008)

linfordlunchbox said:


> You forgot 6082


And Btre6, And 6005, 1024, etc etc 
I wouldn't want a bike made out of '82 though, 1st pebble and you got a snapped frame !! **

**depending how its treated though.
You're right though, '63 is your glazing, decorative trim etc. '82 more architectural.


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## LLB (10 Mar 2008)

I worked on tooling which extruded solid bar out of 6082 (HDA Workington).

Boeing was the customer and it was used as a stiffener in the wings.

It was all controlled stretch stuff to work out he elasticity and get the temper grades IIRC 

6082 is the ally of choice for many high stress situations and is used by all of the ally ladder companies like ABRU.


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## LLB (10 Mar 2008)

I'm not involved in the extrusion process directly (only if the dies don't run properly), but IIRC the temper grades are achieved by running presses up to a specific speed to give an extrusion speed through a water curtain or air blowers which give the correct temperature drop to achieve the desired temper.

One of our customers in Sweden has managed to achieve an extrusion speed of 50 metres a minute down the tables on 2 cavity 50mm dia (2mm WT)


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## yenrod (10 Mar 2008)

I'll have to look what mine is...

Frame, that is...


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## alecstilleyedye (10 Mar 2008)

7005 seems to be the most popular these days on mid range bikes, merida still use 6061 (it's how you can spot a merida frame with a carrera badge on), as do some other other makes. colnago have some 600 series alu frames too.


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## Elmer Fudd (10 Mar 2008)

linfordlunchbox said:


> I'm not involved in the extrusion process directly (only if the dies don't run properly), but IIRC the temper grades are achieved by running presses up to a specific speed to give an extrusion speed through a water curtain or air blowers which give the correct temperature drop to achieve the desired temper.
> 
> One of our customers in Sweden has managed to achieve an extrusion speed of 50 metres a minute down the tables on 2 cavity 50mm dia (2mm WT)


Spent my life correcting dies of all sorts, and the last place was totally responsible for one of the presses (Fielding) *Do ya know of any jobs ???* 
Workington at one stage was part of BA (or was that Warrington)
'82 has to have an exit temp of 500c and drop by 200c within I think 30secs to get the correct properties 2mm WT ? that's big !! 50m/min is not that hard, just the crappy handling gear can't keep up with the press i.e. billet heaters, pullers, stretchers, the poor old sawmen !!


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## LLB (10 Mar 2008)

Elmer Fudd said:


> Spent my life correcting dies of all sorts, and the last place was totally responsible for one of the presses (Fielding) *Do ya know of any jobs ???*
> Workington at one stage was part of BA (or was that Warrington)
> '82 has to have an exit temp of 500c and drop by 200c within I think 30secs to get the correct properties 2mm WT ? that's big !! 50m/min is not that hard, just the crappy handling gear can't keep up with the press i.e. billet heaters, pullers, stretchers, the poor old sawmen !!



Plenty in China if you know your onions. Boss went out there and one company had 30 presses all working flat out. Workington gone, HDA Warington & Almetex gone, Latchford gone, Banbury going soon now Alcoa has been taken over by SAPA 

Definitely a shrinking market. Who do you work for Hydro Birtley ?


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## Tim Bennet. (10 Mar 2008)

These are the typical increases in properties we see to the 6000 series when T6 treated:
Yield Strength (MPa): 55 increased to 241
Tensile Strength (MPa): 125 increased to 290
Elongation A5 (%): 27 decreased to 10
Hardness Vickers (HV): 5 increased to 100

However it is a process that is applied to the raw material and unfortunately welding the frames together destroys much (2/3rds) of this increase in its properties at the very place that is subject to the most stress. This is in direct contrast to say the 853 (and its family) type steels that actually increase their strength with welding. I think some very high end Al frames (Colnago?) did have some form of post weld treatment. Unless you know which are post treated, its impossible to compare 6061-T6 frames on the criteria of the raw material alone.

There the minimum wall thickness and size of the tubing to form a satisfactory weldment is one of the design constraints of aluminium in bikes.

7005 has slightly better properties, but its real advantage is it only looses about half its T6 enhanced properties when welded. This is why it's used for mid range frames as you can get an okay frame without the hassle of any post weld treatment. Cheap 6061-T6 frames just make sure they have lots of material in the welded region. And then add fillet pieces, etc, etc.


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## simonali (11 Mar 2008)

Elmer Fudd said:


> 1050 / 1070 is virtually pure alloy



Pure alloy?


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## Elmer Fudd (11 Mar 2008)

linfordlunchbox said:


> Definitely a shrinking market. Who do you work for Hydro Birtley ?



Worked there on contract a few years back, how I met the woman I'm with now.
Started off at BA Redditch** many moons ago and I've "been around a bit" since then. I heard about Banbury being taken over but didn't know that their days may be numbered.

** Was back their for 2 or 3 years just before moving up here. They only do tubes these days. Very boring from a Correctors point of view although you could have _some_ fun


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## Elmer Fudd (11 Mar 2008)

simonali said:


> Pure alloy?


Ok, Ok, pure ally ! (Well 99.5% and 99.7% p.a.)


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## simonali (11 Mar 2008)

That's more better!


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## LLB (11 Mar 2008)

Elmer Fudd said:


> Worked there on contract a few years back, how I met the woman I'm with now.
> Started off at BA Redditch** many moons ago and I've "been around a bit" since then. I heard about Banbury being taken over but didn't know that their days may be numbered.
> 
> ** Was back their for 2 or 3 years just before moving up here. They only do tubes these days. Very boring from a Correctors point of view although you could have _some_ fun




BA tubes fortune has been turned around. They were bought out by a German company last year and have had a guaranteed order book filled for another 2 years as well as £1 million cash injection by the new parent company. IIRc they have taken on about 70 new workers in the last few months.

Banbury is winding down and will be closed by august with all the tooling being transfered to Sapa Cheltenham (old Indalex) and Sapa Tibshelf, so they are getting busier. They would be your best bet if you are looking for work.

Are you working for an extruder now ?


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## Mac66 (11 Mar 2008)

Thanks all. Slightly more material tech added to my pin-head size inventory of such facts


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## Elmer Fudd (11 Mar 2008)

linfordlunchbox said:


> Are you working for an extruder now ?



I believe the terminology is ""resting"" ! But definitely looking


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## Elmer Fudd (11 Mar 2008)

linfordlunchbox said:


> *BA tubes fortune has been turned around.*** They were bought out by a German company last year and have had a guaranteed order book filled for another 2 years as well as £1 million cash injection by the new parent company. IIRc they have taken on about 70 new workers in the last few months.


That would be to replace the workers they sacked made redundant during the last couple of years I worked there.

** So leaving did some good then !!


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## LLB (11 Mar 2008)

Is it specifically correction work you are looking for or would you consider working as a polisher for one of the die makers, would you move south if the right job came up ?


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## Elmer Fudd (11 Mar 2008)

simonali said:


> That's more better!


TuT, Tut,
That's more betterer, man, that's more *betterer*
(Gawd I hate people who have to nitty picketery )


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## Elmer Fudd (11 Mar 2008)

linfordlunchbox said:


> Is it specifically correction work you are looking for or would you consider working as a polisher for one of the die makers, would you move south if the right job came up ?


Did a stint of that at Elite a few years back now, Err not really my cup of tea (not all their/ my fault, the beginning of a lot of personal issues came to light during my employ with them), wouldn't mind doing the roving contract stuff for a Die maker though as I've done that before as well


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## Zoiders (11 Mar 2008)

alecstilleyedye said:


> 7005 seems to be the most popular these days on mid range bikes, merida still use 6061 (it's how you can spot a merida frame with a carrera badge on), as do some other other makes. colnago have some 600 series alu frames too.


I spoke to Merida to source a hanger for a Carrera Subway, they stopped making the Carrera frames almost two years ago

Dont know who they are sourcing them from now


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## alecstilleyedye (11 Mar 2008)

carrera and merida fell out over something. my carrera is of that vintage, so it's a merida frame (the 6061 being the giveaway, the more recent ones are 7005 and have steel forks as opposed to the aluminium ones mine came with, which i swapped for carbon).


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## simonali (11 Mar 2008)

Elmer Fudd said:


> TuT, Tut,
> That's more betterer, man, that's more *betterer*
> (Gawd I hate people who have to nitty picketery )



That does sound a bit more gooder, now you mention it.


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## Zoiders (15 Mar 2008)

alecstilleyedye said:


> carrera and merida fell out over something. my carrera is of that vintage, so it's a merida frame (the 6061 being the giveaway, the more recent ones are 7005 and have steel forks as opposed to the aluminium ones mine came with, which i swapped for carbon).


They probably fell out over cost

Merida being based in Taiwan, Tawian having a skilled work force with an ever rising standard of living

I bet Halfrauds wanted the frames for naff all and Merida werent having it, good for them I say, they have better fish to fry and better brands to manufacture for.


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## Monty Dog (20 Mar 2008)

Virtually all decent quality aluminium frames are 6000 series because the heat treatments removes the residual stresses from welding and help ensure a homogenous structure - it's more expensive though.


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## alecstilleyedye (22 Mar 2008)

Monty Dog said:


> Virtually all decent quality aluminium frames are 6000 series because the heat treatments removes the residual stresses from welding and help ensure a homogenous structure - it's more expensive though.



looks like i got a bargain then (£250 for the bike, but have spent as least as much upgrading)


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## bonj2 (22 Mar 2008)

Elmer Fudd said:


> T0 is as extruded.
> T4 is solution treated and naturally aged.
> T6 is solution treated and artificially aged.
> Solution treated is where the alloy is extruded and cooled either by air or water to give a rapid temperature drop, this changes the grain structure to give a harder alloy.
> ...



interesting...
where does 6082 fit into that 'scale'?
both my bikes are 7005.


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## Keith Oates (25 Mar 2008)

Found this if anyone is interested:

Aluminum


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Aluminum is quickly gaining ground as the material of choice for bicycles such as Trek, Cannondale, Mongoose, Klien and other top brands. New technologies have emerged recently that have lowered the cost of aluminum fabrication making it a strong contender to CroMo. The proverbial 6061-T6 grade aluminum is now the industry standard for aluminum frame composition. This is in part because this type of aluminum can be easily welded and is relatively strong. 

Home builders may find aluminum fabrication challenging as it requires a TIG or MIG process and is more difficult to weld than CroMo or carbon steel using the same process. Additionally, 6061 T6 losses half its total strength when welded. Consequently, a post heat treatment process is required to regain it's full T6 strength.

The 6061 series of aluminum is alloyed with magnesium & silicon. However, these are only the majority of alloying elements as other elements are included such as copper, zinc, maganese and titanium. A total of 4% of alloying elements comprise the 6061 specification. The 6061 series is divided into grades or designations that refer to the post temper process. The most common grades are T0, T4, and T6. The grades, processes and strengths are depicted below: 

Temper Process Tensile(PSI) Yield(PSI) 
T0 fully annealed aluminum 18,000 8,000 
T4 Solution heat treated and naturally aged 35,000 21,000 
T6 Solution heat treated and artificially aged 45,000 40,000 

Aluminum is extremely easy to work and machine making frame fabrication painless. Depending on the diameter and wall thickness, aluminum tubing can be easily formed using a standard conduit bender. Since aluminum is relatively soft, it can be filed, drilled and sanded with ease.

Just for conversation, I'll also mention the 7075 series aluminum. This type of aluminum is heavily alloyed with zinc making it incredibly tough and strong. However, this aluminum is very difficult to weld making it's use limited to machined components or glue bonded frames.


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