Is GMAW short-circuit transfer prequalified for groove welds on A572-50?

Not for PJP groove welds. AWS D1.1 Clause 5 explicitly excludes GMAW short-circuit transfer from prequalified PJP groove welds because of lack-of-fusion risk. Spray, globular, and pulsed transfer are prequalified subject to the usual Clause 5 constraints.

What's the matched filler for A572 Gr. 50?

A572 Gr. 50 (65 ksi minimum tensile) is a Group II material. Matched filler per Table 5.4 is typically A5.18 E70S-6 (or equivalent classification with at least 70 ksi minimum tensile).

What shielding gas do I specify?

For GMAW spray transfer on A572-50, an 80/20 or 90/10 Ar/CO2 mix is standard. C25 (75 Ar / 25 CO2) is common for short-circuit and globular transfer. Always specify both composition and flow rate on the WPS.

GMAW WPS for A572 Grade 50: parameters and pitfalls

GMAW with E70S-6 on ASTM A572 Grade 50 is common in structural fab. Here's the full WPS — including the short-circuit-transfer caveats that trip up prequalified status.

GMAW with E70S-6 on A572 Grade 50 is one of the most common structural welds in the US. It is also one of the most frequently failed WPSs at audit, because of the GMAW transfer-mode rules under AWS D1.1 Clause 5.

Here is what a clean WPS looks like.

Identification block

WPS number: WPS-25-007
Revision: 0
Date: 2026-05-08
Code: AWS D1.1/D1.1M:2025
Scope: GMAW spray transfer on ASTM A572 Gr. 50, Group II, thickness 3/16 in to 1-1/4 in, in 1G / 2G / 1F / 2F positions
Status: Prequalified per AWS D1.1:2025 Clause 5 (spray transfer; short-circuit excluded for PJP grooves)

Process and joint

Process: GMAW (Gas Metal Arc Welding), semi-automatic
Transfer mode: Axial spray
Joint detail: B-U2 (V-groove with backing) or B-U4 (double-V-groove without backing, with backgouging) from Annex B
Joint sketch: embedded as figure 1

The transfer-mode declaration is critical. Without it, an auditor cannot determine whether the WPS is prequalified.

Base metal

Specification: ASTM A572 Gr. 50
Group number: II (per Table 6.9 in 2025)
Thickness range: 3/16 in (5 mm) to 1-1/4 in (32 mm)

Filler metal

AWS classification: A5.18 E70S-6 (or A5.28 E70S-X for low-alloy variants)
Diameter range: 0.035 in, 0.045 in, 1/16 in
Wire feeder: semi-automatic, constant-voltage power supply

Shielding gas

Composition: 90% Argon / 10% CO2 (or 80% Ar / 20% CO2)
Flow rate: 35–45 CFH [16–21 L/min]
Nozzle distance: 1/2 in to 3/4 in from work
No drafts: wind speed < 5 mph at the arc, or windbreak provided

C25 (75 Ar / 25 CO2) is acceptable for short-circuit transfer but NOT for spray. Document the gas blend explicitly.

Position

1G, 2G groove (flat, horizontal)
1F, 2F fillet (flat, horizontal)
Spray transfer is NOT prequalified vertical-up or vertical-down at standard parameters

Electrical

Current: DC
Polarity: DCEP (Direct Current Electrode Positive)
Amperage range: 200–320 A (depends on diameter)
Voltage range: 24–30 V (spray transfer requires high voltage)
Travel speed range: 14–22 ipm
Wire feed speed: corresponds to current; document if welder-set
Transfer mode: Spray (above transition current — typically 200+ A for 0.045 in wire)

The spray-transfer call is essential under Table 6.6 — short-circuit, globular, spray, and pulsed are distinct modes. Switching modes is an essential-variable change.

Preheat and interpass

Minimum preheat: per Table 5.8 — for Group II A572 Gr. 50 up to 3/4 in with H-designated GMAW filler, typically 50°F [10°C]; thicker plate raises preheat to 150°F [65°C] or higher
Maximum interpass: 500°F [260°C] (non-CVN); tighter under Table 6.8 for CVN-required work
Method: contact thermocouple or temperature-indicating crayon

Technique

Bead style: stringer beads in 1G, 2G; weave beads acceptable up to 4× electrode diameter
Cleaning: light brush between passes; high CO2 content produces some silica which must be removed
Tack welds: maximum 2 in [50 mm] long; tacks fully melted into the root pass

Common pitfalls on this WPS

Transfer mode not declared. "GMAW" alone is ambiguous; spray vs short-circuit vs pulsed are different essential variables.
Short-circuit transfer used on a PJP groove weld while claiming prequalified status. Clause 5 excludes this.
Gas composition listed only as "Ar/CO2" without percentages. Auditor flag.
Vertical-up position claimed prequalified with spray transfer. Spray isn't prequalified for vertical positions under standard parameters.
No flow-rate range. Single value of "40 CFH" without a range is technically incomplete.

A rule engine that knows AWS D1.1:2025 Clause 5 limits catches all five at draft time. Spray-transfer GMAW is a textbook prequalified procedure, but the documentation discipline is what separates a clean WPS from a failed audit.