ASTM standards play an important role in the global metal and engineering industries. From nickel alloys and stainless steels to forged rings, forged bars, plates, tubes, and other critical components, ASTM specifications provide recognized requirements for material composition, mechanical properties, manufacturing, heat treatment, testing, and product quality.
For engineers and procurement teams, understanding ASTM standards is essential when specifying materials for demanding applications such as aerospace, oil and gas, chemical processing, power generation, marine equipment, and industrial machinery.
However, an ASTM designation alone does not always fully define a material or finished product. The material grade, UNS number, product form, dimensions, heat treatment condition, testing requirements, and applicable supplementary specifications may also need to be confirmed.
This guide explains how ASTM standards are used for metal materials and forged products, the differences between ASTM, UNS, and ASME designations, and how to select the appropriate specification for nickel alloys, stainless steels, and custom forgings.
ASTM standards are technical standards developed and published by ASTM International. They cover a wide range of materials, products, testing methods, manufacturing processes, and technical requirements used across industrial and engineering applications.
In the metal industry, ASTM specifications are commonly used to define requirements for:
ASTM standards are particularly important for high-performance materials because their properties can depend heavily on alloy chemistry, processing history, heat treatment, and product form.
For example, a nickel alloy forging may need to meet requirements for chemical composition, tensile strength, yield strength, elongation, hardness, heat treatment, and nondestructive testing in addition to the basic material grade.
The exact requirements depend on the applicable ASTM specification and its current edition.
ASTM originally stood for the American Society for Testing and Materials. The organization is now known as ASTM International.
ASTM develops consensus-based standards through technical committees covering different materials and industries. Its standards are widely referenced in engineering specifications, purchasing documents, manufacturing requirements, inspection procedures, and international supply chains.
It is important to distinguish between an ASTM standard and a material grade.
For example:
Inconel 718 is a commonly used commercial name for a nickel-based superalloy.
UNS N07718 identifies the alloy within the Unified Numbering System.
ASTM B637 is a product specification covering precipitation-hardening and cold-worked nickel alloy bars, forgings, and forging stock for moderate or high-temperature service. The current ASTM listing is B637-26.
These designations are related, but they are not interchangeable.
ASTM standards provide a common technical language between material manufacturers, forging companies, engineering firms, distributors, inspectors, and end users.
A customer in Germany, for example, may specify a nickel alloy forging according to an ASTM specification, while the manufacturer is located in China or another country. Using a recognized ASTM specification helps both parties establish a common technical basis for production and inspection.
ASTM specifications help define which material compositions and product categories are covered.
Applicable standards may establish requirements for tensile strength, yield strength, elongation, hardness, impact properties, or other mechanical characteristics.
Many alloy materials require specific heat-treatment conditions to achieve the required microstructure and mechanical properties.
Depending on the specification, requirements may apply to forging, rolling, cold working, finishing, or other manufacturing processes.
ASTM specifications may define required or applicable tests, sampling procedures, and acceptance criteria.
For example, ASTM B637-26 covers chemical analysis, heat treatment, tensile testing, hardness testing, and stress-rupture testing for the materials within its scope.
An ASTM specification should generally be viewed as a technical framework rather than simply a material name.
A complete material requirement can involve several dimensions:
Material → Grade → UNS → Product Form → ASTM Specification → Condition → Testing
For example:
Inconel 718 → UNS N07718 → Forging → ASTM B637 → Required Heat Treatment → Mechanical Testing
This distinction is particularly important for custom metal products.
The same alloy may be available in bars, plates, tubes, forgings, or other forms, but different ASTM specifications may apply depending on the product form and intended application.
Chemical composition is one of the fundamental requirements of many ASTM metal specifications.
Depending on the material, limits may be established for elements such as:
The exact chemistry requirements depend on the applicable grade and ASTM specification.
For nickel alloys, controlling alloy chemistry is particularly important because chromium, molybdenum, nickel, niobium, titanium, aluminum, and other elements can strongly influence corrosion resistance, strength, oxidation resistance, and high-temperature performance.
ASTM specifications may define minimum or required mechanical properties for specific materials and product conditions.
Typical requirements include:
The required values can vary according to alloy grade, product size, heat treatment condition, and temperature.
For example, ASTM B637-26 includes requirements related to tensile strength, yield strength, elongation, reduction of area, Brinell hardness, and stress-rupture performance for materials within its scope.
Heat treatment is especially important for nickel-based superalloys and precipitation-hardening stainless steels.
Depending on the alloy and specification, applicable processes may include:
The correct heat-treatment condition can significantly affect the final mechanical properties and service performance of a forged product.
For this reason, an engineering specification should normally identify not only the material and ASTM standard but also the required heat-treatment condition where applicable.
Metal products manufactured to ASTM specifications may require different levels of testing depending on the applicable standard and customer requirements.
Common inspection activities include:
For example, ASTM B564 covers nickel alloy forgings and includes requirements related to chemical analysis, grain size, mechanical properties, tension testing, and ultrasonic nondestructive testing.
ASTM, UNS, and ASME are frequently mentioned together in metal purchasing specifications, but they serve different purposes.
| System | Main Purpose | Example |
|---|---|---|
| ASTM | Material and product specifications | ASTM B637 |
| UNS | Unified material identification system | UNS N07718 |
| ASME | Engineering codes and specifications | ASME SB637 |
ASTM specifications establish technical requirements for materials and products.
The Unified Numbering System provides a standardized designation for many metallic alloys.
For example: UNS N07718 identifies the nickel alloy commonly known as Inconel 718.
ASME develops engineering codes and standards used extensively in pressure equipment, boilers, piping, and other engineering applications.
In many cases, ASME specifications reference or adopt ASTM material specifications with an SA or SB designation.
Therefore, the following should not be treated as three alternative names for the same thing:
Inconel 718 ≠ UNS N07718 ≠ ASTM B637
They describe different aspects of the material and product specification.
ASTM publishes a large number of standards covering different metals, product forms, and applications. For alloy and forging manufacturers, several groups are particularly relevant.
Nickel alloy standards are generally found within ASTM's B-series specifications.
Commonly referenced standards include specifications covering:
ASTM B637 is particularly relevant to precipitation-hardening nickel alloy bars, forgings, and forging stock for moderate or high-temperature service. The current ASTM listing is B637-26.
ASTM B564 is the Standard Specification for Nickel Alloy Forgings. The specification covers a broad range of nickel alloy forging materials and includes requirements associated with chemistry, grain size, mechanical properties, tension testing, and ultrasonic testing.
ASTM B166 covers specified nickel-chromium-iron and nickel-chromium-cobalt-molybdenum alloys in rod, bar, and wire forms. The current ASTM listing is B166-25.
These specifications demonstrate an important point: the ASTM designation depends not only on the alloy but also on the product form and technical requirements.
Stainless steel products are commonly covered by ASTM A-series specifications.
Examples include:
ASTM A182/A182M-26 covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and valves and parts for high-temperature service.
ASTM A564/A564M-25 covers hot-rolled and cold-finished age-hardening stainless steel bars and shapes. The specification includes products that may be produced by hot rolling, extrusion, or forging and includes requirements for mechanical testing.
For stainless steel procurement, the applicable ASTM specification should therefore be selected according to both the material and the required product form.
Forging is one of the areas where ASTM specifications become particularly important.
A forged product is not defined only by its alloy grade. The final specification may also depend on:
Common product forms include:
Forged rings are widely used in applications requiring high strength, pressure resistance, corrosion resistance, or elevated-temperature performance.
Depending on the material and application, applicable specifications may include nickel alloy or stainless steel forging standards.
A complete forged ring specification may therefore look like:
Material Grade + UNS + ASTM Standard + OD × ID × Height + Heat Treatment + Testing
For example:
Inconel 718 / UNS N07718 / ASTM B637 / Forged Ring / Required Heat Treatment / Inspection Requirements
The exact standard and edition should always be confirmed against the customer's engineering specification.
Forged discs are commonly used for:
The applicable ASTM specification depends on the material and product requirements.
Nickel alloy forged discs may fall under specifications such as ASTM B564 or ASTM B637 depending on the alloy and product requirements.
Forged bars are commonly used as starting stock for machining critical components.
Important requirements may include:
ASTM B637, for example, covers precipitation-hardening and cold-worked nickel alloy rod, bar, forgings, and forging stock for moderate or high-temperature service.
ASTM specifications should be selected according to the actual product form rather than simply the alloy name.
Applicable specifications depend on alloy grade, dimensions, heat treatment, and application.
Typically specified according to material family, forging requirements, heat treatment, and mechanical properties.
Commonly covered by alloy-specific or stainless steel bar and forging specifications.
Usually manufactured according to the applicable material and forging specification with customer-specific dimensional and testing requirements.
Nickel alloy and stainless steel round bars may fall under different ASTM specifications depending on alloy chemistry and product condition.
Plate and sheet products are generally covered by specifications specific to the alloy family and product form.
Tubular products have their own ASTM specifications based on material, manufacturing route, dimensions, and service requirements.
The key principle is:
ASTM specification = material + product form + technical requirements
rather than simply: ASTM specification = material grade
One of the most common mistakes in metal purchasing is treating the ASTM number as if it were the material grade.
A better way to understand a material specification is to look at the complete relationship.
A typical engineering requirement may identify:
ASTM B637-26 specifically covers precipitation-hardening and cold-worked nickel alloy rod, bar, forgings, and forging stock for moderate or high-temperature service.
ASTM B564 is specifically titled Standard Specification for Nickel Alloy Forgings.
It covers a range of nickel alloy forging materials and establishes requirements associated with chemical analysis, grain size, mechanical properties, tension testing, and ultrasonic testing.
This makes ASTM B564 particularly relevant when specifying nickel alloy forged components.
ASTM A564/A564M covers age-hardening stainless steel bars and shapes. Its scope includes Type 630 material, which is commonly associated with 17-4 PH stainless steel, as well as other age-hardening stainless grades.
For an actual purchase order, however, the buyer should specify the exact grade, UNS designation, condition, dimensions, and applicable requirements rather than relying on the ASTM number alone.
Selecting the correct ASTM specification should follow a structured process.
Determine the required alloy family and grade.
Examples include:
Where applicable, confirm the corresponding UNS designation.
For example: Inconel 718 → UNS N07718
The UNS number helps eliminate ambiguity between commercial alloy names and standardized material designations.
Specify whether the requirement is for:
This step is critical because ASTM specifications are often product-form specific.
After confirming the alloy and product form, determine the applicable ASTM specification.
For example:
The exact specification must be verified against the current ASTM edition and the customer's technical requirements.
Determine whether the product requires:
Heat treatment can have a major effect on the final properties of nickel alloys and precipitation-hardening stainless steels.
Depending on the specification and application, confirm requirements for:
ASTM specifications are widely used across industries where material performance and traceability are important.
Nickel-based superalloys and precipitation-hardening materials are commonly used in high-temperature and high-stress components.
Typical requirements may involve:
Nickel alloys, stainless steels, and forged components are used in environments involving:
Material selection and applicable ASTM specifications therefore need to be aligned with the actual service environment.
Nickel alloys such as Inconel and Hastelloy are often selected where corrosion resistance is critical.
Relevant requirements may include:
High-temperature nickel alloys and stainless steels are used in:
ASTM specifications help establish consistent material and product requirements.
Stainless steels, duplex stainless steels, nickel alloys, and other corrosion-resistant materials can be used in marine environments where chloride exposure and corrosion resistance are major considerations.
Meeting an ASTM specification is not simply a matter of printing the ASTM number on a material certificate.
A reliable supply process should include appropriate technical documentation and traceability.
Depending on the product and customer requirements, documentation may include:
The MTC can document:
For heat-treated nickel alloys and stainless steels, records may document:
Depending on the applicable standard:
Depending on the specification and customer requirement:
Critical forged components may also require dimensional inspection against customer drawings and tolerances.
An important point for engineers and purchasing teams is that an ASTM designation alone may not fully define the product.
For example: ASTM B637 does not by itself communicate every detail needed to manufacture a specific forged ring.
A more complete requirement might include:
This approach minimizes technical ambiguity and helps manufacturers provide an accurate quotation.
When sourcing nickel alloy or stainless steel products, customers should provide as much technical information as possible.
A good RFQ should ideally include:
For custom forgings, drawings or dimensional sketches are also highly recommended.
A manufacturer can then review the requirements and confirm the appropriate material, manufacturing route, heat treatment, inspection plan, and documentation.
ASTM standards provide an important technical foundation for specifying and purchasing metal materials and engineered products. For nickel alloys, stainless steels, and forged components, ASTM specifications can define requirements covering chemical composition, mechanical properties, heat treatment, manufacturing, testing, and product quality.
However, selecting the correct ASTM standard requires more than identifying a material grade. The complete requirement should consider the relationship between:
Material Grade → UNS Number → Product Form → ASTM Specification → Heat Treatment → Testing → Certification
For example:
Inconel 718 → UNS N07718 → Forging → ASTM B637 → Heat Treatment → Mechanical & NDT Inspection
Similarly, nickel alloy forgings may be specified under ASTM B564, while certain stainless steel forged products may fall under ASTM A182 or other applicable specifications depending on the product and application.
For critical engineering applications, always confirm the applicable ASTM edition and the complete customer specification before production. ASTM standards are periodically revised, and the applicable edition, material grade, product form, and supplementary requirements should be verified for each project.
Alloy-Ronsco supplies nickel alloys, stainless steels, and custom forged products for demanding industrial applications. If you are sourcing Inconel, Incoloy, Monel, Hastelloy, 17-4 PH stainless steel, nickel alloy forgings, forged rings, forged discs, forged bars, or other engineered metal products, provide your material grade, UNS number, ASTM specification, dimensions, quantity, and testing requirements.
Our team can review your technical requirements and recommend an appropriate material and manufacturing solution.
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