We conclude David Pye's blog series on the causes and effects of distortion. Parts 1-3 can be found here.

Surface Treatments

Surface treatment of steels will also contribute to the distortion factor. Anytime that the steel surface is changed by volume, growth has occurred. Therefore, a volumetric change will occur when introducing carbon, nitrogen, oxygen, boron and sulfur into the steel surface.


If a failure has occurred, the first and (perhaps) most important thing to do is to gather as much of the failed part as possible. Then retrieve all of the events leading up to the part failure, such as environmental conditions, part loading, engineering, material and so on.

Remember, your heat treater is only a phone call away. Remember also that the heat treater sees many issues, suggests many heat-treatment methods and solves many problems.

Talk to the heat treater when you are designing the part, and obtain their input. It could have the potential to prevent and solve many problems before the part gets to the heat-treatment operation.