Grades of Tool Steel

steel tools setThere are different types of steel, each with various applications. The carbon alloyed steel used for manufacturing tools is called tool steel. It is famous for its resistance to chafing, its hardness, and its ability to maintain its shape even at high temperatures. Typically, tool steel will be heat treated to improve hardness.

Steel service providers will use different grades of tool steel for various applications. The categories vary by the scale of resistance to scraping, the metal alloy content, and the response to different manufacturing processes. For instance, some grades crack during water quenching while others do not. The various classes consist of the following:

Water and air hardening grades

Also called w-grades, grades under this category have high amounts of carbon. They are only useful for applications that do not need high temperatures. This type of steel can become hard without getting brittle. Note that all the tools made with this grade need water quenching and this can cause them to crack. W-grades are used to make cutlery, knives, reamers, and embossing.

A-grades (air hardening), on the other hand, are versatile. The steel used does not distort upon heat application because it contains high amounts of chromium. Consequently, it balances wear resistance well and is tough. Typical uses for this steel include gages, cold swaging, blanking, and coining.


D-Grades have high chromium and carbon levels. They are formulated to create an option that is resistant to abrasion but has characteristics found in A-grades. Popular applications for the steel include drawing and forging dies. This steel may also apply to the making of paper cutters, burnishing tools, shear knives, thread rolls, and rotary slitters.

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O-grades are general purpose and are usually hardened with oil. They have excellent toughness and resistance to abrasion, making them perfect for numerous applications. The most common uses include collets, gages, chasers, knurling tools, and arbors.

Shock-resisting grades

Shock-resisting grades (S-grades) are designed for applications that will need shock resistance. They need to be usable in both high and low-temperature applications. S-grades usually have low levels of carbon, a factor that explains their toughness. Typical applications include chisels, battering tools, hot trimming, and hot grippers.


These tool steel types are used for materials that cut at very high temperatures. Hot working grade tools are characterized by high strength and increased hardness even during prolonged exposure to high temperatures. H-grades have low carbon levels but are high in other alloys. Often, these steel types are used in hot forging, hot swaging, casting dies, dummy blocks, and hot grippers.

Different things should inform your choice of the grade of tool steel. Will you need to use the tool for sharp cutting? Do the conditions necessitate a device that can withstand high impact loading? – Like with picks, axes, and hammers. Do you need the tool to be resistant to abrasion? What kind of heat treatment is required for the device you have in mind? Finally, you will need to factor in the kind of tool failure that is most likely for the application you have in mind.

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