ASTM A514 quenched-and-tempered (QT) structural steel appears in heavy crane girders, pressure vessel supports, mining equipment structures, and high-restraint splice connections where lighter steel would require impractically thick sections. Its 100 ksi minimum yield strength makes it attractive for load-critical details, but QT microstructure is far more sensitive to welding heat than A36 or A572. A WPS that works on mild structural steel will not work on A514 — and using it anyway risks HAZ softening, hydrogen cracking, or weld metal that can't meet tensile requirements.
This article covers the WPS content requirements and production controls that AWS D1.1:2025 and sound QC practice demand for A514.
What makes A514 different
A514 achieves its strength through a heat-treatment cycle — austenitizing, quenching, and tempering. This QT condition produces a fine-grained martensitic microstructure with high strength and reasonable toughness. The tempered condition is temperature-sensitive: if the base metal in the HAZ or the weld metal is held above the original tempering temperature for any meaningful time, the temper is relieved and strength drops.
This creates constraints on welding that don't apply to normalized or hot-rolled steels:
- Heat input must be limited to prevent excessive HAZ width and temperature
- Preheat must be high enough to prevent hydrogen cracking but not so high that it pushes base metal above the tempering temperature for extended periods
- Interpass temperature has a hard upper ceiling
- PWHT at conventional stress-relief temperatures is destructive, not remedial
Standard WPS documentation approaches that work for A36 or A572 — sometimes using a prequalified procedure with minimal documentation of heat input — are inadequate for A514.
A514 is not a prequalified base metal
AWS D1.1's prequalified WPS path (Clause 4) specifies a list of base metals eligible for prequalification. A514 is not on it. There is no shortcut here: every WPS for A514 must be backed by a PQR with:
- Full tensile testing of weld metal and the weld-HAZ interface
- Bend testing per D1.1 requirements
- CVN impact testing if the contract or structural code requires it
The PQR test plates should use material from the same heat, or a heat with a similar carbon equivalent, as the production material. A514 comes in multiple grades (A, B, E, F, H, and others); the alloy composition varies by grade. A PQR qualified on A514 Grade B does not automatically cover Grade F if the CE values differ significantly.
For the mechanics of PQR tensile and bend testing, see PQR tensile and bend test requirements.
Preheat requirements
Because A514 is not prequalified, there is no single AWS D1.1 prequalified preheat table value to cite. Minimum preheat is established through one of two routes:
- PQR-qualified preheat: The minimum preheat applied during the PQR test defines the minimum permitted in production. Using a lower preheat than the PQR is an essential variable violation under Table 6.6.
- Carbon equivalent calculation: AWS D1.1 Annex I provides a CE-based methodology for estimating minimum preheat. For most A514 grades, CE values typically fall in the 0.50–0.75 range, which translates to elevated preheat requirements — commonly 150–225°F [65–107°C] for sections under 1-1/2 in [38 mm] and up to 300°F [150°C] for heavier sections. Verify actual values using the CE method on the material certification you have in hand.
Whatever preheat your WPS specifies, document it explicitly with minimum and maximum values. "Preheat as required" is not a conforming WPS entry.
Rule library based on AWS D1.1:2025; verify against your governing edition.
Maximum interpass temperature
The maximum interpass temperature for A514 welding is 400°F [205°C]. This limit is not arbitrary — it is tied to the tempering temperature of the QT condition. Running above 400°F during multipass welding means each subsequent pass is soaking adjacent base metal and previously deposited weld metal at a temperature approaching the temper range.
In heavy-plate multipass welds, maintaining interpass temperature is operationally difficult. Welders working on thick sections with high preheat often find interpass temperature climbing with each pass. Your QC procedure must include:
- Interpass measurement before striking each pass
- A cooling protocol when interpass approaches the limit (typically enforced with a temperature-indicating crayon or contact thermometer)
- Documentation of measured interpass temperatures in the inspection record
This is not optional process paperwork — it directly affects whether the base metal properties declared on the material certification are still valid in the finished joint.