The Four Types of Steel (Part 4)

This article is the fourth in a four-part series on the different types of steel. Read Part 1.

Tool steel stands apart from ordinary steel grades thanks to its exceptional hardness, wear resistance, and ability to maintain structural integrity even under extreme conditions. If you’re manufacturing cutting implements, forming dies, or components that must withstand repeated stress, understanding tool steel types and their characteristics can help you select the optimal type for your application.

What is Tool Steel?

Tool steel is a specialized type of carbon alloy steel specifically designed for manufacturing tools, dies, and industrial components that require exceptional hardness, wear resistance, and durability. These high-performance metals are engineered to withstand extreme conditions and maintain their properties even under heavy loads or high temperatures.

Tool steel contains various amounts of tungsten, molybdenum, cobalt, and vanadium to increase the heat resistance and durability of the metal. This makes them ideal when used for cutting and drilling.

What distinguishes tool steel from regular carbon steel is its ability to maintain sharpness and structural integrity even when subjected to extreme heat generated during metalworking operations.

Tool Steel Types

Tool steel encompasses a range of specialized metal formulations, each designed with unique properties to handle particular manufacturing challenges. Whether you need a material that can withstand extreme heat, resist wear, or maintain a sharp cutting edge, there’s a tool steel variant engineered for the task.

Tool steel is divided into these six groups:

• Water-Hardening
• Cold-Work
• Shock-Resisting
• High-Speed
• Hot-Work
• Special Purpose

The determination of a choice from the group will depend on:

• Cost Effectiveness – Water-hardening grades are generally the most economical, while high-speed tool steel is typically more expensive.
• Working Temperature – For applications involving heat generation, such as high-speed cutting or hot forming, specialized tool steel formulated to maintain properties at high temperatures is required.
• Required Surface Hardness – Applications requiring exceptional wear resistance typically demand tool steel capable of reaching high hardness values.
• Strength – Tool steel with appropriate strength characteristics prevents premature tool failure and maintains dimensional accuracy throughout the tool’s service life.
• Shock Resistance – Applications involving impact or sudden loading require tool steel with good toughness and shock-absorbing capabilities.
• Toughness Requirement – Applications involving irregular shapes, interrupted cuts, or variable loads generally require tougher tool steel types that resist chipping and cracking, even if maximum hardness is somewhat reduced.

If there is a more severe demand requirement, such as extreme temperature, increased abrasiveness, high corrosion, or excessive loading, higher alloy content (and carbides) may be required.

Water-hardening class – Named from its property of having to be water quenched. This grade of tool steel is essentially plain high-carbon steel. It is commonly used because of its low cost.

Cold-work classes – A group of three tool steels: oil-hardening, air-hardening, and high-carbon-chromium. The steels in the group have high hardenability and wear resistance, with average toughness. Typically, they are in the production of larger parts or parts that have a minimum distortion requirement when being hardened.

• Both oil-hardening and air-hardening reduce the distortion and higher stress caused by the quick water. Because of this, they are less likely to crack.
• D-grade tool steel in the cold-work class can contain approximately 10% to 13% chromium. This type of tool steel retains its hardness at increased temperature (425°C / 797°F max). The most typical applications for this tool steel type are in forging dies, die-casting die blocks, and drawing dies.

Shock-resisting class – This class has high shock resistance and good hardenability. It is designed to resist shock at both low and high temperatures. It also has a very high impact toughness and relatively low abrasion resistance.

High Speed Class Tool Steel Types

T-type and M-type tool steels are used for cutting tools when strength and hardness must be retained at high temperatures.

Hot-working class – H-group tool steels were specifically developed to maintain strength and hardness while exposed to prolonged elevated temperatures.

Plastic Mold & Special Purpose classes:

• P-Code (Plastic Mold Steel) – Designed to meet the needs of zinc die casting and the special requirements of plastic injection molding
• L-Code – A low alloy special purpose tool steel.
• F-Code – Water hardenable/more wear resistant than W-type tool steel.

At Metal Supermarkets, we offer tool steel cut to your exact specifications. Contact your nearest location to discuss your specific tool steel requirements and find the ideal material for your next project.