Effect of scanning strategy on grain structure and crystallographic texture of Inconel 718 processed by selective laser melting

Crystallographic Features of Microstructure in Maraging Steel Fabricated by Selective Laser Melting

“…The primary solid phase (γ phase in the studied composition as indicated in Figure 7) is observed to form at the interface between the solid and liquid phases and grows to the center of the melt pool (the hottest point under the laser irradiation) in solidification (Figure 8a), as reported in the literature [16,17]. The γ grains solidify along the preferential <001> solidification direction, as reported in other fcc metals (Ni [26,27] or Al alloys [16][17][18]) that have been fabricated using the SLM process. The preferential solidification direction can explain the observed {001} texture of the retained γ phase (Figure 8e).…”

“…In the studied composition, the initial solid phase is γ (fcc) below 1440 • C, whereas a γ single-phase region forms below the solidus temperature of approximately 1400 • C, and has a wide temperature range from 800 • C to 1400 • C. Below 800 • C, µ-Fe 7 Mo 6 phase appears and then α (bcc) phase form at lower temperature than 650 • C. The thermodynamic calculation assesses γ phase initially forms in liquid (L) phase. The assessment indicates the γ grains solidifying in the direction of the hottest point of the melt pool, considering the <001> preferential solidification direction of the fcc solid phase [25] as well as other fcc metals (Ni [26,27] or Al alloys [16][17][18]). This result is consistent with the observed retained γ grains oriented at <001> along the Z direction ( Figure 5).…”

Texture control of 316L parts by modulation of the melt pool morphology in selective laser melting

“…High tensile properties of 316L manufactured by SLM, superior to wrought and cast 316L steel properties were measured by Andreau et al (2017), that Röttger et al (2016) attributed to the fine cellular or cellular-dendritic microstructure generated by the fast heating and cooling solidification process. This microstructure has been observed in recent work by Wan et al (2017) for Inconel 718 SLM samples. Similar types of microstructure have previously been observed in various rapid solidification processes.…”

On the fatigue crack growth behaviour of selective laser melting fabricated Inconel 625: Effects of build orientation and stress ratio

“…Selective laser melting (SLM) is one of the most promising additive manufacturing (AM) technologies with the convenience and feasibility of producing high temperature superalloy components, and this has received much attention in various fields, such as aerospace, automobile and biomedical industries. 1 Previous studies have been mainly carried out on the processing parameters, [2][3][4][5] microstructure characteristics of formed parts, [4][5][6][7] welding cracking 6 and effect of post-process, 7-9 such as heat treatment (HT) and hot isostatic pressing (HIP). In order to apply the SLM superalloy into the manufacturing of turbine blades and combustors with high reliability, 10,11 the fatigue behaviour of this kind of materials should be investigated.…”