EN 2398:2008

Overview

EN 2398:2008 is a European Standard developed by CEN that specifies the technical requirements for heat-resisting steel designated as FE-PA2601 (X6NiCrTiMoV26-15). This steel grade is designed specifically for aerospace applications, focusing on bars used for machined bolts with a diameter (D) of up to 25 mm and minimum tensile strength (Rm) of 900 MPa. The standard ensures material consistency, reliability, and performance to meet the rigorous demands of aerospace environments.

This standard is part of the aerospace metallic materials series, prepared in accordance with aerospace-specific drafting rules and aligned with related standards such as EN 4258 for general organization and EN 4700-2 for technical specifications of bars and sections. The standardized heat treatment, chemical composition, mechanical properties, and testing methods outlined make EN 2398:2008 critical for aerospace manufacturers and suppliers involved in producing high-strength fasteners for aircraft and engine components.

Key Topics

• Material Specification: Defines the chemical composition limits for the heat-resisting steel FE-PA2601 (X6NiCrTiMoV26-15), including elements such as Chromium (Cr), Nickel (Ni), Titanium (Ti), Molybdenum (Mo), and Vanadium (V), which contribute to its heat resistance and strength.

• Mechanical Properties:

  • Minimum tensile strength (Rm) of 900 MPa
  • Proof stress (Rp0.2) ≥ 590 MPa
  • Elongation (A) ≥ 13%
  • Reduction of area (Z) ≥ 20%
  • Hardness range between 248 HB and 341 HB to ensure durability without brittleness.

• Heat Treatment Conditions: Specified sequences such as solution treatment at 900 °C followed by air cooling and optional precipitation treatment at 720 °C for 16 hours enhance mechanical strength and heat resistance.

• Dimensional Scope: Bars used for machining bolts with diameters up to 25 mm under strict delivery and quality control protocols.

• Testing and Inspection Methods:

  • Non-destructive testing (e.g., penetrant and ultrasonic inspection per EN 2002-16 and EN 4050-4)
  • Micrographic determination of non-metallic inclusions (EN 2951)
  • Dimensional and marking inspections (per EN 4700-2 and EN 2344)

• Delivery Conditions: Includes softened, cold worked, solution treated, and machined products to ensure optimal microstructure and mechanical properties for demanding aerospace service environments.

Applications

EN 2398:2008 is crucial for aerospace component manufacturers requiring high-performance steel bars used in machined bolts. These fasteners undergo intense mechanical loads and elevated temperatures in aircraft structures and engine assemblies. Typical applications include:

• Aerospace Bolts and Nuts: Used extensively in airframe construction and engine components where heat resistance and mechanical strength are critical for safety and longevity.

• Aircraft Structural Components: Providing reliable fastening solutions in areas subject to varying thermal and mechanical stresses.

• Engine Assemblies: Parts subjected to elevated temperatures that demand superior heat-resisting properties.

The standard supports aerospace supply chains by ensuring consistent material quality, enabling manufacturers to meet stringent design and regulatory requirements inherent to the aviation industry.

Related Standards

• EN 4258 – General organization of aerospace metallic material standards and relationships between different types of EN standards.

• EN 4700-2 – Technical specifications for steel and heat-resisting alloys in bar and section form, detailing delivery and testing methods.

• EN 2344 – Dimensions and tolerances for round bars machined in heat-resisting alloys, diameter range 10 mm to 180 mm.

• EN 2399 – Heat-resisting steel FE-PA92-HT bars for forged bolts with diameter up to 25 mm, related to forged bolt applications.

• EN 2002-16 – Non-destructive testing methods including penetrant testing essential for quality control of aerospace materials.

• EN 2951 – Micrographic analysis for the content of non-metallic inclusions, supporting cleanliness standards.

• EN 4050-4 – Ultrasonic inspection and acceptance criteria for metallic bars and forgings.

By aligning with these standards, EN 2398:2008 integrates into a comprehensive framework for aerospace material certification, ensuring the highest levels of quality and safety.

Keywords: EN 2398:2008, aerospace standard, heat resisting steel, FE-PA2601, X6NiCrTiMoV26-15, machined bolts, tensile strength 900 MPa, aerospace bolts, heat resistant alloys, non-destructive testing, aerospace metallic materials, CEN standard, aerospace fasteners, steel bars for aerospace