aluminum or magnesium

Date 10-03-2009 06:00 Edited 10-03-2009 06:11

Hello grizzzly, if you can find access to some silver nitrate you can apply a small droplet to your material and if it turns black it is magnesium, if it stays clear it will be aluminum. I also did a search of the forum and someone else suggested using the juice squeezed from a lemon. They said that if it bubbled upon contact that it was magnesium and if didn't do anything it would be aluminum. Still another poster stated that if it displays a green arc when you fire-up on it then it would likely be magnesium and if the arc stays relatively unchanged that it is likely aluminum. Using a file and making some "dust" you could use a flame to see if this dust burns with a "white" sparklers or light, aluminum will not react in this manner. So there you have a few different possibilities to choose from. Best regards, Allan

By awill4x4 (**)

Date 10-03-2009 06:13

Grizzzly, there's a couple of reliable ways to tell whether it's aluminium or Magnesium.
My 2 methods are: file or die grind gently around the area to be welded and collect the filings in a small pile and either wave a gently burning oxy/acetylene flame over it where the bright sparks will be noticeable if it's Mag. The 2nd method is to put a drop of vinegar on those filings and if it's Mag the pile will expand and fizz up.
Regards Andrew from Oz.

By awill4x4 (**)

Date 10-03-2009 06:15

beat me by 2 minutes Aevald. lol.

By aevald

Date 10-03-2009 08:07

Hello Andrew, I was suprised that somebody else didn't beat me too! I also did a search of the forum because I know that this has been mulled over many times before, oddly enough my searches came up different many times even though I included the exact title of the thread. Best regards, Allan

By phaux

Date 10-03-2009 13:02

In what applications is magnesium used instead of aluminum?

By Lawrence (*****)

Date 10-03-2009 15:34 Edited 10-03-2009 15:37

Phaux

Magnesium might be used in any number of casting situations where weight is a primary factor in design. In some cases a weight reduction of as much as 30% can be achieved by using magnesium in place of aluminum castings.

Aerospace, Automotive, Motorcycles... Lot's of applications

Here is a small bit of data reporting on Alum vs Mag on Ford Contours in the 1990s.. There are some discussions about benefits and drawbacks but not much on actual material performance
http://www.p2pays.org/ref/03/02602.pdf

By grizzzly (**)

Date 10-03-2009 16:11

Thanks for all the replies, I did a little search on a few different forums and came up empty handed. The parts that I am going to be welding on are the cylinder guards on this bike http://grizzzly.smugmug.com/photos/662901493_jYE77-L.jpg
http://i126.photobucket.com/albums/p82/JodyHuggins/socorro5.jpg

By FixaLinc (****)

Date 10-03-2009 17:13

I was waiting to see what answers came up on this one too. My problem is not with magnesium but needing to know how much zinc is also in the aluminum on magneto housings before I waste time taking them to tig welder. Usually I can tell by the weight but if too much zinc they usually can't weld it.

By Tommyjoking (****)

Date 10-04-2009 01:39

LOl the flame on filings method is my preferred diagnostic quick, easy and its sure fire.

FixaLinc no great way to tell with zinc coated aluminum......thats pretty rare .......you will know as soon as you strike an arc on it.

Tommy

By FixaLinc (****)

Date 10-04-2009 20:28

Yes, think have to try the flame trick with filings. Just know one old retired air force aircraft welder I use to take aluminum to had something he brushed on quick to check them and would tell me yes or no right then and bet he was using the silver nitrate. His grandson never learned to weld aluminum like that old man knew how he could fix it or tell right away when you dropped it off from his experience. Now I can't get the guys in town to do it quickly or even tell me if they can fix it wait and wait so might have to find me a tig and learn again myself. There are lots of magnetos and other things made from a different aluminum alloy out there still running yet made during WW II years when good pure aluminum was hard to get for manufacturing other things here. Those are the ones with more pot metal zinc mix that give us grief when they fail and often just become scrap metal now so not really a zinc coating. I can usually tell by the weight or aluminum casting grain but not always because those magneto housings have some steel laminations embedded in them also.

By geebee509 Date 10-14-2009 21:56

This is from welding-advisors.com

"Tip!: Magnesium can be easily distinguished from aluminum. It is attacked rapidly by usual inorganic acids (excluding hydrofluoric and chromic acid). It is not attacked by alkalis and caustic soda (Warning! it may be dangerous to use). On the contrary aluminum is readily attacked by alkaline solutions and not by acids like nitric and sulfuric."

By aevald

Date 10-14-2009 22:39

Hello qeebee509, thanks for including that information. Best regards, Allan

By stone112 Date 10-16-2009 17:12

Agreed with you geebee509 :)

By 357max

Date 10-16-2009 02:27

strike a gtaw arc on the material; if it is aluminum it should be a white arc, if magnesium it should be green, if it is zinc die cast it will be purple.