Porosity in a weld; what caused it

[ericher69]

On a garden tractor probably a very low grade casting. What makes you think it is cast steel? Figuring out what it's made off is the most important thing to know in order to repair it. Cast steel is much easier to weld than cast iron and cast aluminum is an entirely different animal so comparing how it welds is a moot point. Too much gas flow can also cause turbulence which can cause porosity. TIG is best for cast aluminum but for cast steel, I'd use stick 7018 but MIG would also work. 6013 is the last thing I would use on just about anything. Preheat is good on anything that's cast.

I used the grinder on the part and some angle mild steel and the sparks where identical which leads me to believe it is cast steel (no expert)

What would the sparks from grinding manganese look like?

MIG ended up getting it after grinding the porous weld and re-welding.

 

[weldermike]

I used the grinder on the part and some angle mild steel and the sparks where identical which leads me to believe it is cast steel (no expert)

What would the sparks from grinding manganese look like?

MIG ended up getting it after grinding the porous weld and re-welding.

Orange sparks, but the tip off would be it's non magnetic, or very week if mixed with anything.

 

[Shield Arc]

Here are some charts that may help.

 

[ericher69]

Here are some charts that may help.

Weldermike;

Yes strong magnet attraction with orange sparks. I did this before even grinding to see if it was steel or something else. Thanks for the input!

SA; yes this helps a lot. I will print and laminate some of these and keep them handy.

The coating on the part looked like some grade 1 bolts that you buy at the hardware store which leads me to believe it was zinc coated but may be wrong; wouldn't be the first or last time!

Definitely learned a few things with this repair and seems that maybe I made some educated guesses to make the repair.

 

[Arc weld]

Why would you think manganese?

 

[weldermike]

Why would you think manganese?

I've had it pop up in the past.

 

[Oldpath05]

11018 is the strongest rod I've used, welded my bench vice back together with it, it's a low/high DC rod, so porosity will be next to non if any. My bench vice looked like it was cast something, and 20 year's old.

 

[Arc weld]

A higher tensile rod won't do anything to eliminate porosity.

 

[Oldpath05]

In my experience, when welding with 70s-6 mig wire, the dirtier/rusty the steel/barrel is, the more often I get porosity, and when I welded with 7018 AC electrode, I would get a lot of porosity, so I don't use that rod anymore. When I use 7018, 8018, 11018, DC electrode, I hardly ever get porosity, and I only take off the heavy rust. If I want to do a lot of fast welding with stick, I use 7024, or 7014-3/16". and if someone doesn't have a mig welder, and want's to do a lot of tacking, 7014-3/32 works good for that. Last but not least, if I'm sick of grinding, and don't feel like cleaning rusty mild steel, I use 6011 electrode, also works good for filling gaps, and cutting.