Welding Tips and Tricks

I am enrolled at a tech college and am trying to do some autogenous welds on a lap joint with 16gauge mild steel I am using 100% argon at 18cfh and have tried it at 1pps. I also have tried with the pps turned off for some reason as I am welding the joint the weld seems to blow up like there are air bubble popping out of the weld before it cools I cant seem to figure out what is causeing this problem any help would be appreciated thanks. I am also using a 3/32 electrode is that to big for welding 16 gauge?

1-I'd use 1/16th electrode for 16 guage steel.

2-Those air bubbles coming up are contamination cooking out.

3-Are you just tacking the plates together or are you welding the whole joint antogenously? If your just tacking you can leave the pulse off, just strike your arc, rocking your foot pedal up, watch the plates melt together then lean back on the pedal and break your arc.

4-Antogenous welding requires a REAL tight fit up. You cant have any visible gap there or you'll just melt the edges away and they wont combine and melt together. If yuo have to use a c clamp or something, or spread a couple tacks out on the joint a few inchs apart. If you do that keep the heat -real- low so you minimize warpage.

What is an "Autogenous weld"?

Its where you melt the edges of the weldment together with no filler metal. Usually makes for very brittle welds, and as such is usually reserved only for tack welding.

If you did not remove the mill scale that will be the cause of your problem.

I often hear these called "fusion" welds, which is kind of silly, since all welds require fusion. I do them regularly, in one particular instance. I close a 6" hole for an inset gauge on 11 ga. SS with a piece of 16 ga. ss for a surface mounted gauge. The 16 ga. is cut as an irregular octagon (alternating long and short sides), and I "fuse" the four short sides. (This is an overlay, so these are lap joints.)

About 3/32" of the 16 ga. becomes the "filler metal". As long as the metal is clean, and the fit is tight, I never have a problem with appearance, and these welds only see the weight of the gauge +/- about 2g. They hold up fine.

Steve

P.S. I RARELY use anything but 3/32" 2% Th tungsten.