X153CrMoV12
1.2379
High-carbon, high-chromium alloy cold-work tool steel · EN ISO 4957:2018 / ISO 4957:2018 — Tool steels
X153CrMoV12 (1.2379) is a deep-hardening, ledeburitic cold-work tool steel containing about 1.5% carbon and 12% chromium, with molybdenum and vanadium. Its high carbide population provides excellent abrasive-wear resistance and high compressive strength, but limits toughness and makes machining and grinding relatively demanding. It is best suited to wear-dominated cold-work tooling where chipping and gross cracking are controlled by tool design, material quality, heat treatment and working hardness.
- 1.45–1.60% C; 11.0–13.0% Cr; 0.70–1.00% Mo; 0.70–1.00% VDefining chemistry · EN ISO 4957 specified ranges by mass.
- ≤255 HBW in condition +AAnnealed hardness · Standard maximum; annealed and cold-drawn material may be permitted up to 275 HBW.
- Minimum 61 HRCReference hardened hardness · Associated with the standard reference hardening and low-temperature tempering schedule, not a universal service-hardness requirement.
- Very high abrasive-wear resistance; moderate-to-low toughnessProperty balance · Chipping resistance is strongly affected by hardness, carbide distribution, section size and loading geometry.
- Air, gas, oil or martemper quench capableHardening behavior · High hardenability permits comparatively mild quenching, but quench intensity must still suit section size and geometry.
- Not a stainless steelCorrosion classification · Much of the chromium is tied up in carbides; the grade should not be specified for stainless-steel corrosion performance.
Overview
- Designation system
- EN symbolic designation and European material number
- Product forms
- Hot-rolled and forged bar, Flat bar and precision-ground flat stock, Plate and tool-steel blocks, Cold-drawn or cold-rolled products, Forgings and rings
- Condition
- Soft annealed (+A), Soft annealed and cold drawn (+A+C), Hardened and tempered for service
- Density
- 7.7 g/cm³ (Representative room-temperature value from producer data; density is not a defining grade requirement.)
Grade definition and designation
ISO 4957 defines X153CrMoV12 as an alloy cold-work tool steel. The standard covers tool-steel products in relevant hot-worked, cold-worked and heat-treatment conditions; it establishes matters such as grade chemistry, delivery condition and reference heat-treatment response. It does not establish one universal working hardness, toughness value or tool-life expectation for every component.
| Designation element | Meaning |
|---|---|
| X | High-alloy steel designation. |
| 153 | Nominal carbon content expressed as approximately 100 × mass percent C; here about 1.53% C. |
| CrMoV | Principal alloying elements chromium, molybdenum and vanadium. |
| 12 | Encoded indication of the principal chromium content, approximately 12%. |
| 1.2379 | European material number identifying this standardized tool-steel grade. |
The former designation X155CrVMo12-1 is widely encountered on legacy drawings and certificates. Material number 1.2379 is particularly useful when old and current symbolic designations coexist.
Standard requirements
| Element | Minimum, mass % | Maximum, mass % |
|---|---|---|
| C | 1.45 | 1.60 |
| Si | 0.10 | 0.60 |
| Mn | 0.20 | 0.60 |
| P | — | 0.030 |
| S | — | 0.030 |
| Cr | 11.0 | 13.0 |
| Mo | 0.70 | 1.00 |
| V | 0.70 | 1.00 |
These are grade limits, not a producer's typical analysis. Individual heats commonly target narrower internal ranges.
| Condition | Hardness requirement | Interpretation |
|---|---|---|
| Soft annealed, +A | ≤255 HBW | Normal machinable delivery condition for bars, blocks and flat stock. |
| Soft annealed and cold drawn, +A+C | ≤275 HBW | Higher limit recognizes work hardening introduced by cold drawing. |
| Reference hardened and tempered condition | ≥61 HRC | Demonstrates hardening response using the standard reference schedule; it is not a mandatory working hardness for every finished tool. |
Conventional tensile properties are not normally the controlling acceptance criteria for this grade. In service, hardness, compressive strength, carbide structure, cleanliness, retained austenite, residual stress and resistance to chipping are more relevant. Values quoted without the product form, heat treatment, orientation and specimen geometry should not be treated as grade guarantees.
Metallurgy and engineering behavior
The high carbon and chromium contents produce a ledeburitic structure containing a substantial volume of primary and secondary alloy carbides. Chromium-rich carbides provide the principal abrasive-wear resistance, while molybdenum and vanadium contribute to hardenability, temper resistance and carbide stability. After hardening, the matrix is predominantly tempered martensite with dispersed carbides and a heat-treatment-dependent amount of retained austenite.
| Characteristic | Engineering significance |
|---|---|
| Abrasive-wear resistance | The grade's principal advantage; appropriate for sliding or cutting contact involving hard work material or abrasive particles. |
| Compressive strength | High at typical working hardnesses, supporting punches, dies, rolls and other heavily loaded tooling. |
| Hardenability | Permits through hardening in substantial commercial sections and the use of air, gas or staged quenching. |
| Dimensional stability | Generally favorable for a high-alloy tool steel, but not distortion-free; retained austenite, residual stress and section geometry remain important. |
| Toughness | Limited compared with lower-carbide cold-work grades. Sharp corners, impact, misalignment and excessive hardness increase chipping or cracking risk. |
| Machinability and grindability | Relatively poor because even annealed material contains abundant hard carbides. Grinding damage can dominate tool performance if heat and wheel loading are not controlled. |
| Corrosion resistance | Better than many low-alloy tool steels in mild exposure, but insufficient for classification or use as a stainless steel. |
In conventionally produced large sections, carbide segregation and directional carbide stringers can materially affect transverse toughness, edge integrity and polishability. Chemical compliance alone does not establish equivalent structural quality between suppliers or manufacturing routes.
Heat treatment and hardness selection
| Operation | Reference parameter | Important qualification |
|---|---|---|
| Soft annealing | 800–850°C | Slow cooling is required to develop a machinable spheroidized structure. |
| Stress relieving | 650–700°C | Applicable to material in a soft delivery condition; useful after extensive rough machining. |
| Austenitizing | 1010–1030°C | Protect against oxidation and decarburization and allow adequate preheating and temperature equalization. |
| Quenching | Air, oil, approximately 500°C hot bath, fluidized bed or gas pressure | Selection depends on section, geometry, furnace capability and acceptable distortion or cracking risk. |
| Tempering | 170–190°C | The standard reference route is associated with a minimum hardness of 61 HRC. Finished-tool requirements may call for a different schedule. |
Reference parameters establish grade response and should not replace a heat treater's component-specific procedure.
A low-temperature temper is commonly selected when maximum hardness and abrasive-wear resistance are the priorities. X153CrMoV12 also exhibits secondary-hardening behavior and can be treated using a high-temperature, multiple-temper route. The latter can be advantageous where subsequent nitriding or PVD coating will expose the tool to elevated temperature. Austenitizing temperature, tempering temperature and number of tempers must be considered together; mixing values from unrelated supplier charts can produce excessive retained austenite, grain coarsening or an unexpected final hardness.
Air or gas hardening reduces quench severity but does not eliminate dimensional change. Rough-machining stresses should be relieved before final machining, heating should be uniform, and quenching must be sufficiently rapid through the transformation range. Higher austenitizing temperatures increase carbide dissolution and may increase retained austenite. Sub-zero treatment can be used where retained-austenite transformation and long-term dimensional stability are critical, but it adds cracking risk and must be integrated immediately into a qualified quench-and-temper sequence.
Working hardness should be selected from the failure mode, not automatically maximized. Reducing hardness can improve resistance to chipping and gross cracking when tools encounter impact, deflection, thick stock or alignment errors.
Machining, grinding and surface processing
| Process | Practical consideration |
|---|---|
| Machining in +A condition | Use rigid setups, suitable carbide tooling and controlled feeds. Interrupted cutting and inadequate rigidity accelerate edge failure because the annealed carbide population remains abrasive. |
| Grinding after hardening | Use an open, correctly dressed wheel and effective coolant. Grinding burn, tensile residual stress and microcracking can negate the grade's nominal wear advantage. |
| EDM | EDM leaves a thermally affected recast layer that may contain microcracks and tensile stress. Remove the damaged layer by finishing operations where fatigue or edge integrity is important. |
| Post-EDM tempering | Producer guidance commonly recommends an additional temper below the preceding tempering temperature after EDM of hardened material; the exact procedure must match the original heat treatment. |
| Nitriding or nitrocarburizing | Possible after hardening and tempering. The nitriding temperature should remain below the prior tempering temperature if loss of core hardness is to be avoided. |
| PVD coating | The secondary-hardening route can provide a suitable substrate for coating. Base hardness, coating temperature, edge preparation and support against coating collapse must be specified together. |
| Polishing | The coarse carbide structure limits the achievable polish compared with cleaner, lower-carbide or powder-metallurgy grades. Carbide pull-out can be a concern. |
Heat-treatment scale or decarburization at a working edge can cause premature deformation or chipping. Protective-atmosphere or vacuum treatment and adequate finish allowance are especially important for precision tooling.
Applications and selection limits
| Application group | Why X153CrMoV12 is used |
|---|---|
| Blanking, punching and fine-blanking tools | High wear resistance and compressive strength for stable cutting edges, provided shock and lateral loading are controlled. |
| Shear and industrial knives | Good edge retention in wear-dominated cutting; working hardness must reflect stock thickness and impact. |
| Cold-forming and coining dies | Resists abrasive and adhesive wear under high contact pressure. |
| Thread-rolling dies and forming rolls | Combines high surface durability with good through-hardening response. |
| Powder-compaction and abrasive-plastic tooling | Carbide population resists erosion and abrasion from hard particles. |
| Gauges, guide components and wear parts | Suitable where dimensional stability and wear resistance dominate over impact toughness. |
X153CrMoV12 is not automatically the best choice whenever high wear is mentioned. A tougher cold-work steel is usually preferable where gross cracking or edge chipping controls life, particularly in thick-stock blanking, severe impact, flexible tools or misalignment-prone equipment. Powder-metallurgy tool steels may provide a better combination of wear resistance, toughness, isotropy and fine-edge stability where conventional 1.2379 carbide segregation is limiting performance.
Specification, purchasing and verification
A purchase description should not stop at “1.2379” or “D2.” The required governing standard, edition, product form, dimensions, tolerances, delivery condition and surface condition should be stated. Soft-annealed condition +A is the usual starting point for machining; +A+C is a distinct condition with a different hardness limit.
| Item | Reason |
|---|---|
| Designation and standard | Use X153CrMoV12 / 1.2379 to EN ISO 4957, with the required edition, rather than relying solely on an informal D2 cross-reference. |
| Product form and dimensions | Available properties, segregation and achievable heat-treatment response can vary with section size and manufacturing history. |
| Delivery condition and hardness | State +A or +A+C and the applicable hardness limit. |
| Manufacturing route | Conventional, remelted and powder-metallurgy products can have materially different cleanliness and carbide distributions even where nominal chemistry is similar. |
| Surface and machining allowance | Allow for removal of decarburization, scale and heat-treatment or EDM-affected layers. |
| Internal quality | For large or highly stressed tools, agree ultrasonic quality, allowable discontinuities and any carbide-distribution or macrostructure criteria. |
| Certification | Specify the required inspection document and traceability; chemical analysis alone is insufficient where structural quality is critical. |
| Finished-tool requirements | Define target hardness, hardness test location, heat-treatment route, sub-zero treatment, coating or nitriding sequence and distortion allowance. |
| Substitution review | Compare chemistry, annealed hardness, product route, section, cleanliness, heat-treatment response and certification—not merely a cross-reference table. |
Sources
- ISO 4957:2018 — Tool steelsInternational Organization for Standardization
- Technical Data Sheet — X153CrMoV12 (1.2379)Stahlwerk Augustfehn Schmiede GmbH & Co. KG
- Uddeholm Sverker 21 Technical BrochureUddeholms AB
- BÖHLER K110 Technical Datavoestalpine BÖHLER Edelstahl GmbH & Co KG
- ASTM A681-24 — Standard Specification for Tool Steels AlloyASTM International
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