Experimental determination of solute redistribution behavior during solidification of additively manufactured 316L

The interplay of local chemistry and plasticity in controlling microstructure formation during laser powder bed fusion of metals

“…Notably, in the case of the larger chemical cell size, a superposition of 100 and 110 orientations are observed. This is consistent with experimental observations of "nested" sub-cell structures [15,42,47]. In contrast, the absence of cellular segregation leads to a diffuse autocorrelation function without obvious periodicity (bottom row).…”

“…To mimic the temperature-dependent microstructure evolution in additively manufactured 316L SS, we performed large-scale 3D DDD simulations at 1300K, 1100K, 900K and 700K in a 5 3 µm 3 system volume containing cellular segregation according to experimental observations [12,13,42]. As a comparison, we also performed one simulation at 700K without cellular segregation.…”

“…A step-wise transition between cell wall and cell interior was assumed using a cell wall thickness of 200 nm. The segregation cell walls are oriented parallel to the [100] and [010] plane with 800 nm or 1600 nm spacing according to the experimental observations [12,13,42], leading to cells elongated in the [001] crystal direction, as shown by the schematics of the different DDD simulations in Fig. 1a-c.…”

“…We account for a physically meaningful representation of the dislocation evolution in 316L SS via a temperature-dependent dislocation mobility law adapted from molecular dynamics (MD) simulations [40] and a recently developed model for the local composition-dependent critical resolved shear stress (CRSS) [37]. The experimentally observed 100 -aligned and periodic spatial variation in chemical composition (local Mo and Cr enrichment) adapted from [13,14,42] are explicitly incorporated in the simulations, see Fig. 1c for the solidification cell wall geometry.…”

“…The influence of cellular solidification (directional solidification driven by micro-segregation) on the formation of the dislocation structure at 700K is further analyzed by isothermal 3D DDD simulations as explained in section 2.3. We consider 100 -aligned solidification cells with either 800 nm or 1600 nm cell wall spacing to mimic experimental observations [12,13,42] (see Fig. 1a,b for the geometry) and compare with a 3D DDD simulation in the absence of cellular segregation (i.e.…”