EN 3531:2025

Overview

EN 3531:2025 is a European standard published by CEN that specifies the technical requirements for Steel X2NiCoMo18-8-5 (1.6359), designed specifically for aerospace applications. This steel grade is vacuum induction melted and vacuum arc remelted to achieve high purity and superior mechanical properties. The material is available in sheets and strips with a maximum thickness of 6 mm, and possesses tensile strength ranging between 1,750 MPa and 2,000 MPa. The standard covers both solution treated and precipitation treated conditions, ensuring optimal performance for demanding aerospace environments.

This standard supersedes EN 3531:2007 and aligns with the aerospace series standards governing metallic materials intended for critical aerospace components.

Key Topics

• Material Specification
  Steel X2NiCoMo18-8-5 (W.nr 1.6359), known for its high strength and corrosion resistance due to its carefully balanced alloying elements such as Nickel (Ni), Cobalt (Co), and Molybdenum (Mo).

• Manufacturing Process

  • Vacuum Induction Melting (VIM) combined with Vacuum Arc Remelting (VAR) ensures low inclusion content and uniform microstructure.
  • Rolled into sheets and strips with thickness a ≤ 6 mm for precise dimensional control.

• Heat Treatment Conditions

  • Solution treated at 790 °C to 840 °C followed by air cooling.
  • Precipitation treated at 465 °C to 495 °C for at least 3 hours to achieve enhanced strength.

• Mechanical Properties

  • Ultimate tensile strength (Rm) between 1,750 MPa and 2,000 MPa.
  • Proof stress (Rp0.2) of at least 1,650 MPa.
  • Minimum elongation of 3% to 4% depending on thickness.
  • Hardness maintained within 510 to 600 HV to balance strength and ductility.

• Quality and Testing Requirements

  • Compliance with EN 4700-001 for technical specifications of steel plates, sheets, and strips.
  • Micrographic evaluation of non-metallic inclusions per EN 2951 to ensure cleanliness.
  • Dimensional and visual inspections consistent with aerospace quality demands.
  • Product qualification under EN 2043 to validate material performance for aerospace use.

Applications

• Aerospace Structural Components
  The high-strength X2NiCoMo18-8-5 steel sheets and strips are ideal for critical load-bearing aerospace parts that require superior mechanical properties combined with excellent fatigue resistance.

• Engine and Airframe Manufacturing
  Used extensively in manufacturing lightweight, high-strength steel elements of engines and airframe assemblies that must withstand extreme operational stresses and environmental conditions.

• Precision Aerospace Fabrication
  The controlled thickness and mechanical uniformity facilitate precision forming and fabrication processes necessary for tight aerospace tolerances.

• Materials Engineering and Certification
  EN 3531:2025 provides a reliable framework facilitating certification and material qualification for aerospace suppliers, simplifying compliance with international aerospace sector demands.

Related Standards

• EN 4700-001: Technical specification for wrought steel and heat-resisting alloys in plate, sheet, and strip form-provides detailed production and testing guidance aligned with EN 3531:2025.
• EN 2951: Specifies micrographic methods for determining non-metallic inclusion content, vital for maintaining aerospace material purity standards.
• EN 2043: Covers qualification programs for semi-finished metallic products, ensuring material readiness for aerospace manufacturing.
• EN 4258: Defines the general organization of aerospace metallic material standards and the relationship between various types of European standards.
• EN 4500-005: Outlines specific drafting and presentation rules for steel standards within the aerospace series, supporting document consistency and clarity.

This standard is essential for aerospace engineers, materials specialists, and quality assurance professionals seeking to implement reliable, high-performance steel materials in aerospace manufacturing. With strict controls over composition, melting methods, heat treatments, and mechanical properties, EN 3531:2025 ensures safety, durability, and performance compatibility in aerospace service conditions.