Measurement of the threshold galling stress of hardfacing alloys

Galling is a severe type of wear that occurs when relative motion exists between contacting surfaces with extensive local adhesion. The ASTM button-on-block test method for galling resistance of a material couple requires a large number of specimens and an apparatus with very high load capacity for testing at a range of different loads to find the threshold galling stress. In contrast, the galling test method of sliding two crossed cylinders over each other has the advantages of determining the galling resistance by using a small number of samples and utilizing a standard metallurgical/mechanical test apparatus. In this study, the crossed cylinder method is used to test cobalt- and iron-based hardfacing alloys with very high threshold galling stresses. How to measure or calculate the threshold galling stress in the crossed cylinder method is also studied.