Hot extrusion dies, mandrels, containers, dummy blocks and liners operate under harsh working conditions combining continuous high temperature, heavy compressive load and severe surface friction. The choice of hot work tool steel largely depends on the workpiece material and billet temperature. Incorrect grade selection can lead to premature thermal cracking, surface wear, plastic deformation and unexpected production downtime.
1. Master Grade Selection Table for Hot Extrusion
The table below provides practical grade recommendations for common extrusion applications, covering aluminum, brass, copper, steel, titanium and superalloy production. Corresponding international standards are listed for easier cross-border procurement.
| Extrusion Application | Recommended Tool Steel | Selection Reason |
|---|---|---|
| Aluminum extrusion dies (billet: 400–500°C) | H13 (1.2344 / SKD61) | Balanced hot strength, wear resistance and thermal fatigue resistance. ESR refined material is preferred for long production runs. |
| High-wear inserts for aluminum extrusion | H19 | Cobalt and vanadium alloying delivers extended service life under abrasive conditions. |
| Aluminum extrusion, high cracking risk | H11 (1.2343) | Higher toughness to resist thermal shock and crack propagation. |
| Brass extrusion dies | H21 (1.2581 / SKD5) | Stable red hardness matched with typical brass extrusion operating temperatures. |
| High-wear brass extrusion inserts | H19 | Improved wear performance compared to standard H21. |
| High-temperature copper extrusion | H21 / H22 | Sufficient hot hardness to withstand higher billet temperatures than brass processing. |
| Steel extrusion (billet: 900–1200°C) | H21 / H22 or 3Cr2W8V | High hot strength to avoid die deformation under extreme heat and pressure. |
| Nickel & superalloy extrusion | H21 / H22 / H26 | Superior red hardness suitable for high-temperature difficult-to-form alloys. |
| Magnesium extrusion | H13 | Industry standard for moderate working temperatures of magnesium alloys. |
| Titanium extrusion (specialized forming) | H21 / H22 | Reliable performance under high-temperature alloy extrusion conditions. |
| Dummy blocks for all extrusion lines | H13 | Good combination of toughness and thermal fatigue resistance. |
| Mandrels / piercing plugs | H13 | Widely accepted standard grade for extrusion mandrel components. |
| Container liners | H13 or H11 | Balanced toughness and heat resistance for continuous cyclic operation. |
2. Detailed Application & Grade Notes
Aluminum Extrusion (Most Widely Used Application)
H13 acts as the default material for aluminum extrusion dies across the industry. Tools are generally heat-treated to 46–50 HRC.
ESR refined H13 is strongly recommended for the following scenarios: dies larger than 200 mm, presses above 2000 tons, hollow porthole dies, and profiles requiring high surface quality for automotive or architectural usage.
H11 is selected when thermal shock and cracking represent the main failure risk. H19 is reserved for wear-critical insert parts contacting abrasive aluminum alloys. Nitriding treatment for H13 extrusion dies is common practice, raising surface hardness above 60 HRC to extend die service life.
Brass & Copper Extrusion
H21 remains the standard grade for brass extrusion dies. H19 offers better wear performance for insert components. H22, H24 and H26 grades are specified for copper and nickel alloy extrusion at elevated temperatures.
3Cr2W8V, the Chinese equivalent grade of H21, is widely sourced by mold manufacturers across Asian markets.
Steel Extrusion (Most Demanding Working Conditions)
Billet temperatures range from 900°C to 1200°C during steel extrusion. Standard chromium hot work steels such as H11 and H13 cannot sustain such thermal loads. Tungsten-alloyed grades including H21, H22, H24 and H26 are required.
3Cr2W8V has long been adopted for steel extrusion in China. H26 is specified for the most extreme forming environments. For water-cooled container liners, H11 can be considered thanks to its outstanding toughness.
3. Core Performance Requirements for Extrusion Dies
When comparing hot work tool steel grades, evaluate the material properties listed below according to your dominant failure mode.
| Material Property | Importance Level | Practical Explanation |
|---|---|---|
| Hot strength | Critical | Prevents permanent plastic deformation under extrusion pressure at operating temperature |
| Wear resistance | Critical | Resists abrasion caused by continuous friction between billet and die bearing surfaces |
| Thermal fatigue resistance | High | Reduces surface cracking from repeated heating and cooling cycles |
| Toughness | High | Protects tooling against sudden pressure spikes and material defects |
| Annealed machinability | Medium | Affects processing efficiency for complex die cavity geometries |
| Polishability | Medium-High | Determines surface finish quality of extruded profiles |
4. Simplified Grade Selection Decision Tree
Follow this logic to narrow down suitable hot work steel starting from your extrusion workpiece material:
- Extruding Aluminum (400–500°C)
- Standard production → H13 (choose ESR grade for long runs)
- Toughness & anti-cracking priority → H11
- High-wear inserts → H19
- Extruding Brass (600–700°C)
- Standard dies → H21
- High-wear inserts → H19
- Extruding Copper (700–900°C)
- Recommended: H21 / H22
- Extruding Steel (900–1200°C)
- General service: H21 / H22 / 3Cr2W8V
- Extreme high-temperature conditions: H26
- Extruding Nickel-based superalloys (≥1000°C)
- Recommended: H21 / H22 / H26
5. Frequently Asked Questions
Generally not. H13 loses hardness rapidly above 600°C. Steel extrusion billets reach 900–1200°C, requiring tungsten hot work steels like H21, H22 or 3Cr2W8V.
ESR refining reduces internal impurities and segregation. It delivers better toughness and longer service life for large, high-load aluminum extrusion dies.
3Cr2W8V is the Chinese equivalent of H21, but slight variations in production standards exist. Testing is recommended when switching between imported H21 and domestic 3Cr2W8V.
Nitriding is widely adopted for aluminum extrusion H13 dies to improve surface wear resistance. The process needs strict control to avoid brittle nitride layers that accelerate thermal crack growth.
Request Technical Support
If you need customized grade recommendations, material datasheets or quotations for hot extrusion tool steel, contact our team. We select suitable grades according to your workpiece material, press tonnage and target production volume.