H13 vs 8407 – Composition, Heat Treatment, Properties, and Applications
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Table Of Content
Table Of Content
Introduction
Engineers, procurement managers, and manufacturing planners commonly face the choice between two close-but-distinct hot-work tool steels: the globally recognized AISI H13 and a regionally specified grade commonly quoted as 8407 in Scandinavian/European supplier lists. The decision typically hinges on tradeoffs between availability and cost, reproducibility and material cleanliness, and subtle differences in hardenability, toughness, and heat-treatment practice.
Broadly speaking, both grades serve hot-work tooling roles (dies, cores, punches) and are alloyed for hardenability and temper resistance; the practical selection often comes down to whether a supplier/mill standard (regional grade control and traceability) or an internationally standardized specification is preferred. Because design performance depends strongly on heat treatment and cleanliness, engineers should always confirm certificate chemistry and heat-treatment practice from the supplier.
1. Standards and Designations
- AISI/ASTM: H13 (hot-work tool steel) — widely referenced in American and international procurement.
- EN/DIN: A typical European equivalent to H13 is X40CrMoV5-1 / X38CrMoV5-1 variants (nomenclature varies by standard).
- National/regional: 8407 — a designation found in some Scandinavian/European mill catalogs and cross-reference tables; often produced to Swedish mill specifications with traceability and process control specific to that mill.
- Classification: Both are high-alloy tool steels (hot-work tool steels), not stainless, not HSLA. They are alloy tool steels designed for elevated-temperature strength and thermal-fatigue resistance.
2. Chemical Composition and Alloying Strategy
The following table gives typical composition ranges for AISI H13 and a representative 8407 composition commonly cited as a European/Scandinavian variant. Because national/regional designations and mill chemistries can vary, treat the 8407 ranges as indicative; always confirm the exact composition on the mill certificate.
| Element | H13 (typical AISI ranges, wt%) | 8407 (representative, typical ranges, wt%) |
|---|---|---|
| C | 0.32 – 0.45 | 0.36 – 0.44 |
| Mn | 0.20 – 0.50 | 0.30 – 0.60 |
| Si | 0.80 – 1.20 | 0.80 – 1.20 |
| P | ≤ 0.03 | ≤ 0.025 |
| S | ≤ 0.03 | ≤ 0.025 |
| Cr | 4.75 – 5.50 | 4.5 – 5.3 |
| Ni | ≤ 0.30 | ≤ 0.30 |
| Mo | 1.10 – 1.75 | 0.9 – 1.3 |
| V | 0.80 – 1.20 | 0.8 – 1.2 |
| Nb | — (trace) | — (trace) |
| Ti | — (trace) | — (trace) |
| B | — | — |
| N | — | — |
How alloying affects properties: - Carbon: primary hardenability and attainable hardness; higher C increases strength and wear resistance but reduces weldability and ductility. - Chromium and molybdenum: raise hardenability, high-temperature strength, and temper resistance. - Vanadium: refines carbides and grain size, improving wear resistance and toughness. - Silicon and manganese: deoxidation and strength; Mn contributes to hardenability but excessive Mn can promote segregation. - Trace element control and low P/S improve toughness and cleanliness—an area where mill-specific grades (like certain 8407 material offerings) may emphasize tighter limits.
3. Microstructure and Heat Treatment Response
Typical microstructures: - As-quenched and tempered H13 and 8407 are tempered martensite matrices containing dispersed alloy carbides (Cr, Mo, V carbides). The microstructure will include prior-austenite grain boundaries, martensitic laths, and alloy carbides depending on heat treatment.
Heat-treatment response and routes: - Anneal/normalize: Soft anneal for machining to a specified hardness level (commonly ~200–260 HB) and to homogenize structure. Normalizing refines prior-austenite grains. - Hardening (quench): Austenitize in the 1000–1050 °C range (typical AISI H13 practice depends on section size and supplier recommendations) followed by air, oil, or controlled quench to room temperature. Because these are alloy steels with moderate hardenability, quench medium and section size strongly affect hardness uniformity. - Tempering: Multiple tempering cycles in the 500–600 °C range to achieve a balance of hardness and temper resistance; tempering at higher temperatures raises softening resistance for hot-work applications. - Thermo-mechanical processing: For 8407 produced by some European mills, tighter control over forging and rolling schedules and post-forging normalization can produce improved homogenization, cleanliness, and toughness.
Differences in response: - Both grades respond similarly to standardized quench-and-temper cycles. Milling-specific practices (controlled atmosphere, vacuum degassing, forging schedules) applied to 8407 in some mills can yield more consistent through-hardening and slightly improved toughness for a given hardness.
4. Mechanical Properties
Mechanical properties depend heavily on heat treatment, section size, and tempering. The table below presents typical property ranges after hardening and tempering for tooling service conditions. Use these as indicative ranges only; verify with supplier data.
| Property | H13 (typical, post heat-treatment) | 8407 (representative, post heat-treatment) |
|---|---|---|
| Tensile Strength (MPa) | ~900 – 1600 | ~900 – 1600 |
| Yield Strength (MPa) | ~700 – 1400 | ~700 – 1400 |
| Elongation (%) | ~8 – 15 | ~8 – 15 |
| Impact Toughness (Charpy, J) | ~10 – 40 (depends on hardness) | ~12 – 45 (may be higher for cleaner steel) |
| Hardness (HRC) | ~40 – 56 (typical tooling range 45–52) | ~40 – 56 (typical tooling range 45–52) |
Interpretation: - Strength and hardness ranges overlap for H13 and 8407 because chemistry is similar. Practical differences come from mill processing and impurity control: a cleaner 8407 batch may show marginally higher toughness at the same hardness. - For applications prioritizing maximum hardness and wear resistance, both grades can be heat-treated to comparable HRC; for peak toughness at given hardness, a high-quality 8407 variant may offer advantages.
5. Weldability
Weldability is governed by carbon equivalent and alloy content (hardening elements). Use standard indices to estimate weldability qualitatively:
$$CE_{IIW} = C + \frac{Mn}{6} + \frac{Cr+Mo+V}{5} + \frac{Ni+Cu}{15}$$
$$P_{cm} = C + \frac{Si}{30} + \frac{Mn+Cu}{20} + \frac{Cr+Mo+V}{10} + \frac{Ni}{40} + \frac{Nb}{50} + \frac{Ti}{30} + \frac{B}{1000}$$
Qualitative interpretation: - Both grades have moderate carbon and significant alloying (Cr, Mo, V). These raise $CE_{IIW}$ and $P_{cm}$ relative to low-alloy steels, indicating a propensity for cold cracking and martensitic hardening in the heat-affected zone. - Practical recommendations: preheat before welding, use matching or lower-hardness filler metals, control interpass temperature, and perform post-weld tempering or stress relief. For critical tooling, welding repairs should be planned with defined weld procedure specifications (WPS) and qualified procedures. - Between the two, weldability differences are minor and dominated by exact carbon content and section thickness; if 8407 batches are produced with slightly higher Mn or C, weld requirements may be stricter.
6. Corrosion and Surface Protection
- Neither H13 nor 8407 is stainless; corrosion resistance in humid or corrosive environments is limited. Typical protective strategies:
- Paints, varnishes, or solvent-based coatings for atmospheric protection.
- Galvanizing is not typical for tooling parts (coat may interfere with dimensions and thermal contact).
- Localized surface treatments such as PVD/CVD coatings (TiN, CrN) for wear and abrasion; thermal barrier coatings for high-temperature applications.
- Shot peening and surface polishing to mitigate fatigue initiation.
- PREN is not applicable because these are non-stainless tool steels: $$\text{PREN} = \text{Cr} + 3.3 \times \text{Mo} + 16 \times \text{N}$$ This index only applies to stainless alloys; H13/8407 are not evaluated by PREN.
7. Fabrication, Machinability, and Formability
- Machinability: In the annealed (soft) condition both grades machine well; typical practice is to anneal to ~180–260 HB for machining. Carbide content and alloying can reduce machinability in the hardened condition—use carbide tooling, rigid setups, and appropriate cutting parameters.
- Hard machining vs. conventional: Hard milling/grinding after heat treatment is common for final sizing — diamond grinding or CBN tooling is used for high hardness.
- Formability: These steels are not intended for extensive cold forming in hardened condition. Forging and hot-working are standard in mill processing; bending or forming should be done in the soft-annealed state.
- Surface finishing: Polishing and EDM are common; EDM affects the heat-affected surface and normally requires rehardening or finishing to remove recast layer if service-critical.
8. Typical Applications
| H13 (Typical Uses) | 8407 (Typical Uses) |
|---|---|
| Hot-work die casting dies, ejector pins, inserts | Hot forging dies, die casting cores, extrusion tooling |
| Hot forging and die dies for high-temperature stamping | Tools requiring high traceability and low impurity content (e.g., aerospace tooling) |
| Extrusion and hot shear blades | High-performance hot-work applications where mill control is specified |
| Plastic mold cores that require thermal fatigue resistance | Similar hot-work applications where European/Scandinavian mill standards are specified |
Selection rationale: - Choose either grade for hot-work applications where heat and thermal cycling resistance is required. Select 8407 when mill-specific traceability, tighter impurity control, or specific European mill processing is required. Choose H13 when specification calls for the AISI/ASTM designation or when broad supplier availability is important.
9. Cost and Availability
- Cost: H13 is broadly produced worldwide and can be more cost-competitive because of volume production. 8407, if produced by specialty mills with tighter process controls, can carry a premium.
- Availability: H13 is widely available in multiple product forms (bars, plates, forgings, tool blanks) from many global suppliers. 8407 availability may be regional or tied to specific mills — lead times can be longer outside supplier regions.
- Product forms: Both are available as forged blocks, bars, and pre-hardened blanks. For large, critical dies, specify mill certificates, non-destructive testing, and agreed delivery/inspection terms.
10. Summary and Recommendation
| Metric | H13 | 8407 |
|---|---|---|
| Weldability | Moderate — requires preheat/post-weld temper | Moderate — similar, depends on exact chemistry |
| Strength–Toughness balance | High strength and temper resistance; established heat-treat curves | Comparable strength; potential for slightly higher toughness if produced with tighter cleanliness |
| Cost & Availability | Widely available, generally more cost-effective | Potential premium for mill-controlled quality; may have regional lead times |
Recommendation: - Choose H13 if you need a widely recognized, readily available hot-work tool steel with established specifications, extensive supplier options, and competitive pricing. It is the standard choice for general-purpose hot-work dies, die-casting cores, extrusion tooling, and repair stock. - Choose 8407 if your project requires a mill-specified European/Scandinavian grade emphasizing material cleanliness, traceability, and consistent thermo-mechanical processing, or when procurement specifications call for that designation. 8407 can be advantageous for high-reliability applications where marginal gains in toughness and consistency justify potential cost or lead-time differences.
Final note: Because performance in service depends critically on exact chemistry, section size, and heat-treatment schedule, always request the mill certificate, recommended hardening/tempering cycles, and, for critical tooling, supplier NDT/cleanliness documentation prior to selection and procurement.