Numerical simulations and experiments were utilized to study the removal of oxide scale formed on 300 M steel special-shaped hot forging surfaces during heating at elevated temperature by a high-pressure water descaling process. Specifically, the experimental setup of the special-shaped hot forging was designed and manufactured according to the descaling parameters and simulation results obtained from the hot rolling process. The force states of three typical hot forging surfaces impinged by high-pressure water jets were analyzed. Moreover, the mechanism of the high-pressure water descaling process was proposed based on the research results. The numerical simulations and experimental results revealed that the velocity distribution of the high-pressure water jets is relatively different in various areas of the special-shaped hot forging surfaces. Therefore, the descaling performance is synergistically influenced by the velocity of the high-pressure water jet and the shape of the special-shaped hot forging. Given a certain spray pressure, the value of impact force $F_i$ plays a significant role in the descaling of the typical hot forging. The larger the value of $F_i$ on the typical hot forging surface, the easier it is to remove the oxide scale, and vice versa. Accordingly, the difficulty of removing the oxide scale formed on the 300 M steel special-shaped hot forging surfaces during heating at elevated temperature by a high-pressure water descaling process is in the following order: plane surface < convex surface < concave surface. Additionally, only the inner-layer FeO of the oxide scale remained after the high-pressure water descaling process due to the appearance of FeO-Fe₂SiO₄ eutectic in the FeO layer.

The thermal-mechanical process (TMP) plays an important role in the industrial production of 7050 Al alloys for aircraft components. In this work, the microstructural evolution and influence on hardness of a 7050 alloy ingot, during the process from preheating, deformation and cooling to final heat treatment, have been investigated considering the effect of temperature and the post-deformation cooling path. The results showed that an increasing temperature and decreasing cooling rate during TMP can lead to enhanced hardness of the alloy after heat treatment. Moreover, the variation of recrystallization before and after heat treatment was strongly dependent on the cooling path after deformation. Finally, this study provided a general understanding on the relationship between microstructural evolution and harness of the 7050 alloy.

A series of compression tests were performed on Ti-6Al-4V-0.1Ru titanium alloy in nine temperatures between 750 and 1150 °C and a strain rate range of 0.01 to 10s ⁻¹ . The hot deformation behaviors of Ti-6Al-4V-0.1Ru showed highly non-linear intrinsic relationships with temperature, strain and strain rate. The flow curves exhibited different softening mechanisms, dynamic recrystallization (DRX) and dynamic recovery (DRV). In this study, the rheological behaviors of Ti-6Al-4V-0.1Ru were modeled using a special hybrid prediction model, where genetic algorithm (GA) was implemented to do a back-propagation neural network (BPNN) weights optimization, namely GA-BPNN. Subsequently, the predicted results were compared with experimental values and GA-BPNN model showed the ability to predict the flow behaviors of Ti-6Al-4V-0.1Ru with superior accuracy. Then a 3-D continuous interaction space was constructed to visually reveal the successive relationships among processing parameters. Finally, the predicted data were applied to process simulation and accuracy results were achieved.

The hot deformation behavior and mechanism of Ti65 alloy with a bimodal microstructure were investigated by isothermal compression experiments conducted on the Thermecmastor-Z simulator equipment at temperatures ranging from 950 to 1110 °C and strain rates ranging from 0.01 to 10.0 s⁻¹. The Arrhenius constitutive model, based on strain compensation, and Grey Wolf optimization-neural network with back propagation model (GWO–BP), were both established. The differences between the experimental and predicted value of flow stress were compared and analyzed using the two models. The results show that the prediction accuracy of GWO–BP in the two-phase region is higher than that of Arrhenius model. In the single-phase region, both methods demonstrated high prediction accuracy. Compared to the single-phase region, the flow stress of Ti65 alloy shows a higher degree of softening in the two-phase region. During deformation in the two-phase region, the initial lamellar α phase transformed from a kinked and elongated morphology to a globularized topography as the strain rate decreased. Boundary-splitting was the primary mechanism leading to the spheroidization process. The degree of recrystallization increased with the increase in strain rate during the deformation in the single-phase region, while dynamic recovery and strain-induced grain boundary migration were the main deformation mechanisms at a lower strain rate. Discontinuous dynamic recrystallization may be the dominant recrystallization mechanism under a high strain rate of 10 s⁻¹.