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What alloy and heat treatment was used for Girdraulics?

Magnetoman

Well Known and Active Forum Website User
VOC Member
I sent a piece of the first, broken, blade to 'Bodycote materials testing Teeside' for destructive analysis. The results were as listed at the end of this. This seems to equate to a 2000 series aircraft alloy when checked on http://www.matweb.com/...
AL - Base
Cr <0.01%
Cu 2.25%
Fe 1.02%
Mg 0.67%
Mn 0.10%
Ni 1.21%
P <0.005%
Pb 0.02%
Si 1.03%
Sn <0.01%
Ti 0.10%
Zn 0.06%
Reviving a post from over four years ago, does anyone have additional information on the precise alloy and heat treatment used for the Girdraulics? The above composition doesn't correspond to any standard alloy. However, testing companies can be remarkably far off in the compositions they quote, even to the extent of reporting significant quantities of elements that aren't even present.

…as Phil. Irving said in his article for "Light Metals" in 1950…
I've already sent a PM to ask, but I might as well ask again here -- does anyone have this article and, if so, does he describe the composition and heat treatment in it?
 

david bowen

Well Known and Active Forum Website User
Non-VOC Member
History Vincent girdrulics blade were made out of alloy the same material as the Bristol Britania aircraft 1948 propeller I have tried a lot of sites but no results perhaps Duxford museum may know
 

Martyn Goodwin

Well Known and Active Forum Website User
VOC Member
History Vincent girdrulics blade were made out of alloy the same material as the Bristol Britania aircraft 1948 propeller I have tried a lot of sites but no results perhaps Duxford museum may know
What follows is an extract of an item that is scheduled to appear in the December 2013 edition of 998, the News Letter of the Victoria Section, Australia.

Girdraulic Heat Treatment

If you ever find yourself with bent Girdraulic fork blades that require straightening you might be interested in the following information provided by Dave Large, of the Victoria Section, back in 1998.

“The fork blades, part FF40 are made from L40 alloy material which is an old British specification superseded by HE15 which is similar to AS1866-1977 grade 2014.

For straightening or welding first anneal at 360 to 400 degrees centigrade. Solution heat treat at 505 to 515 degrees centigrade for 2 hours. Quench in boiling water then straighten within 30 minutes.

Precipitation harden at 155 to 185 degrees centigrade for 5 hours and furnace cool. This will restore the original hardness of 72 Rockwell B.”

Dave bolted both blades together for the process and did not have any problems with distortion.

Hope this is of help,

Martyn
 

Magnetoman

Well Known and Active Forum Website User
VOC Member
Gentlemen,

Thank all three of you for your replies (and chankly bore for his PM). This is great information, and knowing the original British Standard (i.e. L40) should let me track down its precise composition, heat treatment, physical properties, etc.

My recent interest in this particular question was prompted by an interest in the welding of the wide variety of Al alloys used on motorcycles over the past century. Although I'm not planning to weld my Girdaulics, they're an excellent example of the less common use of Al alloy in a structural element during the "pre-modern" era of motorcycle manufacturing (notwithstanding the use of the entire Vincent engine as such...).

Typically, back in the classic era Al was used simply to reduce weight in non-stressed components like engine cases, gearboxes, timing covers, etc. so the engineers didn't have to put much, if any, thought into optimizing the cross sections of the castings (or forgings) for strength. Most often if a boss is in a casting it is there, not for strength, but because the designer needed it to be thicker in that position in order to place a tapped hole. Obviously, that's not the case with Girdraulics.
 

piggywig

Well Known and Active Forum Website User
Non-VOC Member
Mr Magneto man,
Some time ago I asked the club technical officer (Bill Parr) a question ref. Girdraulic blades composition . In reply he stated................
Girdraulic fork blade
The girdraulic fork blade is made from L40, a wrought aluminium alloy
(4.5% Copper, 0.5% Magnesium, 0.7% Silicon, 0.8% Manganese, rest Aluminium).


This may not fully answer your question but will save you looking elsewhere for this info.
Col.







 
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