Numerical study on multi-field evolution and optimal temperature of Inconel 718 alloy forging

Inconel 718 nickel-based superalloy is widely used in aerospace key components, and its forging quality is dominated by the coupled evolution of temperature, stress, strain, microstructure and internal damage. Aiming at the lack of systematic research on temperature-dependent multi-field coupling behavior in existing studies, finite element simulations were conducted to investigate the forging process at 1000 °C, 1100 °C and 1200 °C. The evolution rules of temperature field, equivalent stress, equivalent strain, average grain size, dynamic recrystallization fraction and damage distribution were quantitatively analyzed. The results indicate that higher forging temperature improves the uniformity of temperature field and dynamic recrystallization fraction, while it also increases grain size and damage value. At 1100 °C, the alloy achieves the maximum equivalent strain, the most uniform stress distribution and an extremely low damage value of 0.122. Meanwhile, the grain structure and dynamic recrystallization reach an optimal balance. This temperature realizes the synergistic control of large plastic deformation, uniform multi-field distribution, low damage and refined microstructure. The present work clarifies the temperature regulation mechanism of multi-physics coupling during forging, and 1100 °C is determined as the optimal forging temperature. The findings can provide theoretical basis and data support for the hot forging parameter optimization of Inconel 718 and similar superalloys.