Cold Weld ???

I made a pin puller yesterday as a project with my dad when he and my mom stopped over yesterday for Thanksgiving. Basically I welded a 5/8
mild steel rod to a pair of locking pliers (Great Neck, not Vise Grip) put a drilled out piece of steel on the rod for a hammer, and welded the a cap on the rod for a striking surface.
Most of it went pretty well... after I remembered to turn on the gas on the old Miller 212 Mig welder.
When I was welding the cap on I had something weird happen. I was being conservative with my approach. The cap was about 3/4 thick with a 5/8 hole drilled through it. I chamfered one end of the inside of the cap with a deburring tool in the lathe, and chamfered the end of the rod with the benchtop belt grinder. I wanted to only weld on side so I didn't have to remove more weight from the hammer to clear the weld. I figured if the cap broke off I could do what I needed to when I put it back.
Anyway, I set the welder for 1/4" stock. I know. I know. I should have cranked it up. What was weird is it arced up and melted wire, but I got a nearly silent arc compared to that hot sizzle I am used to. I wasn't happy so I ground it all off, cranked up the welder to a hotter setting and it welded just like I am use to.
On my to low setting what exactly was happening? My first reaction is the larger mass of steel just sucked the heat out of the arc. I remember something similar when trying to weld 3/8 aluminum with the spool gun. Had to preheat the heck out of it to get good welds.
For anybody who might be wondering the slide hammer pin puller works just like its supposed to. I did have to bend the rod to get the hammer in line with the pulling point. Fired up my O/A torch to do that. First time I have lit the torch in probably two years. When you want to get something hot its pretty hard to beat a rosebud.
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