LAUSR

Abstract Gas tungsten arc deposits were made on substrate of stainless steel 304 using IN625 wires modified with 0.4 wt% B in shielding argon. The temperature profiles were simulated by the modified Rosenthal 3D equation. The re-melting boundary correlated well with the hardness profile and corresponding microstructure evolution along the as-manufactured sample. The upper section had higher hardness than the lower section. This high hardness was attributed to the existence of continuous eutectics (Laves phase and NbC) in the inter-dendritic regions. These eutectics in the lower section partially re-melted in this multi-pass process to form non-continuous features contributing to a lower hardness. Moreover, fine isolated borides precipitated out from the γ matrix in lower section as a result of the multiple thermal cycles. The eutectic phases were identified to be Laves phase with few NbC. The isolated borides were confirmed as M 5 B 3 type of boride by TEM. Modeling of the segregation behavior of the major alloying elements according to Clyne-Kurz equations was conducted and the results were in good agreement with chemical concentration profiles.