Selective laser melting of iron-based powder

Abstract

Selective laser melting (SLM) is driven by the need to process near full density objects with mechanical properties comparable to those of bulk materials. During the process the powder particles are completely molten by the laser beam. The resulting high density allows avoiding lengthy post-processing as required with selective laser sintering (SLS) of metal powders. Unlike SLS, SLM is more difficult to control. Because of the large energy input of the laser beam and the complete melting of particles problems like balling, residual stresses and deformation occur. This paper will describe SLM applied to a mixture of different types of particles (Fe, Ni, Cu and Fe 3 P) specially developed for SLM. The different appearing phenomenons are discussed and the process optimization is described. The latter includes an appropriate process parameter adjustment and the application of special scanning strategies. Resulting parts are characterized by their microstructure, density and mechanical properties.

Selective Laser Melting (SLM) of pure gold

“…A powder bed temperature of 100ºC was maintained for all experiments. greater than 2.1 then the molten metal would break up into small droplets instead of a continuous line [4]. The balling observed at higher scan speeds could have been due to the increase in the length of the melt pool and a reduction in the melt pool width thus increasing the L/D ratio over 2.1 and destabilising the melt pool.…”

“…As compared to the sintering of powder in some other RM processes, the complete melting of powder in SLM could produce parts with much higher density and strength. SLM has already been successfully applied to process aluminium, copper, iron, stainless and tool steel, chromium, nickel alloys, titanium and composites of these materials [1][2][3][4][5][6][7][8][9]. Gold has been used for ornaments for centuries; however, very little work has been published [10] on the laser melting of precious metals like gold and its alloys.…”

Chemical reaction engineering, process design and scale-up issues at the frontier of synthesis: Flow chemistry

“…In this case melting usually ensure the formation of dense parts. The most applied material is AISI316 stainless steel [125], but examples are found also with aluminum [126] or titanium. The advantages and disadvantages of the different AM techniques have been effectively compared by Capel et al [123] as synthesized in Table 2.…”

Fabrication of Fe–Cr–Al Oxide Dispersion Strengthened PM2000 Alloy Using Selective Laser Melting

“…In contrast, the 50W wall produced at the faster scan speed of 0.2ms -1 exhibited no agglomeration and a homogeneous distribution of oxide particles in the columnar grain structure. It is believed that this is the result of the rapidly resolidification of the melt pool behind the laser spot, [23] thus reducing the effects of melt flow due to surface tension driven Marangoni convective stirring. [24] The influence of laser scan speed on oxide coarsening was revealed in the oxide particle size distributions measured after SLM consolidation of the powders.…”