Effect of different chromium contents on microstructure and two-body abrasive wear behavior of Fe-Mn-B surfacing alloys

Abstract

In this study, the effects of different Cr content on the microstructure, impact properties, and wear resistance of Fe-Mn-B wear-resistant surfacing alloy layers were investigated using plasma powder surfacing technology. The results indicate that the addition of Cr does not alter the phase of the surfacing alloy layer. Cr is primarily found in solid solution within the primary phase, with a small amount in the eutectic structure. The primary phase transforms from (Mn,Fe)2B to (Mn,Fe,Cr)2B, and the eutectic structure shifts from small blocks to lamellar (Mn,Fe,Cr)2B + γ-Fe. The incorporation of Cr increases the impact energy of the surfacing alloy layer, with the highest impact energy of 44.8 J/cm2 observed in the sample containing high Mn content and Cr. The fracture mode transitions from brittle fracture to a combination of brittle and ductile fracture. The addition of Cr promotes the precipitation of the primary crystal phase, enhancing its microhardness and consequently improving the macrohardness of the surfacing alloy layer. The macrohardness increases from 59.5 HRC in the low Mn content sample without Cr to 63.8 HRC in the high Mn content sample with 6.36 wt% Cr. The increased toughness and hardness of the primary phase, along with the transformation of the eutectic structure to lamellar, allow the primary phase to better resist abrasive particle indentation. As a result, the wear resistance of the surfacing alloy layer under two loads is significantly improved.