Plasma chromizing and wear resistence of Ti6Al4V alloy and AISI420 stainless steel

Glow plasma chromizing was conducted on the surface of Ti6Al4V alloy and AISI420 stainless steel respectively to improve their wear resistance. Effect of microstructure on the friction and wear properties of the alloyed layers was also investigated. The results show that both alloyed layers are more than 60 μm in thickness. The alloyed layers have good compactness and high bonding strength. The alloyed layer on Ti6Al4V substrate consists of Cr-deposited layer, Cr₂Ti-rich layer, CrTi₄ layer and Cr-Ti solid solution layer. The Cr₂Ti-rich layer has the highest hardness (2.3 times of that of Ti6Al4V substrate); The alloyed layer on AISI420 substrate contains the Cr-deposited layer and Cr₂₃C₆-rich diffusion layer. Moreover, the transition zone between Cr-deposited layer and diffusion layer has the highest hardness (4.5 times of that of AISI420 substrate). The chromized layer can improve the wear resistance of the two substrates remarkably, which closely relates to the phases of the chromized layers. For Ti6Al4V alloy, the Cr-deposited layer and the Cr₂Ti-rich layer both have excellent wear resistance, while the Cr-Ti solid solution layer has poor wear resistance. For AISI420 steel, the Cr-deposited layer and the transition zone have excellent wear resistance, while the inner of diffusion layer has poor wear resistance. The chromizing makes the main wear mechanism transfer from the abrasive wear to the adhesive wear for the two substrates.