Modification of M2 hardfacing: effect of molybdenum alloying and laser surface melting on microstructure and wear performance

Abstract

The influence of alloying (10 wt% Molybdenum) and post deposition treatment (Laser Surface Melting) on the structural characteristics and wear performance of Plasma Transfer Arc deposited M2 hardfacings have been investigated. The nature of matrix and carbides of M2 hardfacing had changed upon Molybdenum addition while the Laser Surface Melting caused structural refinement and a decrease in carbide volume fraction. Despite an increase in hardness, Laser Surface Melting has resulted in reduction in sliding wear resistance against alumina counterface, while the Molybdenum enhanced the wear resistance even with decrease in hardness. This counter intuitive behaviour is attributed to Magnelli oxide containing tribo-oxide layer formation on the worn surface of Molybdenum alloyed hardfacings.