1.2379 steel (1.2379): properties, composition, equivalents
1.2379 (X153CrMoV12) is the 12 % Cr / 1.5 % C cold-work tool steel — the European D2. Hardens to 58–62 HRC, high wear resistance, dimensionally stable. Composition, heat treatment, hardness and D2/SKD11/Cr12MoV equivalents.
What is 1.2379?
1.2379 (X153CrMoV12) is the ledeburitic 12 % chromium cold-work steel known everywhere as D2. With 1.5 % carbon and 12 % chromium it solidifies with a network of hard chromium carbides (M₇C₃) that, after hardening to 58–62 HRC, give the best wear resistance of any conventional tool steel below the powder-metallurgy grades. Molybdenum and vanadium refine the carbides and allow air or vacuum hardening with minimal distortion — the reason 1.2379 is the default steel for blanking and punching dies, shear blades and forming rolls.
Its weaknesses are the ones that come with coarse carbides: moderate toughness, difficult grinding, and heavy machining allowances in the annealed state (≤ 255 HB but abrasive). Tempering at 500–530 °C gives secondary hardening and allows PVD coating (TiN, TiCN) without losing hardness; the low-temperature temper (180–220 °C) gives maximum hardness for short-run tools.
AISI D2, JIS SKD11, GB Cr12Mo1V1 and BS BD2 are the same steel; Böhler K110, Uddeholm Sverker 21 and Buderus Cryodur 2379 are proprietary versions. The powder-metallurgy alternatives (1.2380 / Vanadis 4E, K390) are cross-referenced as functional upgrades.
1.2379 chemical composition
| Element | Mass % | Note |
|---|---|---|
| C | 1.45 – 1.6 | |
| Si | 0.1 – 0.6 | |
| Mn | 0.2 – 0.6 | |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Cr | 11 – 13 | |
| Mo | 0.7 – 1 | |
| V | 0.7 – 1 |
EN ISO 4957:2018 Table 4 (X153CrMoV12). The former DIN name X155CrVMo12-1 is the same steel. AISI D2 allows C 1.40–1.60, Mo 0.70–1.20, V ≤ 1.10, Co ≤ 1.00.
1.2379 mechanical properties
| Thickness / condition | Yield strength ReH / Rp0.2 MPa (ksi) | Tensile strength Rm MPa (ksi) | Elongation A % | Hardness |
|---|---|---|---|---|
| +A soft annealed (delivery) | — | ≈ 750–850 (typ.) (≈ 108.8–123.3 (typ.)) | — | ≤ 255 HB |
| Hardened 1020–1040 °C oil/air, as-quenched | — | — | — | 62–64 HRC |
| Tempered 180–220 °C (1×) | — | — | — | 60–62 HRC |
| Tempered 500–530 °C (2×, secondary hardening) | — | — | — | 58–60 HRC |
| Tempered 550 °C (2×) | — | — | — | 55–57 HRC |
| Compressive yield at 60 HRC (typical) | ≈ 2200 (≈ 319.1) | ≈ 2500 (bend strength ≈ 3000) (≈ 362.6 (bend strength ≈ 435.1)) | — | — |
Tool steels are specified by chemistry and annealed hardness only; hardness after heat treatment is the working property. Values are typical for a 25 mm section. Toughness (unnotched impact) ≈ 20–40 J at 60 HRC — moderate; 1.2379 is chosen for wear, not shock.
1.2379 equivalent grades
| Grade | System | Match | Why / differences |
|---|---|---|---|
| D2 | AISI / SAE | Identical | AISI D2 (UNS T30402, ASTM A681): C 1.40–1.60, Cr 11–13, Mo 0.70–1.20, V 0.50–1.10. Same steel; 1.2379 has a slightly tighter V/Mo window. |
| BD2 | BS (superseded British) | Identical | BS 4659 BD2. |
| Cr12Mo1V1 | GB/T (China) | Identical | GB/T 1299 Cr12Mo1V1 (D2 type): C 1.40–1.60, Cr 11–13, Mo 0.70–1.20, V 0.50–1.10. Cr12MoV is the older lower-Mo Chinese grade. |
| SKD11 | JIS (Japan) | Identical | JIS G4404 SKD11: C 1.40–1.60, Cr 11–13, Mo 0.80–1.20, V 0.20–0.50 — vanadium lower; hardenability and wear resistance close. |
| 1.2436 | EN (European) | Near | X210CrW12 (D6): tungsten-bearing 12 % Cr, slightly higher wear resistance, lower toughness. |
| Kh12MF | GOST (Russia/CIS) | Near | GOST 5950 Kh12MF: C 1.45–1.65, Cr 11–12.5, Mo 0.40–0.60, V 0.15–0.30 — lower Mo and V. |
| 1.2363 | EN (European) | Functional | X100CrMoV5 (A2): 5 % Cr air-hardening steel with better toughness, lower wear resistance. |
| 1.2842 | EN (European) | Functional | 90MnCrV8 (O2) oil-hardening steel for less demanding dies. |
Identical = same composition and mechanical limits within rounding. Near = one limit differs (e.g. carbon max or impact temperature). Functional = interchangeable for most uses after an engineering check. Full cross-reference for 1.2379 →
Old and superseded designations
| Old name | Standard | Note |
|---|---|---|
| X155CrVMo12-1 | DIN 17350 (withdrawn) | Same number 1.2379; renamed X153CrMoV12 in EN ISO 4957. |
| X210Cr12 (1.2080) | DIN 17350 | The older 2 % C / 12 % Cr steel (D3) it replaced — harder but more brittle. |
| BD2 | BS 4659 | |
| Z160CDV12 | NF A 35-590 | |
| K110 | Böhler trade name | Sverker 21 (Uddeholm), Cryodur 2379 (Buderus), Thyrodur 2379. |
Product forms and tolerance standards
Product forms: flat bar and round bar (annealed), plate and blocks, ground flat stock (precision), forgings.
Dimensional tolerances: annealed flat/round: EN ISO 4957 Annex / supplier tolerances (typically +1/+3 mm oversize for machining); ground flat stock: DIN 59350 / ISO 4957 precision.
Key property values
1.2379 hardness
Annealed ≤ 255 HB; as-quenched 62–64 HRC; working hardness 58–62 HRC after tempering. Secondary hardening peak 60–61 HRC at ~520 °C (for PVD coating), 55–57 HRC at 550 °C.
Heat treatment
Soft anneal 800–850 °C, slow cool (≤ 10 K/h to 600 °C). Stress relieve 600–650 °C. Harden 1020–1040 °C (preheat 650 and 850 °C), oil, air or vacuum gas quench; hold 20–40 min at temperature. Temper twice for ≥ 2 h: 180–220 °C for maximum hardness, or 500–540 °C for secondary hardening and coating. Deep freeze (−80 °C) after quenching reduces retained austenite. Ms ≈ 200 °C.
Dimensional change
Air/vacuum hardening from 1030 °C with 520 °C temper: typically +0.05 to +0.10 % length change; low-temperature temper: 0 to +0.05 %. Allow grinding stock of 0.15–0.30 mm.
Wear resistance and toughness
Abrasive wear resistance among the highest of conventional cold-work steels (carbide volume ≈ 15 %); adhesive wear moderate. Unnotched impact ≈ 20–40 J at 60 HRC — choose 1.2363 (A2) or 1.2767 for shock loads.
Physical properties
Density 7.70 g/cm³, E = 210 GPa, thermal conductivity ≈ 20 W/m·K, expansion 10.5 × 10⁻⁶/K (20–100 °C), 11.5 × 10⁻⁶/K (20–500 °C).
Weldability
Poor weldability. Repair welding only: preheat 300–450 °C (or weld in the annealed state), TIG with matching or 1.2379-type rods, peen, and re-temper immediately at the previous tempering temperature. Hardened tools should be pre-warmed and post-tempered; cracks are common without these steps.
Machining, forming and heat treatment
Machinability in the annealed state ≈ 30–40 % (abrasive carbides): carbide tooling, moderate speeds, generous allowances. Hard machining after hardening is possible with CBN/ceramic at 58–62 HRC. Grinding requires soft, open wheels and light passes to avoid grinding cracks (dry grinding forbidden). EDM (wire or sink) is the standard route for complex dies; remove the white layer by grinding or by a further temper. Surface treatments: PVD TiN/TiCN/CrN after 520 °C temper, nitriding (500–520 °C) for extra surface hardness.
Typical applications
- Blanking, punching and fine-blanking dies for sheet up to ~6 mm
- Shear blades, slitting knives, rotary cutters
- Cold forming, drawing and bending dies, thread-rolling dies
- Profile rolls and roll-forming tools
- Plastic-moulding tools for abrasive filled polymers (with PVD)
- Wear parts, gauges, measuring tools
- Ceramic and powder-compaction dies
Frequently asked questions
Is 1.2379 the same as D2?
Yes. 1.2379 (X153CrMoV12, EN ISO 4957) and AISI D2 (T30402) share the 1.5 % C / 12 % Cr / 1 % Mo / 1 % V analysis; the EN specification is marginally tighter on Mo and V. JIS SKD11 and GB Cr12Mo1V1 are also identical for tooling purposes.
What hardness does 1.2379 reach?
62–64 HRC as-quenched, 58–62 HRC in service after tempering. Tempering at 500–540 °C gives a secondary-hardening peak of about 60 HRC and is the standard cycle before PVD coating.
Is 1.2379 stainless?
No. Although it contains 12 % chromium, most of it is tied up in carbides, leaving too little in solution for a passive layer. It rusts in humid storage and must be oiled.
1.2379 or 1.2363 (A2) — which should I use?
1.2379 for maximum wear resistance and long runs on thin sheet; 1.2363 when the tool sees impact, thick sheet or interrupted cuts, because its 5 % Cr structure is roughly twice as tough. Both air-harden with low distortion.
Can 1.2379 be nitrided or coated?
Yes. Temper at ≥ 520 °C first, then PVD (TiN, TiCN, CrN at 450–500 °C) or gas/plasma nitride at 500–520 °C. Coating extends punch life several-fold on galvanized or stainless sheet.
Related grades
Verified against EN ISO 4957:2018; EN ISO 4957:2018 Table 4; ASTM A681-08 (D2 comparison). Last checked: September 2026.