Is D2 the Same as 1.2379?
Yes. D2 and 1.2379 are widely considered equivalent grades of the same high-carbon, high-chromium cold-work tool steel.
D2 is the designation used in the North American ASTM/AISI standard system, while 1.2379 is the European DIN/EN material number. Although small differences may exist in allowable chemical tolerance ranges or testing requirements between these standards, the tooling industry generally treats them as interchangeable for most applications.
If you are evaluating this material for industrial tooling or large-volume supply, see the full specification on the D2 Tool Steel product page, which provides detailed information about available sizes, delivery conditions, and typical applications.
Understanding Tool Steel Standards
Different grade names exist because international standards organizations developed independent classification systems.
North America (ASTM/AISI)
Tool steels are designated using a letter-and-number system. The letter “D” identifies high-carbon, high-chromium cold-work tool steels, and D2 is a specific grade within that category. In the Unified Numbering System (UNS), this grade is identified as T30402.
Europe (DIN/EN)
European standards use a numeric Werkstoff (material number) format. Tool steels are assigned numbers in the 1.XXXX series. The material number 1.2379 corresponds to the same cold-work tool steel grade commonly known as D2.
The EN naming system may also use the descriptive designation X155CrVMo12-1 (or X160CrMoV12), which reflects the approximate alloy composition.
Chemical Composition
D2 and 1.2379 are regarded as equivalent primarily because their chemical compositions fall within nearly identical ranges. Both grades contain high levels of carbon and chromium, which promote the formation of hard alloy carbides and provide exceptional wear resistance.
Typical composition ranges include:
| Element | Composition (wt. %) |
| Carbon (C) | 1.50 – 1.55 |
| Chromium (Cr) | 11.50 – 12.00 |
| Molybdenum (Mo) | 0.70 – 0.90 |
| Vanadium (V) | 0.90 – 1.00 |
| Silicon (Si) | ~0.30 |
| Manganese (Mn) | 0.30 – 0.35 |
The balance consists primarily of iron (Fe), with trace elements such as phosphorus (P) and sulfur (S) present at very low levels.
Mechanical Properties and Applications
Because both grades contain approximately 12% chromium and 1.5% carbon, their microstructure forms a large volume of chromium-rich carbides (M₇C₃ type). This carbide structure produces very similar mechanical behavior across both standards. Typical characteristics include:
- Extremely high wear and abrasion resistance
- Deep hardening capability through air quenching
- Good dimensional stability during heat treatment
- High working hardness, typically around 60–62 HRC
These properties make the steel suitable for long-running cold-work tooling applications. Common industrial uses include:
- Blanking and cold-forming dies
- Deep-drawing and lamination dies
- Thread-rolling dies
- Shear blades and slitter knives
- Forming rolls and piercing punches
Procurement Considerations
When specifying D2 or 1.2379 in international procurement, buyers should verify the exact specification being supplied. Although the two grades are functionally equivalent, differences may occur in:
- allowable trace element limits
- testing standards between ASTM and DIN/EN specifications
- mill-specific chemistry tolerances
- documentation and certification requirements
For critical tooling applications, purchasers should confirm the mill heat analysis and certification data rather than assuming that all equivalent grades are identical.
Conclusion
D2 and 1.2379 represent the same high-wear, air-hardening cold-work tool steel, defined within different international standard systems. In practical engineering and tooling applications, the grades are widely treated as equivalents and can generally be substituted for one another.
As with any tool steel procurement, confirming the supplier’s chemical analysis and certification ensures that the delivered material meets the required specification.
FAQ
Yes, D2 and 1.2379 are widely considered equivalent grades of the same high-carbon, high-chromium cold-work tool steel. They are generally treated as interchangeable in the tooling industry.
D2 is the designation used in the North American ASTM/AISI system. In contrast, 1.2379 is the European DIN/EN material number for the same steel grade.
Both grades contain nearly identical ranges of carbon (1.50–1.55%) and chromium (11.50–12.00%). They also include molybdenum, vanadium, silicon, and manganese to promote wear resistance.
Yes, these grades are widely treated as equivalents in practical engineering and can generally be substituted for one another. However, buyers should verify specific mill certifications for critical applications.
These steels offer extremely high wear resistance, deep hardening through air quenching, and good dimensional stability. They typically reach a high working hardness of 60–62 HRC.
In the Unified Numbering System (UNS), the D2 tool steel grade is identified as T30402. This corresponds to the same material classified as 1.2379 in Europe.
Different names exist because international standards organizations, such as ASTM in North America and DIN in Europe, developed independent classification systems for materials.
These grades are used for long-running cold-work tools, including blanking and cold-forming dies, thread-rolling dies, and shear blades. They are also used for piercing punches and forming rolls.