Common Issues with Induction Hardening

07 February 2020

The process of induction hardening is for the purpose of hardening the surface of components made from steel or other carbon-alloy metals. Components or parts include a wide assortment of axles, pins, rollers and shafts. As much as 15-mm hardness depths can be achieved. Parts are placed in a special furnace that utilizes a coil to perform its function. When this coil is energised, it induces the parts with thermal energy via a strong magnetic field. While this process enhances the fatigue-resistance and toughness of various types of parts, the following issues do exist with this method.

Material Limitations

Typically, induction hardening is utilised on a wide variety of steels and carbon alloys. However, it is important to note that medium-carbon steels ensure the best results in hardening. Issues can arise in metals with a high carbon content, which will be discussed further later. Decarburized surfaces and surfaces with a low-carbon content will not harden properly with this process.

The Shapes of the Components Can Negate the Utilisation of Induction Hardening

Since the components must fit into the furnace without interfering with the induction coil, certain shapes may not be compatible with the shape of the coil or for that fact, the tooling of the furnace. Even though, there is a range of sizes and shapes of coils readily available for this use, some projects may require custom coils, which may cost more than the project merits. As a result, the shape and size of the components must be fully analysed to discover their compatibility with the available equipment for induction hardening.

Cracking Can Occur during the Induction Hardening Process

Another common issue that can happen with the induction hardening process is cracking. This can happen immediately during the process or as a delayed reaction days after the process. Top reasons for cracking include:

• Overheating during the process
• A high-carbon content in the steel or other carbon alloy
• Rapid heating and quenching also increases the risk for cracking in comparison to other heat-treating methods
• Geometric irregularities may interfere the proper operation of the induction coil

Distortions May Occur

The risk of distortion is higher with induction heating that with gas or ion nitriding, but it can be lower than the traditional heat treatment if it is applied to only a specific area.

Luckily, all these issues are preventable. Companies must analyse the materials closely to ensure that they contain the right contents for the ideal results. Also, the components need to be compatible with the shape and size of the induction furnace, coil and tooling. Proper monitoring is another necessity to keep problems from occurring due to overheating. When the process is performed correctly in all these areas, the results will be satisfactory.

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