Editing Galling (section)

==Incidence and location==
Galling is often found between metallic surfaces where direct contact and relative motion have occurred. [[Sheet metal]] forming, thread manufacturing, and other industrial operations may include moving parts, or contact surfaces made of stainless steel, aluminium, titanium, and other metals whose natural development of an external oxide layer through [[passivation (chemistry)|passivation]] increases their corrosion resistance but renders them particularly susceptible to galling.<ref>{{cite web |url=http://www.estainlesssteel.com/gallingofstainless.html |title=Stainless Steel Galling / Locking Up / Freezing Up |publisher=Estainlesssteel.com |access-date=2013-11-04}}</ref>

In metalworking that involves cutting (primarily turning and milling), galling is often used to describe a wear phenomenon that occurs when cutting soft metal. The work material is transferred to the cutter and develops a "lump." The developed lump changes the contact behavior between the two surfaces, which usually increases adhesion, and resistance to further cutting, and, due to created vibrations, can be heard as a distinct sound.

Galling often occurs with aluminium compounds and is a common cause of tool breakdown. Aluminium is a ductile metal, which means it possesses the ability for plastic flow with relative ease, presupposing a relatively consistent and significant plastic zone.

High ductility and flowing material can be considered a general prerequisite for excessive material transfer and galling because frictional heating is closely linked to the structure of plastic zones around penetrating objects.

Galling can occur even at relatively low loads and velocities because it is the real energy density in the system that induces a phase transition, which often leads to an increase in material transfer and higher friction.