Novel integrated forming process for fabricating complex thin-walled AlSi10Mg alloy tubular parts via laser powder bed fusion and hot gas forming

Abstract

Currently, both additive manufacturing technologies and fluid pressure forming process face significant challenges in fabricating large-sized, complex thin-walled metal components. To address these challenges, this paper introduces a novel integrated forming process that utilizes laser powder bed fusion (LPBF) preforming and hot gas forming (HGF). This method employs LPBF technology to fabricate near-net-shape preforms, which are subsequently subjected to HGF treatment to realize micro-scale precise deformation. This study systematically investigates the performance of AlSi10Mg alloy thin-walled preforms prepared by LPBF, along with the characteristics of the formed parts following the HGF process. Furthermore, subsequent heat treatment protocols are employed to improve the microstructural properties of the formed parts. Compared to the direct LPBF technology, this method exhibits marked enhancements in dimensional accuracy and density of the fabricated parts, effectively controlling dimensional deviations and substantially reducing porosity. Ultimately, the process culminates in the fabrication of complex thin-walled AlSi10Mg alloy parts characterized by a superior microstructure and mechanical properties. Specifically, the formed parts, measuring 165 mm with a wall thickness of 1.2 mm, achieve a dimensional accuracy of ± 0.24 mm and a maximum wall thickness reduction rate of less than 14.2 %, while attaining an impressive density of 99.93 %. Additionally, the parts exhibit excellent uniformity concerning the distribution and morphology of the precipitated phases, along with the shape and structure of the grains. Following solution heat treatment, the formed parts exhibited tensile strengths of 282 MPa at room temperature and 186 MPa at 230 °C, accompanied by elongations of 15.9 % and 11.7 %, respectively. This favorable combination of strength and ductility renders these materials well-suited for engineering applications that demand high overall mechanical performance. However, aging heat treatment after solution treatment resulted in a significantly improved of the mechanical properties. The tensile strengths increased to 350 MPa at room temperature and 201 MPa at 230°C, while the elongations were concurrently reduced to 6.9 % and 10.1 %, respectively. Such a property profile makes these materials particularly suitable for specialized applications where high strength is prioritized over ductility. The feasibility of LPBF-prepared preforms via the subsequent HGF process was systematically confirmed, thereby establishing a foundational basis for the prospective application of this integrated forming methodology.