Heat Treating

Basics of Heat Treating

Heat treating is the process of heating and cooling steel in a controlled manner. This process modifies the steel’s properties optimizing for end use or the next processing step. At King Steel, we utilize induction heat-treating processes to meet customer requirements.

Austenitizing (Harden Station)

Austenitizing is the first step in our heat-treating process. In this stage, the bar transfers to a uniform, austenitic state. Austenite transformation takes place above 1,500 degrees Fahrenheit. The specific austenitizing temperature used for each item depends on the grade, diameter, and customer specifications. Holding steel to a particular temperature for the required time is key to creating a uniform, austenitic structure.

Quench Process

Quenching is the rapid cooling of steel in water, oil, or air to achieve certain material properties. In our quenching process, we use temperature-controlled water to uniformly harden the steel. Additionally, just like other stages of the heat treatment process, quenching also relies on time and temperature. The difference is that quenching achieves a critical cooling rate and final temperature. Quenching transforms the austenite into martensite.

A glowing red (hot) piece of steel is placed on a workpiece to rapidly cool with water. This is process is known as quenching.


Tempering is required in almost all applications to ensure that the steel is not too brittle. During this stage of the heat treatment process, we hold the bar at a predefined temperature for a specific duration, which then determines the final hardness of the bar. Both the time and temperature are determined by the steel grade and diameter, as well as any hardness or mechanical properties that are specified by the customer.

Cooling, Testing and Cutting

  • Following tempering, we cool the bars before we test and cut them.
  • Once relatively cooled, we pass the bars through our non-destructive testing equipment. Our equipment identifies any defects like cracks or improperly hardened or tempered material.
  • Once the bars pass our tests, we trim both ends and cut hardness testing samples.
  • We may also gather samples for any tensile or Charpy impact testing required by our customers.
  • After the heat-treated material passes all testing, it is officially certified by our metallurgical lab. 

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