Duralumin ?

[LGL737]

Hey !!!

can anyone confirm or answer this question

Duralumin is a

1) Aluminium/copper base
2) Aluminium/magnesium base
3) Hard to weld
4) Easy to weld
5) good thermal conductivity
6) poor resistance to air corrosion

I would say the answer should be 1, 2, 3, and then maybe maybe 5 but thats the one Im not so sure about. Can anyone answer this and am I right about 1,2,3 ??
Thanks for you answer

rgds
LGL

[Troley]

LGL737

The following entry from the Encyclopaedia Britannica site just about covers everything.

Duralumin
strong, hard, lightweight alloy of aluminum, widely used in aircraft construction, discovered and patented in 1910 by Alfred Wilm, a German metallurgist; it was originally made only at Düren in Germany. The original composition has been varied for particular applications; it may contain about 3 or 4 percent copper, 1/2 to 1 percent manganese, 1/2 to 1 1/2 percent magnesium, and, in some formulations, some silicon. After heat treatment and aging, these alloys are comparable to soft steel in strength and hardness.

Duralumin alloys are relatively soft, ductile, and workable in the normal state; they may be rolled, forged, extruded, or drawn into a variety of shapes and products. Their light weight and consequent high strength per unit weight compared to steel suit them for aircraft construction. Because Duralumin loses strength in welding, a special laminated sheet form called alclad is used for aircraft construction; it has thin surface layers of pure aluminum or a corrosion-resistant aluminum alloy covering the strong Duralumin core.


Troley

[foghorn]

I recognise that one - it's a JAR ATPL airframes question.

The answer is 1,3,5.

[LGL737]

Thank you very much !!!

rgds
LGL

[critcaact]

I thought the answer was -the stuff used by Boeing not Airbus.

[LGL737]

Talked to a guy yesterday, who has worked with metals for years, and he says that aluminium/copper is very easy to weld, whereas aluminium/magnesium is very hard. So that would make the answer 1, 4 ,5 wouldnt it??

Foghorn, is your answer something you have from someone who knows it for 100% sure ??

rgds
LGL

[Genghis the Engineer]

Duralumin is almost impossible to find now outside of a museum.

In the 1970s it was finally replaced by the 2000 series alloys developed for concorde, and in the 1980s, the boffins built on the Concorde work and developed the 6000 series alloys. The most common now is 6061 which has pretty much replaced the less available 6082 for tube-stock, although panels are still mostly 2024.

Which basically means that that question (which frankly is irrelevant to a pilot anyway) has been in the ATPL exams for far too long!

Genghis

Chartered Engineer and private pilot.

[foghorn]

737 - that was what I was told at groundschool. Don't know any more than that.

As Genghis points out the JAA gets yet another mark deducted for exam question relevance...

[rock_the_tower]

Some info about the 5XXX and 6XXX series ( wrought alloy designation)which both contain magnesium:

5XXX series:

When magnesium is added to aluminum, the alloy has excellent weldability with a minimal loss of strength and is basically not prone to hot cracking. In fact, the 5XXX series has the highest strength of the nonheat-treatable aluminum alloys. It is used for chemical storage tanks and pressure vessels at elevated temperatures as well as structural applications, railway cars, dump trucks and bridges because of its corrosion resistance. It looses ductility when welded with 4XXX series fillers due to formation of Mg2Si.

6XXX series:

Incorporates both silicon and magensium for medium-strength and possible heat-treatment. It is principally used in automotive, electrical, pipe, railings, structural and extruding applications. The 6XXX series is somewhat prone to hot cracking, but this problem can be overcome by the correct choice of joint and filler metal. This series can be welded with either 5XXX or 4XXX series without cracking – adequate dilution of the base alloys with selected filler alloy is essential. A 4043 electrode is the most common for use with this series.

Cheers

rtt

[Sensible]

This is from a non boffin (me) Duralumin is mostly aluminium 90%+ but has copper and other trace elements added to it to form an alloy. It mostly demonstrates the properties of Aluminium although it is harder than aluminium due to a heat trestment during manufacture. If it is heated to an appreciable extent, it loses it's hardness induced during manufacture - so to me and the other blokes in the street it's hard aluminium but if you muck about welding it it is becomes pretty much the same as aluminium.