Customizing mechanical properties of additively manufactured Hastelloy X parts by adjusting laser scanning speed

This paper systematically studies the effect of laser scanning speed, one of the main process parameters in laser powder-bed fusion (LPBF), on the quasi-static tensile response of Hastelloy X at room temperature. The experimental results demonstrate that the macrostructure and the microstructure of the samples changes significantly by altering the laser scanning speed. Results show that for a fixed laser power, extremely high (>1300 mm/s) and low (<550 mm/s) scanning speeds result in lack of fusion and keyhole defects, respectively, which were found to have a detrimental effect on the tensile strength and ductility of printed parts. On the other hand, moderate speeds (850–1300 mm/s) resulted in parts with high density and varying mechanical properties due to the as-built microstructure. Analysis of grain size and yield strength for high-density parts shows a good agreement with the Hall-Petch equation. The results obtained in this study suggest a new method to customize the mechanical properties of LPBF parts by changing the laser scanning speed.