SIST EN 4685:2011

Overview

EN 4685:2011 is a CEN (ASD‑STAN) aerospace material standard that specifies requirements for Titanium Ti‑10V‑2Fe‑3Al wrought bars intended for aerospace use. It covers bars with diameter D < 110 mm and mandates a minimum tensile strength Rm ≥ 1 240 MPa. The standard defines chemical composition limits, production and melting methods, delivery and use heat‑treatment conditions, microstructure expectations, mechanical properties and inspection requirements.

Key topics and technical requirements

• Material designation: Titanium Ti‑10V‑2Fe‑3Al (Ti‑10V2Fe3Al).
• Chemical limits: Specified ranges for Al, V, Fe and interstitials (O, C, N, Y) and max impurities; titanium balance.
• Melting and production: Vacuum melted with last melting by consumable electrode; bars produced by hot rolling.
• Dimensions: Bars with diameter < 110 mm; sub‑ranges and specific dimensional inspections apply.
• Delivery condition: Delivered not heat‑treated; delivery code F (per EN 2032‑2).
• Use condition (required heat treatment): Solution treat and age - solution temperature 33–56 °C below the β‑transus for ≥1 h, water quench (WQ), then age ≥480 °C for ≥8 h (air cool).
• Mechanical properties (after solution + aging):
  • Tensile strength Rm ≥ 1 240 MPa
  • Proof stress Rp0.2 ≥ 1 110 MPa
  • Elongation A ≥ 4%
  • Reduction of area Z values specified by diameter class
• Microstructure: Primary alpha phase within an aged beta matrix; continuous alpha networks along prior beta grain boundaries are not acceptable.
• Inspection & defects: Macrostructure, internal/external defect acceptance and sampling per EN 4800‑002 and EN 2954; β‑transus determination per EN 3684.

Applications and who uses this standard

• Primary users: Aerospace material purchasers, component manufacturers, procurement/specification engineers, metallurgists, quality and inspection teams, and certification authorities.
• Practical uses: Specifying high‑strength titanium bar stock for aerospace components where high tensile strength and controlled microstructure are critical (e.g., structural forgings, precision machined parts). EN 4685:2011 is used to:
  • Ensure consistent chemical/physical properties from suppliers
  • Define heat‑treatment cycles and acceptance criteria for procurement contracts
  • Guide inspection plans and material qualification between purchaser and manufacturer

Related standards

Normative references used by EN 4685:2011 include:

• EN 2032‑2 (coding of metallurgical condition)
• EN 2954 (macrostructure of titanium wrought products)
• EN 3684 (β‑transus determination)
• EN 4050‑1 (test method general requirements)
• EN 4258, EN 4500‑4 (series organization and drafting rules)
• EN 4800‑002 (technical specification for bars and sections)

Keywords: EN 4685:2011, Titanium Ti10V2Fe3Al, Ti‑10V‑2Fe‑3Al, aerospace titanium bars, high‑strength titanium, vacuum melted, solution treated and aged, β‑transus, Rm ≥1240 MPa.