SIST EN 3678:2026

Aerospace series - Steel X5CrNiCu17-4 (1.4542) - Air melted - Solution treated and precipitation treated - Forgings - a or D ≤ 200 mm - Rm ≥ 930 MPa

This document specifies the requirements relating to:
Steel X5CrNiCu17-4 (1.4542)
Air melted
Solution treated and precipitation treated
Forgings
a or D ≤ 200 mm
Rm ≥ 930 MPa
for aerospace applications.
W.nr: 1.4542.
ASD-STAN: FE-PM3801.

Luft- und Raumfahrt - Stahl X5CrNiCu17-4 (1.4542) - Lufterschmolzen - Lösungsgeglüht und ausscheidungsgehärtet - Schmiedestücke - a oder D ≤ 200 mm - Rm ≥ 930 MPa

No Scope available

Série aérospatiale - Acier X5CrNiCu17-4 (1.4542) - Élaboré à l'air - Mis en solution et précipité - Pièces forgées ou matricées - a ou D ≤ 200 mm - Rm ≥ 930 MPa

Le présent document spécifie les exigences relatives à :
Acier X5CrNiCu17-4 (1.4542)
Élaboré à l'air
Mis en solution et précipité
Pièces forgées ou matricées
a ou D ≤ 200 mm
Rm ≥ 930 MPa
pour les applications aérospatiales.
W.nr : 1.4542.
ASD-STAN : FE-PM3801.

Aeronavtika - Jeklo X5CrNiCu17-4 (1.4542) - Taljeno - Topilno žarjeno in izločevalno utrjeno - Izkovki - a ali D ≤ 200 mm - Rm ≥ 930 MPa

General Information

• Status: Published
• Public Enquiry End Date: 04-Sep-2024
• Publication Date: 15-Dec-2025
• ICS: 49.025.10 - Steels
• ICS: 77.140.85 - Iron and steel forgings
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 10-Dec-2025
• Due Date: 14-Feb-2026
• Completion Date: 16-Dec-2025
• Ref Project: EN 3678:2025 - Aerospace series - Steel X5CrNiCu17-4 (1.4542) - Air melted - Solution treated and precipitation treated - Forgings - a or D ≤ 200 mm - Rm ≥ 930 MPa

Relations

• Revised: SIST EN 3678:2009 - Aerospace series - Steel FE-PM3801 (X5CrNiCu17-4) - Air melted - Solution treated and precipitation treated - Forgings - a or D ≤ 200 mm - Rm ≥ 930 MPa
• Effective Date: 19-Jan-2023

Overview

SIST EN 3678:2026 is a European standard developed by CEN and ASD-STAN specifically for aerospace applications. It defines the stringent requirements for steel X5CrNiCu17-4 (1.4542)-a high-strength stainless steel grade processed by air melting, solution treatment, and precipitation treatment. The standard is essential for the production of forgings with thickness or diameter (a or D) up to 200 mm, ensuring a minimum tensile strength (Rm) of 930 MPa. SIST EN 3678:2026 replaces the previous 2007 version and incorporates updated material designations and testing criteria.

This standard plays a critical role in guaranteeing material performance and reliability in aerospace components where safety and durability under demanding conditions are paramount.

Key Topics

• Material Specification
  SIST EN 3678:2026 covers steel grade X5CrNiCu17-4 (W.nr 1.4542), an air-melted stainless steel with controlled chemical composition optimized for aerospace use. The steel contains chromium (Cr), nickel (Ni), copper (Cu), among other elements, adhering to strict limits to ensure quality and performance.

• Heat Treatment Requirements
  The steel forgings must be solution treated (1,025 °C to 1,055 °C for at least 30 minutes) followed by precipitation treatment (610 °C to 630 °C for at least 4 hours) to achieve the desired mechanical properties.

• Mechanical Properties
  Key mechanical thresholds include a minimum tensile strength (Rm) of 930 MPa, proof stress of at least 725 MPa, elongation parameters, and hardness values ensuring material toughness and resistance.

• Dimensional Scope
  The standard applies to forgings with thickness or diameter not exceeding 200 mm, suitable for the manufacture of precision aerospace components.

• Testing and Inspection Methods
  It mandates rigorous inspection protocols including ultrasonic testing (EN 4050-4), micrographic evaluation for non-metallic inclusions (EN 2951), visual testing for surface imperfections, and batch uniformity assessments as per EN 4700-006.

• Microstructure Requirements
  The δ-ferrite phase content must not exceed 5%, and grain size should achieve a minimum grade of G ≥ 4, ensuring high-quality metallurgical structure.

Applications

SIST EN 3678:2026 steel forgings find extensive use in aerospace manufacturing, where high strength, corrosion resistance, and reliability under stress are demanded. Typical aerospace applications include:

• Structural components subjected to dynamic loads
• High-strength fittings and parts requiring good toughness
• Engine components requiring heat-resistant steel grades
• Airframe forgings where material integrity is critical
• Aerospace hardware items such as bolts, shafts, and mechanical linkages

By complying with SIST EN 3678:2026, manufacturers can assure clients of consistent steel quality optimized for the rigorous aerospace environment.

Related Standards

For comprehensive aerospace material standards management, SIST EN 3678:2026 aligns with and complements other standards including:

• EN 3163: Addresses the same steel grade in softened (annealed) condition for forging stock with dimensions up to 300 mm.
• EN 4258: Provides the general organization framework for European aerospace metallic material standards and their interrelationships.
• EN 4500-005: Specifies the rules for the drafting and presentation of aerospace metallic material specifications.
• EN 4700-006: Provides technical specifications, production, and pre-production forging requirements used in conjunction with EN 3678.
• EN 2951: Outlines test methods for determining non-metallic inclusion content.
• EN 4050-4: Defines ultrasonic inspection criteria for forgings and related metallic products.

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Keywords: Aerospace steel standard, steel X5CrNiCu17-4, 1.4542 stainless steel, air melted steel, precipitation treated forging, aerospace forgings, high-strength steel forgings, tensile strength 930 MPa, aerospace material requirements, CEN aerospace standards, SIST EN 3678:2026 compliance.

Standards Content (Sample)

SLOVENSKI STANDARD
01-februar-2026
Aeronavtika - Jeklo X5CrNiCu17-4 (1.4542) - Taljeno - Topilno žarjeno in
izločevalno utrjeno - Izkovki - a ali D ≤ 200 mm - Rm ≥ 930 MPa
Aerospace series - Steel X5CrNiCu17-4 (1.4542) - Air melted - Solution treated and
precipitation treated - Forgings - a or D ≤ 200 mm - Rm ≥ 930 MPa
Luft- und Raumfahrt - Stahl X5CrNiCu17-4 (1.4542) - Lufterschmolzen - Lösungsgeglüht
und ausscheidungsgehärtet - Schmiedestücke - a oder D ≤ 200 mm - Rm ≥ 930 MPa
Série aérospatiale - Acier X5CrNiCu17-4 (1.4542) - Élaboré à l'air - Mis en solution et
précipité - Pièces forgées ou matricées - a ou D ≤ 200 mm - Rm ≥ 930 MPa
Ta slovenski standard je istoveten z: EN 3678:2025
ICS:
49.025.10 Jekla Steels
77.140.85 Železni in jekleni kovani Iron and steel forgings
izdelki
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 3678
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2025
EUROPÄISCHE NORM
ICS 49.025.10 Supersedes EN 3678:2007
English Version
Aerospace series - Steel X5CrNiCu17-4 (1.4542) - Air
melted - Solution treated and precipitation treated -
Forgings - a or D  200 mm - Rm  930 MPa
Série aérospatiale - Acier X5CrNiCu17-4 (1.4542) - Luft- und Raumfahrt - Stahl X5CrNiCu17-4 (1.4542) -
Élaboré à l'air - Mis en solution et précipité - Pièces Lufterschmolzen - Lösungsgeglüht und
forgées ou matricées - a ou D  200 mm - Rm  930 ausscheidungsgehärtet - Schmiedestücke - a oder D 
MPa
200 mm - Rm  930 MPa
This European Standard was approved by CEN on 5 October 2025.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 3678:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Requirements . 5
Bibliography . 9

European foreword
This document (EN 3678:2025) has been prepared by ASD-STAN.
After enquiries and votes carried out in accordance with the rules of this Association, this document has
received the approval of the National Associations and the Official Services of the member countries of
ASD-STAN, prior to its presentation to CEN.
This document shall be given the status of a national standard, either by publication of an identical text
or by endorsement, at the latest by June 2026, and conflicting national standards shall be withdrawn at
the latest by June 2026.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 3678:2007.
— update of the material designation;
— correction of the format of Table 1 to comply with the requirements of the EN 4500 series;
— update of Clause 2;
— addition of a bibliography.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this document: Austria, Belgium, Bulgaria, Croatia, Cyprus,
Czech Republic, D
...