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The 6 Most Common Forms of Heat Treatment

December 16th, 2020

Steel is one of the most widely used materials in the world. From appliances to home construction to car parts, steel is everywhere. To manipulate this and other types of metal and make them appropriate for use, manufacturers heat metals. When deciding how to go about this, engineers and product developers must choose from the most common forms of heat treatment.

Different heat treatment options create varying changes in the physical properties and malleability of steel from the inside out. Access to certain options can, therefore, affect the design, product development and material choices.

Soaking

Soaking is one labor-intensive and time-consuming way to heat steal. It involves heating the metal to the desired temperature and then keeping the metal at that temperature, evenly, through the entire structure. The bigger or thicker the structure, the longer professionals must soak it to achieve the desired effect. This type of heat treatment is applicable to a wide variety of metal types.

Drawing or Tempering

When the steel cools, it hardens and becomes too brittle for manipulation in this state. Through tempering, which is one of the most common forms of heat treatment, professionals reheat the material to release some of the internal stressors that make it so brittle. These stressors were originally created by the rapid cooling process when the steel was initially heated and hardened. Unlike other treatment options, professionals allow it to cool in the open air.

Annealing

Like tempering, annealing can help to relieve some of the internal stresses caused by a rapid cooling process. Professionals reheat the metal to the desired temperature in an attempt to accomplish several tasks:

• Refine the metal’s grain structures
• Make the metal more ductile
• Soften the metal

When cooling after this process, the rate of cooling makes a big difference. One of the drawbacks of this addition to the most common forms of heat treatment is that workers do not usually allow the metal to cool in the open air. Instead, they may bury the hot portions of the metal to insulate it while it cools very slowly. Annealing may work for both ferrous and non-ferrous metals.

Normalizing

Some specialists prefer normalizing over annealing. One reason for this is that normalized metal, particularly steel, is usually stronger than annealed metal. This process usually follows high levels of manipulation to metal, which includes forging, welding and machining. Manufacturers generally normalize the parts of steel that they expect to suffer the most vigorous conditions in the real world.

Nitriding

This is another form of case-hardening that is commonly used to treat ferrous metals. When choosing nitriding, workers use nitrogen on the surface of the metal. This hardens the exterior. While very effective, it is only commonly used on low-alloy and high-carbon steels. Some treatment specialists may also apply this to aluminum, titanium and molybdenum.

When choosing from the most common forms of heat treatment for your production process, you may come to the realization that you prefer to outsource this process. Outsourcing heat treatment may save you hundreds of thousands of dollars in the capital you would otherwise need to invest in expanding your operations and re-training workers. It also allows you to capitalize on other professionals’ economies of scale.