SIST EN 2543:2009

Overview

EN 2543:2009 is a CEN (ASD‑STAN) aerospace material standard that specifies requirements for Steel FE‑PL1502 (25CrMo4) in the annealed condition, supplied as sheet and strip with thickness 0.3 mm ≤ a ≤ 2 mm. The standard is intended specifically for use in prevailing torque nuts and other aerospace fastener components where a low‑alloy, heat‑treatable steel in thin gauges is required.

Keywords: EN 2543:2009, FE‑PL1502, 25CrMo4, annealed steel, sheet and strip, prevailing torque nuts, aerospace.

Key topics and requirements

• Material designation: FE‑PL1502 (25CrMo4) with chemical composition ranges:
  • C 0.22–0.29 %, Si 0.10–0.35 %, Mn 0.50–0.80 %, Cr 0.90–1.20 %, Mo 0.15–0.25 %, Ni ≤ 0.30 %, P ≤ 0.020 %, S ≤ 0.015 %, Fe balance.
• Form and dimensions: sheet and strip, thickness 0.3–2.0 mm.
• Delivery condition: annealed (delivery code U).
• Melting method: air melted.
• Heat treatment / reference: the standard gives a reference heat treatment (step quench in salt bath 850–860 °C followed by salt bath quench ≥365 °C or equivalent) and notes the product is supplied annealed for prevailing torque nuts.
• Surface and decarburization limits: material shall be free from carburization; total decarburization not permitted, partial decarburization limited to 5 % of thickness on each face with a maximum depth of 0.2 mm per face.
• Inspection and tests: dimensional inspection per EN 2033, marking and inspection per EN 4700‑1; other test/sample rules referenced to EN 4700‑1 and EN 4258.
• Hardness: annealed product hardness is limited (see standard - HV5 ≤ 150 for annealed material; additional hardness ranges are listed in the document for other conditions).

Applications

• Primary use: prevailing torque (self‑locking) nuts in aerospace fastener assemblies.
• Also applicable where a thin, low‑alloy, annealed 25CrMo4 strip/sheet is required for aircraft/space structures or components subject to standardized material control.
• Useful for manufacturers of nuts, cold‑forming and stamping shops, aerospace fastener suppliers, and procurement departments specifying material for flight hardware.

Who should use this standard

• Material and metallurgical engineers, fastener designers, quality and inspection teams, procurement/specification writers, and aerospace manufacturers who require standardized thin‑gauge 25CrMo4 steel for prevailing torque nuts.

Related standards

• EN 2033 (cold‑rolled strips in steel)
• EN 2600 (designation rules for semi‑finished products)
• EN 4258 (organization of aerospace metallic standards)
• EN 4700‑1 and EN 4500‑5 (technical and drafting rules for aerospace steels)

For exact test methods, numerical limits and procurement wording, consult the full EN 2543:2009 text as adopted by your national CEN member.