What Is Peening in Heat Treatment?

There are many aspects to metal working and heat treatment processes in Gastonia, NC. If it’s not your area of expertise, metal working is best left to professional metallurgical and heat treatment specialists. One part of the heat treatment process is called peening in Gastonia, NC, which involves working with the metal when it’s cold. There are many types of peening processes. Learn more below!

The cold working process

Peening in Gastonia, NC involves working with the metal when it’s cold. The surface of the metal is deliberately deformed by hammering during the peening process. The material reacts to peening in a favorable way. The surface layer tries to expand laterally upon impact, but can’t do so because of the elastic nature of the layers beneath. This creates residual stress in the surface layer and residual stresses throughout the material. The stress created by peening on the surface is more apt to reduce cracks and is more resistant to erosion, corrosion and fatigue. There are several main peening techniques:

  • Shot peening: In shot peening, the surface is bombarded by shots, or spheres of cast iron, cast steel or stainless steel. A high velocity stream of air usually is the force behind the shot, and the process can be manual or automatized.
  • Roto peening: Also known as flail peening, roto peening involved impacting the surface with two or more shot-coated flaps from a spindle. Each flap includes a cast steel or tungsten carbide shot in a wire mesh. The flail is inserted into a drill, which can rotate the flaps at the appropriate speed.
  • Needle peening: Needle peening uses a de-scaling gun with needles with radiused ends. The metal needles are usually made of hardened steel. The surface being peened is impacted multiple times with the needle.
  • Hammer peening: Hammer peening is done with a single metal rod and applied similarly to needle peening. A ball is fixed to the end of a hammer, which applies stress relief between passes.

Controlling the process

A high degree of control and precision are necessary during peening in Gastonia, NC. The intensity of each method is controlled and calibrated for each metal component being peened. Sometimes, an Almen strip is used to measure the deformation. The metallic strip is peened as well and deformed, and then the extent of deformation is measured and adjusted to reach the appropriate intensity.

J.F. Heat Treating Inc. is your local professional metallurgical and heat treatment company in Gastonia, NC. We provide all types of heat treating services to soften, harden, relieve stress and remove contaminants from your metal parts and components. Our professional heat treatments in Gastonia, NC include annealing, aging, quenching and tempering of all types of equipment, from basic parts to state-of-the-art machines. All our services are designed to completely soften, harden, carburize, relieve stress on, remove contaminants from or alter your components without changing the shape of the product. We are a full-service lab and can treat all types of parts or machines. Reach out to us today to schedule a consultation!

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