Overview
SAE four-digit steel numbers organize selected carbon and alloy steel chemistry families. They are useful material identifiers, but they do not by themselves define product form, hardenability, heat treatment, mechanical properties, surface condition or inspection acceptance.
Designation and acceptance
SAE J403 maintains selected carbon-steel compositions and states that AISI no longer issues the listed grade designations; SAE J404 covers alloy-steel chemistry with explicit product-form boundaries. The familiar series digits convey chemistry-family context, while the complete product order must add a governing material specification, size, condition, properties and tests.
Members and selection
| Designation | Selection context |
|---|---|
| 10xx | Plain-carbon family context; carbon-level digits do not establish delivered strength, cleanliness, surface quality or product form. |
| 41xx | Chromium-molybdenum alloy family context; confirm exact chemistry, hardenability option, section response and heat-treatment specification. |
| 43xx | Nickel-chromium-molybdenum family context; high-strength use still requires heat treatment, toughness, size and inspection controls. |
| 86xx | Nickel-chromium-molybdenum case-hardening family context; define core/hardened-case requirements through the product and process specification. |
Comparison framework
| Criterion | Decision context |
|---|---|
| Chemistry series | Early digits identify a family convention; the full number and governing SAE document are needed for composition context. |
| Product scope | J403/J404 chemistry listings do not automatically cover every sheet, tube, forging, wire or structural product. |
| Properties | Strength, hardness and toughness depend on size and thermal processing, so a grade number is not a mechanical-property class. |
| Authority | Current catalog wording should use SAE for grades maintained by SAE; legacy AISI/SAE usage must not imply current AISI issuance. |
Performance
- Hardenability and through-section response vary with chemistry control, section size, prior processing and heat treatment.
- Machinability, formability and weldability cannot be ranked reliably from series digits without exact condition and product history.
- Fatigue and fracture performance require cleanliness, surface, heat-treatment and inspection requirements beyond the SAE number.
Orderable product scope
- Bars, billets and wire rod require an orderable product specification, dimensions, surface condition and heat/lot controls.
- Forgings require forging stock or forging specifications plus heat treatment, test location and acceptance properties.
- Sheet, strip and tubing must be ordered under product-specific documents because SAE chemistry scope does not make forms interchangeable.
Processing
- Define annealed, normalized, quenched-and-tempered, spheroidized or other delivery condition before machining or forming plans are fixed.
- For hardenability-controlled orders, state the recognized hardenability requirement instead of inferring it from the base number.
- Qualify welding and post-weld treatment from actual chemistry, carbon-equivalent context, section size and service—not series alone.
Applications
- Carbon-steel machined parts where the product specification and condition are separately controlled.
- Quenched-and-tempered alloy-steel shafts, fasteners and components with section-specific property requirements.
- Carburized gears and wear components ordered with explicit case and core performance requirements.
Selection
- Choose the chemistry family from service, hardenability, fabrication and heat-treatment needs.
- Verify the selected SAE grade is listed or permitted in the product specification for the requested form.
- Set size-dependent properties, delivery condition, surface quality, testing and certification before requesting substitution.
Procurement
- State the SAE grade and applicable J403/J404 or product-document context.
- Define product form, manufacturing route, dimensions, tolerances and surface condition.
- Define heat treatment, hardenability or mechanical-property requirements with test location.
- Require heat analysis, product analysis when applicable, traceability, inspection and certificates.