welding 304ss to mild steel

By johnny bickham Date 10-14-2008 21:33

I am using a 309L to weld ss to ss and also ss to mild. I am welding AWWA-D flanges(mild & ss) to ss pipe about 1/8" thick. The ss-ss does great, however, the ss to ms does not. while welding the inside bead the puddle moves around making the bead look like a snake. Is this the right wire for this job? Am using stainmix shielding gas. If this is not right, or if you have any suggestions, let me know. Thanks. E-mail is bigbassjohnny@yahoo.com

By Kix

Date 10-15-2008 12:46

Yes, this is the right wire for the job. Are you MIG welding with the stainmix gas I hope? The puddle moving around and giving the bead ripples and ackward shape is usually due to turbulence in the gas shielding, but this is noticed more with TIG welding then with Mig welding. Make sure the cut end of the pipe is clean and preped after cutting. Check your flow rate and make sure it it set for the diameter nozzle you are using. Smaller dia nozzles require less flow. Are your welds looking like they are wetting in ok, or are they looking kind of ropey?

By 803056

Date 10-15-2008 14:20 Edited 10-15-2008 18:37

Preparing the mild steel pipe by grinding can result in some residual magnetic field that can deflect the welding arc. If Kix's suggestions doesn't help, demagnetize the mild steel pipe before trying to weld it.

Best regards - Al

By johnny bickham Date 10-15-2008 21:53

Thanks for the info. Yes I am mig welding. i am welding on stainless pipe to mild steel flange ring. What gas pressure is recommended, I am using a 1/2" nozzle and am currently running around 35 psi on flowmeter. I experimented today with a higher voltage and wire feed today and had better results, but still not even welds all around. I am using a robot for this procedure. I am welding the o.d. of the part first, you could almost say in horizontal position, then flipping it over on a rotator a 90 degrees and running the inside bead about 10 - 15 degrees from center, dragging the puddle downhill. I have to make a small weld on the inside and it does good part of the way around then will mess up. I am not having any problems with the outside bead, but can't run the inside the same. I will try turning gas pressure down to see if this helps. the weld is wetting in good except for where it is moving around. thanks again, any more would be appreciated. Johnny

By 803056

Date 10-15-2008 22:29

Make sure the stainless steel is properly cleaned, i.e., wire brushed, before welding to break down any surface oxides. Even though the stainless may look clean, there are oxides present that can hinder the welding operation.

Best regards -Al