Quenching for Induction Heat Treating (Why It’s Essential)

Manufacturers know that a cracked part can lead to devastating results for their products. Each stage of a part’s production needs to guarantee quality and durability. Zion Industries’ proven business model creates an induction heat treating process specific to your part, including inspection and quality control. From shafts to valves to gears, we ensure that your parts are heat treated with quality and precision.

Induction heat treating is a method that uses electricity to heat up a specific area of a metal part. For successful induction hardening to take place, two critical steps must occur:

1. the metal part must be heated to the correct temperature, and
2. the metal part must be cooled down at the appropriate rate to eliminate cracks and to achieve the correct hardness.

Quenching is the process of cooling a part. There are many ways to cool a part, and each one provides different results. The most common way to cool a part when using induction heat treating is with water. Zion will often add a polymer to the water to change the cooling properties of the water.
There are a couple reasons to change the cooling properties of the water.

First, a vapor barrier might form around the part when the water is directed toward a heated material. The vapor barrier occurs when the water approaches the heated material and the water vaporizes before it can reach the part. Adding as little as 2% concentration to the water can start to eliminate that vapor barrier. It can cool the part down faster than plain water because the water/polymer mix will coat the part. The second reason to change the cooling properties of the water is to control the speed for cooling down a part.

To slow down how quickly the heat is pulled from the part, increase the percentage of polymer in the water.

Controlling the speed of quenching can affect a few areas of the quality of the induction hardening process, including the hardness of the part and the stresses in the material. Sometimes the stresses in the material will propagate as a crack, which is seldom a good thing in a manufacturing process.

Both the carbon content and the alloys added to the steel determine the ultimate hardness capability of the material. This means every material has a different cooling curve. The rate to reduce the temperature of a part from its ideal maximum temperature to its metallurgical “cooled” temperature differs, based on the properties of the material.

Zion specializes in induction heat treating and has a concrete understanding of how each metal behaves. With more than 39 years of experience, our engineers know the right recipe to use for each type of metal to make sure that we supply our customers with the specific induction heat treating process required for their part.
Request a quote today or call us at 330-483-4650 for more information.