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A new hardfacing alloy within the Fe-Ti-Nb-Mo-V-C alloying system was utilized to restore the working surfaces of cone crusher rotors using Flux-Cored Arc Welding (FCAW). TiC, NbC, Mo2C, VC, Mn, and ferromanganese powders were selected as the base materials for manufacturing the welding wire. The resulting hardfaced layer exhibits a composite structure, with manganese austenite as the matrix and complex solid solution reinforcements with a NaCl structure, closely resembling the formula (Ti0.3Nb0.3Mo0.3)C. The primary advantages of this hardfacing alloy include its capacity for intensive deformation hardening along with high abrasion resistance. The hardness of the hardfaced layer is approximately 47 HRC in the as-deposited state and increases to around 57 HRC after work hardening, surpassing typical hardfacing alloys derived from high manganese steel by about 10 HRC. The efficacy of the alloy was tested in restoring rotors made of Hadfield steel in a PULVOMATIC series crusher model 1145, during the milling of sand-gravel mixtures ranging from 25 to 150 mm into spalls measuring 5 to 20 mm. With an average productivity of approximately 60 tons per hour and a production volume of 300 tons, the utilization of this hardfacing alloy enabled multiple restorations of the rotor while maintaining productivity at a level of 15 thousand tons of spalls.

In the present study, the new "casing-friendly" hardbanding alloy based on high-manganese steel reinforced with complex carbide particles was developed by combining thermodynamic modelling within the CALPHAD approach and first-principles calculations. The alloy, deposited by flux cored arc welding on a steel substrate, has a composite structure consisting of manganese-austenite with the ability to work hardening, fine (up to 5 µm) inclusions of the multicomponent carbide (Nb, Ti, Mo, V) and C the thin layers of (Mo,V)C at the austenite grain boundaries. The comparative wear tests carried out with commercially available hardfacing materials of the Fe-W-C and Fe-Cr-C systems showed that the proposed alloy has the best combination of properties preventing the wear of the drill casing, while its abrasion resistance, as well as wear resistance in sliding friction conditions by steel counter body, is close to hypereutectic high chromium alloys. The microhardness tests performed on deformed specimen areas after the friction tests show the presence of a significant hardness gradient in the range of 800-450 HV at a distance of about 300 µm when moving perpendicularly away from the zone of friction contact. During the microscopic observation of the layer deposited with the developed alloy and the interfaces between the deposit and the base steel, no cracks or pores delamination were detected, indicating a strong metallurgical bonding. The hardbanding process was performed for drill pipe joints with the worn Fe-based high chromium alloy hardbanding after exploitation, which allows the drill pipe to be re-used with the same durability. [ABSTRACT FROM AUTHOR]

In this study hardfacing by flux-cored arc welding with Fe-Mo-Mn-B-C-based alloy as an alternative technique for improving wear resistance of mining machines conical picks was investigated. The microstructure of hardfaced layer consists of the uniformly distributed faceted grains of binary (Fe,Mn)Mo2B2 boride phase with average size of 25 μm and austenite-based eutectic. The hardness measured by microindentation and microscratching techniques across the interfaces between deposited layer and base steel was within 2.2 -- 18 GPa. No welding defects such as cracks, pores or non-metal inclusions in the hardfaced layer and heat affected zones were detected. Comparative studies of the developed hardfacing alloy with commercially available Capilla HR MAG hardfacing and heat treated 35HGS steel were carried out using testing machine developed at the department of machinery engineering and transport of AGH university of science and technology for semi-industrial wear tests of mining machines conical picks. Wear measurement results show that using hardfacing with proposed alloy of Fe-Mo-Mn-B-C system leads to decreasing of impact-abrasion wear rate in approximately 3 times than that for tested commercial materials. This allows to recommend hardfacing by FCAW with proposed material in form of flux-cored wire for conical picks insert holders' surfaces during mining of hard rocks. [ABSTRACT FROM AUTHOR]