ASTM A128, GB/T 5680 and EN GX120Mn12 belong to the same broad family of austenitic manganese cast steels, but they should not be treated as automatically interchangeable material designations. The standards differ in classification systems, grade naming, chemical-composition requirements, heat-treatment provisions, testing and acceptance requirements. ASTM A128/A128M specifically covers Hadfield austenitic manganese steel castings and alloy modifications, while China’s current GB/T 5680-2023 covers austenitic manganese steel castings and replaced GB/T 5680-2010. In the European system, GX120Mn12 is used as an austenitic manganese cast-steel designation under EN 10293. 

The Three Standards Are Related, Not Identical

The most important distinction is that the three references operate as standard-and-grade systems, rather than three different names for exactly the same specification. ASTM A128/A128M is a dedicated specification for austenitic manganese steel castings. GB/T 5680 is China’s national product standard for austenitic manganese steel castings. EN GX120Mn12 identifies a European austenitic manganese cast-steel grade within the EN casting framework. 

ASTM A128: The North American Reference

ASTM A128/A128M is titled Standard Specification for Steel Castings, Austenitic Manganese. The current ASTM listing identifies ASTM A128/A128M-19(2025) as the active version. Its scope covers Hadfield austenitic manganese steel castings and alloy modifications. The specification requires suitable heat treatment to achieve the required toughness and ductility and sets chemical-composition requirements for the covered grades. 

The grade structure is particularly important when an inquiry simply says “A128 manganese steel.” ASTM A128 does not define one universal chemistry. It contains several grades, so the purchaser should identify the actual grade rather than using the standard number alone.

GB/T 5680: Check the Edition Before Comparing Grades

One frequently overlooked issue is that GB/T 5680 has been revised several times. The national standards database shows that GB/T 5680-2010 was withdrawn and replaced by GB/T 5680-2023, which was published and implemented on May 23, 2023. The 2023 edition is titled Austenitic manganese steel castings. 

This matters when an older drawing, supplier database or internal ERP system still identifies a manganese casting using an earlier edition. A technically similar grade number does not automatically mean that all requirements in the old and new editions are identical.

The 2023 standard is also reported by the Chinese national standards platform as a modified adoption of ISO 13521:2015. The earlier GB/T 5680-2010 was based on ISO 13521:1999. 

EN GX120Mn12: Understanding the European Designation

GX120Mn12 is a European-style cast-steel designation used for austenitic manganese cast steel. Foundry references identify GX120Mn12 with EN 10293 and associate it with the Hadfield manganese casting family. Other technical references also identify the older G-X120Mn12 form and material number 1.3401 in European/German material systems. 

The designation itself contains useful information. The initial G indicates a cast steel designation, while X indicates that the alloy is designated through significant alloying elements. The numerical and elemental portions identify the nominal composition system rather than serving as a simple commercial product name.

However, buyers should distinguish GX120Mn12 from other closely related European manganese grades such as GX120Mn13 or GX100Mn13. These grades can occupy the same general application family while having different specified composition ranges.

ASTM A128 vs GB/T 5680 vs GX120Mn12: What Actually Changes?

Are These Grades True Equivalents?

They can be technically comparable, but “equivalent” should be used carefully. Published cross-reference material places ASTM A128, X120Mn12/1.3401 and GX120Mn12 within the same general Hadfield manganese steel family. However, cross-reference tables are useful for identifying candidates; they do not by themselves establish contractual equivalence.

The reason is straightforward: two specifications can have similar nominal carbon and manganese levels while differing in limits for silicon, phosphorus, sulfur, chromium and other elements, as well as heat treatment, mechanical testing and acceptance criteria.

For example, published comparative data commonly places the conventional Hadfield composition around 1.0–1.4% carbon and approximately 11–14% manganese, but the exact permitted range depends on the specific standard and grade. 

Chemical Composition Should Be Compared Element by Element

When converting an inquiry from one standard to another, do not compare only carbon and manganese. Silicon, phosphorus, sulfur and intentional alloying additions can affect casting behavior, weld repair procedures, heat treatment and service performance.

Heat Treatment Is Part of the Grade Requirement

Austenitic manganese castings depend heavily on heat treatment. ASTM A128 explicitly requires suitable heat treatment to obtain toughness and ductility. 

This is why purchasing a casting by chemical composition alone can be risky. The same broad chemistry can produce substantially different service behavior if casting practice or heat treatment differs.

For a technical inquiry, specify whether the supplied casting must be solution treated, water quenched or otherwise processed according to the applicable standard. Do not assume that a material certificate showing chemistry alone demonstrates compliance with the complete material specification.

Mechanical Properties: Do Not Mix Test Requirements Across Standards

A common mistake is to take a tensile-strength, elongation or hardness value from one standard and use it as the acceptance requirement for another. Mechanical-property requirements are tied to the applicable material standard, specimen preparation, heat treatment and testing procedure.

ASTM A128 requires the castings to be suitably heat treated for toughness and ductility, while general ASTM casting requirements can also involve chemical analysis, mechanical assessment and surface-quality controls. 

For an international order, the safest approach is to put the required mechanical values directly into the purchase specification or clearly reference the exact standard and grade edition.

Casting Quality Matters as Much as Grade Selection

High-manganese steel components are commonly used for severe impact and wear applications such as crusher components, railway components and heavy-duty equipment. In these applications, casting integrity can be as important as nominal chemistry.

ASTM's general casting requirements address issues such as surface discontinuities and inspection of weld repairs, while ASTM A128 also states that weld repairs are to be inspected to the same quality standards used for the castings. 

When comparing suppliers, therefore, the technical checklist should include dimensional inspection, visual inspection, nondestructive testing where required, repair-weld controls and heat-treatment records rather than focusing only on the grade designation.

Manganese Wear Plate

Mangalloy Steel

Manganese Plate

Manganese Steel Overlay Plate

Which Standard Should Be Written on the Purchase Order?

A Practical Cross-Reference Workflow

1. Identify the original grade. Do not start with the supplier's proposed equivalent.
2. Confirm the standard edition. This is particularly important for GB/T 5680 because the 2023 edition replaced the 2010 edition. 
3. Compare chemical limits. Review every specified alloying and residual element.
4. Compare heat treatment. Verify the required thermal condition and documentation.
5. Compare mechanical requirements. Check tensile properties, elongation, hardness or toughness requirements where applicable.
6. Compare casting acceptance. Confirm dimensional tolerance, surface condition, internal soundness and repair requirements.
7. Approve the substitution in writing. A supplier cross-reference should not silently replace the customer's specified standard.

Teda Ganghua Support for High-Manganese Steel Procurement

Teda Ganghua can support procurement teams that need high-manganese steel material identified against different international specifications. For a cross-standard inquiry, the most useful information includes the required ASTM, GB/T or EN reference, exact grade, casting drawing, dimensions, heat-treatment requirement, inspection standard, quantity and service application.

When the project involves high-manganese wear components, high manganese steel sourcing can be coordinated around the customer's original specification rather than relying on a grade name alone. This helps the purchasing team verify chemistry, heat treatment, casting quality and documentation before approving a cross-standard substitution.

FAQ

Is ASTM A128 the same material as GX120Mn12?

They belong to the same broad austenitic manganese cast-steel family, and technical cross-reference sources associate them with conventional Hadfield manganese steel. However, they are different specification systems, so the exact ASTM grade, EN designation, chemistry, heat treatment and acceptance requirements must be checked before treating them as interchangeable. 

Is GB/T 5680-2010 still the current Chinese standard?

No. The Chinese national standards database identifies GB/T 5680-2023 as the current edition and states that it replaced GB/T 5680-2010. The 2023 edition was published and implemented on May 23, 2023. 

What does GX120Mn12 mean?

GX120Mn12 is a European cast-steel designation associated with austenitic manganese cast steel. It is identified with EN 10293 in current foundry references. Older European material references may also show the G-X120Mn12 form and material number 1.3401. 

Can a supplier automatically substitute one manganese-steel standard for another?

No. A supplier can propose a technically comparable grade, but the purchaser should verify chemistry, heat treatment, mechanical properties, casting quality and inspection requirements against the original specification before approving the substitution.

What information should be included in a high-manganese steel inquiry?

Include the standard and edition, exact grade, casting drawing, dimensions, quantity, heat-treatment condition, mechanical requirements, inspection requirements, surface and internal-quality requirements, and any special certification or testing requirements.