Effect of Ti, Al, Si on the Structure and Mechanical Properties of Boron-Rich Fe–B–C Alloys

Abstract

The effects of substitution of Fe in the boron-rich Fe–B–C alloys, containing 10.0–14.0 % B; 0.1–1.2 % C; Fe – the remainder, 5.0 % Ti, Al, or Si (in wt. %) have been studied with optical microscopy, X-ray diffractometry, scanning electron microscopy, energy dispersive spectroscopy. Mechanical properties, such as microhardness and fracture toughness, have been measured by Vickers indenter. The microstructure of the master Fe–B–C alloys cooled at 10 and 103 K/s consists of primary dendrites of Fe(B,C) solid solution and Fe2(B,C) crystals. It has been found that titanium has the lowest solubility in the constituent phases of the Fe–B–C alloys, with preferential solubility observed in the Fe(B,C) dendrites, where Ti occupies Fe positions. This element has been shown to be mainly present in secondary phases identified as TiC precipitates at the Fe2(B,C) boundaries. Titanium slightly enhances microhardness and lowers fracture toughness of the boron-rich Fe–B–C alloys due to substitutional strengthening of Fe(B,C) dendrites and precipitation of the secondary phases. The level of the content of Al or Si in the Fe(B,C) and Fe2(B,C) solid solutions and quantity of the secondary phases observed in the structure suggest that more Al or Si are left in the constituent phases as compared with Ti. These elements mainly enter the crystal lattice of Fe2(B,C) phase replacing iron atoms and form at their boundaries AlB12C and SiC compounds respectively. The additions of Al and Si to the boron-rich Fe–B–C alloys help to modify their fragility: while they slightly decrease microhardness values, addition of these elements improves the fracture toughness of the constituent phases. Increase in a cooling rate from 10 to 103 K/s does not bring about any noticeable changes in the solubility behavior of the investigated alloying elements. The rapid cooling gives rise to microhardness and fracture toughness of the phase constituents which average sizes significantly decrease. The effects of the alloying elements on the structure and mechanical properties of the investigated boron-rich Fe–B–C alloys have been explained considering differences in the atomic radii and electronic structure of the solute Ti, Al, or Si atoms.

Prediction of phase composition and mechanical properties Fe–Cr–C–B–Ti–Cu hardfacing alloys: Modeling and experimental Validations

“…Aluminum and silicon are sp-elements, whereas copper atomic configurations tend to the stable d5–states. The higher solubility of Al and Si in the boron-rich Fe–B–C alloys, as compared with Ti, may be attributed to the stronger acceptor abilities of these elements [ 65 ]. Copper is not dissolved in hemioboride Fe 2 (B,C) and borocementite Fe 3 (B,C), but titanium carbide TiC is dissolved only in the matrix.…”

“…In addition, it is necessary to reduce the cost of filler materials and improve the hardfacing process efficiency In this connection, Fe–C–B system alloys being highly resistant to abrasive wear and having relatively low cost, become more widely spread [ 59 , 60 ]. Today, there are numerous investigations into simple ternary alloys of the Fe–C–B system [ [61] , [62] , [63] , [64] ], as well as additionally alloyed with a carbide-forming element [ 25 , [65] , [66] , [67] ] such as Cr [ 41 , [68] , [69] , [70] ], V, Nb, Mo [ 71 , 72 ], Ti [ 47 , 73 ], ferrite forming element (Al, Si) [ 58 , 73 ] and austenite forming element [ 74 ] (Cu [ 75 , 76 ], Ni, Mn). Boron can form the following compounds in these alloys: iron monoboride FeВ, hemioboride Fe 2 B, Fe 3 (B,C) and cubic boron carbide Fe 23 (C,B) 6 .…”

Effect of Exothermic Additions in Core Filler on Arc Stability and Microstructure during Self-Shielded, Flux-Cored Arc Welding

“…For the flux-cored arc welding process of filler materials, melting is mainly carried out by arc welding [47,48]. Additionally, an important aspect is the study of the mechanical properties of the deposited metal [49][50][51][52]. The final microstructure and mechanical properties depend on the cooling conditions of the deposited metal [53,54] and heat input.…”

Investigation of the arc stability during self-shielded flux-coed arc welding with exothermic additions

“…The final microstructure and mechanical properties depend on heat input and weld bead morphology. It determines the wear resistance of the deposited metal to various types of wear [37,38,39,40,41]. Unstable arc would deteriorate weld appearances and increase the amount of imperfections [42].…”