Effect of Microstructure on Properties of NiCrBSi Alloys Applied by Flame-Powder Deposition

Abstract

This article deals with studying the relationships among the chemical composition, microstructure and properties (hardness, micro-hardness, wear resistance) of powder additives based on NiCrBSi after their deposition. Tested materials reached a relatively wide range of hardness after deposition, which corresponds to their chemical composition and microstructure. The abrasive wear resistance of materials was tested on an emery cloth. The results indicate that both the hardness and abrasive wear resistance of tested materials depend especially on the content of carbon and chromium. Microstructural analysis indicates that the structure of tested materials is formed by the γ-Ni solid solution and intermediate phases based on boron, silicon and carbon. Those mostly form eutectics (three types), or are excluded by precipitation. There was also found a significant effect of chromium, but especially carbon content on the ratio between the solid solution and eutectics in the microstructure of tested materials. These different ratios of solid solution and eutectics were markedly reflected in micro-hardness behaviours in deposited layers. Micro-hardness values confirmed also the presence of carbidic particles in the layers with carbon content higher than 0.7 wt%.

Factors Influencing Cavitation Erosion of NiCrSiB Hardfacings Deposited by Oxy-Acetylene Powder Welding on Grey Cast Iron

“…Based on the analysis of metallographic investigations done using SEM and analysis of the cavitation erosion (CE) curves followed by the profilometric measurements allow confirming the effect of microstructure on the CE process. First of all, the microscopic investigation supports the literature data information regarding the microstructure of the coating [30,48]. Oxy-acetylene deposits microstructures consist of a relatively ductile Ni-based matrix with various amounts of hard particles (Fig.…”

“…From the broad grades of metallic materials, the nickel alloys present promising applicability to cast iron workpieces [26]. The self-fluxing nickel alloys Ni-B-Si and Ni-Cr-B-Si can be deposited by different methods likewise oxy-acetylene powder welding [30], plasma arc welding [26,31], laser cladding [32], flame spraying [33,34], HVOF [35,36]. The low melting point and high substrate wettability guarantee effective deposition of NiCrSiB on different metallic substrates likewise steel [37], Ti6Al4V titanium alloy and cast iron [26,34].…”

“…The self-fluxing nickel alloys have a complex microstructure dominated by nickel-based solid solution, eutectics e.g. Ni 3 B, Ni 5 Si 2 , chromium carbides mainly Cr 23 C 6 and Cr 7 C 3 , borides or complex chromium carboborides [30,35,38]. Furthermore, usually deposits hardness increases as the content of chromium, boron, silicon and carbon [38].…”

Cavitation erosion damage of self-fluxing NiCrSiB hardfacings deposited by oxy-acetylene powder welding

“…In the case of metallic materials, nickel-based materials present a promising applicability to different types of metallic substrates [17]. The self-fluxing NiCrSiB and NiBSi alloys can be deposited by various techniques, such as flame spraying [23,24], oxy-acetylene powder welding [25], laser cladding [26], plasma arc welding [17,27] and HVOF [28,29].…”

“…The self-fluxing nickel-based alloys have a multiphase microstructure consisting of nickel-based solid solution, chromium carbides, mainly Cr23C6 and Cr7C3, borides or complex chromium carboborides and eutectics e.g. Ni3B, Ni5Si2 [25,28]. Furthermore, the hardness of deposits usually increases along with the percentage ratios of chromium, silicon, carbon and boron.…”