Abstract
Hardfacing is widely used to restore worn gate-valve surfaces, but the choice of process parameters must account for residual stress, distortion, plastic strain, and the heat-affected zone (HAZ). This study investigated the hardfacing of 09G2S steel numerically in Simufact Welding using a Taguchi L9 design for three filler materials, Np-65G, Stoodite 6M, and PrNl-3V14K, giving 27 simulated conditions. The Goldak heat source was calibrated against a theoretical penetration depth of 1.2–1.5 mm. Conditions resulting in metal boiling, an unmelted bead center, or a penetration depth outside 1.0–2.0 mm were excluded. Lower residual stresses were obtained only together with insufficient penetration or overheating. Run 6 was selected for Np-65G (285 MPa; HAZ depth, 4.7 mm) and Stoodite 6M (373 MPa; 4.6 mm), and Run 2 for PrNl-3V14K (289 MPa; 3.5 mm). On a model of a 90-mm-thick gate plate, the selected Np-65G condition gave a penetration depth of only about 0.5 mm; an adjusted condition within the investigated levels (160 A, 12 V, 3 m/h, 200 °C) gave 1.45–1.80 mm with a fully melted bead for both Np-65G and Stoodite 6M. Conditions selected on specimens must therefore be reassessed for the actual component. Specimens hardfaced under industrial conditions were characterized by microscopy and microhardness testing: 386–466 HV0.05 for the Stoodite 6M deposit and 345–440 HV0.05 for Np-65G.