Ever wonder why your 1.2344 tool steel sometimes machines like butter while other times it destroys tooling? The difference comes down to delivery condition. It’s not just hardness numbers—it’s how the steel was processed before it reached your shop floor.
Standard annealed, EFS-annealed, or pre-hardened conditions each change your machining experience. Most suppliers deliver annealed stock around ≤229 HB, balancing machinability with heat-treatment flexibility. However, one delivery detail often separates a smooth job from costly problems.
This guide provides a detailed overview of available delivery conditions, machining specifications, quality assurance, and how delivery state impacts tool life and heat treatment.
1. Available Delivery Conditions for 1.2344 Tool Steel
Most 1.2344 tool steel comes in annealed condition. This choice balances ease of machining with readiness for heat treatment. The annealed state has maximum hardness values of ≤229–230 HB (Brinell) or ≤235 HBS depending on your supplier. This equals about 21–22 HRC on the Rockwell scale. This soft state lets you drill, mill, turn, and wire EDM with good tool life. You do this before the final hardening cycle.
1.1 Standard Annealed Delivery (+A)
Standard annealed (+A) is the most common delivery form for 1.2344 tool steel. Steel mills use controlled isothermal annealing to get this condition. They heat the material to (850 ±10)°C and hold it for 2 hours. Then they furnace-cool it to (720 ±10)°C for another 4-hour hold. After that, they cool it below 500°C before exposing it to air. This multi-stage cooling creates uniform microstructure. Hardness values stay at ≤229 HBW (Brinell Hardness Vickers).
Some mills use alternative soft annealing. They work within the 760–810°C temperature range with furnace cooling. This targets maximum hardness of 240 HB. It’s a bit higher than isothermal annealing results. But it still gives excellent machinability for pre-hardening fabrication work.
1.2 EFS-Annealed (Extra Fine Structure)
Beyond standard annealing, many suppliers offer EFS-annealed (extra fine structure) material. It keeps the same hardness ceiling of ≤229 HBW. But you get refined grain structure. Some manufacturers call this ESR (electroslag remelted) fine structure annealed. The material goes through electroslag remelting before annealing. This achieves superior internal cleanliness and homogeneity. For ESR-annealed 1.2344, maximum hardness sits at 230 HB (21 HRC).
The EFS label means more than marketing talk. Extra fine structure means more uniform carbide distribution. It also means reduced segregation. This impacts heat treatment response and final tool performance. Makers of critical hot-work applications—aluminum extrusion dies, high-pressure die-casting molds—often specify EFS-annealed delivery. This cuts the risk of early cracking or uneven wear patterns.
2. Typical Product Forms and Quality Assurances
1.2344 tool steel comes in several shapes: round bars, plates, and sawn blocks. Premium suppliers provide forged bars and blocks. These go through the complete LF (ladle furnace) + VD (vacuum degassing) + ESR (electroslag remelting) + forging chain. This ensures maximum cleanliness and structural integrity.
Quality checks come with these delivery conditions. They use standard testing methods. Ultrasonic testing (UT) follows SEP 1921-84 Class 3 D/d, E/e or SEP 1921 Class E/e standards. This detects internal flaws that could hurt tool life. Purity specs reference ASTM E45 Method A with strict inclusion limits. Sulfide inclusions (Type A) stay at ≤0.5. Oxide, silicate, and spherical oxide types (B, C, D) each stay at ≤1.0. Some suppliers certify to DIN 50602-K1 ≤10 for equal cleanliness.
3. Hardness Progression from Delivery to Application
Understanding delivery hardness helps you pick the right specs. Material arrives in annealed state at about ≤22 HRC. You machine it to near-net shape. Then it goes through hardening cycles to reach application hardness between 30–56 HRC. This depends on your service needs. Hot-work die jobs target 42–52 HRC after tempering. Special extrusion tooling may need different hardness zones in the same part.
The annealed delivery hardness window of 229–235 HB gives you the key starting point. Machinists can cut complex shapes, cooling channels, and surface details. They do this before heat treatment locks the structure into its final hardness range.
4. Key Delivery Specs for 1.2344 Tool Steel Machining
Delivery specs define what you get: the technical state of 1.2344 tool steel as it arrives. This affects how you machine, form, and process it. These specs go beyond hardness numbers. They set the full technical framework. This framework determines cutting forces, tool wear, size stability during processing, and heat treatment results.
4.1 Material Grade and Standard Compliance
- Correct designation: 1.2344 (DIN EN ISO 4957)
- Equivalents: X40CrMoV5-1 (EU), H13 (AISI), SKD61 (JIS)
- Governing standards: ASTM A681, EN 10027
- Chemistry limits: Cr 4.80–5.50%, Mo 1.10–1.50%, V 0.85–1.15%, C 0.35–0.42%
- No grade substitutions allowed without approval
4.2 Mechanical Properties in As-Delivered Condition
Delivery hardness controls your machining setup. Standard annealed 1.2344 arrives at hardness ≤229 HBW (≤21 HRC). This range allows high-speed steel (HSS) tooling for roughing. You can hit cutting speeds of 18–25 m/min with decent tool life.
Put both Brinell (HBW) and Rockwell C (HRC) values on your technical drawing. Add the test method: ISO 6506-1 for Brinell and ISO 6508-1 for Rockwell. Some mills report hardness in Vickers (HV). Ask for conversion tables if you see multiple scales on certificates.
Tensile properties matter for heavy stock removal. Annealed 1.2344 shows tensile strength Rm ≈ 850–950 MPa. Yield strength sits at Re ≈ 650–750 MPa. Elongation: A5 ≥ 12%. These numbers tell you the material won’t crack during heavy milling. They also show springback behavior during bending before you harden the steel.
Impact toughness doesn’t usually show up on mill certificates in annealed state. But it affects deep hole drilling and sharp internal corners. Request Charpy V-notch impact values at room temperature (20°C). Values should beat KV ≥ 40 J for premium material. Lower values mean poor cleanliness or too much segregation.
4.3 Size Tolerances for Machining Setup
| Feature | Standard | Precision / Tight Tolerance | Notes / Benefits |
|---|---|---|---|
| Round Bar Diameter | h11 ±0.13 mm | h9 ±0.043 mm | Tighter tolerance cuts roughing time 30–40% on CNC lathes; costs +15–25% per kg |
| Plate Flatness | ≤2 mm/m | ≤0.5 mm/m | Tight flatness allows secure clamping and faster milling |
| Bar Straightness | — | ≤0.3 mm/m (for L>500 mm) | Reduces stress and distortion during machining |
| Sawn End Squareness | ±0.5 mm/100 mm | ≤0.2 mm/100 mm | Improves first-cut accuracy on multi-axis machining centers; use GD&T ⊥0.2 |
| Edge Condition | Flame-cut: HAZ 1–3 mm, hardness 300+ HB | Stress-relieved or precision-sawn | Protects carbide inserts; max burr height 0.1 mm |
4.4 Surface Condition and Machining Stock
Surface roughness in delivery state affects your first cutting pass. Hot-rolled bars show Ra 12.5–25 µm with thick oxide scale. Peeled bars offer Ra 3.2–6.3 µm with scale removed. Precision-ground stock delivers Ra ≤1.6 µm on diameter. Each step up costs more but saves machining time.
Scale removal method matters for later operations. Shot-blasted surfaces give uniform Ra 6.3 µm. But they may push silica particles into the surface. These cause tool wear jumps during finish milling. Mechanically descaled material avoids this problem. Specify descaling method on purchase orders for critical work.
Coating compatibility affects welding and EDM operations. Temporary rust preventives should be water-soluble or alkaline-cleanable. Oil-based films mess with wire EDM. They cause smoking during high-speed machining. Require VOC-free corrosion protection compatible with aqueous cutting fluids.
Machining stock allowances depend on heat treatment distortion predictions. Add +1.5 to +3.0 mm per side for parts you’ll through-harden. Complex shapes with thin sections need +0.8 to +1.5 mm to avoid breakthrough during final grinding. Call out stock allowances for critical dimensions. Mark them on technical drawings with “STOCK: +2.0 mm to final” notes.
5. Heat Treatment Condition Documentation
5.1 Heat Treatment Documentation
Heat treatment certificates prove proper annealing. Mills should provide furnace charts. These show time-temperature curves. Check that the annealing cycle matches standard practice: heating to 850°C, holding 2 hours, cooling to 720°C, holding 4 hours, furnace cooling to below 500°C. Deviations mean rushed processing or poor equipment.
Microstructure check confirms annealing quality. Request metallographic examination at 500× magnification for critical jobs. Look for spheroidized carbides in a ferrite matrix. Avoid material with retained austenite or bainitic structures. These show incomplete annealing. They cause uneven machining. They create unpredictable hardening response.
Grain size affects surface finish ability. Specify ASTM grain size 5–7 for most hot-work tooling. Finer grain sizes (ASTM 7–8) work better for applications needing polished surfaces. Coarser grain (ASTM 4–5) gives better thermal shock resistance. But you get rougher as-machined finishes.
5.2 Cleanliness and Internal Soundness
| Feature | Requirement | Benefit |
|---|---|---|
| Macro-Etch | Blocks >500 kg; sample core | Detect segregation, banding, porosity |
| Ultrasonic Testing | Class 3 D/d ≥1.5 mm | Catch internal defects pre-machining |
| UT – Premium | Class E/e ≥0.8 mm | Prevent scrapped parts; +8–12% cost |
| Inclusions (ASTM E45 A) | A ≤0.5, B/C/D ≤1.0 | Predict tool life & fatigue |
| DIN 50602 K | K1 ≤10 | Equivalent European standard |
| Observations | Uniform carbide, no porosity/banding | Avoid drilling/EDM cracks |
Conclusion:
Delivery condition is the foundation of every cut you make. Choosing standard annealed provides flexibility, EFS-annealed supports critical tooling, and pre-hardened stock reduces lead time. Specifying your 1.2344 tool steel correctly ensures predictable machining, consistent heat-treatment performance, and long-lasting dies and molds.
The right delivery condition doesn’t just make machining easier—it makes the impossible possible.