Grade H21
H21 tool steel is a premium tungsten-based hot-work tool steel specifically engineered for applications involving extremely high temperatures and thermal stress. As part of the H-series tungsten grades (H20–H26), it is designed to deliver exceptional performance in environments where conventional chromium-molybdenum steels such as H11 and H13 may fail. Its unique composition enables it to retain strength, hardness, and dimensional stability even under continuous exposure to elevated temperatures.
One of the key advantages of H21 is its outstanding red-hardness, which allows it to maintain cutting ability and structural integrity even when exposed to direct flame or hot metal flow. This makes it highly suitable for tools operating in extreme heat conditions, such as forging, extrusion, and steel processing. Additionally, its superior thermal fatigue resistance ensures long service life by minimizing the risk of cracking under repeated heating and cooling cycles.
The presence of tungsten and chromium in H21 enhances its wear resistance, even at elevated temperatures, making it ideal for abrasive hot-working environments. Despite its high hardness and heat resistance, the material maintains reasonable toughness compared to other tungsten-based steels, reducing the likelihood of sudden tool failure during operation.
H21 tool steel is widely used in industries such as steel manufacturing, forging, foundries, and aerospace engineering. It is commonly utilized for hot shear blades, extrusion tooling, furnace components, and tools exposed directly to molten metal or flame. Its ability to perform reliably under extreme conditions makes it a preferred choice for high-temperature tooling applications.
Chemical Properties of Grade H21
| Element | Percentage (%) |
|---|---|
| Carbon (C) | 0.30 – 0.40 |
| Silicon (Si) | 0.20 – 0.40 |
| Manganese (Mn) | 0.20 – 0.40 |
| Chromium (Cr) | 2.50 – 3.50 |
| Tungsten (W) | 8.50 – 10.00 |
| Vanadium (V) | 0.30 – 0.60 |
Mechanical Properties of Grade H21
| Property | Value |
|---|---|
| Hardness | 45 – 55 HRC |
| Tensile Strength | 1000 – 1300 MPa |
| Yield Strength | 800 – 1000 MPa |
| Thermal Resistance | Up to 700°C |
| Impact Toughness | Moderate to High |
| Density | ~7.8 g/cm³ |
| Wear Resistance | Excellent at high temperature |
Key Properties
- Outstanding High-Temperature Strength: Maintains hardness and structural stability at temperatures up to 650–700°C, ideal for extreme hot-working environments.
- Excellent Red-Hardness: Retains hardness even under direct flame, hot metal exposure, and prolonged heating conditions.
- Superior Thermal Fatigue & Fire Crack Resistance: Withstands repeated heating and cooling cycles without cracking, ensuring long tool life.
- Good Abrasion Resistance at High Heat: Tungsten and chromium carbides provide strong wear resistance even at elevated temperatures.
- High Toughness: Offers better toughness compared to other tungsten grades, reducing the risk of sudden failure.
- Good Hardening Ability: Achieves typical working hardness of 45 – 55 HRC depending on application and heat treatment.
Common Applications
- Hot shear blades
- Hot extrusion tooling
- Drop forging dies and inserts
- Punches for hot punching applications
- Furnace tooling (fixtures, bars, rollers)
- Mandrels and hot forming tools
- Tools exposed directly to flame or molten metal
- High-temperature wear plates and guide rails
- Cutting tools for hot steel or billets
PUROHIT STEEL is a trusted name in the tool steel industry, with humble beginnings dating back to 1965 and over three decades of expertise in delivering high-quality materials and solutions. Today, the group operates multiple well-established units, maintaining a vast inventory ranging from hot work and cold work tool steels to specialized materials. Known for reliability and strong technical support, PUROHIT STEEL caters to the diverse requirements of small, medium, and large-scale industries. The company specializes in manufacturing moulds and tooling components using premium grades such as Grade H21 which is ideal for applications including injection moulds (medium to large size), blow moulds, low-pressure die-casting dies, automotive moulds, tooling plates, extrusion dies, machine parts, shafts, and general tooling components. With a focus on quality, performance, and precision, PUROHIT STEEL continues to deliver durable and efficient tooling solutions.