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 Fi plays a significant role in the descaling of the typical hot forging. The larger the value of Fi 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.

Hot tensile tests of the GH3625 superalloy were carried out under the temperature range of 800–1050 °C and strain rates of 0.001, 0.01, 0.1, 1, and 10 s−1 on a Gleeble-3500 metallurgical processes simulator. The effect of temperature and holding time on grain growth was investigated to determine the proper heating schedule of the GH3625 sheet in hot stamping. The flow behavior of the GH3625 superalloy sheet was analyzed in detail. The work hardening model (WHM) and the modified Arrhenius model, considering the deviation degree R (R-MAM), were constructed to predict the stress of flow curves. The results showed that WHM and R-MAM have good prediction accuracy by evaluating the correlation coefficient (R) and the average absolute relative error (AARE). Additionally, the plasticity of the GH3625 sheet at elevated temperature drops with the increasing temperature and decreasing strain rate. The best deformation condition of the GH3625 sheet in the hot stamping is in the range of 800~850 °C and 0.1~10 s−1. Finally, a hot stamped part of the GH3625 superalloy was produced successfully, which had higher tensile strength and yield strength than the as-received sheet.

To improve the service life and reduce the repair cost of continuous casting rollers, a new welding-hammering hybrid remanufacturing process in which the roller was designed with a gradient structure was proposed, and corresponding equipment was developed. First, the failure modes and their causes for a continuous casting roller were analyzed by numerical simulation. The cyclic tension–compression shear stress, cyclic tension–compression normal stress, thermal cycle, and highly corrosive environment caused fatigue cracking and overall peeling of the roller surface. Second, the gradient structure composed of a base layer, transition layer, and strengthened layer of a continuous casting roller was designed, and materials for each layer were selected according to their different service conditions. Third, novel equipment for continuous welding-hammering composite remanufacturing was developed, and the optimized process parameters were obtained through welding experiments. Finally, an application test was carried out; the microscopic analysis showed that refined grains, fewer welding defects, and better surface toughness were obtained. Compared with traditional remanufacturing processes without hammering, the welding-hammering hybrid process achieved a forged structure instead of as-cast structure, which significantly improved the service life of the continuous casting roller by about 100%.