Poroisty

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Ok,heres the question,Ive been welding with ER70s-6 on mild steel and get porosity,but if I change to 309 or 316 stainless filler rod I dont get porosity on the same base metal.Why is that?.
Reply:Short answer is that the chromium in 3xx series stainless steels has a much higher affinity forh oxygen/nitrogen than anything in carbon steels.  So instead of gas pockets you end up with an abundance of oxides.Have we all gone mad?
Reply:I had the same thing a few weeks ago. If I used 70s6 on clean mild steel, I got a ton of porosity, but if I used 70s2 on the same piece, everything was great. I think it has something to do with the way I weld for some reason.kidtigger24  They think I’m crazy, but I know better. It is not I who am crazy. It is I who am MAD!
Reply:I have found that when welding seriously rusty material with wire, especially hard wire and metal core I do a moderate whip so that the puddle is elongated.  It gives the molten metal more time to float out impurities.  As soon as I go to a steady weave and smaller puddle the porosity comes back.   You might try that with the S6 before you give up on it..It is odd that you get porosity on clean steel.... Too little sheilding gas?  Some people turn up their gas over 40 cfh and the turbulence gives them porosity.   If I remember correctly S2 has lots of deoxidizers like extra silicon to grab oxygen.
Reply:Originally Posted by lotechman   If I remember correctly S2 has lots of deoxidizers like extra silicon to grab oxygen.
Reply:The difference between an S2 and an S6 is the amount of silicon in the filler, more silicon makes the metal flow a little different and works as a deoxidizer. It also causes the glassy looking "slag" deposits on top of your mild steel welds (more seen on mig welds)
Reply:yur right it is Aluminum and Zirconium .  ... intended for rusted steels.  S6 has no aluminum.
Reply:I was able to narrow down some porosity issuesto being oily/dirty gloves and leaving some sort ofresidue on the filler rod. I have to say I was veryfrustrated trying to figure it out as I must have handled the ends of the whole box of filler withthem on. After that the gloves didn't matter.How do you know the blacksmith's dog? When you hollar at him he makes a bolt for the door!
Reply:Test out different cup sizes and play with your gas.