Chemical Heat Treatment of Tool Steel
Tool steel is a type of tough and durable metal produced for a variety of industrial applications, ranging from construction tools and automotive engines to surgical tools and instruments. Due to its extreme hardness and resistance to wear and tear, tool steel is often produced and treated using heat treatment processes. The most common type of heat treatment process used for tool steel is chemical heat treatment.
Chemical heat treatment is a process that selectively uses acids, bases or solvents to alter and develop specific physical, chemical or mechanical characteristics in a workpiece. By utilizing various chemicals, these treatments can be adjusted to increase hardness, increase wear resistance and improve the life of the tool.
As with all heat treatment processes, chemical heat treatment of tool steel is the process of heating a metal to a certain temperature, typically high above its recrystallization temperature, to cause changes within the metal at the atomic level. The heat treatment begins by cleaning the workpiece to remove any dirt, impurities, and scale that could potentially interfere with the process. After this initial cleaning process, the workpiece is then heated to the desired temperature and held there for a predetermined period of time. This process is known as quenching and is typically completed by submerging the part into an oil bath or an electrically heated furnace.
Once the part is quenched, it is then exposed to a chemical solution that will help induce the desired transformation within the steel. Depending on the type and nature of the desired physical, chemical or mechanical characteristic, the treatment will use different acids, bases or solvents. The solution is typically applied as a spray, dip or pour, and the part is left in this bath until the desired effects have been achieved.
An important consideration in chemical heat treatment of tool steel is the fireproofing of the material being treated. Fireproofing is required to prevent the part from combusting during the process. This is especially important when increased temperatures are used, as not only will the part be more prone to combusting, but its finished characteristic will also be different.
Finally, the part is then cooled again in an oil bath or an electrically heated furnace. Upon cooling, the desired chemical or mechanical changes will have occurred, and the tool steel will have been transformed.
In summary, chemical heat treatment of tool steel is a process that utilizes acids, bases or solvents to alter and develop specific physical, chemical or mechanical characteristics in a part. The process begins by cleaning the workpiece to remove dirt and impurities. Next, the part is quenched in an oil bath or an electrically heated furnace. After being quenched, the part is exposed to a chemical solution that will transform the steel in the desired way. Fireproofing is essential to prevent the part from combusting during the process, and then the part is cooled and the desired transformation is finished.
