Spot welding aluminized steel 1

[Wicsteve]

Anyone know of a good reference for information about spot welding or projection welding of aluminized steel sheet metal?

 

[metengr]

Some background reading on general weldability of aluminzed steel

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD401176&Location=U2&doc=GetTRDoc.pdf

For spot weldability

http://www.nsc.co.jp/en/tech/report/pdf/n8805.pdf

 

[Wicsteve]

Thanks metengr for your response.

I'm surprised that there seems to be very little information out there from any of the welding companies or from SAE.

I know there are concerns about contamination of the weld and weld strength. In our past,we've experienced problems with pin hole leaks through the weld sections, and we're having current problems with welds falling apart the day after, even with they passed strength tests on the day of welding. We've been told by one of the small engine manufactures, that they only use projection welds (avoiding spot welding altogether), and one of my old contacts used compacitor discharge welders to improve weld quality.

Somebody out there must have some additional guidance they'd like to share about making good (or at least acceptable) welds on aluminized steel sheet metal.

Thanks.

 

[berkshire]

Wicsteve
Are you spot welding pure aluminum coatings or are you spot welding "Galvalume"? The small amount of Zinc in "Galvalume" makes it easier to spot weld than pure aluminum coatings. Best technique is to use a 2 stage spot weld, stage one preheats to melting point of the coating, allowing the electrodes to squeeze the coating out of the way, stage 2 melts the base metal and finishes the weld.
There is an SAE paper on the subject of spot welding Aluminum coated steel,

http://www.sae.org/technical/papers/2009-01-0035

B.E.

 

[Wicsteve]

Thanks BERKSHIRE for your response. In our case we're mostly welding steel with a Type I alumininum-silicon alloy coating. [per ASTM 463M-05 or JIS G3314) where the parts are used at elevated temperatures. I don't think the zinc additive would be acceptable in our high temperature applications.

I've downloaded the SAE article. Although mostly about spot welding aluminimum to aluminizied steel it still gives some clues for poor weld strength relating the strength to the welding amperage and nugget size; material alloy (9% Si in the report); and to problems caused by the Al/Fe intermetallic compound (between the steel and aluminum).

Thanks

 

[TVP]

Wicsteve,

There is some information available on this subject. Take a look at the citations from this Google Scholar search, especially those that appear on the second page:

http://scholar.google.com/scholar?h...aluminized+steel&as_sdt=2000&as_ylo=&as_vis=0