Objective Nickel-based superalloy porous components exhibit excellent heat and mass transfer capabilities, making them significantly important in fields such as aerospace. Due to their excellent permeability, porous structures are increasingly preferred for thermal conduction devices, such as high-temperature heat pipes. Using Laser Powder Bed Fusion (L-PBF) to form porous materials enables the customized fabrication of key features such as pore size and porosity. However, the presence of pores significantly reduces the mechanical properties of the materials, which limits the integrated design and manufacturing of the mechanical performance and functional characteristics of porous components. For this purpose, a lattice-reinforced porous structure that integrates functional characteristics and load-bearing capacity is designed in this paper.
Methods To achieve a synergy between mechanical performance and functional properties in porous components, this study employed L-PBF to fabricate Inconel718 (IN718) lattice-reinforced porous structures. This paper analyzes the effects of laser power, scanning speed, and hatching space on porosity through orthogonal experiments, and establishes the relationship between the porosity of the porous structure and its tensile strength. By comparing the mechanical properties of porous structures and lattice-reinforced structures, the mechanical behavior of both the porous and lattice components is analyzed. Finite element simulations were used to analyze the stress state of the pores and lattice-reinforced structures during loading, investigating the impact of different porosities and lattice-reinforced structures on the mechanical behavior of the porous material.
Results and Discussions This paper designs and forms a lattice-reinforced porous structure. The porosity of the L-PBF manufactured IN718 porous structure increases exponentially as the laser energy density decreases, while the tensile strength of the porous structure decreases exponentially with increasing porosity. Tensile tests show that the porous structure primarily exhibits brittle fracture, with unmolten powder particles and irregular pores leading to stress concentration and crack initiation during stretching. Simulation results indicate that the stress in the lattice-reinforced porous structure is primarily borne by the lattice, with increased thickness enhancing structural strength. The mechanical properties of the lattice-reinforced porous structure are positively correlated with the thickness of the lattice, and the reinforcing effect becomes more pronounced with increasing porosity.
Conclusions The orthogonal test results indicate that among the three parameters (laser power, scanning speed, and hatching space) scanning speed has the most significant effect on porosity. The lattice-reinforced porous structure, which combines minimal surfaces with a porous structure, exhibited a tensile strength of 244 MPa with a lattice thickness of 0.5 mm, demonstrating ductile fracture. As the lattice thickness increased to 0.9 mm, the tensile strength rose to 356 MPa. The mechanical performance of the lattice-reinforced porous structure outperformed that of the porous structure alone. With a porosity of 26%, the tensile strength of the lattice-reinforced porous structure was approximately 200 MPa higher than that of the porous structure, and the elongation after fracture increased by 3.5%. ABAQUS finite element simulations were used to analyze the stress distribution of the porous material under applied loads, revealing significant stress concentration at the pores, which first reached fracture strength, leading to failure. As porosity increased, the load-bearing capacity of the porous material decreased.
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