[TheApprentice]

Hey guys, new to the forum and as the name states I'm an apprentice, I live in the uk, I'm 19 and recently started working for a relatively big company, I've been working for them for a month and I was recently put forward for a 2G coding with mig, I'm an all round welder so I can do tig, mig and stick but this coding was for mig welding, the material was normalised mild steel and the procedure was for a 35 degree bevel with a 70 degree included angle, 1/1.5mm landing and no gap (the job the coding is required for the client wants no gap, 1/2mm skimmed after welding) the bevel was done by our machine shop aswell, out of 5 of us 3 failed on gas pores and porosity, one of then being the pqr, we were weldin by open shutter doors and the test pieces weren't thoroughly cleaned, my question is do any of you think that the porosity may have been caused from the lubricant used by machine shop, even though it was dry, could it have been there was a draft or down to incorrect welding technique, the particular day of the test was 28 degrees so wind was minimal, I was one that failed just to add, my first coding and I was quite frankly shitting myself! Regards Matthew

[Otto Nobedder]

I suspect cleaning... If it were air movement, the porosity (and discoloration) would show on the weld surface.

The machine shop may have used a coolant or lubricant while cutting the coupons. There are oil-based and water-based coolant/lubricants, so the coupons should be solvent-cleaned, and "soap and water" cleaned, in that order, then dressed with a SS wire-wheel front, back, and faces.

It's a test, so get obsessive about the test conditions.

My two Pence...

Steve S