Modulating laser intensity profile ellipticity for microstructural control during metal additive manufacturing

By T. Roehling, Sheldon S. Q. Wu, S. Khairallah, J. Roehling, S. Soezeri, Michael F Crumb, Manyalibo Matthews. 2017

248 citations recorded by the source corpus.

Abstract Additively manufactured (AM) metals are often highly textured, containing large columnar grains that initiate epitaxially under steep temperature gradients and rapid solidification conditions. These unique microstructures partially account for the massive property disparity existing between AM and conventionally processed alloys. Although equiaxed grains are desirable for isotropic mechanical behavior, the columnar-to-equiaxed transition remains difficult to predict for conventional solidification processes, and much more so for AM. In this study, the effects of laser intensity profile ellipticity on melt track macrostructures and microstructures were studied in 316L stainless steel. Experimental results were supported by temperature gradients and melt velocities simulated using the ALE3D multi-physics code. As a general trend, columnar grains preferentially formed with increasing laser power and scan speed for all beam profiles. However, when conduction mode laser heating occurs, scan parameters that result in coarse columnar microstructures using Gaussian profiles produce equiaxed or mixed equiaxed-columnar microstructures using elliptical profiles. By modulating spatial laser intensity profiles on the fly, site-specific microstructures and properties can be directly engineered into additively manufactured parts.

Subfields: Materials Chemistry, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/78ca5b06a143d2b0e8e1e87035ed0acf9dad67d0

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In Materials Chemistry

In Mechanical Engineering

Citations in the corpus

Microstructure modelling for metallic additive manufacturing: a review (2020, background): “duces columnar grains with a mix of equiaxed grains that consist of cellular dendrites (Figure 2) (Murr et al. 2012; Frazier 2014; Roehling et al. 2017).”
Modeling of solidification microstructure evolution in laser powder bed fusion fabricated 316L stainless steel using combined computational fluid dynamics and cellular automata (2019, background): “computational studies on the laser scan speed effect on the powder bed fusion process[10, 20], most of them are at the macro or meso scale.”
Revisiting fundamental welding concepts to improve additive manufacturing: From theory to practice (2020, background): “By modulating the laser intensity [83], or by modifying the scan strategy [99,159] the solidification conditions experienced by the”