ISO 683-1
Heat-treatable steels, alloy steels and free-cutting steels — Part 1: Non-alloy steels for quenching and tempering
Technical delivery requirements for non-alloy steels for quenching and tempering (C22 to C60 with their E and R variants, 28Mn6) supplied as bar, rod, wire rod, flat products and forgings in the untreated, treated-for-shearability, annealed, normalized or quenched-and-tempered condition.
What ISO 683-1 specifies
ISO 683-1 (aligned with EN 10083-2) defines the carbon steels that are bought to be quenched and tempered — C22E, C25E, C30E, C35E, C40E, C45E, C50E, C55E, C60E and 28Mn6 — and what the buyer may require: chemical composition, hardenability as Jominy end-quench bands for the +H, +HH and +HL grades, mechanical properties in the +QT condition by ruling section, and hardness limits in the +A, +N, +S and +TH delivery conditions. For C45E in +QT the minimum yield, tensile range and minimum elongation are 490 MPa, 700–850 MPa and 14 % up to 16 mm; 430 MPa, 650–800 MPa and 16 % from 16 to 40 mm; and 370 MPa, 630–780 MPa and 17 % from 40 to 100 mm. Informative annexes give recommended heat-treatment temperatures (C45: harden at 820–860 °C in water or oil, temper at 550–660 °C). Testing follows ISO 6892-1 (tension), ISO 148-1 (impact), ISO 6506-1 (Brinell) and ISO 642 (Jominy).
ISO 683-1 types and classes
Every designation the document defines, with the thickness it requires and the tests it imposes.
| Designation | Meaning | Requirement / test |
|---|---|---|
+U | Untreated (as rolled or as forged); heat treatment is entirely the purchaser's. | — |
+S | Treated for shearability: heat treated to a hardness maximum that allows cold shearing of bar. | Brinell hardness per ISO 6506-1 |
+A | Soft annealed to a hardness maximum for machining or cold forming. | Brinell hardness per ISO 6506-1 |
+N | Normalized; minimum yield, tensile and elongation tabulated by ruling section. | Tension per ISO 6892-1 |
+QT | Quenched and tempered by the supplier; e.g. C45E up to 16 mm: yield 490 MPa min, tensile 700–850 MPa, elongation 14 % min. | Tension per ISO 6892-1; impact per ISO 148-1 when specified |
+TH | Treated to a specified hardness range by any route. | Brinell hardness per ISO 6506-1 |
Tests and the drawing call-out
Tests the document imposes
- Tensile test per ISO 6892-1 by ruling section in the +QT or +N condition
- Charpy V-notch impact per ISO 148-1 when specified
- Brinell hardness per ISO 6506-1 for the +A, +S and +TH conditions
- End-quench hardenability (Jominy) per ISO 642 for +H / +HH / +HL grades
- Grain size (ISO 643), decarburization depth (ISO 3887) and non-metallic inclusions (ISO 4967) when ordered
- Product analysis against the composition table
How to cite it
Drawing call-out
MATERIAL: C45E +QT PER ISO 683-1, RULING SECTION 40 MM MAX (RE 430 MPA MIN, RM 650–800 MPA)Angle brackets mark the choices the drawing must make; every finish page shows a completed example.
Heat treatments specified to ISO 683-1
| Treatment | Role | Cost |
|---|---|---|
Austempering forms bainite by quenching austenitized steel or ductile iron into a hot bath and holding isothermally. | Related | $$$ |
Full annealing heats steel through its critical transformation range and then furnace-cools it slowly. | Related | $$ |
Martempering is an interrupted quench that equalizes austenitized steel just above its martensite-start temperature before cooling through martensite formation. | Related | $$$ |
Normalizing heats steel above its critical range and cools it in air. | Related | $ |
Quench and temper transforms hardenable steel to martensite and then tempers it to the required balance of strength and toughness. | Related | $$ |
ISO 683-1 — frequently asked
What is the "ruling section"?
The diameter (or equivalent thickness) of the part at the time of hardening that controls the quench rate at the core; the +QT property tables are stepped by it because a carbon steel like C45 through-hardens only to about 16–20 mm in water. A 60 mm bar of C45E cannot be certified to the 16 mm values however it is tempered.
What do E and R mean after the grade?
E grades have a maximum sulfur of 0.035 %; R grades have sulfur controlled to 0.020–0.040 % to improve machinability at some cost in transverse ductility. Both share the same carbon range and the same mechanical property tables.
How does C45E compare with AISI 1045?
They are close equivalents (0.42–0.50 % C, 0.50–0.80 % Mn), but ISO 683-1 defines delivery conditions and +QT properties by ruling section, which ASTM bar specifications for 1045 do not; "C45E +QT" is a complete material-and-heat-treatment statement, while "1045" needs a separate heat-treat note.
Can I order +QT and machine to finish?
Yes — that is the purpose of the +QT condition: the bar arrives at a machinable 200–250 HB with certified properties. Parts that need more strength than the ruling-section table allows are bought +A or +N and hardened as finished parts instead, or moved to an alloy steel from ISO 683-2.
ISO 683-1 is copyrighted by International Organization for Standardization. This page explains the document so a drawing can be read; it does not reproduce the standard. Purchase the current edition from the publisher. Official source ↗