Mig welding wire to avoid porosity due to mill scale

[Ratheesh_n]

Dear All,
We are using MIG welding with 75 % argon and 25% co2 to weld cable trays .single Porosity is coming every stich weld.We have checked welding with mill scale removed. We got good welding quality . we cant able to remove mill scale before welding every time because of our process..So can anyone suggest a filler material which can give good welding over mill scale ...?

. Is flux coated filler wire helpful...?does it produce slag over welding ??

Please help......

 

[metengr]

Your asking to weld over mill scale using MIG? No way, you need a clean weld joint for this process.

 

[Mr168]

Are you cleaning the weld area with acetone/solvent prior to welding over the scale?

 

[david339933]

ER70S-6.

 

[DekDee]

we cant able to remove mill scale before welding every time because of our process..

Change your "process"

 

[Ratheesh_n]

Cleaning before welding is effecting production and cost.


Is flux coated helpful ...?

 

[metengr]

Ratheesh_n;
In other words, you low bid a job with little experience in MIG welding or welding, and now you are looking for a short cut to make a profit or break even. I can tell you this, if you were working at my plant I would have you clean the welds or don't bother to perform the work.

As mentioned above try the ER70S-6 and 100% CO[sub]2[/sub]. You may get lucky and have welds supporting cable trays that are visually ok, and fail later in service from lack of fusion weld defects.

 

[MintJulep]

.We have checked welding with mill scale removed. We got good welding quality

There you go.

Cleaning before welding is effecting production and cost

What will be the cost of replacing all of these parts for free when your customer rejects the defective products that you send them?

What will be the cost of never getting more business from this customer?

 

[weldstan]

Flux cored wire would be a better option. We have used it on multiple projects of a similar nature. We have also used SMAW with E6010 and E6012 in similar applications.

 

[Tmoose]

http://www.lincolnelectric.com/en-us/support/welding-solutions/Pages/welding-rusty-steel-detail.aspx

 

[Mr168]

Also, are you fabricating cable trays, or welding TO cable trays? If its the latter, you may be dealing with a galvanized coating, not mill scale.