Monday, November 2, 2009

To Rodney and Friends about Welding

Here is the lesson for today as requested by Rodney -

Magnesium welding and general info

8th most abundant element in earths
melting point - 1200 deg f

Welding and Prep tips

One quick way to test the base metal to double check and verify its Magnesium and not Aluminum is to apply a small tea spoon of Vinegar to the metal and watch for any reaction. The base metal should get a dark spot and bubbles to form if it is magnesium, as the vinegar reacts to the base metal. If the base metal is Aluminum the small amount of Vinegar will NOT change from the water like clear. This is a quick and cheap way to test, it won't tell you any specifics on grade but at least you are pointed in the correct direction on welding and prep.

Use non chlorinated brake cleaner for the cleaning

Use stainless steel wool on clean metal - use of a wire brush may cause scratching where dirt or other contaminates may hide when cleaning. Use of a Stainless Steel brush may be used when the Mag has paint or high levels of oxide on the surface.

DO NOT USE - ALUMINUM FILLER MATERIAL !!! This will create cracking upon the weld cooling. It may appear to be welded but it is NOT! This is very common is shops that have both filler materials available for the welder, the welder will grab the Aluminum filler rod and use it on Magnesium because of the look and weight of the rod, it is very hard to tell. All filler material is stamped with the info about the rod but it happens where the end with the info is used and no one knows what material it is. DON'T USE IT IF YOU DON'T KNOW

The material that is most used for filler rods are AZ-61A or AZ92-A

ER AZ61-A is used for welding wrought products
ER AZ92-A is used for welding castings ( less crack sensitive )

Most Mag is weldable but proper filler material is VERY important


Heres the breakdown for the Rodney and the kids

Magnesium alloys are designated by a combination letter / number system composed of four parts

1. A - Aluminum
2. E - Rare Earth
3. H - Thorium
4. K - Zirconium
5. M - Manganese
6. Q - Silver
7. Z - Zinc

OK here is the info that is important

AZ63A-T6 for an example is a common material used for all kinds of machining and molds, lets break it done for Rodney to understand.

A above is Aluminum
Z about is ZINC

6 is the first number
3 is the second


6% Alumium and 3% Zinc

Now what does the A behind 63 mean?

Each metal has an assigned letter to distinguish how many changes the alloy had while it was made.

A = 1st Alloy Made
B = 2nd Alloy Made
C = 3rd Alloy Made
So our example was made only once as the letter " A " follows the 63

and the last part is the dash T1 - T10 and just like aluminum is the designation of the finishing of the material such examples are heat treating, aging and so on. ( i will do a lesson about what all the Ts mean some other day )


MAGNESIUM Will BURN !!!!!!!!!!! They make fire starters out of it for a reason

NEVER USE WATER on a mag fire - it will combine with the oxygen in the water as well as the CO2, it can also react with the nitrogen in the atmoshere.

If there is a fire use a CLASS D, most aerospace shops have these that work with all kinds of metals, Titanium and Magnesium can both start fires in machining and a Class D can put it out.

Sand can be used but the amount of sand it takes is crazy, its like 5 pounds of sand to a pound of metal, it needs to be very dry as well.

Hope that helps out to the kids out there trying to have fun with MAG !

Thanks to Bill West from Lincoln Electric, one of the most knowledgeable welders in the welding field and an great welder as well. My teacher and friend. RIP Buddy

No comments:

Post a Comment