Key takeaways
- Specify 42CrMo4 and SAE 4140 through their own standards routes; do not order either as an unexplained equivalent.
- Tie heat-treatment condition to section, product form, process lot, test representation, and downstream operations.
- Require a supplier alternative to disclose chemistry, product, condition, testing, certificate, cost, and schedule deviations.
- Freeze the route before manufacture and reconcile results to the shipped heat and treatment lot.
Use condition language before process assumptions
Buyers should first state the required delivery condition, such as annealed, normalized, or quenched and tempered. The actual route should then be reviewed against grade, size, property target, and downstream process.
QT requires more than the abbreviation
When QT condition is required, the RFQ should include the target property range or hardness range, bar diameter, application, certificate requirement, and whether the bar will be peeled, ground, machined, or otherwise processed afterward.
Annealed and normalized routes need context
Annealed or normalized wording should be connected to machinability, downstream hardening, structural requirement, or project standard. If a buyer only writes the grade name, the route may remain unclear.
Certificate wording should match the route
Heat-treatment certificate expectations, MTC wording, hardness inspection, mechanical testing, heat number traceability, and third-party inspection should be listed before shipment document review.
Keep the ISO and SAE routes distinct
42CrMo4 in ISO 683-2 and SAE 4140 in SAE J404 belong to different designation and specification systems. ISO 683-2 provides a product and condition framework for covered alloy steels. SAE J404 defines alloy-steel chemistry, not a universal quenched-and-tempered bar property contract. A buyer who allows both should name one required route and demand a clause-level alternative rather than writing a slash designation that leaves precedence unresolved.
Approve one complete heat-treatment route
Use this table to compare technical scope rather than treating familiar grade numbers as the decision.
| Decision | Required-route field | Alternative-offer evidence | Buyer action |
|---|---|---|---|
| Specification identity | Exact grade, product standard, edition, product form, and precedence | Separate ISO-to-SAE clause map and named ASTM product basis | Engineering accepts or rejects the alternative in writing |
| Treatment representation | Condition, ordered and ruling section, furnace-lot definition, and straightening sequence | Proposed processor, lot model, sample representation, and route deviations | Quality confirms the evidence represents production material |
| Testing and inspection | Ordered properties, methods, locations, frequency, NDT if justified, and retest | Comparable test plan without transferred values from another standard | Approve one acceptance schedule before processing |
| Documents and release | Inspection-document type, actual fields, traceability map, hold points, and deviations | Sample dossier, subcontract reports, price, and schedule effects | Release only the accepted route and closed deviation status |
Compare controlled standards, product scope, section and condition, test representation, documents, and commercial effects before approval. Only accepted order terms define the requirements for a specific supply.
Link test results to the actual treated section and lot
Avoid asking for a generic QT certificate. Define the material state being accepted and the unit represented by each sample. Require heat, diameter or section, treatment batch, specimen source and location, test method, actual result, and disposition to reconcile. If the supplier uses a prolongation or separately prepared test piece, its representation must be authorized by the controlling product route and accepted schedule rather than inferred after testing.
ISO 10474 classifies inspection documents according to order requirements. The buyer should list the actual fields and linked reports needed, including treatment-lot identity, process record where ordered, test locations, deviations, re-treatment or retest, bar or bundle marks, and final packing link. Make document review timing explicit so the certificate cannot arrive after the shipment decision.
Worked RFQ example for a primary and alternative route
The example makes 42CrMo4 the required route and keeps SAE 4140 as a controlled alternative. Reverse the hierarchy only when the drawing owner requires the SAE route.
Do not populate mechanical or hardness values until the accepted product standard, section, condition, and engineering schedule establish them.
Item: Alloy-steel round bars for [shaft drawing and revision], [size and quantity]
Required route: 42CrMo4 to ISO 683-2:2016, [condition and surface], with ordered and ruling section stated
Alternative: SAE 4140 to SAE J404_200901 plus ASTM A29/A29M-23 and the attached purchaser property schedule; quote separately
Heat treatment: Supplier to declare processor, treatment-lot definition, cycle-record fields, straightening sequence, and sample representation
Inspection: Approved methods, locations, frequency, judgment, retest, dimensions, surface, marking, and separately specified NDT
Documents: ISO 10474 type [state], actual results, heat-treatment-lot-bundle map, process and subcontract reports, and deviations
Approval: No alternative manufacture or route change without written purchaser authorization
Only accepted order terms define the requirements for a specific supply.42CrMo4 / 4140 heat-treatment route language for RFQs buyer questions
When should 42CrMo4 / 4140 buyers request QT condition?
Buyers should request QT condition when the application requires reviewed strength, toughness, or hardness targets after quenching and tempering. The RFQ should include diameter, target values, certificate wording, and inspection requirements.
What is the difference between annealed, normalized, and QT RFQ wording?
Annealed wording usually supports machinability review, normalized wording supports structure and condition review, and QT wording supports strength or hardness target review. The buyer should connect each condition to the application and standard.
What heat-treatment documents should buyers request?
Buyers may request MTC, heat-treatment record or certificate wording where applicable, hardness or mechanical test results, heat number traceability, dimensional inspection, and third-party inspection records if specified by the order.
42CrMo4 / 4140 heat-treatment route language for RFQs RFQ checklist
- Required delivery condition: annealed, normalized, QT, or other wording
- Grade standard and acceptable cross-reference names
- Diameter, length, quantity, and section-size information
- Target hardness, tensile strength, yield strength, or impact requirement if specified
- Downstream processing route such as peeling, grinding, or machining
- MTC, heat-treatment record, and certificate wording requirements
- Hardness inspection, mechanical testing, UT, or third-party inspection needs
- Application, drawing, destination, and packing requirements
- Required grade route, product standard, edition, product form, and precedence
- Alternative product basis, clause map, price, schedule, exclusions, and deviations
- Ordered and ruling section, delivery condition, surface, and downstream work
- Treatment processor, lot definition, straightening sequence, and sample representation
- Test methods, locations, frequency, judgment, retest, NDT, and actual results
- Inspection document, process records, traceability map, approval points, and release
References
- ISO 683-2:2016 Alloy steels for quenching and tempering
Supports: Provides the official product, condition, and size-bounded route for covered alloy steels including 42CrMo4.
Limitation: The catalog does not make 42CrMo4 equivalent to SAE 4140 or select finished-part properties and processing.
- SAE J404_200901 Chemical Compositions of SAE Alloy Steels
Supports: Defines the SAE alloy-steel chemical-composition route used when SAE 4140 is specified or proposed.
Limitation: SAE J404 is not a complete bar product, heat-treatment, mechanical-property, dimensional, inspection, or certificate specification.
- ASTM A29/A29M-23 General Requirements for Steel Bars
Supports: Provides the general-requirements context for hot-wrought carbon and alloy bars when invoked with an ASTM route.
Limitation: It does not turn an SAE chemistry designation into a complete QT bar order or approve ISO-to-SAE substitution.
- ISO 10474:2013 Steel and steel products — Inspection documents
Supports: Defines inspection-document categories supplied according to the requirements fixed in a steel-product order.
Limitation: A category does not create missing treatment records, tests, traceability fields, deviation approvals, or shipment authority.
Revision note: Added route-specific comparison and approval controls for 42CrMo4 and SAE 4140, including treatment-lot representation, a decision table, two context figures, and a worked alternative RFQ.
Inquiry support
Send processing route, tolerance, surface condition, grade, and destination.
JOTAIN can review the stated grade, size, delivery condition, processing route, inspection requirements, and export details against the project requirement.