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An Overview of the Heat Treatment Process of Metals and Its Benefits

The heat treatment process of metals is important to understand. Learn more below.

Heat Treatment Process of Metals and Its Benefits - KB Delta

The basic heat treatment process has not changed much over the years. There was a time when blacksmiths used heat treatment in shaping metals for horseshoes, wagon components, etc.

When heated to high temperatures, metals become malleable and can be cooled quickly. Rapid cooling makes the metal less brittle but much harder than usual.

But modern metalworking and machining processes have taken the heat treatment of metal to another level as they are more sophisticated and precise.

Experts employ several techniques for shaping metals used for a wide variety of purposes. Heat treatment processes alter or change how metals respond to precision machining. The processes also change the properties of these metals. Some of these properties include strength, elasticity, strength, machinability, formability, etc.

This article highlights what you need to know about heat treatment.


Heat Treatment: What Is It?

The heat treatment of metal – such as steel, iron, etc. – involves heating the material to a particular temperature. Then it is cooled rapidly in order to harden the heated metal. This process also helps uncover the metal’s desired chemical, physical, and mechanical properties.

Altering the properties of specific materials hold lots of benefits. When a metal undergoes heat treatment, the process increases the metal’s surface hardness, ductility, temperature resistance, and strength.

When a metal component is improved this way, it enables the component to ably withstand considerable wear and tear. This is why heat treatment is one of the major aspects of the manufacturing process of metals.


How Heat Treatment of Metals Work

Numerous heat treatment processes exist, but they generally follow the same principle. First, the metal or alloy is heated to a specified temperature range. The time it takes to heat the metal to that specific temperature is referred to as the “soak time.” The temperature could be as high as or even above 2,400 degrees Fahrenheit. The material is maintained at this particular temperature for some time before it is cooled.

But while the metal or alloy is still very hot, some microstructural changes occur. As the metal undergoes almost undetectable changes, the structure also changes.

Here’s where the soak time matters: it is one of the essential factors in heat treatment processes. A metal or alloy can be soaked for extended periods. The more extended the period, the more microstructural changes the material undergoes.

How the metal is cooled also plays a vital role in the outcome of the entire process. For instance, a quick cooling process is known as “quenching.” Another cooling process is performed slowly in a furnace.

No cooling method is better than the other. Everything depends significantly on the result or outcome expected from the entire process. This is why considering these factors is highly crucial before embarking on the heat treatment of metals and alloys.

Some metals also require several heat treatment processes before achieving the desired result. Understanding the best ways to carry out these heat treatment operations is also essential as it helps eliminate time wastage.


Types of Heat Treatment

All heat treatment processes involve heating and cooling. Here are the 4 major heat treatment types you should know and their distinct purposes:


1. Annealing

This heat treatment process is highly suitable for metals like aluminum, brass, copper, steel, or silver. It increases a metal’s ductility and decreases its hardness. This process helps relieve some metals’ internal stresses and fixes weak metals.

Annealing involves heating the material until it reaches a specified temperature. Then you maintain the temperature of the metal for a specific period so that some transformation occurs. Air cooling the metal comes next.

Cooling of the metal may occur quickly or slowly for brass, copper, and silver. But effective annealing is felt when steel is cooled gradually.


2. Tempering

This heat treatment process helps boost the resilience of metals such as steel. Most iron-based alloys are too brittle to be used for particular applications. But tempering helps alter iron-based alloys’ brittleness, hardness, and ductility. This heat treatment process aims to help make machining processes easier.

Tempering involves heating the metal at temperatures below the critical point. Low temperatures are known to maintain hardness while minimizing brittleness. This heat treatment process reduces the hardness caused by hardening.

This is why in many cases, tempering follows hardening (discussed next) during heat treatment.


3. Hardening

This heat treatment process is all about heating metals to a particular temperature. The temperature is usually the specific point at which all the elements that make up the metal dissolve into a solution.

Metals have crystal lattice structures, which may be defective and bring about plasticity. But hardening is the process that deals decisively with such defects.

This occurs when the metal goes into the solution of incredibly fine particles, and the metal becomes strengthened. After extensive heating of the metal, it is quenched.

Quenching efficiently helps the metal to trap the particles in the solution. But in some cases, technicians add impurities in order to enhance the alloy’s strength.

The primary purpose of hardening is to boost the material’s overall strength. But it also makes the metal more brittle and decreases its flexibility. This is why it is highly recommended that you temper the metal (discussed above) right after the hardening process.


4. Normalizing

This is another heat treatment process akin to annealing. The metal is heated until it reaches about 200 degrees Fahrenheit. This is much higher than the temperature for annealing processes.

The metal in this process is held at this critical temperature until some transformations occur. Then air cooling comes next.

Normalizing results in smaller austenitic grains. Air cooling the metal results in the production of highly refined ferritic grains. It eliminates all forms of internal stress from the material. Internal stress can result in metal failure, which is an undesirable outcome. This is why normalizing metals is highly critical.


What Are the Benefits of the Heat Treatment of Metals?

The heat treatment of metals has lots of benefits. For instance, the metal components for equipment such as reciprocating compressors will not exist without heat treatment. Even if they do, they will never function in the exact manner that is desired.

Heat treatment also strengthens alloys and metals such as aluminum and steel. These materials have found numerous applications in various industries. Some reciprocating compressor components are also constructed from these metals, resulting in improved performance.

Using highly effective heat-treated metals ensures machines’ cost-effective operation as they ensure durability and efficiency.



The heat treatment of metals is an excellent way of enhancing their mechanical attributes. The process also boosts the magnetic and electrical properties of metals. This makes such metals more compatible with other materials used in reciprocating compressors, etc.

The benefits associated with heat treatment processes cannot be overstated. These processes help ensure the smooth functioning of machines such as reciprocating compressors. They also ensure the production of vital components that many equipment and devices use in various industries.



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