Alternative materials for rapid tooling

Mechanical properties and microstructure evolution of 17-4 PH stainless steel processed by laser-powered bed fusion.

“…densification with energy density was significant for water-atomized powders of median particle size, 24 and 43 µm. Similar results of an increase in % theoretical density with increased energy density have been observed in previous research studies [1,14,15].…”

“…Simchi also reported a similar trend of higher densification with decreased particle size for iron powders [13]. The smaller size powders exhibit higher surface area possibly absorbing more laser energy resulting in better densification [14,19]. At the energy density indicates that, using high energy density, parts with similar densification can be achieved using inexpensive, coarser water-atomized powders compared to the relatively expensive fine size gas-atomized powders that are typically used for L-PBF.…”

“…At high energy density, a large amount of molten liquid with low viscosity is likely to be formed in the powder bed. The low viscosity liquid presumably results in better wettability of the melt ensuing in enhanced densification of powders [14].…”

“…Better packing ability and low oxygen content of the gas-atomized powders have been previously claimed to be critical requirements for achieving high densification during the L-PBF process [14,15]. 17-4PH stainless steel water-atomized powders exhibit relatively poorer packing characteristics due to their irregular shape and typically have higher oxygen content.…”

“…Most of the studies identified processing conditions like laser power, scan rate, scan line spacing and thickness of layer to have significant effects on the densification of powder during L-PBF. Parts with high density were obtained when L-PBF was carried out at high laser power, low scan rate, low scan line spacing and low thickness of the sintered layer [1,7,12,14,15]. Apart from the processing conditions, the properties of the starting powder such as size, shape, and purity were also recognized to be critical for successful fabrication of parts with good properties.…”