An Integrated Forming Process for Manufacturing Ti6Al4V Impeller with a Functional Coating Layer Using Hot Isostatic Pressing

摘要

The complex aircraft components are difficult to manufacture because of their complicated shapes and high requirements of mechanical properties. Besides, those components usually need a functional coating layer on the surface to improve the reliability, which adds an extra production cycle after manufactured. In this study, an integrated forming process was proposed to manufacture a complex-shaped impeller together with the surface coating layer using hot isostatic pressing (HIP). In this new process, an HIP mold with the graphite core pre-deposited a Ni coating layer was designed and conducted with the HIP experiment. The results show that the manufactured impeller had a dimensional precision of 0.15mm. The scanning electron microscope/X-ray diffraction (SEM/XRD) analyses show that the internal microstructure was compact with alpha+beta phases and the surface had a uniform Ti2Ni/TiNi coating layer. The mechanical experiments show that the HIPped specimens had a 70MPa higher yield strength and 95MPa higher tensile strength than the same-size forgings. Besides, a Ti2Ni/TiNi coating layer was formed on the surface of the impeller and the hardness and wear resistance had an obvious improvement. All the results show that the new process was successfully applied to near net shaping of an integrated Ti6Al4V impeller with a functional coating layer.