Tool steel is a carbon alloy that manufacturers use for a variety of purposes, including machining and cutting. Their special properties, including hardness, abrasion resistance and deformation resistance, make them suitable for shaping other materials by cutting and machining.
So what is tool steel? What properties does tool steel have? How is it different from stainless steel? What are the different grades of tool steel? How do you choose the ideal grade for your machining purposes?
Read on as we provide answers to these questions based on extensive knowledge about tool steel.
What is tool steel?
Unlike carbon steel, tool steels have densely packed metal networks containing carbon and metallic components. They also contain elements that form carbides, such as molybdenum, chromium, vanadium and tungsten. Furthermore, its resistance to softening while maintaining excellent performance at high temperatures is due to the presence of nickel and cobalt.
The carbide content of tool steel makes it an exceptionally tough, wear-resistant and hard carbon alloy. Furthermore, its chemical and physical properties make it ideal for difficult jobs such as punching, cutting, drilling and grinding. This also makes it suitable for the production of tools such as hand tools and machine stamps.
Now let's take a look at the classification and applications.
Tool steel classifications and their applications
There are six different categories of tool steel, including cold work steel, water hardening steel, hot work steel, high speed steel, shock resistant steel and specialty steel. Below are the classifications of tool steel and its applications.
1. Cold work steel
This is one of the most important types of tool steel. It is tenacious, hard and resistant to wear in cold environments with temperatures below 200ºC. However, cold work steel does not perform well when exposed to hot environments.
Additionally, cold work steel is easy to machine. This is due to the presence of graphite and the lubrication it provides. Furthermore, the types of tool steel most used in this category are: D2, O2, A2, D3 and D6.
These are the different subcategories of cold work steel.
1.1 High carbon tool steel or D series
This cold-formable tool steel is also known as stainless due to its high chromium content and contains 11-13% chromium. Although it has limited corrosion resistance, its carbon content of 1.4-2.5% gives it high resistance to abrasion. This means it can also be used at temperatures of up to 425°C.
Furthermore, this tool steel can be quenched in oil or air with minimal deformation, making it suitable for manufacturing cutting tools. Additionally, D series tool steel is ideal for bending and forming rolls, plastic injection molds, rotating tips, and woodworking knives. Its other applications include the production of polishing tools, rolling tools, drawing dies and cold extrusion tools.
1.2 Air Hardening or A Series Tool Steel
These types of tool steel have a carbon content of 0.05-2.85% and a chromium content of up to 5%. Furthermore, this type of tool steel is very tough and has high wear resistance. Common applications include engraving, drilling and mixing tools.
1.3 Oil hardened tool steel or O series
This series of tool steels is quenched in oil during production and has a carbon content between 0.85 and 2.00%. They are also robust and have high resistance to abrasion. Applications of oil-hardened tool steel include the manufacture of bushings, collets, gauges, engraving master rolls, punches, and thread-cutting cutters.
2. Water hardened tool steel
This category of tool steel includes heat-treated carbon steel. Water-hardened tool steel is cheaply produced and hardened in water. It has a carbon content between 0.5 and 1 to 5%. The high carbon content of water-hardened steel makes it brittle and hard. However, other metal alloys such as tungsten, nickel or molybdenum are low, generally less than 0.5%.
3. Hot work steel
Tool steel types in this category typically have a carbon content of less than 0.6%. However, they contain a higher proportion of other alloying elements. This means that they maintain their properties and function optimally even at extreme temperatures of up to 540ºC, because more carbides are formed.
Due to its resistance to high temperatures, hot work steel is ideal for producing materials such as metal and glass that require high temperatures for optimal formability.
Another benefit engineers gain from using tool steel in this category is its continued functionality, even after prolonged exposure to heat. The most commonly used tool steel in this category is H13.
Based on the percentage of alloying elements used, there are three main alloying elements in this category: molybdenum and chromium.
3.1 Molybdenum tool steel
This is a hot work steel with high molybdenum content. Furthermore, this type of tool steel has high resistance to wear and heat, especially at extreme temperatures. Additionally, because of its ability to withstand force and heat, molybdenum tool steel can be used in metal milling cutters such as cutters or dies.
3.2 Tungsten tool steel
This type of tool steel contains 9-18% tungsten and 2-4% chromium. Although tungsten hot work steel is brittle, it has excellent heat resistance. One way to get around the brittleness of this tool steel is to preheat it to operating temperature before use.
3.3 Chrome-plated tool steel
The chromium type is the most commonly used hot work tool and contains 3-5% chromium. It may also contain less than 5% other alloying elements such as molybdenum, tungsten or vanadium. Common applications of chrome steel include hot forging, hot stamping and plastic injection molding.
4. High speed steel
High-speed steel contains many elements, including 0.6% carbon, 3-5% chromium and 14-18% tungsten. Furthermore, the invention of this category of tool steel is partially responsible for the beginning of the era of modern production. Before the invention of high-speed steel, the efficiency of tools and cutting machines decreased when they operated for long periods of time due to friction. However, with this tool steel, cutting and edge tools continue to work efficiently and at optimum speed.
Common uses for high-speed steel include making chainsaw blades, milling cutters, milling cutters, gear cutters, and drills. M2 high speed steel is the most common in this category.
5. Shockproof tool steel or S grade steel
Impact resistant tool steels are designed to have high impact resistance and are extremely strong. Furthermore, the strength of this tool steel is due to its high toughness value and low carbon content. This category of tool steel contains alloying elements found in other categories, as well as 0.15-3% silicon.
Although this steel does not have great abrasion resistance, it is very resistant to shocks, regardless of temperature. Furthermore, these properties make S grade tool steels ideal for the production of jackhammer parts, forging tools and coupling parts.
Additionally, other applications can be found in hot stamping tools, pneumatic tools, cleavers, hot and cold machining chisels, hot forming tools, and cold clamping tools. S7 tool steel is the most popular in this category.
6. Plastic mold or special tool steels
They are tool steels with an excellent combination of toughness, corrosion resistance, hardness and wear resistance. In addition, tool steel in this category also has high impact resistance and is easy to polish.
Additionally, tool steels for plastic molds are ideal for companies that use extrusion and injection molding processes to produce plastic. Using this tool steel to make molds ensures the durability and reliability of the tool.
They are also tool steels manufactured for special purposes. Just like water-hardened tool steel, they are tempered with water. Tool steels in this category contain iron-rich steels, while other alloying elements are absent or present in small amounts. The moderate addition of other alloying elements helps improve the mechanical properties of this tool steel while ensuring that it is not as expensive as other tool steels.
An example of special tool steel is the low-carbon mold steel used in molding thermoplastics. This specially manufactured molded steel does not need to have high impact resistance, but it does need to have excellent wear and heat resistance. In general, P20 is the most commonly used tool steel in this category.
Tool steel properties
This table of tool steel grades contains the most common tool steels and their comparable properties.
| Type | Comparative characteristics |
| O1 | It is one of the types of tool steel with high dimensional stability when hardened. Its hardness behavior at low temperatures is also ideal. It has a maximum HRC value of 65. |
| W1 | This water-hardened tool steel, also known as commercial carbon steel, is ideal for use in situations where simple heat treatment is best. It has excellent wear resistance and good toughness. It has a maximum HRC value of 68. |
| A2 | It is more resistant to heat and wear than O1. It has a maximum HRC value of 63 and less deformation. It is resistant to abrasion and wear. |
| T2 – The second day | This type of tool steel has superior toughness and wear resistance, reaching a maximum HRC of 65. However, it is difficult to machine. |
| S7 | This impact-resistant tool steel has high strength and ductility, but medium resistance to abrasion and wear. It has a maximum HRC value of 61. |
| P20 | This special tool steel has a maximum HRC value of 32. It is ideal for processing die-cast parts and plastic molds. |
| H13 | This hot working steel has good wear resistance and hardenability. It also has high resistance to thermal fatigue cracking. It has a maximum HRC of 54 |
| M2 | With a maximum HRC of 65, this high-speed steel has excellent abrasion resistance and toughness. |
Considerations When Selecting a Tool Steel Machining
The tool or product you want to machine plays an important role in choosing the types of tool steel. Furthermore, types of steel have different properties that make them ideal for different applications and uses. When choosing a grade for tool steel machining, the following characteristics must be taken into consideration.
Tool steel properties
Different tool steels are available for metal processing. They also differ in their chemical composition, temperature range and type of hardening.
However, ideal tool steel grades for machining include cold work steels such as O1, D2, and A2, as well as high-speed tool steels such as M2. Although O1 has high hardness, it is easy to machine. This type of steel is ideal for machining cutting tools and drills.
D2 is also easy to machine due to its high carbon and chromium content. It has good toughness and wear resistance makes it ideal for machining tools that are intended to last a long time.
Furthermore, A2 tool steel presents a good balance between toughness and wear resistance. It's also easy to edit. This tool steel is ideal for forming punches, injection molds and cutting dies.
Speed Levels
Not all tool steels are ideal at high speeds. Using the wrong type of tool for machining would reduce the hardness and wear resistance of the tool steel over time. Therefore, when using tool steel at high movements, it is better to make the tool from high-speed steel. The reason for this is that they have greater resistance to wear and extreme temperatures, even at high speeds.
Tool steel cost
Cost is an important factor when selecting a type of tool steel for CNC steel machining. However, it is always better not to skimp when selecting the material, as you could end up spending more if the tool fails prematurely.
Therefore, before deciding on a specific type of tool steel for machining, it is best to carry out a cost-benefit analysis. This analysis ensures that the chosen material is suitable enough to provide the required performance.
What is the difference between tool steel and stainless steel?
Although both are steel alloys, stainless steel and tool steel differ from each other in composition, properties and application. Here are the differences between these two types of steel.
Tool Steel vs. stainless steel: properties
Both stainless steel and tool steel have different properties. This difference is due to the different components. Chemically, tool steel is an alloy of carbon with other alloying elements such as tungsten, chromium, molybdenum and vanadium.
For example, tool steel is extremely durable, machinable, and wear-resistant due to the carbides it contains. In general, tool steels are tougher and have better tensile strength than stainless steel. This makes them ideal for producing high-performance cutting tools. The disadvantage is that this steel is susceptible to corrosion due to a lack or reduced chromium content.
Furthermore, stainless steel is a chromium-nickel alloy with nickel, nitrogen, titanium, sulfur, molybdenum and silicon as other alloying elements. The presence of chromium makes it highly resistant to rust and corrosion. Furthermore, it usually has a smooth, shiny and shiny surface.
Tool Steel vs. stainless steel: applications
Manufacturers use tool steel primarily to make tools. It is used in tools such as drills, hammers, saws and other cutting tools, basic tools used in the workshop. Manufacturers create tools in this category for manufacturing and fabrication with little or no consideration for appearance and hygiene. Instead, the emphasis is on toughness and wear resistance, properties that would improve the efficiency of such tools while reducing their maintenance and replacement rates.
Stainless steel, on the other hand, is used in many industries. Its corrosion resistance and shiny appearance make it ideal for use in architecture and other outdoor environments where it will certainly be exposed to environmental influences. Steel in this category is also hygienic and easy to clean and maintain, making it ideal for use in the food and medical industries. It is used, for example, in the production of kitchen utensils and medical instruments such as specula, needles, bone saws and scalpels.
Get high-quality tool steel parts at WayKen
What if you're not sure which type of tool steel is best for your product? Don't worry, we have a team of professionals and engineers to ensure you choose the right steel materials to get the best results. Please contact us for an offer or if you have any further questions.
Concluding
Tool steel is a carbon alloy with a wide range of uses and is divided into different categories depending on the proportion of other alloying elements, type of quenching and temperature range. Choosing the right tool steel grades for your project often makes the difference between a successful tool and a failed one.
Common questions
Why does tool steel fail?
Tool steel often fails due to heat treatment issues and a lack of understanding of the properties of tool steel. This leads to defects in the form of chips, plastic deformation, cracks, etc.
Why is tool steel ideal for machining?
Tool steel is ideal for machining because it has advantageous properties such as abrasion resistance, resistance to deformation, hardness and the ability to retain its cutting edge even at elevated temperatures.
Can you mill tool steel?
Yes, you can mill tool steel. However, the process of milling tool steel is different from that for normal milling operations.
What is the hardest tool steel?
The hardest tool steels are those with a high vanadium content. The category of tool steel with the highest vanadium content is cold work steel, which has excellent wear resistance.
