Research on formability of Al-Mg-Sc-Zr alloy based on SLM process

ABSTRACT

The fabrication technology of SLM forming Al-Mg-Sc-Zr alloy is widely used in the lightweight structure design of spacecraft. However, there is a need to optimize the process parameters and heat treatment process. The study analyses the process parameters of SLM on the forming density, microstructure and mechanical properties. The results show that the influence of laser power on the relative density is the greatest, followed by the scanning distance, and the scanning speed is the least. The optimal process parameters of Al-Mg-Sc-Zr are obtained as follows: the laser energy density is 130–140 J/mm³, laser power is 360 W, scanning speed is 1100 mm/s, and scanning spacing is 80 μm. Finally, samples with an average pore size of 15 μm and a relative induced density of 99.9% were obtained. On this basis, the effects of different annealing systems on the microstructure and mechanical properties were studied. Due to a large amount of second-phase precipitation in the remelting zone, the edge of the molten pool and the bottom, it has a pinning effect, which effectively inhibits recrystallization and grain growth during liquid phase solidification, and no abnormal grain growth occurs during the annealing process. The results show that after low-temperature annealing with 325°C insulation for 4 h, the mechanical properties were significantly enhanced and the maximum ultimate tensile strength (UTS) of the sample could reach 524.89 MPa, the maximum yield strength (YS) of the annealed sample can reach 506.01 MPa, the elongation rate of the annealed sample can reach 5.24%, the dimples and defects at the fracture interface were significantly reduced after annealing.

Keywords:
SLM forming; Al-Mg-Sc-Zr alloy; Forming defect; Microstructure; Mechanical properties