Investigations on microstructure, mechanical properties and abrasion resistance of 4wt%Cr-2wt%Mn-2wt%Cu-Fe-B alloy

摘要

The microstructure, mechanical properties and abrasion resistance of Fe-B alloy with 4wt%Cr-2wt%Mn-2wt%Cu addition have been systematically investigated. The results show that the microstructures mainly consist of martensite and boride (M2B) in the as-cast and heat treated Fe-B alloys; after heat treatment, the morphology and volume fraction of the M2B have little change, meanwhile the nucleation and precipitation of secondary borocarbide M-23(C, B)(6) probably take place in an in situ manner within martensite. Moreover, the M2B is identified as chemical formula of Fe2.04Cr0.11Mn0.07(B, C) reflecting body-centred tetragonal (bct) structure, and the secondary borocarbide M23(B, C)(6) has the stoichiometry of Fe18.84Cr2.84Mn0.57(B, C)(6) with face-centred cubic (fcc) structure. After heat treatment, the matrix hardness and bulk hardness of Fe-B alloy decrease owing to the decreasing of B/C concentration of matrix caused by the precipitation of M-23(C, B)(6), while the fracture toughness of Fe-B alloy increases. Meanwhile, the heat treatment will decrease the wear resistance of Fe-B alloy, i.e. the wear resistance of Fe-B alloy would decrease with reduction of the matrix hardness.