EN 3956:2001

Overview

EN 3956:2001 is a European Standard published by CEN that defines the specifications for the aerospace-grade silver base alloy AG-B14001 (AgCu42Ni2) used as filler metal for brazing in wire form. This standard is an essential reference within the aerospace industry, ensuring the consistent quality, chemical composition, and performance characteristics of brazing wires used in critical aerospace manufacturing and maintenance processes. The alloy comprises primarily silver, copper, and nickel, optimized for joining carbon, low alloy, and non-heat-treatable austenitic steels.

Key Topics

• Material Composition
  The silver base alloy AG-B14001 is precisely formulated with approximately 42% copper and 2% nickel, alongside silver content ranging between 55% and 57%. Chemical analysis limits ensure trace elements like silicon, phosphorus, aluminum, bismuth, cadmium, and lead remain within strict thresholds to maintain alloy integrity.

• Wire Form and Production
  The filler metal is supplied exclusively as wire, which is cold formed and carefully cleaned to meet aerospace quality standards. Melting processes for the alloy use air or inert gas to guarantee purity and performance reliability.

• Thermal Properties
  Critical thermal characteristics include a solidus temperature around 780 °C and a liquidus temperature near 895 °C, ensuring adequate melting and flow properties for brazing applications involving sensitive aerospace components.

• Technical Specifications and Testing
  The standard references EN 3875 for detailed technical specifications such as external defect inspection, thermal and differential thermal analysis, wettability (fusion test), batch uniformity checks, marking, and dimensional inspections. Mechanical properties like shear strength, proof stress, elongation, hardness, and impact strength are rigorously evaluated to ensure conformity.

• Quality and Qualification
  Product qualification follows EN 2043 guidelines with qualification programs arranged between manufacturers and purchasers to assure each batch meets aerospace industry expectations. The standard mandates consistent batch uniformity and identification.

Applications

EN 3956:2001 silver base brazing wire is widely used in aerospace manufacturing and repair, especially for:

• Joining carbon steels
• Brazing low-alloy steels
• Connecting non-heat-treatable austenitic steels

This filler metal is ideal for producing reliable, high-strength joints in aircraft structures, engine components, and other aerospace systems where both mechanical integrity and corrosion resistance are paramount. Its controlled composition and proven performance under thermal cycling make it suitable for high-stress environments encountered in aviation.

Related Standards

This standard is part of the broader EN aerospace metallic materials series, linked with several other standards for comprehensive material control and usage guidance:

• EN 2043 – Metallic materials general requirements for semi-finished products
• EN 3875 – Technical specification for filler metal for brazing
• EN 4258 – General organization of standardization including links between various EN standards
• EN 4500-6 – Rules for drafting and presentation of filler metals for brazing standards

Collectively, these standards ensure harmonized practices related to material selection, testing, treatment, and application in aerospace manufacturing, emphasizing quality assurance and operational safety.

Keywords: EN 3956, silver base alloy AG-B14001, AgCu42Ni2, aerospace brazing filler metal, brazing wire, silver alloy wire, CEN standard, aerospace brazing wire specification, silver copper nickel alloy, aerospace manufacturing materials