Magnesium-Alloy Forgings

B91: Standard Specification for Magnesium-Alloy Forgings

Navigating the complexities of material selection and manufacturing for high-performance applications requires adherence to authoritative standards. For engineers and designers working with lightweight yet robust materials, ASTM B91: Standard Specification for Magnesium-Alloy Forgings is an essential document that ensures quality, consistency, and predictable performance in critical components. This standard provides a proven framework for specifying and procuring magnesium alloy forgings, vital for industries where weight reduction and strength are paramount.

What is B91?

ASTM B91 is a leading industry standard that defines the requirements for magnesium alloy forgings. Developed by ASTM International, this specification establishes critical parameters for chemical composition, mechanical properties, and manufacturing processes, ensuring that forgings meet stringent performance criteria for a wide range of demanding applications. Its primary purpose is to provide a clear, unambiguous benchmark for both suppliers and users of magnesium alloy forgings.

Scope & Purpose

This comprehensive standard governs the production and acceptance of magnesium alloy forgings, encompassing various alloys and tempers. It details the acceptable chemical compositions and specifies minimum tensile properties, including tensile strength, yield strength, and elongation. The standard applies to die forgings and hand forgings, outlining requirements for sampling, testing, and documentation to ensure material integrity and conformance to specified design parameters. It does not cover raw ingot material or other forms of wrought magnesium products.

Who Must Comply?

• • Primary audience: Materials Engineers, Metallurgists, Design Engineers, Quality Inspectors, Production Engineers, and Procurement Specialists.
• • Industries affected: Aerospace, Automotive, Defense, Sporting Goods, and General Manufacturing sectors that utilize lightweight, high-strength components.
• • Compliance nature: Voluntary, but widely adopted as a de facto industry requirement for quality assurance and contractual agreements.
• • Enforcement: Typically enforced through contractual agreements between purchasers and manufacturers, and often specified in government or military procurement documents.

Key Requirements Overview

The ASTM B91 standard mandates several critical aspects for magnesium alloy forgings:

• • The standard requires that all forgings conform to specific chemical composition limits for various magnesium alloys, as detailed in its tables.
• • Professionals must ensure that forgings meet or exceed the minimum specified tensile strength, yield strength, and elongation properties.
• • Key provisions include detailed procedures for sampling and chemical analysis to verify alloy composition.
• • The standard outlines requirements for tension testing, including specimen preparation and testing locations relative to the forging's grain flow.
• • It also addresses ordering information, ensuring clarity on alloy, temper, quantity, and any special inspection or finishing requirements.

Related Standards & References

ASTM B91 works in conjunction with several other ASTM standards to provide a complete framework for magnesium alloy forgings:

• • ASTM B557: Test Methods for Tension Testing Wrought and Cast Aluminum- and Magnesium-Alloy Products, which provides the standardized methods for performing the tensile tests required by B91.
• • ASTM B951: Practice for Codification of Unalloyed Magnesium and Magnesium-Alloys, Cast and Wrought, which establishes the nomenclature and designation system for the alloys covered.
• • ASTM B660: Practices for Packaging/Packing of Aluminum and Magnesium Products, which ensures proper handling and protection of forgings during transit.