What Is Tool Steel?

Tool steel is a type of carbon alloy steel that is well-matched for tool manufacturing, such as hand tools or machine dies. Its hardness, resistance to abrasion and ability to retain shape at increased temperatures are the key properties of this material. Tool steel is typically used in a heat treated condition which provides increased hardness.

Several grades have additional resistance to corrosion due to added chemical properties such as vanadium. Also, with certain grades the manganese content is restricted in order to minimize the potential of cracking while water quenching. Other grades offer various methods other than water to quench the material, such as oil.

Types of Tool Steel

The different tool steel grades include:

• Water Hardening
• Air Hardening
• D Type
• Oil Hardening
• Shock resisting types
• Hot-Working.

The choice of Tool Steel grade depends on a number of factors, such as:

• Is sharp cutting required?
• Does the tool have to withstand impact loading (axes, hammers, picks, etc.)?
• Is abrasion resistance an important criteria?
• What type of heat treating is needed?

Tool Steel Grades

Water Hardening (W-Grades)

This is basically a high carbon steel. While it generally has a lower cost it cannot be used where high temperatures are involved. This steel can achieve a high hardness, but it is rather brittle when compared to other tool steels. All W-Grade tool steels must be must be water quenched, which can lead to increased warping and cracking.

Typical applications of W-Grade tool steel include Cold Heading,Cutting tools and knives, Embossing, Reamers and Cutlery.

Air Hardening (A-Grades)

This is a very versatile, all-purpose tool steel that is characterized by low distortion factor during heat treatment, due to the increased chromium content. This tool steel has good machinability and a balance of wear resistance and toughness.

Typical applications of A-Grade tool steel include Arbors, Cams, Die Bending, Blanking, Coining, Embossing, Cold Forming, Lamination, Cold Swaging, Cold Trimming, Gages, Chipper Knives, Cold Shear knives, Woodworking Knives, Lathe Center Knives.

D Type (D-Grades)

This is a high carbon, high chromium (air hardening) tool steel. It was formulated to combine both the abrasion resistance and air-hardening characteristics. Common applications for these tool steels include forging dies, die-casting die blocks, and drawing dies.

Typical Applications of D-Grade tool steel include Burnishing Tools, File Cutting, Paper Cutters, Die Bending, Blanking, Coining, Cold Heading Die Inserts, Embossing, Cold Extrusion, Cold Forming, Lamination, Cold Swaging, Thread Roll, Cold Trimming, Wire Drawing, Gages, Paper Knives, Rotary Slitters, Cold Shear Knives, Woodworking Knives, Knurling tools and Lathe Center Knives.

Oil Hardening (O-Grades)

This is a general purpose oil hardening tool steel. It has good abrasion resistance and toughness for a wide range of applications.

Typical applications of O-Grade tool steel include Arbors, Bushing, Chasers (Thread Cutting), Collets, Die Blanking, Cold Forming, Cold Trimming, Drill Bushing, Gages, Knurling Tools.

Shock resisting types (S-Grades)

This type of tool steel has been designed to resist shock at low or high temperatures (E.g. Jackhammer bits). Its low carbon content is required to achieve the necessary toughness. This group of metals has high impact toughness, but a low abrasion resistance.

Typical applications of S-Grade tool steel include Battering Tools, Boiler-Shop Tools, Chisel Blacksmiths, Chisel Cold Working, Chisel Hot Working, Chuck Jaws, Clutch Parts, Collets, Cold Gripper, Hot Gripper, Cold Swaging, Hot Swaging, Hot Trimming, Chipper Knives, Cold Shear and Hot Shear.

Hot-Working (H-Grades)

This tool steel group is used to cut material at high temperatures. The H-Group has added strength and hardness for prolonged exposure to elevated temperatures. They are low in carbon and moderately high in additional alloys.

Typical applications of H-Grade tool steel include Cold Heading Die Casings, Die Casting Dies and Cores for Zinc and Aluminum, Hot Extrusion for Aluminum and Magnesium, Hot Forging, Hot Gripper, Hot Swaging, Hot Trimming, Dummy Blocks (Hot Extrusion), and Hot Shear Knives.