Material evidence · Heat input and temperature

Q&T / TMCP steel: what evidence belongs in a WPS review?

For Q&T and TMCP steels, a grade-family label is not enough to set heat input or temperature. Trace the delivered condition, obtain producer guidance for that product, and compare it with the applicable code route and actual PQR support.

Decision rule: Do not use a cross-grade heat-input or interpass limit. Link the MTR and exact delivery condition to the producing mill’s applicable guidance, then check the PQR, CVN and contract. AWS D1.1 has a specific Q&T heat-input provision in 7.7, including an ASTM A913/A913M exception from that provision; this does not waive other requirements.

Start with the delivered steel, not just the grade family

Q&T and TMCP describe different processing routes and do not create a universal heat-input or interpass-temperature number. Identify each base-metal side from the material specification and mill test report: grade, product form, thickness, heat or lot traceability and stated delivery condition. Record any supplemental contract requirement and the actual mill/producer guidance for that grade and condition.

Evidence question	Q&T steel	TMCP steel
What does the material record establish?	Confirm the exact quenched-and-tempered delivery condition, grade and product form on the MTR; do not infer it from a strength designation alone.	Confirm the exact thermomechanically controlled processing condition and grade from the MTR and material specification.
What producer limit is needed?	Obtain the grade/product-specific maximum heat input and maximum preheat/interpass recommendations required for the proposed welding condition.	Obtain applicable grade/product guidance for heat input and temperature; do not transfer Q&T limits or a nearby grade’s chart.
What does the code route add?	Clause 7.7 imposes Q&T production heat-input control together with maximum preheat and interpass limits, based on the producer’s recommendations. The provision excludes ASTM A913/A913M from that particular 7.7 heat-input limitation; other Code and project conditions still apply.	Check applicable Code and contract requirements, including any CVN, preheat/interpass or PWHT condition. Do not assume the Q&T-specific 7.7 provision or the A913 exception applies to TMCP steel.
What if evidence is missing?	Do not state a generic upper limit. Hold the affected WPS field until the required producer data and qualification support are available.	Do not substitute generic “low heat input” guidance for an applicable grade-specific requirement or project criterion; document the unresolved input.

Map each source to the WPS field it supports

Source evidence	WPS or review field	Boundary
MTR and material specification for every member	Base-metal specification/grade, delivery condition, product form and thickness	Supports material identity and applicable table lookup; it does not set a welding temperature by itself.
Producer welding guidance for the exact grade/product and revision	Maximum heat input, maximum preheat/interpass temperature and any stated restrictions	Preserve the specific condition, units, process and thickness range covered by that guidance.
Applicable PQR and original reports	Qualified process, materials, joint, actual parameters, preheat/interpass, heat-input and CVN evidence	Actual PQR support and Code limits are separate checks; a PQR does not automatically supply the mill’s production limit.
Contract, design documents and Engineer direction	CVN, service temperature, acceptance criteria, any project maximum temperature or heat-input controls	Do not invent missing CVN acceptance energy/temperature or interpret a design requirement without its governing source.
Production monitoring records	Measured current, voltage, travel speed/heat-input method, preheat and interpass temperatures	Use the method required for the applicable process and equipment; waveform procedures may require instantaneous energy/power evidence rather than an assumed average A×V calculation.

Do not confuse three different limits

Producer recommendation: a material-specific restriction intended to preserve the properties of that steel and product condition. It can set a maximum heat input or temperature that is tighter than a code qualification envelope.

PQR support: the range and conditions demonstrated by the actual qualification record, with the applicable essential and supplementary variables. Where CVN applies, heat input and Table 6.8 conditions can further constrain an existing PQR-based WPS. Do not derive an absent PQR value from a mill chart.

Production control: the values and limits written on the WPS and measured in production. They must respect the applicable Code, PQR, producer and contract constraints together. A calculator can compute a value from entered inputs; it cannot decide which limit applies to an unidentified grade or establish qualification.

Q&T heat-input controls in 7.7 are not a universal heat-input ceiling for every structural steel. ASTM A913/A913M has a stated exception from that specific 7.7 limit, while the rest of the applicable requirements remain. TMCP must be handled from its own material evidence and applicable Code/project terms.

Bounded example: a grade name is not enough

A package identifies a high-strength steel plate as “Q&T,” but the MTR is missing and the welding note gives no heat-input limit. That is not enough to choose the production maximum. First obtain the traceable grade and delivery condition, identify the producing mill and applicable product guidance, then check the existing PQR and CVN requirements. Until those records align, leave the affected limits unresolved and do not issue a completed production WPS with a generic value.

For a TMCP plate, repeat the same evidence chain using its own product-specific guidance and contract requirements. Do not copy a Q&T temperature or heat-input recommendation solely because the nominal strength is similar.

Manufacturer references

SSAB Welding Handbook — producer guidance for Hardox and Strenx steels, including thermal cycles, consumables and welding recommendations. Use the exact grade and edition relevant to the MTR.
SSAB, Welding of Strenx (2026 edition) — grade-family guidance with product-specific recommendations; it is not a D1.1 qualification rule and must not be generalized to other grades.

Manufacturer information constrains the selected WPS conditions where applicable; it does not, by itself, establish a prequalified procedure, demonstrate a PQR result or replace the project’s governing code requirements.

Code basis and related guides

AWS D1.1/D1.1M:2025 base edition plus registered 2026-07-28 base-edition errata, excluding AMD1. Review 6.8.4–6.8.5 and relevant supplementary variables, 7.6–7.8, material-specific provisions and the governing contract. Producer guidance is supporting material evidence, not Code qualification.

Determine the applicable minimum preheat basis Record minimum and maximum interpass temperature Check CVN and heat-input support Review PWHT conditions for the material and route Calculate heat input from recorded values Existing-PQR WPS preparation · $499 Edition and errata basis

Need a supported WPS prepared from an existing qualification record?

Send the project drawing, exact consumable or material identification, and complete supporting records where applicable.

Review WPS preparation scope

Continue this WPS review

Connect the actual delivery state and producer thermal guidance to supported WPS fields.

Minimum preheat and measurement
Compare code minima with actual material limits.
CVN qualification evidence
Check the relevant test reports and supplementary variables.
Thermal and pass records
Record the measured settings and their source.
Prequalified WPS preparation · $299
For a complete procedure meeting all applicable Clause 5 conditions.
Existing-PQR WPS preparation · $499
For a procedure fully supported by applicable existing records; no new qualification testing.