The new ISO 20431:2023

Heat treatment — Control of quality


This international standard defines the quality requirements and recommendations for the heat treatment of mechanical parts intended for use in industry (e.g. automotive, aerospace, piping systems, civil engineering equipment, earthmoving equipment, agricultural equipment, marine industry, power equipment, tools and fasteners).

This new standard serves as a reference for quality audits and monitoring of heat treatment facilities, whether these processes are integrated in-house or used by contract heat treaters. This standard can also be used as a basis for discussion and development of specifications or company guidelines.

See Appendix A for a description of equipment calibration and test frequencies. An example of an evaluation table can be found in Appendix B. An example of an audit report can be found in Appendix C. The various measurement chain test (SAT) methods are shown in Appendix D.


Contents at a glance

  • General requirements for heat treatment facilities and personnel
  • Requirements for documentation and traceability of heat treatment processes
  • Requirements for calibration and verification of measuring and test equipment
  • Requirements for process validation and monitoring
  • Requirements for process approval and acceptance
    Requirements for error handling and prevention


The difference to ISO 20431 is that CQI-9 focuses more on the technical requirements and process monitoring, while ISO 20431 focuses more on the quality management system and process validation and serves as a guideline for conducting heat treatment audits. This includes the specification of a degree of fulfillment as an audit result. The CQI-9 also contains specific requirements for different heat treatment processes, such as induction hardening, carburizing, nitriding, etc.

ISO 20431, on the other hand, is more general and applies to all heat treatment processes to be used in industry.

Thus, the two standards are not identical, but complement each other. It may be that a company needs to comply with both CQI-9 and ISO 20431, depending on the requirements of its customers. It may also be that a company only needs one of the two standards, depending on the type of heat treatment it performs and the industry in which it operates.


on the new ISO 20431:2023-07 via TEAMS in german & english.


Fr. 13.10.2023        13:00 - 14:00             fully booked

Fr. 13.10.2023        2:30pm-3:30pm         English


Di. 12.12.2023        13:00 - 14:00              Deutsch

Tu. 12.12.2023       2:30pm-3:30pm         English


Fr. 15.03.2024        13:00 - 14:00              Deutsch

Fr. 15.03.2024        2:30pm-3:30pm         English


Fr. 21.06.2024        13:00 - 14:00              Deutsch

Fr. 21.06.2024        2:30pm-3:30pm         English


Please register at, a simple informal e-mail with your contact details, clear date, time and mention of the language is sufficient.

For registration confirmation and a TEAMS link, you will receive an outlook invitation a few days before the event date.


ISO 20431 seminars, dates and prices:

Coming soon……



Table of Content of the ISO 20431:2023:




1 Scope

2 Normative references

3 Terms and definitions

4 System for assessment and scoring of requirements and recommendations

4.1 General

4.2 General requirements

4.3 Scoring of requirements and recommendations

4.4 Assessment of the heat treatment facility

5 Requirements and recommendations

5.1 General organization of a heat treatment facility

5.2 Contract review and heat-treatment conception

5.3 Carrying out heat treatments: preparation

5.4 Carrying out heat treatment: Control of the thermal cycle

5.5 Mastering of the heat-treatment medium

5.6 Control of cooling

5.7 Control of product

5.8 Finishing process

Annex A Equipment calibration and frequency control

Annex B Example of scoring table for requirements and recommendations

Annex C Example of heat-treatment facility assessment

Annex D Measuring chain testing methods (SAT - system accuracy test)

D.1 General

D.2 Method 1

D.3 Method 2

D.4 Method 3



(Source:, text taken from ISO20431 description and partly modified)


General information about ISO20431:2023-07

Status : Published

Date of publication : 2023-07

Edition : 1

Number of pages : 41


At TopQM we are your expert for heat treatment and the new ISO 20431 2023 standard. With our in-depth know-how, we support you with consulting, training and audits to ensure that your heat treatment processes meet the latest industry standards. Together, we optimize your processes, increase quality and ensure sustainable success. Trust TopQM - your partner for success in heat treatment.

✆  +49 6261 639980