[TheForge] welding gasses

[Cindy and James]

on the question of which gas for MIG welding, the following is my 
understanding of the products.  If someone has a different take, I would 
be glad to hear it.

Straight C02 in  a wire machine = 6011 stick electrode or equivalent, 
lots of spatter, more penetration, not as pretty, etc.
Mix gas in a wire machine, 75 Argon/25 C02 or one of the other mixes, 
85/15, etc. (there are several) = more like a 6013 or maybe 7014 or 
7024, less penetration, prettier weld, less spatter and less cleanup.

I have both setups and normally use the mix gas thru a Lincoln 215.  
Raise or lower the amp level depending on the thickness of metal to be 
welded and raise or lower the wire feed speed accordingly.  I think I am 
using a .035 wire, haven't looked in a while.  Multiple passes may be 
required, bevel plate or bar to achieve penetration through the joint in 
the root pass.

A welding engineer told me (and I have no other source to verify this 
with), that a wire welder w/ gas shield is the equivalent of a "no 
hydrogen electrode", as opposed to a 70xx LOW hydrogen or other series 
of electrodes manufactured with hydrogen in the flux (such as 6010/11, 
etc.).  There may be some differences in the metal deposit from rod/wire 
composition.  My question to him was relative to welding oilfield upset 
tubing to mild steel plate, i.e. dissimilar metals therefore did I need 
to use the 7018 or would the wire feed work?  This was a structural 
application for myself personally, not a client and I had just bought 
the wire machine, having always used a stick welder before.  Also, as I 
am sure most of you know low hydrogen electrodes must be kept dry.

James Allcorn
Bois D'Arc Blacksmith Studio
Paris, TX