To address the issue of cracking in aluminum extrusion dies during operation, this study employs laser cladding technology to modify the surface of these dies. This modification aims to enhance their hardness and friction resistance. Laser cladding technology was utilized to coat the surface of H13 steel with Stellite 12, a cobalt-based alloy, at varying laser power levels. The surface formation quality, microstructural organization, phase composition, microhardness, and wear resistance of the coatings were investigated using optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction (XRD), microhardness testing, and confocal microscopy. The results indicated that as the laser power increased, the surface formation quality of the coating gradually improved, while the dilution rate of the coating increased. Changes in the phase composition and microstructure were not significant, and both microhardness and wear resistance initially increased before decreasing. Optimal process parameters for achieving good surface formation quality, high microhardness, and strong wear resistance were found to be a laser output power of 2200 W, scanning speed of 10 mm/s, feeding rate of 1.2 r/min, and overlap rate of 40%. The results indicate that the coating applied to the surface of H13 steel using Stellite 12 enhances the performance of aluminum extrusion dies.

To solve the problem of the long forming process for hollow shafts with constant wall thickness (HSCWT), a new process for forming HSCWT, namely three-roll skew rolling, has been proposed. First, the working principle of the three-roll skew rolling process is presented. Then, the finite element model (FEM) of the three-roll skew rolling HSCWT is established. The strain-stress field and temperature field distribution rules of the three-roll skew rolling HSCWT are analyzed with FEM. The stress-strain field of the rolled piece is distributed uniformly along the axial direction but not uniformly along the radial direction. The variation of the temperature field is related to the axial traction velocity. The greater the axial traction velocity, the smaller the variation of the temperature field. The temperature of rolled pieces varies within 100 °C during rolling. Finally, the three-roll skew rolling experiment of the HSCWT is carried out. The results show that the three-roll skew rolling process can form HSCWT. The temperature field of the three-roll skew rolling HSCWT is evenly distributed. The selection of larger axial traction velocity is conducive to the forming of rolled pieces. The three-roll skew rolling technology has achieved near constant temperature forming of HSCWT.

To address the challenges posed by the complex shapes of hollow parts, this study examined the ultrasonic-assisted granular medium hydroforming (UGMF) process for tubular components. The dynamics of the deformation behavior and deformation control during 6063-T5 aluminum alloy tube free forming by UGMF were studied via simulations and experiments. Based on the ABAQUS software platform, a coupled method based on finite element (FE) simulation analysis and discrete element (DE) analysis for the UGMF free forming process was used. The results showed that ultrasonic vibration (UV) could reduce the forming force required for expansion and promote the flow of material at the end to the forming area as well as inhibit the decrease in the wall thickness. The accuracy of the FE-DE coupled simulation model and a parabolic geometric model was verified by testing. The results found that UV enhances material flow, decreases the forming force needed, and minimizes damage to the granular surface.

To address the issue of incomplete formation of low necking coefficient pipe fittings in hot extrusion processes, this study adopts a novel three-roll skew rolling (TRSR) technique to investigate the microstructural recrystallization distribution patterns during necking forming of aerospace thin-walled pull rods using TRSR. The principles of TRSR necking forming of pipe fittings are initially elucidated, followed by the establishment of a finite element model using simufact forming software and secondary development of the software to embed dynamic recrystallization volume and grain size models. The study analyzes the temperature distribution patterns and dynamic recrystallization behavior during necking forming of aluminum alloy thin-walled pipes via TRSR, aiming to contribute to the research on high-quality necking pipe fittings produced through TRSR.