Tools Steels – All You Need to Know
Tool steel is a group of steel that is used in tool manufacturing. Due to their excellent hardness, resistance to abrasive wear and deformation, tool steel is known for its durability and high temperature resistance. In some circles, tool steel is also referred to as “clean high alloy steel” because of their relatively straightforward list of components. Other than carbon and iron, tool steel can also contain tungsten, chromium, vanadium and molybdenum which form carbides in the matrix of the material. Unlike other steel grades, tool steels are always heat treated to improve mechanical properties. There are seven groups of tool steel, which are distinguished by their hardening and quenching technique.
Carbon Content Of Tool Steel
The carbon content of tool steels plays a pivotal role in determining their properties and suitability for specific applications. Typically ranging between 0.5% and 1.5%, the carbon content directly influences the steel’s hardness, wear resistance, and ability to retain a sharp cutting edge at elevated temperatures. The presence of carbon, when combined with other alloying elements, forms carbides in the steel matrix, which significantly enhance the tool steel’s performance characteristics. Properly controlled carbon levels, in conjunction with appropriate heat treatment, ensure that tool steels exhibit the desired balance of hardness, toughness, and wear resistance, making them ideal for shaping, cutting, and machining other materials.
Grades Of Tool Steel
1. Water-Hardening Tool Steel
Water-hardening tool steel, often referred to as W-group steel, is essentially high carbon plain-carbon steel. It’s named for its defining property of needing to be quenched in water. This type of steel is popular due to its cost-effectiveness. However, it’s best suited for parts that won’t encounter high temperatures, as it begins to soften noticeably above 150°C (302°F). Due to its low hardenability, it requires rapid quenching, and its primary use includes making springs, machine parts, chisels, and more.
2. Cold-Work Tool Steel
Cold-work tool steels are designed for cutting or forming materials at low temperatures. This group includes the O series (oil-hardening), A series (air-hardening), and D series (high carbon-chromium). They are known for their high hardenability, wear resistance, and average toughness. These steels are used in the production of larger parts or those that need minimal distortion during hardening.
3. Shock-Resisting Tool Steel
Shock-resisting tool steels are designed for shock resistance at both low and high temperatures. They are characterized by their high impact toughness and relatively low abrasion resistance. These steels are often alloyed with elements like chromium-tungsten, silicon-molybdenum, and silicon-manganese. They are commonly used in the production of tools like jackhammer bits.
4. Hot-Work Tool Steel
Hot-working steels are used to cut or shape material at high temperatures. These steels are designed for strength and hardness during prolonged exposure to elevated temperatures. They are often alloyed with elements like chromium, tungsten, and molybdenum. An example of hot-work tool steel is DIN 1.2344 tool steel (H13).
5. Mold Steels
Mold steels, or P-type tool steels, are specifically designed to meet the requirements of plastic injection moulding and zinc die casting dies. They offer a balance between hardness, toughness, and wear resistance, making them ideal for moulding applications.
6. High-Speed Tool Steels
High-speed steels are designed to retain their hardness at elevated temperatures, making them suitable for tools that operate at high speeds, such as drill bits and power saw blades. They are often alloyed with tungsten or molybdenum to enhance their properties.
7. Special Purpose Tool Steel
Special purpose tool steels include L-type (low alloy) and F-type (carbon tungsten). L6, for instance, is known for its extreme toughness, while F-type tool steel is water-hardened and offers enhanced wear resistance.
Common Applications Of Tool Steels
Tool steels are integral to a variety of applications that demand durability and resilience. Their unique properties make them indispensable in numerous sectors:
- Cutting Tools: Given their ability to maintain structural integrity at elevated temperatures, tool steels are commonly used in the production of drills, taps, and milling cutters.
- Metalworking and Forging: Their high wear resistance is ideal for crafting dies, punches, and other specialized tooling.
- Corrosive Environments: D-group steels, with their high chromium content, are frequently chosen for applications where materials face exposure to corrosive substances.
- Impact Tools: The shock-resisting properties of shock resisting tool steels make them the go-to choice for tools that experience regular impact, such as hammers and certain power tool components.
From automotive to aerospace, the versatility of tool steels underscores their pivotal role in contemporary manufacturing processes.
Overview of Tool Steel Types: Characteristics and Composition
| Tool Steel Type | Description | Key Features & Uses | Composition |
| Water-Hardening | High carbon plain-carbon steel. Quenched in water. | Cost-effective, softens above 150°C (302°F), used for springs, machine parts, chisels. | High carbon content |
| Cold-Work | Includes O series (oil-hardening), A series (air-hardening), and D series (high carbon-chromium). | High hardenability, wear resistance, used for larger parts with minimal distortion during hardening. | Varies: O series (oil-hardening), A series (air-hardening), D series (high carbon-chromium) |
| Shock-Resisting | Designed for shock resistance at both low and high temperatures. | High impact toughness, low abrasion resistance, used for tools like jackhammer bits. | Often alloyed with elements like chromium-tungsten, silicon-molybdenum, and silicon-manganese. |
| Hot-Work | Used to cut or shape material at high temperatures. Alloyed with chromium, tungsten, molybdenum. | Strength and hardness during prolonged exposure to heat, e.g., DIN 1.2344 tool steel (H13). | Alloyed with elements like chromium, tungsten, and molybdenum. |
| Mold Steels (P-type) | Designed for plastic injection moulding and zinc die casting dies. | Balance between hardness, toughness, and wear resistance, ideal for moulding applications. | Varies based on specific requirements for plastic injection moulding and zinc die casting. |
| High-Speed Steels | Retains hardness at elevated temperatures. | Suitable for high-speed tools like drill bits and power saw blades, alloyed with tungsten or molybdenum. | Often alloyed with tungsten or molybdenum to enhance heat resistance. |
| Special Purpose | Includes L-type (low alloy) and F-type (carbon tungsten). | L6 known for extreme toughness, F-type is water-hardened with enhanced wear resistance. | L-type (low alloy), F-type (carbon tungsten). |
Explore Advanced Steel Treatments
For those who appreciate the intricacies of metallurgy and the potential of tool steels, delving deeper into specialized treatments can further enhance steel’s capabilities. BorTec offers a range of services tailored to meet the diverse needs of modern manufacturing:
- Discover the wear-resistant benefits of BOROCOAT® boronizing, a process that offers superior protection against abrasive wear.
- Learn about the corrosion-resistant strength of BORINOX® hardening, a patented process suitable for most stainless steels.
- Dive into the versatile protection offered by NICKELCOAT® nickel plating, an electroless nickel plating process known for its excellent wear protection and corrosion resistance.
Enhance your tool steel’s performance and longevity by exploring these advanced treatments from BorTec.
