COLD WORK TOOL STEELS

What is cold work tool steel?

Cold work tool steel is designed to make tools that work at room temperature. It is used for stamping sheet metal, shearing material, or making molds and dies. Common tools include stamping dies, shearing tools, and some molds used to stretch metal.

Simply put, cold work tool steel is hard and wear-resistant and can withstand the pressure of processing metal at room temperature.

A short explanation of cold working

Cold working is machining metal materials into various shapes below 200°C (roughly 390°F).

Cold work machining includes several common operations:

• Stamping: using a die to press a metal sheet into a desired shape, such as a car door or cell phone case.
• Minting: pressing metal out in a clear pattern, like making a coin.
• Shearing: cutting metal into a desired shape, like cutting tin with large scissors.
• Punching: cutting a part from a metal sheet, like making a round piece of metal.

These processes are usually used on steel sheets, especially mild steel. Mild steel is “soft” and ductile, so it can be easily stretched or pressed into shapes without breaking that easily.

Reasons for needing to work below 200°C

The reason why cold work machining is strictly controlled below 200°C is that too high a temperature can cause some problems: firstly, the properties of the part may change, becoming brittle or inhomogeneous; at the same time, the machining tools may deteriorate due to the high temperature; and lastly, the surface quality of the part may be impaired and become rough. The advantage of cold work machining over hot work, which requires high temperatures, is that it results in smooth, dimensionally accurate parts with higher finished appearance and accuracy. However, cold work machining also has its limitations, due to the high hardness of cold work tool steel at room temperature, it is more difficult.

What are the characteristics of cold work tool steel?

1. High carbon content: Carbon accounts for 0.8% to 1.0%, which makes the steel exceptionally hard, able to withstand wear and stress, and suitable for tooling.
2. Low vanadium and molybdenum: these elements are low in steel. Why? Because vanadium and molybdenum are helpful in high-temperature hardening, cold work tool steels don’t need to maintain their hardness in a high-temperature environment, so they are used sparingly.