Modification of 27Cr cast iron with alloying yttrium for enhanced resistance to sliding wear in corrosive media

Abstract

Yttrium has been found to be beneficial to the wear resistance of (Cr, Al)-containing alloys in corrosive environments. In this study, the performance of chill-cast 27Cr white iron alloyed with yttrium during sliding wear in different media, including tap water, dilute NaOH, and HNO3 solutions, was investigated. Compared to Y-free 27Cr cast iron, the Y-containing cast iron showed improved wear resistance. The study demonstrated that chill-cast 27Cr white iron containing 1 wt pct yttrium performed the best and that too much yttrium, however, deteriorated the material. In order to understand the beneficial role that yttrium played, mechanical properties of Y-containing and Y-free cast irons and their passive films were investigated. The electron work function, corrosion, and anodic polarization behavior of the materials were also studied. It was clarified that the beneficial role of yttrium was attributable to improved passivation capability with enhanced passive film. For comparison, sandcast 27Cr white iron was also investigated.