Tool steel grades explained

Tool steel grades are incredibly diverse, so the last thing any designer or engineer wants is to choose the wrong steel for their projects!

At Edcon, we’re proud to provide a huge range of steel, all of which can be found on our website.

Here, we outline different types of tool steel grades as well as break down one of the most common tool steel grades out in the market, O1 tool steel.

What is tool steel?

Tool steel is primarily used to shape other materials, largely due to its high hardness, resistance to abrasion and deformation, resistance to corrosion and ability to retain its shape at elevated temperatures.

It is these characteristics that make it suitable for the manufacturing of tools like hand tools and machine dies.

Available in various carbon steel and alloy steel grades, depending on the application, tool steel is manufactured in controlled conditions to achieve the required quality.

The alloy elements added into the steel provide different characteristics to the steel, and heat treating to the right condition — according to its application — ensures optimum performance.

Apart from the quality of the tool steel, design, heat treatment and tool, manufacturing plays an important role in the tool performance in service.

Types of tool steel grades

There are thousands of different types of tool steel available worldwide. Some of these tool steel grades are grouped as below:

• Water Hardening
• Air Hardening
• D Type
• Oil Hardening

Water Hardening is a high carbon steel (carbon varies from 0.60 to 1.4%). While generally lower in cost, it can’t be used where high temperatures (above 150C) are involved. Additionally, although Water Hardening steel can achieve a high hardness, it has a low inherent hardenability.

Air Hardening is a versatile, all-purpose tool steel that is characterised by its low distortion factor during heat treatment, thanks to the high hardenability from its main alloying elements — manganese, chromium and molybdenum. This tool steel has good machinability and a good balance of wear resistance and toughness.

O1 and W1 tool steel explained

Two of the most common tool steel grades that we supply here at Edcon are O1 and W1.

Both are general-purpose, hardenenable tool steels which have good abrasion resistance and sufficient toughness for a wide variety of tool and die applications.

The main difference between the two grades is the way they are quenched, with O1 being oil quenched and W1 being water quenched.

The biggest benefit of these two grades is the lower cost, when compared to other tool steels.

They are also relatively easy to heat treat, due to their lower austenitising requirements (which are similar to other low alloy steels), with the benefit of being easy to quench for full hardness.

Edcon Steel stocks and sells O1 tool steel as flat ground stock or gauge plates, in flat or square form and in both metric and imperial dimensions.

W1 is sold as silver steel or drill rods in round bar form, and in both metric and imperial dimensions.

Flat ground stock (Gauge Plates) and silver steel (drill rods) are both precision ground to a specific size and tolerance.