Dioxyde Silicates slag in Mig Welding

[MetFreak]

Hi all,

I've heard that silicates dioxyde slag is a common phenomenon/problem in Mig Welding.

Can anyone tell me more about this ?

Because it gets problematic when you weld on automatic mode and you want to do multiple layers. You don't want to stop the robot and clean the first bead before welding the second one...

So is this related to the process ? (MIG)
Or will any process using a high Si% filler metal will encounter the same problem?

I searched on the forum and haven't found anything helpful.

Thanks in advance for any help!

 

[metengr]

Possibly, if you are using metal cored wire (GMAW-C).

 

[MetFreak]

Effectively, the filler is metal cored.
Could you tell me more?

 

[metengr]

With a metal cored wire versus solid wire, the flux within the core provides limited shielding in the form of a slag coating. Typically, for the GMAW-C wires this slag can be easily removed but does require cleaning between passes.

For solid wire GMAW, the shielding is provided by gas only so there is no real slag that is formed. You can have contaminants in the shielding gas or hydrogen introduced, however, this typically results in porosity or other problems, but not slag.

http://content.lincolnelectric.com/en/pdfs/products/literature/coredwiresbrochure.pdf

 

[metengr]

You might find this AWS article relevant to your concerns;

http://www.aws.org/wj/sept02/feature3.html