Comparison of threshold galling results from two testing methods

In this investigation, threshold galling tests were performed on several types of stainless steel using area contact and line contact testing procedures. The area contact test method employed was the ASTM standard G98, button-on-block test. In this test method, the end of a cylindrical button is placed in contact with a flat block at a desired contact pressure. The button specimen is rotated through one revolution and both specimens are visually inspected for the presence of galling. The line contact test method used was the button-on-cylinder test where the end of a stationary button contacts a cylinder along its length. After a given load is applied, the cylinder is rotated for a fixed number of cycles and the wear surfaces are inspected for galling. A comparison of the threshold galling results from each of the test methods is discussed in this report. Various testing conditions that influence the onset of galling are discussed, including sliding distance, surface oxide layer thickness, and stress distribution as well as the impact of the interpretation of experimental data on reported galling threshold magnitudes.