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Annealing, Soft Annealing and Intercritical Annealing

Dec. 03, 2021


Annealing is a heat treatment process that alters the microstructure of a material to change its mechanical or electrical properties. Typically, in steel, annealing is used to reduce hardness, increase ductility and help relieve internal stresses. CHAOCHANG introduces you to some of the different types of annealing processes.

Annealing will restore ductility after cold working, so additional machining can be done without cracking. Annealing can also be used to relieve mechanical stresses caused by grinding, machining, etc., thus preventing deformation during subsequent high temperature heat treatment operations.

Applications and Materials

One of the main applications of annealing is to reverse the effects of work hardening. During cold forming, stretching, bending, etc., the material may harden to a point where further processing is not possible or causes cracking. Annealing operations at this stage will make the material more ductile, thus allowing further forming. In a similar manner, annealing is used to relieve the internal stresses generated during solidification of the weld.

In addition to steel, other metals may also benefit from annealing, such as copper, aluminum and brass.

Annealing, Soft Annealing and Intercritical Annealing

Steel Pipe Seam Induction Annealing Equipment

Soft annealing

Soft annealing is a high-temperature heat treatment process that revolves around A1. The purpose of the process is to make the material as soft as possible. After soft annealing, the material will have a soft and easily machinable structure. Steels with high carbon content, as well as most high alloy steels, are often difficult to machine when allowed to air cool after hot working (such as forging or hot rolling). Soft annealing reduces hardness and makes the material easier to machine.

Applications and Materials

Soft annealing can be performed on steel as well as copper and brass alloys. Soft annealing is typically performed on steels and tool steels with high carbon content to provide a softer and more machinable structure.

During the cold forming process of copper and brass parts, the material becomes harder. The greater the cold forming, the harder the material will become. The effects of cold forming can be eliminated by soft annealing.

Intercritical annealing

Subcritical annealing is annealing at a temperature slightly below the eutectic temperature. Subcritical annealing does not involve the formation of austenite, whereas critical annealing involves the formation of ferrite and austenite.

The purpose of the soft annealing process is to form a uniform distribution of spherical carbides in the steel, which will make the material softer and tougher. Usually, increasing the size of the spheres increases the machinability of the steel.

Applications and Materials

The spheroidal structure on carbon steel improves the cold formability of the steel and allows for severe deformation such as cold drawing or deep drawing. However, the spheroidized structure of carbon steel is not always suitable for certain machining operations because the material is too soft and can stick to cutting tools.

With the features of high quality, environmental protection, energy saving and high efficiency, Chaochang brand induction heating equipment has been widely used in machinery, metallurgy, mining, building materials, automobile parts manufacturing, fully meet the needs of steel pipe seam welding, H-beam welding, steel pipe annealing, metal heat treatment, smelting, forging, quenching and tempering,etc. Please send us a message if you are interested, and we'll be glad to help you.

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