Microstructure evolution of Inconel 625 with 0.4 wt% boron modification during gas tungsten arc deposition

• Published in: Journal of alloys and compounds Vol. 694; pp. 429 - 438
• Main Authors: Tian, Y., Ouyang, B., Gontcharov, A., Gauvin, R., Lowden, P., Brochu, M.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.02.2017; Elsevier BV
• Subjects: Alloying elements; Arc deposition; Argon; Austenitic stainless steels; Borides; Boron; Computer simulation; Eutectic temperature; Eutectics; Evolution; Gas tungsten arc deposition; Hardness; Inconel 625; Laves phase; Melting; Microstructure; Nickel base alloys; Re-melting; Segregation; Shielding; Superalloys; Temperature profiles; Tungsten; Inconel 625; Re-melting; Microstructure; Gas tungsten arc deposition; Segregation
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2016.10.019

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 M5B3 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. •Inconel 625 with 0.4 wt% boron modification was made on stainless steels 304 using gas tungsten arc deposition process.•Much more eutectics were observed in IN625B than conventional IN625 during gas tungsten arc deposition.•Calculated re-melting boundary was correlated well with hardness profile and observed microstructure evolution.•Segregation patterns of major alloying elements followed Clyne-Kurz model during deposition solidification.