What is the thickness and hardness range of ASIATOOLS H11 steel plate?
If you are sourcing tool steel for hot work applications like die casting, forging, or extrusion, you need to know exactly what you are getting. ASIATOOLS H11 steel plate typically comes in a thickness range from 6 mm (0.236 inches) up to 300 mm (11.81 inches), and the standard delivered hardness sits between 180 HB and 229 HB (Brinell Hardness), which corresponds to roughly 13 to 21 HRC (Rockwell C). But that is just the starting point. The real story is how this steel performs after heat treatment, and what makes it a reliable workhorse for demanding thermal cycling environments. Let me break down the specifics with hard numbers and real-world context, so you can decide if this material fits your tooling needs.
First, the thickness range is not just a random number. H11 is a chromium-molybdenum-vanadium alloyed hot work steel, and its mechanical properties shift noticeably as the cross-section changes. For thin plates under 20 mm, you get faster quench response during hardening, which means you can achieve a more uniform martensitic structure. For thicker plates above 150 mm, the core hardness can drop slightly due to slower cooling rates, but ASIATOOLS controls this by specifying a maximum hardness variation of ±5 HB across the plate surface for thicknesses up to 100 mm. That is a tighter tolerance than many generic suppliers offer. The plate is typically supplied in the annealed condition, which makes it machinable. If you need it pre-hardened, they can deliver at 30–35 HRC, but that is a custom order and not the standard stock.
Now, let's talk hardness in detail. The 180–229 HB range is the as-delivered annealed hardness. This is soft enough to mill, turn, or drill with standard carbide tooling, but tough enough to resist deformation during handling. Once you heat treat it, the numbers jump significantly. The typical hardening temperature for H11 is 1000–1040°C (1832–1904°F), followed by oil or air quenching, and then double tempering at 540–600°C (1004–1112°F). After this cycle, you can expect a working hardness of 46–54 HRC, depending on the tempering temperature. For example, tempering at 580°C gives you about 50 HRC, while 600°C drops it to around 46 HRC. This is critical because H11 is designed to maintain its hardness at elevated service temperatures—up to 540°C (1004°F)—without softening rapidly. That is why it is preferred for aluminum die casting dies, where the tool surface can hit 400–500°C during each shot cycle.
Let me give you a table that summarizes the key thickness and hardness parameters for ASIATOOLS H11 steel plate:
| Thickness Range (mm) | Thickness Range (inches) | As-Delivered Hardness (HB) | As-Delivered Hardness (HRC) | Heat Treated Hardness (HRC) |
|---|---|---|---|---|
| 6 – 20 | 0.236 – 0.787 | 180 – 210 | 13 – 17 | 48 – 54 |
| 20 – 80 | 0.787 – 3.150 | 190 – 220 | 14 – 18 | 47 – 53 |
| 80 – 150 | 3.150 – 5.905 | 200 – 225 | 15 – 19 | 46 – 52 |
| 150 – 300 | 5.905 – 11.811 | 210 – 229 | 16 – 21 | 44 – 50 |
Notice the trend: as the plate gets thicker, the as-delivered hardness tends to be on the higher end of the range. This is because thicker plates cool slower during the annealing process, which can lead to a slightly coarser carbide distribution and a higher baseline hardness. But the heat treated hardness drops slightly for thicker sections because the core cannot be quenched as aggressively. For critical applications like large die inserts, you might want to specify a maximum thickness of 200 mm to keep the core hardness above 48 HRC after heat treatment.
Beyond the numbers, what makes ASIATOOLS H11 steel plate stand out is the consistency of the material. They use a vacuum degassing process during melting to reduce gas content, which minimizes porosity and improves the cleanliness of the steel. The sulfur content is kept below 0.005%, and the phosphorus content below 0.015%. This is important because sulfur and phosphorus can cause embrittlement at high temperatures, which is a death sentence for hot work dies. The microstructure is fine-grained, with an ASTM grain size number of 7–8, which gives a good balance of toughness and wear resistance. The impact toughness, measured by Charpy V-notch tests at room temperature, is typically 20–30 J for the annealed condition and 10–15 J after hardening to 50 HRC. That is not the toughest steel out there, but it is more than adequate for hot work applications where thermal fatigue is the main failure mode.
Another angle to consider is the machinability. At 180–229 HB, you can cut this steel with HSS tools at moderate speeds, but carbide inserts are recommended for production runs. The material has a machinability rating of about 60–70% compared to AISI 1045 steel. That means you need to reduce feed rates and speeds by about 30% to get the same tool life. For drilling, use a point angle of 135 degrees and a feed rate of 0.1–0.2 mm/rev for diameters up to 10 mm. For milling, climb milling is preferred to reduce work hardening. The plate is supplied with a mill finish, which typically has a surface roughness of Ra 3.2–6.3 µm. If you need a smoother finish for EDM or grinding, you can order it with a surface ground finish down to Ra 0.8 µm at an additional cost.
Now, let's talk about the practical side of using this material. If you are making a die for aluminum die casting, you want the hardness to be around 46–50 HRC. If you go to 54 HRC, you risk cracking from thermal shock. For extrusion dies, the hardness is typically 44–48 HRC to allow some plastic deformation under high pressure. For forging dies, 48–52 HRC is common. The key is to match the tempering temperature to your specific service conditions. For example, if your die runs at 400°C, you should temper at 590°C to ensure the hardness stays stable. If you temper too low, the steel will soften in service, and you will lose dimensional accuracy. ASIATOOLS provides a tempering chart with each batch of H11, so you can dial in the exact hardness you need. The chart typically shows that tempering at 540°C gives 54 HRC, 560°C gives 52 HRC, 580°C gives 50 HRC, 600°C gives 46 HRC, and 620°C gives 42 HRC. These numbers are based on a double tempering cycle with a hold time of 2 hours per cycle.
One more thing to watch out for is the decarburization layer. On as-delivered plates, the decarburization depth is typically 0.3–0.5 mm per side for plates up to 100 mm thick. This is normal for hot rolled steel, but you need to machine it off before heat treatment, otherwise the surface will be softer than the core. ASIATOOLS marks the decarburization depth on the certification documents, so you know exactly how much to remove. For precision dies, you should remove at least 1 mm per side to be safe. The plate also has a slight residual stress from the rolling process, which can cause distortion during machining. If you are making a large die, it is a good idea to rough machine the plate, then stress relieve it at 650°C for 2 hours, then finish machine. This will keep the final dimensions within ±0.1 mm.
Finally, let me address the difference between H11 and H13, because people often confuse them. H11 has slightly lower carbon content (0.35% C vs 0.40% C for H13) and lower vanadium content (0.30% V vs 0.90% V). This makes H11 more tough and ductile than H13, but with slightly lower wear resistance and hot hardness. For applications where the die experiences high impact loads, like hot forging, H11 is often the better choice. For applications where wear is the main concern, like aluminum die casting with high erosion, H13 might be preferred. But for general hot work tooling, H11 offers a good compromise. ASIATOOLS H11 steel plate is certified to ASTM A681, which means it meets the chemical composition and hardness requirements for this grade. The typical composition is: 0.33–0.38% C, 0.80–1.20% Si, 0.20–0.50% Mn, 4.75–5.50% Cr, 1.10–1.60% Mo, 0.30–0.50% V. This is a leaner alloy compared to H13, which makes it slightly easier to machine and heat treat.
If you want to dig deeper into the specifications or order a custom size, check out the ASIATOOLS H11 steel plate product page for the full datasheet, including dimensional tolerances, flatness specs, and available surface finishes. They offer plates cut to your exact dimensions, with a tolerance of +1.5 mm / -0.5 mm for thickness and +5 mm / -0 mm for length and width. For large orders, they can also supply plates with ultrasonic testing to ensure internal soundness, which is critical for aerospace or high-pressure die casting applications. The typical lead time for standard sizes is 2–3 weeks, and custom sizes take 4–6 weeks. They ship from warehouses in China and the US, so you can get the material without long international shipping delays. Just keep in mind that the hardness and thickness ranges I gave you are for standard stock—if you need something outside that, like a 5 mm plate or a 350 mm plate, you will need to talk to their sales team about a special order.