Forming characteristics of triple-wire gas indirect arc surfacing

Based on the advantages of triple-wire gas indirect arc welding (TW-GIA), such as small heat input, low dilution rate, and high deposition rate, the surfacing test on Q345 steel was carried out, and the surfacing forming characteristics of TW-GIA were studied. Results showed that due to excessive wetting angle of the weld and the limitation of the heat source mode, there was unfused defect between the weld toes of the adjacent welds. To improve the morphology of the surfacing layer, the inclined substrate surfacing process was used. As the inclination angle increases, the size of unfused defect between adjacent welds gradually decreases. When the angle of inclination is increased to 30° − 40°, the single-layer multi-pass surfacing layer with uniform forming and available fusion between welds can be achieved. Compared with tandem double-wire arc (T-DW) surfacing , the deposition rate of TW-GIA increased by 61.45 %, while the dilution rate of the base metal decreased by 71.91 %. The surfacing method has the advantages of a high deposition rate and low heat input, which is beneficial to improve the microstructure of the surfacing layer, making the coarse columnar crystals smaller, and improving the microhardness. The average microhardness level is 233.1 HV, which is higher than the average microhardness of the T-DW surfacing layer 220.4 HV.