SIST EN ISO 683-3:2022/oprA1:2026

• Status: Not Published
• Public Enquiry End Date: 30-Oct-2026
• ICS: 77.140.10 - Heat-treatable steels
• ICS: 77.140.20 - Stainless steels
• Technical Committee: IFEK - Ferrous metals
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 04-Sep-2026
• Due Date: 22-Jan-2027
• Ref Project: EN ISO 683-3:2022/prA1 - Heat-treatable steels, alloy steels and free-cutting steels - Part 3: Case-hardening steels - Amendment 1 (ISO 683-3:2022/DAM 1:2026)

• Amends: SIST EN ISO 683-3:2022 - Heat-treatable steels, alloy steels and free-cutting steels - Part 3: Case-hardening steels (ISO 683-3:2022)
• Effective Date: 15-Apr-2026

SIST EN ISO 683-3:2022/oprA1:2026 is SIST’s draft amendment to ISO 683-3:2022 for case-hardening steels. It updates the wording for delivery conditions, machinability and hardness verification, including a new rapid cooled and tempered (+RCT) condition. Engineers, buyers, quality managers and test laboratories use it when specifying, supplying, checking or testing case-hardening steels.

What does SIST EN ISO 683-3:2022/oprA1:2026 specify?

SIST EN ISO 683-3:2022/oprA1:2026 amends the case-hardening steels part of ISO 683-3:2022. The amendment updates the document’s terminology and the way delivery conditions, hardness limits and verification are described so that the new +RCT condition fits the existing framework.

The document is organized around clause 3, clause 6.3.2, clause 7.2, Table 1, Table 7, clause 9.2.1 and Table 9. In practice, that means it affects how the steel condition is named, how it is ordered, how machinability is stated and how hardness is checked.

What are the key requirements of SIST EN ISO 683-3:2022/oprA1:2026?

• Clause 3 adds a new term, +RCT. SIST EN ISO 683-3:2022/oprA1:2026 introduces “rapid cooled and tempered (+RCT)” and renumbers the existing definitions. For users, this means orders, certificates and internal specs need the updated symbol and definition.

• Clause 6.3.2 extends the range of particular heat-treatment conditions. The amendment changes the referenced row range from 3 to 8 to 3 to 9. In practice, the delivery-condition framework now includes the newly added condition.

• Clause 7.2 updates machinability language. SIST EN ISO 683-3:2022/oprA1:2026 states that steels are machinable in the soft-annealed, treated to hardness range, treated to ferrite/pearlite structure, normalized and rapid cooled and tempered conditions. This matters when a buyer or processor needs to know whether a supplied condition is suitable for machining.

• Table 1 adds +RCT as a delivery condition. The table links heat-treatment condition symbols to product forms and to the requirement tables used for non-alloy and alloy steel grades. In practice, it is the ordering map for matching product form, delivery state and applicable requirements.

• Table 7 extends hardness requirements to +RCT. SIST EN ISO 683-3:2022/oprA1:2026 adds hardness requirements for products delivered in the rapid cooled and tempered condition, alongside the other listed delivery states. This is the table suppliers and inspectors use to check whether a delivered grade and size meet the ordered hardness condition.

• Clause 9.2.1 includes +RCT in hardness verification. Hardness for +FP, +N and +RCT is measured in accordance with ISO 6506-1. That tells laboratories which Brinell method to use when confirming acceptance.

• Table 9 updates the test conditions for hardness verification. The amendment adds +RCT to the listed conditions covered by the verification procedure. For users, this closes the loop between the delivery symbol, the hardness table and the test method.

What terms does SIST EN ISO 683-3:2022/oprA1:2026 define?

• rapid cooled and tempered (+RCT) - A heat treatment where the steel is rapidly cooled and then tempered to produce a ferritic matrix with homogeneously distributed high tempered martensitic/bainitic phase.
• treated to improve shearability (+S) - A delivery condition aimed at making the steel easier to shear or machine.
• soft-annealed (+A) - A delivery condition in which the steel has been soft annealed.
• treated to hardness range (+TH) - A delivery condition where the steel is supplied within a specified hardness range.
• treated to ferrite-pearlite structure (+FP) - A delivery condition intended to produce a ferrite-pearlite structure.
• normalized (+N) - A delivery condition produced by normalizing or normalizing forming.

Who uses SIST EN ISO 683-3:2022/oprA1:2026?

This amendment is used by steel producers, heat-treatment operations, stockists, buyers, quality managers and inspection laboratories handling case-hardening steels. It helps them agree the delivery condition, record the correct symbol on orders and certificates, and verify hardness in a consistent way.

It is also relevant when a company needs to specify or check product forms such as semi-finished products, bars, wire, flat products, finished products and forgings under the revised +RCT condition.

What changed in SIST EN ISO 683-3:2022/oprA1:2026 from the previous edition?

Compared with ISO 683-3:2022, this amendment:

• adds the new definition for +RCT
• updates clause 6.3.2 to include the new condition in the heat-treatment condition list
• revises clause 7.2 to include +RCT in machinability wording
• adds +RCT to Table 1 as a delivery condition
• extends Table 7 with hardness requirements for +RCT
• includes +RCT in clause 9.2.1 and Table 9 for hardness verification

Which standards are used with SIST EN ISO 683-3:2022/oprA1:2026?

• ISO 6506-1 - Provides the Brinell hardness test method used for hardness verification.
• ISO 4954 - Is named in the Table 1 note for the annealed condition +AC used for cold heading and cold extrusion.

What does the SIST EN ISO 683-3:2022/oprA1:2026 document contain?

The document contains edited clause text, a new definition, a revised machinability statement and updated tables for delivery conditions and hardness limits. Table 1 links condition symbols to product forms and requirement tables, while Table 7 gives hardness requirements by steel grade and condition. Clause 9.2.1 and Table 9 set out how hardness is verified, including the use of ISO 6506-1.

SLOVENSKI STANDARD
01-oktober-2026
Toplotno obdelana, legirana in avtomatna jekla - 3. del: Cementacijska jekla -
Dopolnilo A1 (ISO 683-3:2022/DAM 1:2026)
Heat-treatable steels, alloy steels and free-cutting steels - Part 3: Case-hardening steels
- Amendment 1 (ISO 683-3:2022/DAM 1:2026)
Für eine Wärmebehandlung bestimmte Stähle, legierte Stähle und Automatenstähle -
Teil 3: Einsatzstähle - Änderung 1 (ISO 683-3:2022/DAM 1:2026)
Aciers pour traitement thermique, aciers alliés et aciers pour décolletage - Partie 3:
Aciers pour cémentation - Amendement 1 (ISO 683-3:2022/DAM 1:2026)
Ta slovenski standard je istoveten z: EN ISO 683-3:2022/prA1
ICS:
77.140.10 Jekla za toplotno obdelavo Heat-treatable steels
77.140.20 Visokokakovostna jekla Stainless steels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
Amendment
ISO 683-3:2022/
DAM 1
ISO/TC 17/SC 4
Heat-treatable steels, alloy steels
Secretariat: DIN
and free-cutting steels —
Voting begins on:
Part 3:
2026-08-20
Case-hardening steels
Voting terminates on:
2026-11-12
AMENDMENT 1
Aciers pour traitement thermique, aciers alliés et aciers pour
décolletage —
Partie 3: Aciers pour cémentation
AMENDEMENT 1
ICS: 77.140.20; 77.140.10
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
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STANDARDS MAY ON OCCASION HAVE TO
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Reference number
ISO 683-3:2022/DAM 1:2026(en)
DRAFT
ISO 683-3:2022/DAM 1:2026(en)
Amendment
ISO 683-3:2022/
DAM 1
ISO/TC 17/SC 4
Heat-treatable steels, alloy steels
Secretariat: DIN
and free-cutting steels —
Voting begins on:
Part 3:
Case-hardening steels
Voting terminates on:
AMENDMENT 1
Aciers pour traitement thermique, aciers alliés et aciers pour
décolletage —
Partie 3: Aciers pour cémentation
AMENDEMENT 1
ICS: 77.140.20; 77.140.10
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
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BE CONSIDERED IN THE LIGHT OF THEIR
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Published in Switzerland Reference number
ISO 683-3:2022/DAM 1:2026(en)
ii
ISO 683-3:2022/DAM 1:2026(en)
Heat-treatable steels, alloy steels and free-cutting steels —
Part 3:
Case-hardening steels
AMENDMENT 1
Addition of heat treatment +RCT

Addition to cause 3 2 “Terms and definitions”
Change definition 3.2 to 3.3 and 3.3 to 3.4 and add a new definition 3.2 with following wording:
3.2
rapid cooled and tempered (+RCT)
heat treatment first by rapid cooling and followed by tempering to produce a ferritic matrix with
homogeneously distributed high tempered martensitic/bainitic phase

Change to 6.3.2 “Particular heat-treatment conditions”
Replace “row numbers 3 to 8” by “row numbers 3 to 9”

Change to 7.2 “Machinability”
Replace first sentence by “All steels are machinable in the conditions “soft-annealed”, “treated to hardness
range”, “treated to ferrite/pearlite structure”, “normalized” and “rapid cooled and tempere
...