Numerical simulation and optimization of gas quenching cooling temperature field of sintered NdFeB vacuum sintering furnace

Abstract Precise control over cooling rate and uniformity during gas quenching is essential for achieving the target microstructure and magnetic properties in sintered NdFeB magnets. This study develops a comprehensive 3D numerical model to simulate the transient gas quenching process within an industrial vacuum sintering furnace. Validation against experimental thermocouple data confirms the model’s high accuracy, showing a maximum deviation in cooling rate of less than 9 % over a 15-min cycle. Analysis of the flow and temperature fields identifies significant thermal non-uniformity, with temperature differences between layers exceeding 250 K, largely due to the fixture configuration and insufficient internal convection. Informed by these findings, we propose and simulate an optimized strategy involving the vertical repositioning of the workpiece fixtures. This modification successfully reduces the maximum temperature difference by more than 20 K. The study provides a validated simulation framework and practical insights for optimizing vacuum furnace design and process parameters to improve product quality and consistency.