Numerical modelling of the Water-Quenching Process validated through experiments with IN718 Nickel-Based Superalloy

Quenching is often a necessary step during manufacturing to tailor microstructures of metals and alloys for desired applications. Although employed extensively throughout human history, it relies heavily on experience and often trial and error. Therefore, the availability of computational tools, capable of describing the physics of the process during quenching, would help effective design, lower manufacturing costs, and make the process more environmentally friendly. This work analyses and validates a numerical procedure for immersion water quenching using computational fluid dynamics. The methodology employs the partitioned approach. Hence, the heat transfer information is exchanged at the interface of the part and the surrounding environment (i.e., water). An energy equation and an Eulerian two-fluid model describe the solid and fluid regions, respectively. The validation experiment includes water quenching of an IN718 nickel-based superalloy solid cylinder, in axial direction, with embedded thermo-couples for the measurements of cooling curves during the process. As such, no phase transformation within the solid material is assumed. The computational procedure focuses on determining the heat transfer coefficient due to fluid dynamics and the quenchant (i.e., water) phase change during cooling. The cylinder experiences effects of various heat transfer regimes, including film, transition and nucleate boiling, and natural convection intensified by buoyancy forces due to the presence of two fluid phases. A good agreement with validation data is achieved presenting an innovative numerical tool capable of predicting with high accuracy the temperatures and cooling rates of metal alloys during water quenching. Some complications are observed and reported where vapour movement is obstructed. Therefore we highlight further steps to alleviate any issues.