7 Things To Consider When Choosing A Tool Steel Grade

Tool steels feature increased amount of carbon and other alloying elements which give them enhanced physical properties, making them the ideal choice for a variety of applications. Cutting tools, cams, dies, chuck jaws, blocks, gages, and drill bits are just some examples of the many different tool steel applications. Along with many different applications, there are also many different tool steel grades available, including cold-working tool steels that encompass water-hardening tool steels, oil-hardening tool steels, and air-hardening tool steels. There are high-speed tool steels, hot-working tool steels, and shock-resisting tool steels as well. With so many different choices, it is necessary to be able to identify the correct tool steel for the job.

Seven things to consider when selecting a tool steel grade include:

1. Will the tool steel be subjected to large impacts?
2. Will the tool steel be doing work at high temperatures?
3. Will the tool steel be used at high speeds?
4. Is cost a concern?
5. Will the tool steel be performing in low temperatures?
6. Will it be used for plastic molding?
7. Are there special circumstance considerations?

Will the tool steel be subjected to large impacts?

Tool steels are generally hard and brittle. When impacts occur on materials like this, it can cause fractures. Shock-resisting tool steels are a group made to better withstand impact as they have a higher degree of toughness than other tool steels. However, this increased toughness does come with a reduction in hardness and wear resistance compared to other types of tool steels. Therefore, shock-resisting tool steels should only be used in applications that require the steel to undergo large, sudden impacts. Examples of shock-resisting tool steels are S1, S2, and S5. Shock-resisting tool steels are frequently used in chisels, shears, and hammers.

Will the tool steel be doing work at high temperatures?

High temperatures can affect the mechanical properties of steel. This is especially true of tool steels, because many of them have been heat-treated, and reheating them may render that heat-treatment useless. Hot-work tool steels are a popular option when dealing with high temperature applications because they are less likely to lose their hardness and wear resistance at elevated temperatures. This is because of their relatively high amounts of tungsten and molybdenum. Grades of hot-work tool steels include H12, H13, and H19. They are commonly used for casting dies, extrusion dies, and hot shear knives.

Will the tool steel be used at high speeds?

Some tools are moved so fast that the energy generated can result in elevated temperatures which can impact the tool steel in two ways. The first concern is that the high temperature will reduce the hardness and wear resistance of the tool. The second concern is that since there are many cycles being run on the tool in such a short time, tool wear can occur very quickly. For operations such as these, high-speed tool steels should be used. They are made to not only have mechanical properties that withstand elevated temperatures, but also have high wear resistance to prevent tool degradation when exposed to many cycles in a short time frame. Examples of high-speed tool steels include T1, M7, and M42. They are used in drill bits, cutting blades, and pump components.

Is cost a concern?

For low-budget manufacturing, tool steels with many different expensive alloying elements may not be justifiable. Water-hardening tool steels offer a good compromise of cost and mechanical properties. These grades get most of their enhanced mechanical properties from high amounts of carbon and not from other alloying elements. They are rapidly water quenched to form hard, brittle microstructures that can withstand wear. Examples of water-hardening tool steels are W1, W2, and W3. They are frequently used for low-budget operations that require high wear resistance.

Will the tool steel be performing work at low temperatures?

Cold-work tool steels are ideal for low temperature applications. They consist of air-hardening and oil-hardening tool steels. They do not require as rapid a quench as water-hardening tool steels because of the increased amounts of alloying elements such as chromium, manganese, and molybdenum. This generally makes them more costly than water-hardening tool steels, but with the benefit of enhanced mechanical properties. Examples of these tool steels are D2, O2, and A7. They are used for punches, dies, gages, and many more cold-working applications.

Will it be used for plastic molding?

Plastic molding usually requires the use of a special type of tool steel. This tool steel falls under the Type P family of tool steels. They are generally not used for any other type of tooling applications aside from the manufacture of plastic molds or molds for metals with low melting temperatures. Examples include P2, P3, and P5.

Are there special circumstance considerations?

There are special types of tool steels available for unusual applications. These are usually proprietary. At Metal Supermarkets, we can help you determine the best tool steel to achieve the desired mechanical properties.