SIST EN 3671:2009

Overview

SIST EN 3671:2009 is a European standard published by CEN that specifies the technical requirements for the aerospace-grade heat resisting alloy NI-PH3601 (NiCr22Mo9Nb). This standard applies specifically to non-heat treated forging stock with dimensions a or D ≤ 250 mm. It is specifically tailored for aerospace applications where high-temperature performance and mechanical reliability are critical.

This standard supports manufacturers, suppliers, and aerospace engineers by defining the chemical composition, mechanical properties, and production conditions for NI-PH3601 alloy, ensuring consistency, quality, and interchangeability in aerospace components.

Key Topics

• Material Specification: Defines the chemical composition limits for NI-PH3601 (NiCr22Mo9Nb), including key elements like Nickel (Ni), Chromium (Cr), Molybdenum (Mo), and Niobium (Nb).
• Forging Stock Requirements: Covers non-heat treated forging stock forms, allowing a or D dimensions up to 250 mm.
• Mechanical Properties: Includes minimum requirements for proof stress (≥ 410 MPa), tensile strength (≥ 830 MPa), elongation (≥ 30%), and hardness (≤ 290 HB), crucial for high-temperature aerospace performance.
• Manufacturing Process: Specifies the consumable electrode remelted melting method, with delivery conditions focused on non-heat treated material (condition code U).
• Quality Assurance: Details testing methods such as macrostructure inspection, dimensional checks, and defect classification in accordance with referenced standards like EN 2860-2 and EN 2043.
• Heat Treatment Guidelines: Although the alloy is specified as non-heat treated in this standard, reference heat treatment for annealing is given for comparison or alternate processing with temperature 920 °C ± 10 °C for 1 hour followed by air cooling.

Applications

SIST EN 3671:2009's designation of the NI-PH3601 heat resisting alloy makes it highly valuable in aerospace sectors due to its excellent mechanical properties and high-temperature resistance. Typical practical applications include:

• Aerospace structural components exposed to elevated temperatures
• Turbine engine parts such as discs and shafts
• High-stress aerospace forgings requiring both corrosion resistance and mechanical strength
• Components manufactured from forging stock with diameters or thicknesses up to 250 mm where dimensional precision and metallurgical quality are mandatory
• Usage in environments demanding good elongation and toughness at ambient temperatures, ensuring durability under mechanical and thermal stress

The consistent properties outlined in SIST EN 3671:2009 ensure that aerospace manufacturers can rely on NI-PH3601 alloy stock to perform predictably in demanding operational conditions.

Related Standards

SIST EN 3671:2009 is part of the broader aerospace metallic materials standard series, incorporating and referencing other significant standards for comprehensive quality control and material definition:

• EN 2860-2: Covers detailed specifications for forging stock and forgings of heat resisting alloys, including test samples and defect criteria, ensuring alignment with EN 3671.
• EN 2043: Defines general requirements for semi-finished product qualification for aerospace materials, instrumental for product qualification and supplier certification.
• EN 4258: Provides general organization and linkage guidelines within aerospace metal material standard series.
• EN 4500-3: Sets out rules for drafting and presenting aerospace material standards, including specific mandates for heat resisting alloys such as NI-PH3601.

Implementing SIST EN 3671:2009 alongside these complementary standards facilitates compliance with aerospace quality protocols and international harmonization.

By adhering to SIST EN 3671:2009 standards, aerospace manufacturers and engineers ensure the use of high-performance NI-PH3601 alloy forging stock that meets stringent European and international aerospace industry requirements, supporting the development of safe, reliable, and high-quality aerospace components.