SIST EN 2135:2018

Overview

EN 2135:2017 is a European aerospace material standard that specifies the technical requirements for Steel FE-PL61, supplied as carburized, hardened and tempered bars with an external diameter (De) ≤ 40 mm. Prepared under ASD‑STAN and adopted by CEN, the standard defines chemical composition, production and delivery conditions, heat treatment practice and key inspection/test requirements for use in aerospace components requiring case‑hardening.

Key topics and requirements

• Material designation: Steel FE-PL61, intended as a case‑hardening (carburizing) steel for aerospace use.
• Chemical composition (typical limits):
  • Carbon (C): 0.10 – 0.16 %
  • Silicon (Si): 0.15 – 0.40 %
  • Manganese (Mn): 0.35 – 0.65 %
  • Phosphorus (P) ≤ 0.025 %, Sulfur (S) ≤ 0.020 %
  • Chromium (Cr): 0.60 – 0.90 %
  • Nickel (Ni): 2.75 – 3.25 %
• Form and dimensions: Bars, maximum diameter De ≤ 40 mm.
• Melting method: Air‑melted.
• Delivery condition: Supplied softened (delivery condition code A). Final condition is carburized, hardened and tempered as agreed between supplier and purchaser.
• Reference heat treatment: Hardened and tempered reference given as 820 °C ± 10 °C with oil quench (OQ), followed by temper at 190 °C ± 5 °C.
• Hardenability (Jominy) requirements: Specified HRC ranges at standard distances (examples: 5 mm: HRC 31–44; 9 mm: HRC 28–41; 15 mm: HRC 22–36; maximum values given for 25 mm and 40 mm).
• Testing and inspection: One bar per batch sampling is specified; simulated case‑hardening test is optional; marking and dimensional inspection requirements are included. Hardness may be expressed in HB or HV (HV used for very small diameters where specified).

Applications and users

• Primary users: Aerospace manufacturers, heat‑treatment shops, material engineers, procurement and quality assurance teams specifying case‑hardening steels for flight hardware.
• Typical applications: Components requiring a tough core and hard wear‑resistant case (example listed in the standard: bell pivot). Suitable for bearings, pivots and small shafts in aerospace mechanisms where controlled case depth and core properties are critical.

Related standards

• EN 4700‑002 (steel wrought products - bar and section technical specification)
• EN 2157‑1 (forging stock and forgings - general requirements)
• EN 4258 (organization of aerospace metallic material standards)
• EN 4500‑005 (rules for drafting/presentation of material standards)

EN 2135:2017 provides the necessary material, heat‑treatment and inspection framework to specify and qualify FE‑PL61 carburized bars for aerospace components where case hardening and tight material control are required.