Instructions / Assembly

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GMAW
Bare Dissimilar
Welding PH Stainless
Designation UNS No. Wire Steels
Martensitic Types
17-4PH S17400 AMS 5826 E or ER309,
and (17-4 PH) or E or ER309 Cb
15-5 PH S15500 ER308
Stainless W S17600 AMS 5805C E or ERNiMo-3,
(A-286) or E or ER309
ERNiMo-3
b
Semiaustenitic Types
17-7PH S17700 AMS 5824A E or ER310,
(17-7 PH) ENiCrFe-2, or
ERNiCr-3
PH 15-7Mo S15700 AMS 5812C (PH 15-7Mo) E or ER309, E or ER310
AM350 S35000 AMS 5774B (AM350) E or ER308, E or ER309
AM355 S35500 AMS 5780A (AM355) E or ER308, E or ER309
Austenitic Types
A-286 K66286 ERNiCrFe-6 or E or ER309,
ERNiMo-3
E or ER310
Form Diameter, in. Diameter, mm,
Electrode in coils, with or 0.045, 1/16, 5/64, 3/32, 7/64 1.2, 1.6, 2.0, 2.4, 2.8
without support 1/8, 5/32, 3/16, 1/4 3.2, 4.0, 4.8, 6.4
Electrode wound on standard 0.030, 0.035, 0.045, 1/16 0.8, 0.9, 1.2, 1.6
12-in. O.D. spools 5/64, 3/32, 7/64 2.0, 2.4, 2.8
Electrodes wound on lightweight 0.020, 0.025, 0.030 0.5, 0.6, 0.8
1-1/2 and 2-1/2 lb., 4-in O.D. spools 0.035, 0.045 0.9, 1.2
GMAW of Stainless Steel
If the production application involves long joints in relatively thick
material or a large number of parts, the GMAW process with
solid or metal cored electrodes may be the best choice.
Solid or metal cored electrodes will provide the fastest deposi-
tion rates with the GMAW process but wire feeding equipment,
power supplies and the requirement for inert gas shielding add
to the cost of using these fillers. However, there is little need to
remove slag between passes. Solid and metal cored electrodes
can be used in short-circuiting, globular and spray modes of arc
operation which gives a wide range of deposition rates and heat
input levels. Solid and metal cored electrodes can therefore be
used for welding a wide range of thicknesses.
Gas metal arc welding with spray transfer is used to join sections
thicker than about 1/4” (6.4 mm) because deposition rates are
higher than with other transfer modes. Welding procedures are
similar for conventional austenitic and PH stainless steels.
The shielding gas is generally argon with 1 to 2% oxygen added
for arc stability. Mixtures of argon and helium are employed if a
hotter arc is desired. A small oxygen addition can be added to
provide a stable arc, but some aluminum or titanium can be lost
from certain PH filler metals during transfer across the arc as a
result of oxidation. Response of the weld metal to heat treatment
might be less because of this action.
Stainless steels may be welded by the gas metal arc process,
using either spray arc, short-circuiting or pulsed arc transfer.
For flat position welding, spray transfer is usually preferred. For
other welding positions, short-circuiting transfer is often used
with helium-rich gas such as 90% He, 7.5% Ar, 2.5% CO
2
.
Pulsed spray transfer can be employed using argon or an
argon/helium mixture with a small addition of oxygen or carbon
dioxide.
Copper backup strips are necessary for welding stainless steel
sections up to 1/16” (1.6 mm) thick. Backup is also needed
when welding 1/4” (6.4 mm) and thicker plate from one side
only. No air must be permitted to reach the underside of the
weld while the weld puddle is solidifying.
Oxygen picked up by the molten metal may reduce the
corrosion resistance and ductility of the stainless steel as it
cools. To prevent this, the underside of the weld should be
shielded by an inert gas such as argon. The shielding gas
source can be built into the welding fixture(s).
ELECTRODES
TABLE 20 — Solid, Metal-Cored Wires for Welding Precipitation-Hardening Stainless Steels
ELECTRODES
TABLE 21 — Standard Sizes for Stainless Steel Electrodes