ISO 24674:2022

Method and requirements for plasma nitriding and follow-up PVD hard coatings on cold-work mould steels

This document specifies a method and requirements for plasma nitriding and follow-up PVD hard coatings intended for use in cold-work moulds. This document provides the necessary information, such as the original structure of nitriding steels, process requirements, surface quality and adhesion of duplex PVD coatings, to create an optimal combination of high performance.

Titre manque

General Information

• Status: Published
• Publication Date: 15-Sep-2022
• ICS: 25.220.40 - Metallic coatings
• Technical Committee: ISO/TC 107/SC 9 - Physical vapor deposition coatings
• Drafting Committee: ISO/TC 107/SC 9 - Physical vapor deposition coatings
• Current Stage: 6060 - International Standard published
• Start Date: 16-Sep-2022
• Due Date: 14-Apr-2023
• Completion Date: 16-Sep-2022

Relations

• Consolidated By: ISO 11126-10:2025 - Preparation of steel substrates before application of paints and related products - Specifications for non-metallic blast-cleaning abrasives - Part 10: Almandite garnet
• Effective Date: 17-Feb-2024

Overview

ISO 24674:2022 specifies a method and requirements for combining plasma nitriding with follow‑up PVD hard coatings (a duplex treatment) for cold‑work mould steels. The standard sets out metallurgical prerequisites, process controls, surface quality limits and adhesion evaluation criteria to achieve an optimal duplex system that improves wear resistance, loading capacity and coating lifetime for cold‑work tools used e.g. in the automotive sector.

Key topics and technical requirements

• Substrate requirements
  • Typical acceptance hardness: HRC45 to HRC60 (Rockwell test per ISO 6508‑1).
  • Original microstructure classes (1–5) are defined by optical microscopy (×500); Classes 1–2 are acceptable.
• Plasma nitriding
  • Surface roughness (Rz) before nitriding: < 1 μm; surface must be clean and oxide‑free.
  • Protection of areas not to be nitrided (masking); blind deep holes to avoid hollow‑cathode effects.
  • Process parameters (reactive gas, temperature, time, pressure) control formation of a compound layer and an underlying diffusion zone. For thin‑walled parts use lower temperature + longer holding time.
  • Example parameter ranges are given in the standard (by alloying fraction), illustrating temperature and hold‑time tradeoffs.
• PVD coating preparation and deposition
  • If a compound layer forms, it must be mechanically ground/polished away prior to PVD to ensure adhesion; final surface roughness after treatment: Rz < 1 μm.
  • Substrate cleaning should follow ISO 27831‑1.
  • PVD coating design should consider roughness, friction coefficient, toughness and anti‑sticking for cold‑work applications.
• Metallurgical inspection and testing
  • Nitriding case depth: measured from at least five points per ISO 18203.
  • Diffusion layer nitride distribution and brittleness are classified visually (optical microscopy ×500) and by Vickers impressions (98.1 N) into classes 1–5; Classes 1–2 are acceptable for brittleness.
  • Adhesion of the duplex coating: indentation test (load 1 471.5 N, per guidance from ISO 26443) with defined acceptable crack/spall patterns.

Applications and who uses this standard

• Primary application: cold‑work moulds used in forming, cold extrusion, powder compacting and other high‑wear, high‑pressure tooling-commonly in the automotive supply chain.
• Intended users:
  • Tool and die manufacturers, heat‑treat and surface‑engineering shops
  • PVD coating suppliers and process engineers
  • Quality managers and materials testers specifying acceptance criteria
  • OEMs and Tier suppliers seeking standardized duplex treatment specifications to increase tool life and reduce failures (abrasive wear, galling, delamination)

Related standards

• ISO 6508‑1 - Rockwell hardness test (metallic materials)
• ISO 27831‑1 - Cleaning and preparation of ferrous metal surfaces
• ISO 18203 - Thickness of surface‑hardened layers (nitriding case depth)
• ISO 26443 - Indentation test for adhesion evaluation (reference for duplex adhesion method)

Keywords: ISO 24674:2022, plasma nitriding, PVD hard coatings, duplex treatment, cold‑work mould steels, nitriding case depth, compound layer, diffusion layer, adhesion testing, surface roughness, tool life.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 24674
First edition
2022-09
Method and requirements for plasma
nitriding and follow-up PVD hard
coatings on cold-work mould steels
Reference number
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
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or ISO’s member body in the country of the requester.
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements of cold-work mould steels . 1
5 Process requirements . 2
5.1 Requirements for plasma nitriding . 2
5.1.1 Surface polishing . 2
5.1.2 Surface cleaning . 2
5.1.3 Protection against plasma nitriding . 2
5.1.4 Plasma nitriding process . 2
5.2 Requirements for PVD coatings . 3
5.2.1 Mechanical grinding and polishing. 3
5.2.2 Surface cleaning . 3
5.2.3 PVD coating deposition . 3
5.3 Nitriding compound layer and case depth . 3
5.4 Nitriding diffusion layer . . 3
5.5 Brittleness of nitrided layer . 4
5.6 Adhesion of duplex coating . 5
Bibliography . 6
iii
Foreword
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 107, Metallic and other inorganic coatings,
Subcommittee SC 9, Physical vapor deposition coatings.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
Cold-work moulds in automotive application are subjected to heavy wear and severe pressures, while
meeting key criteria including high surface hardness and good core strength. Due to higher hardness
and better wear resistance compared with the physical vapour deposition (PVD) coating, the duplex
treatment based on plasma nitriding and follow-up PVD hard coating has been widely used to improve
the lifetime of cold-work moulds in the automotive industry. Plasma nitriding is contributed to improve
the loading capacity of the substrate prior to PVD coating deposition. It prevents the plastic deformation
of the substrate and delamination of thin and brittle coating, and provides proper stress and hardness
gradients between the coating and the substrate, which contributes considerably to the increase in
performance of the PVD coating. However, there is no standard to qualify the process, specification and
quality of the duplex treatment, which hinders the further development of duplex PVD coatings in the
cold-work moulds.
v
INTERNATIONAL STANDARD ISO 24674:2022(E)
Method and requirements for plasma nitriding and follow-
up PVD hard coatings on cold-work mould steels
1 Scope
This document specifies a method and requirements for plasma nitriding and follow-up PVD hard
coatings intended for use in cold-work moulds. This document provides the necessary information,
such as the original structure of nitriding steels, process requirements, surface quality and adhesion of
duplex PVD coatings, to create an optimal combination of high performance.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 6508-1, Metallic materials — Rockwell hardness test — Part 1: Test method
IS
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