Hi Scott,

Now I understand the question. It is impossible to prevent
hydrogen embrittlement when gas welding. A natural byproduct
of the combustion of oxygen and acetylene is water vapor, which in
the flame shows up as H+ ions. These H+ ions get mixed in
with the molten steel, and form a mess. These H+ ions turn
good steels into something that is full of glass hard fissures,
and will always crack... sooner or later. Gas welding is really
only suitable for mild steels.

If all you have is a gas rig, and you need to connect good steels,
like 4130, you should be brazing... which essentially is what you
are doing when you use a mild steel filler (coat hanger wire).
(don't really use coat hanger wire. Its a mystery steel. Its only
operating requirement is the alloy must be cheap and soft)

If you are trying to make a joint that is as strong as the base 4130
steel, you should be using a stronger filler steel, and a shielded
arc process. The best would be TIG, or MIG.

-Chuck


pbc76049 wrote:
Chuck..
Decent advice for stick welding, but the question was about gas welding.
There are a number of good filler rods for steel, and for small puddles
with small tips, one of the best is ER70sXXX mig wire. This lets you
place filler rod in the weld without chilling the puddle too hard with a
larger diameter rod. 4130 rod in 4130 welds isn't the best idea
and a softer filler material is advised. Rods for mild steel are preferred.

Have a great day

Scott


"Chuck Harris" wrote in message
...
Hi Orval,

I think what the OP is trying to get at, is there is no standard
off the shelf welding rod.

The most sold is probably 6010/6011. It requires a stitch welding
technique, and tends to stick when starting. It makes strong deep
all position welds that tend to be ugly. Not for beginners.

The easiest to use is 6013, but it makes really pretty looking, flat
position, non xray quality welds, and has little penetration.

The most common low hydrogen rod is 7018, but it is tricky to use,
and must be stored in an oven. It is used almost exclusively for all
position, structural steel welding.

And then there is a host of SS rods that some people like because of
their easy welding characteristics, and the toughness of the weld.

So, what do you mean when you state off-the-shelf? I would recommend
7018, and a whole bunch of practice.

-Chuck