(i) Wear or abrasion
(ii) Impact
(iii) Erosion
(iv) Galling,
(v) Cavitation,
(vi) Heat, and
(viii) Corrosion.
This process is called hardfacing because the deposited surfaces usually are harder than the base metal. (However, this is not always true. In some cases a softer metal, such as bronze, is applied to harder base metal).
The term hardfacing is actually most appropriate when used with alloys such as cobalt, chromium, tungsten carbide, chromium-manganese iron and iron base alloys containing various percentages of cobalt, chromium, vanadium and molybdenum, to mention a few. These alloys are outstanding for extreme abrasion, severe impact and high temperature applications.
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