Comparing two widely used tool steels for cold heading punches — and when each may be considered
In One Sentence
1.2379 (D2) and 1.3343 (M2) are both frequently considered for cold heading punches, but they excel under different conditions — 1.2379 offers high wear resistance, compressive strength and good dimensional stability at generally lower material cost, while 1.3343 provides higher working hardness and superior hot‑hardness performance for demanding operating conditions. The right choice depends on the specific failure mode, production speed, workpiece material, and validated production history — not simply on one material being “better” than the other.
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1. Why Compare These Two Materials?
When specifying cold heading punches, two frequently considered materials are 1.2379 (D2 / SKD11) and 1.3343 (M2 / SKH51) . Both are widely available, both are proven in cold forming, and both can be heat‑treated to high hardness.
But they are not interchangeable. Their alloy compositions give them different strengths:
1.2379 — high‑carbon, high‑chromium cold work tool steel with high wear resistance, high compressive strength, and good dimensional stability during heat treatment
1.3343 — tungsten‑molybdenum high‑speed steel with superior red hardness and higher achievable hardness
Choosing the wrong one can lead to premature wear, chipping, or unnecessary cost. This guide breaks down the differences and helps you evaluate which material is a suitable candidate for your application.
For a broader overview of tool steel selection for cold forming, see our Tool Steel Selection for Cold Forming Tooling: A Practical Guide.
2. Material Overview
2.1 1.2379 (D2 / SKD11)
Typical working hardness: HRC 58–62
1.2379 is a high‑carbon, high‑chromium cold work tool steel. Its high chromium content (around 12%) provides excellent wear resistance and good dimensional stability during heat treatment. It hardens through air cooling, which helps reduce quench distortion compared with more severe quenching methods.
Key strengths:
High wear resistance
High compressive strength
Good dimensional stability during heat treatment
Generally lower material cost than high‑speed steels
Limitations:
Compared with high‑speed steels such as 1.3343, 1.2379 has more limited hot‑hardness capability where significant frictional heating occurs
Not always the best choice for high‑speed operations where friction heat is a dominant factor
For a detailed guide on 1.2379 properties and machining, see our D2 / 1.2379 Tool Steel CNC Machining Guide.
2.2 1.3343 (M2 / SKH51)
Typical working hardness: HRC 62–65
1.3343 is a tungsten‑molybdenum high‑speed steel. Its alloy composition includes tungsten and molybdenum, which provide excellent red hardness — the ability to maintain hardness at elevated temperatures. This makes it suitable for demanding operations where friction heat builds up.
Key strengths:
Superior wear resistance
Excellent red hardness
Higher achievable hardness than 1.2379
Good compressive strength
Limitations:
Higher cost than 1.2379
Generally lower toughness than hot‑work grades
More sensitive to heat treatment
For a broader comparison including 1.3343 and other tool steels, see our Cold Heading Punches & Punch Pins: Material Selection & Precision Machining Guide.
3. Key Differences at a Glance
| Property | 1.2379 (D2) | 1.3343 (M2) |
|---|---|---|
| Typical Hardness | HRC 58–62 | HRC 62–65 |
| Wear Resistance | High | Very High |
| Red Hardness | Moderate | Excellent |
| Toughness | Moderate | Moderate |
| Compressive Strength | High | High |
| Heat Treatment Distortion | Generally good dimensional stability with controlled heat treatment | Process‑ and geometry‑dependent |
| Relative Cost | Lower | Higher |
| Typical Application Focus | Medium‑speed, wear‑critical punches | High‑speed, high‑heat punches |
Note: Both materials can be suitable for a range of applications. The table above provides general guidance; it does not replace application‑specific evaluation.
4. When to Consider 1.2379
1.2379 may be considered when:
Significant hot‑hardness capability is not required
High wear resistance and dimensional stability are important
The workpiece material and forming conditions are moderate in terms of abrasiveness and heat generation
Validated production experience shows adequate resistance to chipping and fracture
Cost sensitivity is a factor
1.2379 is a workhorse material for general‑purpose cold heading punches. Many standard applications perform well with 1.2379 at HRC 58–62.
If your punch is failing by wear, see our Cold Heading Punches: 5 Common Failure Modes for detailed diagnosis and corrective actions.
5. When to Consider 1.3343
1.3343 can be a strong candidate when:
The workpiece and forming conditions produce severe wear or frictional heating that has been confirmed to limit 1.2379 performance
Maximum wear resistance is needed
Higher working hardness is beneficial for edge stability
The cost premium is justified by validated improvements in tool life
1.3343 is often considered for high‑speed cold headers where wear and frictional heating are confirmed limiting factors.
For a comparison of 1.3343 with other tool steels for cold forming, see our Tool Steel Selection for Cold Forming Tooling: A Practical Guide.
6. Other Candidate Materials
1.2379 and 1.3343 are not the only options. Depending on the application, other materials may be worth considering:
1.2344 (H13) — when toughness is the priority, especially for high‑impact or shock‑loading conditions. See our Cold Heading Dies & Inserts: Material Selection & Precision Machining Guide for more on H13 in cold forming.
1.3255 (T4) — a high‑hardness, cobalt/tungsten high‑speed steel candidate where hot hardness and wear resistance are important and its toughness is suitable for the specific load condition.
1.2601 (X165CrMoV12) — a cold work tool steel with high compressive strength and deep hardening. See our 1.2601 / X165CrMoV12 Tool Steel CNC Machining Guide.
Tungsten carbide — for extreme wear resistance in high‑volume production, but with careful attention to impact sensitivity.
For a full comparison of tool steels for cold forming, including 1.2379, 1.3343, 1.2344, and others, see our Tool Steel Selection for Cold Forming Tooling: A Practical Guide.
7. Failure Mode–Material Evaluation Guide
The right material depends on why the punch is failing. Use the following guide to evaluate candidate materials based on the dominant failure mode.
| Failure Mode | Verification Focus | Material / Treatment Considerations* |
|---|---|---|
| Wear | Identify abrasive, adhesive, thermal, or deformation mechanism | 1.2379, 1.3343, or 1.3255 may be evaluated according to mechanism and conditions |
| Chipping | Verify edge geometry, heat treatment, alignment, impact load | Consider tougher grades such as 1.2344 or 1.2343 only if insufficient toughness is confirmed |
| Fracture | Inspect fracture surface, stress concentrators, alignment | Evaluate toughness and heat‑treatment condition; 1.2344 or 1.2343 may be considered where insufficient toughness is confirmed |
| Fatigue | Review geometry, surface finish, residual stress, cycle history | Evaluate toughness, geometry and heat treatment before changing grade |
| Galling | Review lubrication, surface condition, material compatibility | Evaluate lubrication, surface finish, and validated anti‑galling coating/material combinations |
Candidate materials are starting points for evaluation, not definitive recommendations. Final selection must be validated against the specific application conditions and production history.
For a detailed guide on punch failure modes and prevention, see our Cold Heading Punches: 5 Common Failure Modes and How to Prevent Them.
8. Common Starting Points — Not Material Specifications
The table below is a screening reference for common requirements. It is not a material specification. Final selection must consider actual geometry, dominant failure mode, workpiece, heat treatment, machine conditions, and validated production history.
| If your priority is… | Candidate to Evaluate |
|---|---|
| Lower cost with good wear resistance | 1.2379 (D2) |
| Maximum wear resistance and red hardness | 1.3343 (M2) |
| High toughness for impact resistance | 1.2344 (H13) |
| High hardness for wear‑critical conditions | 1.3255 (T4) |
Both 1.2379 and 1.3343 are proven materials for cold heading punches. The right choice depends on your specific operating conditions — production speed, workpiece material, failure mode, and cost sensitivity.
Need help selecting the right tool steel for your cold heading punches?
We machine cold heading punches from 1.2379, 1.3343, 1.3255, and 1.2344. For selected precision features and suitable geometries, our production records include tolerances down to ±0.0015 mm.
Contact us and send us your drawing or failure sample, and we’ll help identify the right material and treatment for your application.
Continue reading:
Transfer Fingers for Cold Forming & Stamping: Material, Precision & Surface Treatment Guide
Cold Heading Punches & Punch Pins: Material Selection & Precision Machining Guide
Cut-off Knives for Cold Heading: Material Selection & Performance Guide
Cold Heading Dies & Inserts: Material Selection & Precision Machining Guide
Tool Steel Selection for Cold Forming Tooling: A Practical Guide
Cold Heading Punches: 5 Common Failure Modes and How to Prevent Them
Cold Heading Dies & Inserts: Common Failure Modes and How to Prevent Them
Cut-off Knives for Cold Heading: Common Failure Modes and How to Prevent Them
References
EN ISO 4957:2018 — Tool steels (reference for tool steel grade properties)
ASTM A600 — Standard Specification for High-Speed Tool Steels (reference for M2 grades)
ASTM E18 — Standard Test Method for Rockwell Hardness of Metallic Materials
Industry practice references for cold heading punch material selection and failure analysis
Editorial Note
This document is educational content only. All material comparisons, recommendations, and capability statements are for general reference and require technical validation against actual application conditions before formal production release.