An Explanation of Steel Heat Treatment

For a steel/" target="_blank" class="keylink">tool steel to perform effectively a component when machined will usually require heat treatment. This will enable the tool to develop the characteristic properties required for a high hardness with good wear, abrasion and impact values, which vary with each specification. Refer to our steel/" target="_blank" class="keylink">tool steel page where we offer specification data sheets on our more popular specifications.

For heat treatment a steel/" target="_blank" class="keylink">tool steel component requires preheating (to avoid cracking and unnecessary distortion of the component), then it is raised to its final hardening temperature. An important point is the great necessity of having the steel/" target="_blank" class="keylink">tool steel uniformly heated through or as generally termed "well soaked". To achieve a high hardness the steel then requires rapid cooling. The name given to this process is "quenching". Dependant on specification the steel may be quenched in oil or cooled in air or inert gas. The steel is now extremely brittle and under great stress. If used in this condition the steel would probably shatter and it is possible the steel may even crack if left for any time in this condition. Therefore, as soon as the steel is quenched it requires tempering immediately. The tempering temperature is dependant on what hardness is required for the component. The steel is heated to the required temperature and held at this temperature for a minimum of one hour per inch of thickness (minimum 2 hours) and then allowed to cool. Certain steel/" target="_blank" class="keylink">tool steels require a double tempering. Certain steels can be given surface treatment, such as nitriding, when required.