How to Resolve Problems Related to Induction Hardening

14 July 2022

Induction hardening is one of the surface hardening processes that manufacturers often maximise. This process entails the hardening of the metal part surface quickly and selectively.

Several manufacturers opt for induction hardening as it can provide tons of advantages to a wide array of metal parts and products such as increased wear resistance, increased strength and fatigue life, and minimised distortion. Workpieces that have undergone induction hardening can also be tempered right after, allowing manufacturers to adjust their hardness level.

Process Details of Induction Hardening

When conducting induction hardening, manufacturers would place the workpieces inside a copper coil to heat them above their transformation temperature. They would then apply an alternating current to the coil, which induces an alternating magnetic field within the workpiece. The outer surface of the workpiece is subsequently expected to attain a temperature above the transformation range. This step is later followed by quenching, which is carried out by a quench that is water-based with the addition of polymer. 

Resolving Induction Hardening Issues

While induction hardening is often done by professionals, the process can still be filled with issues due to a wide array of reasons. Here are some of the most common induction hardening issues and some ways to resolve or avoid them.

  • Low Hardness and Soft Spots: Induction hardening is meant to increase the strength and other properties of the workpieces. If a workpiece, however, possesses a low hardness level or soft spots, it means that the quenching has been done poorly. The improper quenchant concentration, poor or non-uniform agitation, excessive quenchant temperature, and the contamination of the quenchant can all cause the workpiece to attain these issues. Controlling the quenchant elements like temperature, concentration, agitation, and uniformity of agitation can help avoid these issues.  
  • Excessive Distortion or Cracking: As for excessive distortion or cracking of workpieces, they are caused by a low concentration of quenchant. These issues, fortunately, can be resolved by increasing the concentration of the quenchant. Changing to a slower polymer can also slow the quench down, which can minimise the chance of workpiece distortion. Excessive distortion and cracking can likewise be minimised by increasing the dwell time between the time the quench is on and the heat is off as well as reducing the quenchant’s flow or pressure.
  • Foaming: Foaming is another induction hardening issue that must be resolved to prevent wasting resources. Inadequate fluid levels, leaky sealing components on pumps, and excessive pressures can all cause foaming. To fix the foaming issue, manufacturers should add some defoamers. They can also increase fluid levels or repair or replace the pump seals. 
  • Corrosion: Corrosion issues, ultimately, can also be present with workpieces that have undergone induction hardening. These issues often happen when the parts that have been processed with induction hardening are not washed and rinsed properly. To avoid corrosion issues, manufacturers should enhance the corrosion protection of the quenchant. They must also wash and rinse any residual polymer from the processed workpieces. 

These are only some of the problems associated with induction hardening. To know more about them, you can contact us at Alpha Detroit Heat Treatment.

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