What Is Peening, and Why Is It Used in Welding?

Peening is a technique used in welding to help strengthen joints. It consists of a process in which a small metal ball is struck with a peening hammer to create compressive forces on the surface of the metal, creating a denser surface. These forces can be used to improve mechanical properties such as yield strength, tensile strength and fatigue life.

The purpose of using peening in welding is often used to remove surface defects, such as slag or oxides. It’s also used to correct for the effects of cold shuts, which are surface defects that can cause welds to break.

There are three basic types of peening processes:

  • Manual peening: Manual peening can be carried out by striking the surface of the welding joint with a conical (or spherical) hammer. The surface is deformed and compressed where the impact occurs. This method can be used for flat or fillet joints.
  • Automated peening: In automated (mechanical) peening, a machine stamps the surface of the welding joint with an array of needles (similar to nails) and also deforms and compresses the surface. When using this technique, you must ensure that the correct amount of force is applied to prevent the welding joint from becoming too deformed or broken.
  • Shot peening: In shot peening, a motorized wheel bombards the surface of the welding joint with a stream of small metal media. This process is often used when there are weld irregularities or discontinuities in the joint.

What is the purpose of peening?

Peening can help improve the fatigue life and strength of a welded joint. This happens by increasing the surface area and compressive stress on the weld. Peening can also help eliminate surface defects, such as slag inclusions. Slag inclusions are small areas of molten metal trapped within the weld.

What types of welding is peening used in?

Peening isn’t limited to specific kinds of welding. It can be used in many different applications and welding processes, including (but not limited to) gas metal arc welding, tungsten inert gas (TIG) welding, plasma arc welding, stick welding and more.

Peening is often used in the welding of heat-treated steels. It’s widely recognized that the fatigue resistance of welded structures is strongly dependent on the properties and quality of the weld metal. Peening may also be carried out on the surface of non-heat-treated steels.

Why use peening in welding?

Peening offers several advantages that can help improve the welding process. Because it increases the fatigue life of the weld by increasing its surface area, the weld will be able to resist stress.

At J.F. Heat Treating Inc., we’re pleased to offer shot peening and mechanical hammer peening services to improve the properties of our clients’ metal components, along with a full array of other metallurgical services. With our commitment to customer service and first-rate workmanship, you can trust us with your metal treating jobs, every time. Reach out to us today to learn more or get a quote for your project. We look forward to working with you soon.

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