Investigating the effect of varying powder size range on particulate matter emission and mechanical properties of in situ micropowder alloyed WAAM depositions

Wire Arc Additive Manufacturing (WAAM) fabricates 3D products by laying molten filler wire in layers, resulting in final products with properties similar to the parent filler wire. In situ micro powder alloying during WAAM can modify the deposited material without changing the parent filler material to enhance its mechanical properties. This study investigates the effects of adding titanium (Ti) and copper (Cu) micro powders in different size ranges (< 25 µm, 25–45 µm, and 45–95 µm), within the layers of carbon steel in multilayered vertical walls during WAAM. The analysis of the variations in the mechanical and metallurgical properties of WAAM deposited samples is also done along with the dynamics of fine and ultrafine particle (UFP) emissions resulting from WAAM depositions, with and without the incorporation of CuTi powder. Real-time data acquisition of particulate matter (PM) concentration was carried out with a combination of low-cost particulate matter sensors (LCS) and scanning mobility particle sizer (SMPS). The incorporation of CuTi powder in various sizes has been observed to improve the mechanical properties, with the most significant enhancement noted in samples containing CuTi powder with sizes ranging from 25 to 45 µm. This improvement is likely attributable to the superior adhesion and uniform distribution of these particles across the surface compared with samples containing CuTi powder of finer size ranges. Variations in PM and UFP levels across different sizes of CuTi powder revealed that smaller-sized CuTi particles (less than 25 µm or 25–45 µm) demonstrate superior combustion compared with larger particles (45–95 µm). Consequently, larger particles contribute to higher PM and UFP emissions. The importance of micro powder size on mechanical properties enhancement is studied in detail along with the emission characteristics of CuTi micropowder added WAAM depositions, to understand the potential for identifying an optimized size range of micropowders.