Sliding wear of hard materials — the importance of a fresh countermaterial surface

Abstract

The possibility of reproducing the contact conditions at a tool-workpiece interface in machining, using a laboratory wear test, has been investigated. For this purpose, a modified pin-on-ring test with continuous introduction of fresh countermaterial was designed. Using this equipment the wear characteristics of several hard materials (high speed steel, uncoated and coated cemented carbide), sliding against a quenched and tempered steel, were investigated. The results obtained in the modified test were compared with results from conventional pin-on-ring testing, and machining. Post-test metallographic examination demonstrated that it is possible to reproduce the contact conditions and wear processes in machining under controlled laboratory conditions using the modified pin-on-ring test. The dominant sliding wear mechanisms for hard materials against a fresh surface appear to be adhesive wear and solution wear. A conventional wear test cannot be used for wear testing of tool materials since transfer of pin material, depletion of alloying elements and changes in contact geometry produce a contact condition which differs significantly from the intended application.