Characterization of boronized layers on a XC38 steel

Abstract

Boronizing of an XC38 steel was performed by immersion in molten salts. These were based on a borax containing three reducing agents: boron carbide (B4C), aluminium (Al) and silicon carbide (SiC). This work gives a survey on the nature and quality of the layers which were obtained according to the boronizing bath. The mechanical features (hardness, scratch and wear resistance) of the deposited layers are discussed according to the experimental conditions used for their characterization. Effects of the boronizing bath composition on the obtained layers' quality are also discussed.According to the borax's reducing agents, the boronized layer deposited on the XC38 steel was either single- or double-phase. Al and B4C led to double-phased boronized layers, whereas SiC gave way to a single-phase layer. All the layers were of comparable hardness which was about 2100 HV on the samples for the boride FeB and 1800 HV for the boride Fe2B.The scratch and “pin-on-disk” wear resistance depended on the layers' microstructure. The best values of scratch and wear resistance were obtained for SiC which led to the formation of a single-phase layer. The apparition of scaling occurred at loads superior to 200 N.