Microstructure And Wear-resistance Of Fe-C-Cr-V-Ti High-boron Hardfacing Alloys

Since the high-boron hardfacing alloys have the advantages as excellent abrasive wear resistance, low prices, good economic applicability, guaranteed source of raw materials, Fe-C-Cr-V high-boron hardfacing alloys with and without Ti containing 7.0%-17.0% Cr, 0.7%-1.8% C, 0-1.8% B (these were all the mass fraction) were deposited by the method of flux-cored wire automatic submerged arc welding. The microstructure and carbide morphology were investigated systematically by optical microscopy (OM), scanning electron microstructure (SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectrometers (EDS).Firstly, the effects of B4C in flux-core wire on hardness and wear properties were evaluated. The experimental results demonstrate that the microstructure of Fe-Cr-Ti-B hardfacing alloys containing TiB2 phases consisted of a large number of ferrite, a small amount martensite and borides or carbides such as (Fe, Cr)3(C,B), TiB2, TiC, (Fe, Cr)2B, (Fe, Cr)B etc. And abrasion resistance of Fe-Cr-Ti-B hardfacing alloys is excellent because the hardness of TiB2 and TiC is high. With the addition of B4C in flux-core wire, the hardness and relative wear resistanceεfirstly increases, and then reduces. The optimum effect is acquired when B4C content is 5%.In addition, the effects of alloying elements, including the Cr, V, Ti, C and B in the Fe-C-Cr-V high-boron hardfacing alloys on microstructure, hardness and wear properties were also investigated. The effects of experimental load on hardness and wear properties of Fe-C-Cr-V high-boron hardfacing alloys were evaluated by changing the weight of wet sand rubber wheel wear experiment. The experimental results demonstrate that the microstructure of Fe-C-Cr-V high-boron hardfacing alloys consisted ofα-Fe, borides and carbides, too. But the borides and carbides are M3(C, B), M2B, VC, M8B etc. Hardness and abrasion resistance of Fe-C-Cr-V hardfacing alloys changes with the alloying element content. When the Cr content is 11%, V content is 2%, C content is 1.55% and B content is 1.12%, the effect is the most optimum. In addition, after adding the Ti, the microstructure is refined and the abrasion resistance increases obviously. The abrasive wear test results demonstrate that the wear mass loss of Fe-C-Cr-V high-boron hardfacing alloys doesn't increase with the increase of experimental load,but firstly increases, and then reduces. The tendency appears the"Λ"variation curve which is different from the abrasive micro-cutting model proposed by E.Rabnowicz.