Heat treatment of tool steels

In this article, we will discuss the heat treatment of tool steel, specifically hot and cold-rolled, chipper steel, HSS steel, 1.2379, and steel used for shear blades production.

Hot and cold-rolled steel are two common types of tool steel. Hot-rolled steel is produced by rolling the steel at a high temperature, while cold-rolled steel is produced by rolling the steel at room temperature. The heat treatment process for hot and cold-rolled steel is similar, but the cooling rate after heating is different. The standard heat treatment process for both types of steel is quenching and tempering.

Quenching involves heating the steel to a temperature above its critical point, which is the temperature at which the steel loses its magnetic properties and becomes non-magnetic. The steel is then rapidly cooled by immersing it in a quenching medium such as oil or water. The cooling rate is critical as it determines the final properties of the steel.

Tempering is the process of reheating the quenched steel to a temperature below its critical point and holding it at that temperature for a specific time to achieve the desired properties. Tempering reduces the hardness of the steel, increases its toughness, and improves its dimensional stability.

Chipper steel is a type of tool steel used for making wood chippers, which are used to chip or shred wood. The heat treatment process for chipper steel is similar to that of hot and cold-rolled steel, but the cooling rate after heating is slower. The standard heat treatment process for chipper steel is annealing, followed by quenching and tempering.

Annealing involves heating the steel to a temperature below its critical point and holding it at that temperature for a specific time to relieve any internal stresses and soften the steel. The steel is then slowly cooled in a furnace to room temperature.

High-speed steel (HSS) is a type of tool steel used for making cutting tools such as drills, taps, and milling cutters. HSS steel contains a high percentage of tungsten, molybdenum, and cobalt, which gives it excellent wear resistance and toughness. The heat treatment process for HSS steel is similar to that of chipper steel, but the cooling rate after heating is even slower. The standard heat treatment process for HSS steel is annealing, followed by hardening and tempering.

1.2379 is a high-carbon, high-chromium tool steel used for making molds, dies, and cutting tools. The heat treatment process for 1.2379 steel is similar to that of HSS steel, but the cooling rate after heating is even slower. The standard heat treatment process for 1.2379 steel is annealing, followed by hardening and tempering.

Steel used for shear blades production is a type of tool steel used for making shear blades, which are used to cut sheet metal. The heat treatment process for steel used for shear blades production is similar to that of 1.2379 steel, but the cooling rate after heating is slower. The standard heat treatment process for steel used for shear blades production is annealing, followed by hardening and tempering.

Advanced CNC-controlled vacuum furnaces have become increasingly popular in recent years as they offer several advantages over traditional heat treatment methods. Vacuum furnaces provide a cleaner environment for heat treatment, which reduces the risk of contamination and improves the quality of the final product. They also offer precise temperature control and can be programmed to follow specific heat treatment cycles, which results in consistent and repeatable results.

Tempering is an essential step in the heat treatment process for tool steel. After quenching, the steel is very hard and brittle, and tempering helps to reduce the hardness and increase the toughness of the steel. During tempering, the steel is heated to a temperature below its critical point and held at that temperature for a specific time to achieve the desired properties.

The properties of the steel after tempering depend on the temperature and time of the tempering process. Lower tempering temperatures result in higher hardness and lower toughness, while higher tempering temperatures result in lower hardness and higher toughness. It is crucial to select the appropriate tempering temperature and time for the specific application of the tool steel.

Double tempering is a technique that involves two tempering cycles after quenching to further refine the structure of the steel. Double tempering is commonly used for high-performance tool steels, such as HSS steel and 1.2379, to achieve the desired combination of hardness and toughness. The first tempering cycle reduces the residual stresses in the steel and improves the ductility, while the second tempering cycle helps to stabilize the microstructure and reduce the risk of cracking.

The microstructure of tool steel after heat treatment can vary depending on the cooling rate during quenching. If the steel is rapidly cooled, the microstructure will be primarily martensitic, which is very hard and brittle. If the steel is slowly cooled, the microstructure will be primarily austenitic, which is softer and more ductile. The desired microstructure depends on the specific application of the tool steel.

In conclusion, heat treatment is a critical process in the production of tool steel, and quenching and tempering are the standard heat treatment processes for hot and cold-rolled steel, chipper steel, HSS steel, 1.2379, and steel used for shear blades production. The selection of the appropriate heat treatment process depends on the specific application of the tool steel. Tempering is an essential step in the heat treatment process and helps to reduce the hardness and increase the toughness of the steel. Double tempering is a technique commonly used for high-performance tool steels to achieve the desired combination of hardness and toughness.