Does AWS D1.1 specifically name temper bead welding as a qualified technique?

AWS D1.1 does not prescribe a named temper bead procedure the way ASME IX does in QW-290, but Clause 6 qualification testing can fully accommodate it. The WPS must document the controlled bead sequence and pass dimensions, and the PQR must demonstrate acceptable hardness across the HAZ using a hardness survey.

What PQR tests are required when qualifying a temper bead repair WPS under AWS D1.1?

At minimum: transverse tensile, guided bend, and macro examination. A Vickers or Brinell hardness traverse across the HAZ on the macro section is strongly recommended and often required by the EOR. When the owner or contract requires CVN toughness, the supplementary essential variables in Table 6.8 (Rule library based on AWS D1.1:2025; verify against your governing edition) also apply.

When is temper bead repair preferred over conventional repair with PWHT?

Temper bead is preferred when PWHT is impractical—field repairs on crane runways, in-service bridges, or large weldments where furnace heat treatment cannot be applied. If the governing project specification requires PWHT, temper bead alone does not substitute for it.

Which steels most commonly require temper bead technique in structural repair?

High-strength, high-carbon-equivalent grades—A514, A517, A710, and some A709 HPS grades—develop hard, brittle HAZ microstructures when cooled rapidly. Temper bead technique uses the heat of subsequent passes to anneal the prior bead's HAZ before it can crack.

Temper Bead Weld Repair Under AWS D1.1: WPS and PQR Requirements

Temper bead welding lets you heat-treat the HAZ in place without a furnace. Learn what AWS D1.1 requires in the WPS and PQR for structural steel repair.

When a crack or gouge opens up in a high-strength steel weldment that cannot be moved to a furnace, the repair WPS becomes the hardest document in the package. Conventional repair welding works fine on mild steel—you clean out the defect, preheat to the code minimum, fill with a low-hydrogen electrode, and inspect. On high-carbon-equivalent plate, that straightforward sequence leaves a hard, hydrogen-susceptible heat-affected zone behind every repair pass. Enter temper bead welding: a controlled deposition technique that uses the heat of subsequent passes to mechanically heat-treat the HAZ created by earlier ones—no furnace needed.

AWS D1.1 does not define "temper bead" by name the way ASME Section IX does in QW-290. What it does define, in Clause 6, is what the procedure qualification record must demonstrate. A well-written temper bead WPS can qualify under standard AWS D1.1 testing if the PQR coupon is prepared using the same controlled deposition sequence and if the mechanical test results—especially hardness—confirm that the technique worked.

How Temper Bead Technique Works

The principle is straightforward. The first layer of weld metal deposited on the base metal creates a HAZ that is rapidly cooled from the austenitizing temperature. On high-CE steels, this produces a martensitic or bainitic microstructure that is hard, brittle, and susceptible to hydrogen cracking. In a normal repair weld, that HAZ stays hard unless the whole assembly is stress-relieved.

In temper bead welding, the second layer of beads is deliberately placed so that its own heat input reheats the HAZ of the first layer to the tempering temperature range—roughly 1,000 °F to 1,200 °F (540 °C to 650 °C). This tempers the martensite, restoring toughness and reducing hardness to acceptable levels. The third layer tempers the second layer's HAZ, and so on up the joint. The last layer ("butter" or "cap") deposited above the final structural layer is typically ground flush because its own HAZ in the weld metal above has not been tempered.

The technique demands precise control of bead width, placement, and heat input. If the bead is too narrow, it reheats the wrong zone. If heat input is too high, the HAZ is re-austenitized rather than tempered.

When Structural Fab Shops Need It

Temper bead repair applies in situations where PWHT is not an option:

Crane runway repairs in service. Taking down a crane runway for furnace PWHT is often not feasible. A controlled repair WPS using temper bead technique lets the repair happen in place. See the article on crane runway beam weld WPS under AWS D1.1 for related fatigue considerations.
Field repair of A514 or A517 plate structures. These quenched-and-tempered steels are the classic temper bead application. See high-strength steel WPS for A514 for the WPS baseline before repair.
Post-fire repair of existing structures. Fire can re-harden base metal and HAZ zones. AWS D1.1 Clause 8 governs welding on existing structures; the repair WPS must address the altered base metal condition.
Repair of heavy weld joints where distortion from PWHT is unacceptable.

WPS Documentation Requirements

The temper bead repair WPS must specify everything that a standard WPS specifies, plus the elements unique to controlled bead sequence:

Bead placement geometry. The WPS must define the relationship between adjacent beads—typically that each successive bead overlaps the prior one by 50 percent of the bead width. This is the overlap that ensures the prior HAZ is reheated into the temper range. Specify in the WPS as a minimum overlap percentage or a dimensional bead width range.

Heat input range per pass. Too low and the reheating zone is too shallow; too high and you re-austenitize. The WPS should specify minimum and maximum heat input in kJ/in for the fill passes. Arc energy and heat input under AWS D1.1 covers the formula and how to calculate it from your welding parameters.

Butter or temper layer above the final structural weld. A temper bead WPS typically requires one or more passes placed above the finished joint surface specifically to temper the HAZ of the last structural pass. These passes are subsequently ground flush to the base metal surface. Document the minimum number of tempering passes and the grinding requirement.

Preheat and interpass temperature. Requirements are at least as stringent as the base WPS. For A514, the typical interpass maximum is 400 °F (205 °C); the minimum preheat is 125 °F (50 °C) per Table 5.8 of AWS D1.1 for prequalified joints or as established by the PQR. See preheat and interpass temperature on a WPS for how to document the range.

Low-hydrogen filler metal with controlled diffusible hydrogen. H4 or H8 classification is appropriate for temper bead repair on high-CE steels. The electrode must be handled under the same low-hydrogen discipline as any high-strength steel WPS. See hydrogen-induced cracking prevention for electrode handling requirements.

Post-weld hydrogen bake-out. After the final pass, hold the repair area at 450–500 °F (230–260 °C) for four hours or more to drive off residual diffusible hydrogen before the structure cools to ambient. Document the minimum hold temperature and duration in the WPS.

PQR Qualification: What the Tests Must Show

The PQR coupon must be prepared using the exact bead sequence and pass dimensions specified in the WPS—not a free-form fill. Mechanical tests include:

Transverse tensile. Must achieve the minimum tensile strength of the base metal specification.

Guided bend. Root bend, face bend, or side bend depending on thickness per Clause 6 of AWS D1.1. See guided bend test requirements for PQR for acceptance criteria.

Macro examination. The cross-section must reveal the bead sequence, HAZ geometry, and absence of cracks, lack of fusion, or unacceptable porosity.

Hardness survey. AWS D1.1 does not mandate a hardness test for every qualification, but for temper bead repairs on high-CE steels it is effectively required by any competent EOR. A Vickers HV10 traverse from base metal through the HAZ and into the weld metal, on the macro section, should show that peak hardness in the HAZ does not exceed 325 HV (approximately 34 HRC) at any location. Some project specifications set 300 HV or even 280 HV for hydrogen-cracking-sensitive environments. Agree on the limit before you qualify. See hardness testing on PQR structural welds for traverse methodology.

CVN impact testing (if required). If the contract triggers Table 6.8 supplementary essential variables—seismic, cold service, or dynamic loading—the PQR coupon must include Charpy specimens. Rule library based on AWS D1.1:2025; verify against your governing edition.

Common Disqualifiers

The most common reason a temper bead PQR fails is that the welder ran the test coupon like a normal fill sequence, without controlling bead placement. If the macro shows irregular bead stacking, some HAZ zones will not have been reheated into the tempering range, and the hardness traverse will expose it.

The second most common failure is running the last structural pass without subsequently depositing and grinding off the tempering layer. The HAZ of the final structural pass remains in the as-welded, untempered condition. Always specify and always complete the tempering layer.

Practical Notes for CWIs

Before the repair starts, verify that the WPS number on the repair traveler matches a qualified temper bead WPS—not the shop's standard repair WPS, which may not include bead sequence controls. Spot-check bead width and overlap during welding. After grinding, confirm that the temper layer was fully removed to base metal level and that no weld metal above the structural fill remains proud.

Document every repair: location, WPS number, welder ID, preheat temperature before first pass, interpass temperature between passes, bake-out time and temperature, and the NDE result after repair. This documentation trail becomes critical if the structure enters service and the repair location is ever re-examined.

For production-level repair programs, consider tracking these repairs in your WPS management system alongside your standard WPS library. The welding procedure library audit-ready article covers how to structure that package for third-party review.