Bimetallic composites have a wide range of application prospects in various industries. Different bonding temperatures, as one of the influencing factors, directly affect the bonding effectiveness as well as the performance and application of the materials. Using metallurgical bonding techniques ensures a strong bond at the interface of bimetallic materials, resulting in high-quality composite pipe billets. This paper describes an Incoloy825/P110 steel bimetal composite material made by the solid–liquid composite method. By utilizing ProCAST 14.5 software for simulation and deriving theoretical formulas, an initial range of temperatures for bimetallic preparation has been tentatively determined. And this temperature range will be utilized for on-site experiments to prepare bimetallic samples. After the preparation process is completed, samples will be selected. The influence of the external mold temperature on the interface bonding of Incoloy825/P110 steel solid–liquid composite material is studied using an ultra-depth three-dimensional morphology microscope and a scanning electron microscope. Through research, the optimal preheating temperature range for the solid–liquid composite outer mold of Incoloy825/P110 bimetallic composite material has been determined. The casting temperature of the inner mold has a significant impact on the interface bonding of this bimetal composite material. As the casting temperature of the inner mold increases, the interface thickness gradually increases. At lower temperatures, the interface thickness is lower and the bonding is poorer. At higher temperatures, melting may occur, leading to coarse grains at the interface. When the temperatures of the inner and outer molds are within a certain range, a new phase appears at the interface. Indeed, it increases the strength of the interface bonding. Due to co-melting of the bimetal near the interface, element migration occurs, resulting in increased Ni and Cr content at the interface and enhanced corrosion resistance.

The large diameter titanium alloy bars are usually manufactured by forging, which leads to large metal loss, high cost, low efficiency and limited product specifications. This paper adopted three-high skew rolling technology to roll Ti–6Al–4V bar with the diameter of 300 mm. With the reduction of 50 mm, the three-roll skew rolling model was developed by DEFORM-3D finite element software. A cellular automatic model (CA model) of large-sized titanium alloy bar cross-rolled was established, considering the effects of dislocation, recovery and nucleation on dynamic recrystallization. The microstructure evolution process is effectively simulated. During the process of rolling, dynamic recrystallization occurs in the outer layer of the rolled piece at first. The new nucleations form at the grain boundary, then grow into their secondary phase. With the rolling proceeding, the dynamic recrystallization gradually extends to the core of bar. The microstructure of the rolled bar is uniform and the grain size is refined with the average grain size of approximately 10 μm. The simulation results are compared with the experimental results, the actual grain size is a little coarser than that obtained by the CA model. Some reasons are given to reasonably explain the phenomenon.

The reducing rate distribution is critical for the quality and precision of the final pipe during the process of stretch-reducing of the seamless pipe. The inhomogeneous deformation of the pipe may occur if the reducing rate distribution is improper. This paper analyzed the trend of the reducing rate distribution in terms of metal flow and put forward a “three-point and two-section converged” correction theory based on relevant research. In order to verify the theory, the finite element model is established according to the results obtained from the modified model. The simulation is accomplished successfully, and the cross-section of the pipe is evenly reduced with the longitudinal metal flowing uniformly. The result from the experiment is consistent with that from the simulation, which shows the rationality of this theory, providing a new method for the reduction rate allocation.