Is there any reason why you would use copper coated mild steel rod
meant for gas welding instead of ES70-2 for TIG welding carbon steel.
I was told they are the same thing? Thanks again for expert advice.
Chemically, they are close, but not exactly the same. Most important
differences are in the amounts of deoxidizers like Si and Mn. You risk
porosity using a gas rod doing TIG.
Tensile stength also differs. Gas rods RG45 and RG60 have 45 ksi and 60
ksi minimum tensile stength respectively. ER70S-2 has minimum tensile
strength of 70 ksi, and is typically well over that.
If you are welding to procedure under the requirements of one of the welding
codes, you have to use what the procedure calls for.
I have tigged mild steel with gas welding rod. The bead came out ok but at
the end of each bead the end formed a foaming crater of porosity. I was
told that the TIG rod had extra deoxidiers such as silicon in it. Use the
proper rod for a proper weld..
Yes there is a reason(s). But first: the copper coating is very light and
only meant to add some protection against rust.
Are you sure you mean 'carbon steel.' Most stuff like a truck bumper etc.
is made from mild steel which is different from high carbon steel.
My first try at TIG was with RG45, a oxy/acet filler rod. The weld was not
very good, my poor TIG technique notwithstanding--porous and looked rough.
On advice from lamentations here, I got and used ER-70-S2. The general
difference is that a TIG rod has more oxidizers and in most situations
eliminates the little pinholes that a gas rod will leave.
I believe ER-70-S2 is considered the general purpose mild steel TIG rod.
I am not sure why TIG rod needs oxidizers. I am also not sure if a TIG rod
would work with gas welding. I'd like to read some answers here on these
My mistake it should say ER instead of ES on my OEM post.
My other question is that if I needed to stock one rod for general
purpose mild steel (carbon steel) TIG, do I purchase the ER70S-2 or
I've got some stainless rod either 308 or 316 that works great on mild
steel, but not sure if that would be cost effective or as strong? B.G.
General purpose is ER70-S2.
I have used 316 for MS. It flows well. It is the appropriate choice when
joining SS to MS. As you note, when comparing cost, it is more dear than
the ER70S-n series.
See below for information taken directly from the AWS specifications
for both the gas welding rods (R45 and R60) and the TIG welding rods
(ER70-S2 and ER70S-6).
Note the following items regarding the differences in the chemical
1) Both Mn and Si are deoxidiers but ER70S-2 requires the addition of
small amounts of other powerful deoxidizers.
2) Increasing the Si level generally also provides increasing fluidity
to the molten weld puddle (i.e. it should flow easier). Therefore, the
ER70S-6 should provide a smoother weld bead than ER70S-2. This is
indicated in the usage information listed below. Also note how low the
Si levels are for the gas rods compared to the GTAW rods.
Chemical composition requirements from AWS A5.2 (gas rods) and A5.18
(GTAW rods) [I hope the table layout is readable after posting]
rod carbon Manganese Silicon
R45 0.08 % max 0.50 % max 0.10 % max
R60 0.15 % max 0.90 - 1.4 % 0.10 - 0.35 %
ER70S-2 0.07 % max 0.90 - 1.40 % 0.40 - 0.70 %
plus required small amounts of additional deoxidizers Ti, Zr, and Al
ER70S-6 0.06 - 0.15 % 1.40 - 1.85 % 0.80 - 1.15 %
Useage information from AWS A5.18 (GTAW rods)
ER70S-2: "...primarily used for single-pass welding
of...steels...Because of the added deoxidants, these filler metals can
be used for welding steels that have a rusty or dirty surface, with a
possible sacrifice of weld quality depending on the condition of the
surface. ...[U]sed extensively to produce high quality, high toughness
welds with the GTAW process."
ER70S-6: "...intended for both single- and multiple-pass welding.
They are especially suited for sheet metal applications, where smooth
weld beads are desired, and structural and plate steels that have
moderate amounts of rust of mill scale.