For hardware structural components exported to North America, ASTM standards constitute the technical language most frequently specified in drawings and contracts. The ASTM (American Society for Testing and Materials) standard system is categorized by letter series: the A-series covers iron and steel;
the B-series covers non-ferrous metals and coatings; the E-series covers test methods; and the G-series covers corrosion. Understanding this system is essential for accurately interpreting the material grades and testing requirements found on client drawings.
This article outlines the ASTM standards most commonly used for hardware structural components.
I.
Material Specifications: Determining “Which Material to Use”
- ASTM A36: Standard specification for structural carbon steel shapes and plates; most commonly used for construction and general structural components;
- ASTM A240/A240M: Standard specification for chromium and chromium-nickel stainless steel (e.g., 304, 316) plate, sheet, and strip; suitable for both pressure vessels and general applications;
- ASTM A276/A276M: Standard specification for stainless steel bars and shapes (round, square, hexagonal, angle, channel, etc.); commonly used for machined hardware components;
- ASTM A307: Standard specification for carbon steel bolts and studs; frequently specified for general fasteners exported to the US;
- ASTM A193/A320: Standard specifications for alloy steel and stainless steel bolting materials for high-temperature or low-temperature/high-pressure service; suitable for fasteners used in petrochemical and high-temperature environments.
II. Testing Methods: Verifying “Performance Compliance”
- ASTM E8/E8M: Standard Test Methods for Tension Testing of Metallic Materials at Room Temperature—the basis for determining yield strength, tensile strength, and elongation; the “standard procedure” for assessing the mechanical properties of hardware components;
- ASTM A370: Standard Test Methods and Definitions for Mechanical Testing of Steel Products—covers tensile, impact, and hardness testing, among others;
- ASTM E10/E18: Standard Test Methods for Brinell and Rockwell Hardness—used for hardness acceptance of surface-hardened and quenched-and-tempered components;
- ASTM E23: Standard Test Methods for Notched Bar Impact Testing of Metallic Materials—applicable to critical low-temperature toughness applications (e.g., structural components in cold regions);
- ASTM E407: Standard Practice for Microetching Metals and Alloys—used to evaluate microstructure and heat treatment conditions.
III.
Surface and Corrosion: The “Litmus Test” for Coating Quality
- ASTM B117: Standard Practice for Operating Salt Spray (Fog) Apparatus—the global benchmark for evaluating the corrosion resistance of electroplated, spray-coated, and oxidized parts; export orders often specify “Neutral Salt Spray (NSS): no red rust for XX hours”;
- ASTM A967: Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts—the common standard for passivation film quality and inspection;
- ASTM D3359: Standard Test Methods for Rating Adhesion by Tape Test (Cross-Cut Test)—the standard method for measuring the bond strength of spray coatings.
IV. Two Principles for Selecting Standards
The first is “matching based on application”: select structural steel specifications (such as A36 or A992) for load-bearing structural components, stainless steel series (such as A240) for corrosion-resistant parts, and specifications like A307 or A193 for fasteners—as material specifications dictate chemical composition and minimum mechanical properties. The second is the “material-plus-test pairing” principle: engineering drawings typically specify both the material standard (e.g., ASTM A240 304) and the testing method (e.g., ASTM E8 for tensile testing or ASTM B117 for salt spray testing); procurement and quality inspection must align with this pairing.
Note that ASTM standards are subject to continuous updates (e.g., B117-26 is the current version); orders should explicitly state the version number to avoid ambiguity between old and new versions.
V.
Trend: Mutual Recognition Between ASTM and International Standards
While the North American market generally references ASTM standards directly, the European Union favors EN standards, and ISO standards are used globally. Exporting the same product to different markets may require compliance with multiple sets of standards (e.g., one must assess in advance the differences between ASTM E8 and ISO 6892 for tensile testing, or ASTM B117 and ISO 9227 for salt spray testing).
Industry professionals recommend that exporting enterprises create an “ASTM standard mapping table” to formalize the relationships between commonly used materials, test methods, and their GB/ISO/EN equivalents.
This allows for the rapid verification of standard applicability and testing costs during drawing reviews, preventing issues where standard mismatches are discovered only right before shipment.
