Impact of Pulsed Laser Parameters and Scanning Pattern on the Properties of Thin-Walled Parts Manufactured Using Laser Metal Deposition

Abstract

The quality of parts manufactured using laser metal deposition (LMD), similar to other additive manufacturing methods, is influenced by processing parameters. Such parameters determine geometric stability, favorable microstructures, and good mechanical properties. This study aimed to investigate the effects of pulsed laser parameters (duty cycle and pulse frequency) and scanning patterns (unidirectional and bidirectional patterns) on the properties of parts fabricated using LMD. Results show that the properties of the LMD-fabricated parts are obviously influenced by pulsed laser parameters and scanning patterns. Using the unidirectional scanning pattern in both pulsed laser parameters enhances the properties of the thin-walled parts prepared using LMD. An increase in duty cycle can improve geometric stability, increase grain size, and reduce microhardness. Furthermore, the geometric stability does not vary considerably with the use of different frequencies, but the microstructure of fabricated parts shows various grain sizes with different pulse frequencies. In addition, the microhardness increases as the frequency increases from 13.33 to 50 Hz. In general, the influence of the duty cycle on geometric properties is greater than that of frequency. Meanwhile, the impact of frequency on microhardness is greater than that of the duty cycle.

Investigation of Surface Integrity of Conical Hole in Laser Polishing 440C Stainless Steel

“…The surface hardness change can be side−evaluated by the effect of temperature on the polished surface. The surface microhardness after laser scanning was considerably higher than that of the substrate in both titanium alloy and stainless steel 316L [37,39,40]. After scanning and polishing under the parameters of E−6 and E−10, the surface hardness increased considerably to 679.1 and 404.1 HV, respectively.…”

Advances and challenges in direct additive manufacturing of dense ceramic oxides

“…By utilizing multiple powder feed lines, L-DED allows for the arbitrary composition of various materials on the same part or the creation of functional graded structures with location-specific properties [39]. Its adaptability also enables a wide range of processes like coating, repairing, and part retrofitting [60]. However, the laser beam in L-DED is one or two orders of magnitude larger than that in L-PBF, resulting in the formation of a larger molten pool during shaping.…”