Dry Sliding Wear Resistance of Fe-Cr-C hardfacing Deposited by Flux-Core-Double-Wire GTAW

Gas-Shielded Tungsten Arc Welding (GTAW) was modified to a Flux-Cored-Double-Wire GTAW (FCDW-GTAW); in this technique, wires of different compositions are used simultaneously to obtain different microstructures. In the modified GTAW, automatic flux-cored double-wire was used with a combination of four different wires deposited in AISI1020 steel, allowing different microstructures. Pin-on-disk wear tests described by ASTM G99 was used to evaluate the wear coefficients of four hardfacing materials combining Fe–Cr–C, Fe-Cr-C-Nb, Fe-Cr-C-Mo-Nb, and Fe-Cr-C-Mo-Ti alloys. The combination of these wires resulted in a hypoeutectic microstructure with niobium and titanium carbides, with an average hardness of 650 HV_0.3, and hypereutectic microstructures formed by different niobium contents, with a microhardness range from 820 to 1020 HV_0.3. The wear tests were performed without lubrication at room temperature, using a 6.0 mm diameter polished alumina sphere as a counter-body. The total distance covered was 1000 m with a speed of 0.1 m/s, a track radius of 6.0 cm, and an applied load of 10 N. Hardness, microstructure, wear coefficient, and wear mechanisms were compared. The results showed that wear resistance could be differentiated by the predominant wear mechanism: polishing for the hypoeutectic hardfacing and cracking for the hypereutectic ones.

Keywords
: GTAW; Hardfacing; Wear-Resistance; Wear-mechanisms; Carbides