Galling wear occurs when 2 contact surfaces are in sliding friction under relatively high pressure. Often this is exacerbated by either a lack or failure of lubrication, and occurs principally in materials with a high coefficient of friction.

Galling wear or failure can be recognized by deep scoring in the contact surfaces. Galling occurs when a surface (or both surfaces) undergoes plastic deformation, developing gouges in the contact area.

Galling commonly occurs in stainless steel, aluminum and other relatively ductile materials which also exhibit high friction in sliding contact. This type of wear can include or be exacerbated by bits of one surface becoming embedded in the other. This is most likely to occur when the surfaces in contact are of the same or similar materials. Severe galling is likely to result in seizing (in the event that the surface deformations result in the mechanisms degrees of freedom becoming fully constrained, creating an interference fit).

Galling wear can be avoided by material selection and choice of lubrication. Parts which cannot or should not be lubricated can often be prevented with anti seize compound.