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Moderator
Curtis Jacobson
Portland Oregon
(4414 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

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aluminium
Posted by: Moderator
Date: March 13, 2009 02:29PM

I learned some interesting trivia today... I'd been wondering about some of the trade names for aluminum that show up in old books and articles about British sports cars. Specifically, I wondered what the difference between Birmabright and Duralumin was, since those terms come up so often.

"Birmabright" - is the tradename of an aluminum / magnesium alloy that was principally used for formable sheet, as for example on the Austin Healey 100 and 3000 shrouds, on various MG (speed record) prototype bodies, and on Land Rover bodies. The name came from "The Birmetals Company" of Birmingham England. Birmabright is basically equivalent to "5251".

"Duralumin" is the trade name of an aluminum alloy with copper (~4.4%), magnesium (~1.5%) and manganese (~0.6%, by weight). The interesting characteristic of Duralumin is that it "age hardens" at room temperature - it was the first alloy found that behaved this way. This aluminum alloy was used on the Hindenburg and on many other early aircraft because it was relatively strong and also less susceptible to fatigue cracking than other alloys - however, it's also more susceptible to corrosion than other aluminum alloys. In fact, since it corrodes easily, sheet Duralumin is commonly clad with a thin surface layer of nearly pure aluminum to produce a product known as "Alclad". (You've heard of that, right?) When Duralumin is mentioned in the context of old racecars, it's usually being used for parts where strength characteristics are important. If you were looking for a modern "American" equivalent to Duralumin, you'd look within the "2000" series of products.

I don't know what the old-school name for "3003" is. 3003 is the work-hardening alloy of aluminum and manganese that fabricators use for most body parts nowadays. I think the 6000 series (of alloys that principally include magnesium and silicon) is newer... "6061" is very strong and also relatively easy to weld and to machine.

Just thought I'd pass that along... if you know more please don't hesitate to share it.


MGBV8
Carl Floyd
Kingsport, TN
(3807 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB, Buick 215

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Re: aluminium
Posted by: MGBV8
Date: March 13, 2009 05:01PM

Thanks, Curtis.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5853 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

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Re: aluminium
Posted by: BlownMGB-V8
Date: March 15, 2009 02:57PM

The 6000 series are commonly used for "Billet" parts where easy machining and formability is important as well as strength. the 7000 series is a hardenable alloy more commonly used in applications such as aircraft panels which do not require a lot of forming. Some alloys will fracture if bent at a sharp 90* angle. Typically the last two numbers in the series will designate the strength of the alloy, with higher numbers being stronger.

Jim


twentyover
Greg Fast
Burbs of Detroit
(2 posts)

Registered:
02/29/2008 06:33PM

Main British Car:
1968 MGC GT 2.9 C series

Re: aluminium
Posted by: twentyover
Date: June 08, 2009 01:23AM

Need to be careful w/ 6061, as it's prone to silicone nodule cracking as it cools from the melt. Need to use 4043 or 5356 fill wire when welding.

Respectfully disagree w/ Jim "the last two numbers in the series will designate the strength of the alloy"- The first number of the alloy identifies the primary alloying element- 3XXX is manganese, 6XXX is silicone-magnesium, etc. The last 2 digits identify the composition limits of other alloying agents, and are assigned sequentially, for all alloys except the 1XXX (commoercially pure aluminum) alloys. The 2nd digit defines a variation in the base alloy, with substantially the same properties as X0XX. This is frequently a result variations in the bauxite used to refine aluminum.



Edited 1 time(s). Last edit at 06/08/2009 01:24AM by twentyover.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5853 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: aluminium
Posted by: BlownMGB-V8
Date: June 12, 2009 11:40AM

Just going from memory Greg, thanks for the fill. There's a lot of metalurgy that goes into aluminum alloys and for a stressed part it makes a lot of sense to carefully research the composition and properties before hand. For general use and parts that don't see a lot of stress though, the commonly available alloys are usually fine and if they do fail, replacement with a higher grade will often solve the problem. Higher levels of alloying elements usually mean a stronger metal, unless the alloy is intended to develop other properties such as ductility. That's usually where the problems in selection lie, as the alloys have been developed to meet a very wide range of uses so as a general rule of thumb try to select alloys designed for a similar application. Machinery's Handbook and catalogs from metal suppliers are both good sources of information, as well as numerous online sources.

Jim


socorob
Robbie
La
(173 posts)

Registered:
09/17/2009 04:42PM

Main British Car:
1963 Sunbeam Alpine Series 2 Ford 2.8 V6

Re: aluminium
Posted by: socorob
Date: September 26, 2009 01:38PM

What would be the best kind of aluminum to use to make a dash with? Thanks


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