Abstract

Additive manufacturing (AM) allows fabrication of complex components with features that are impractical or impossible to achieve through conventional methods. Selective laser melting (SLM) powder bed fusion AM technology was selected for this study on Inconel 625, a widely utilized high-temperature alloy that is hard to machine. The present work investigates impact of laser power and scanning speed variations on the resulting characteristics of fabricated IN625 samples. Gas atomized metallic alloy powders were acquired and analyzed through laser diffraction to verify acceptable size distribution. Cubic samples were built with a range of laser scan speeds in 200 mm/s intervals for each laser power evaluated (125W, 200W, 275W, and 350W) while holding a constant 0.12 mm hatch spacing, 0.03 mm layer thickness, and 16-degree scan rotation angle. Archimedes' method and optical image analysis were carried out to determine relative density of the samples. All laser powers evaluated yielded at least one sample with relative density above 99.7% as determined through both measurement techniques. Correlation of energy density with resulting sample porosity was identified with highest relative density values associated to energy densities in the 55 – 69 J/mm^3 range. Samples were sectioned and etched for examination of relevant microstructural features through optical and scanning electron microscopy; melt pools were measured and cell size approximated. Consistent cooling rate values in the order of 10^5 – 10^6 K/s were obtained from Rosenthal's equation models and from secondary dendrite arm spacing calculation.

Notes

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Graduation Date

2021

Semester

Spring

Advisor

Sohn, Yongho

Degree

Master of Science in Materials Science and Engineering (M.S.M.S.E.)

College

College of Engineering and Computer Science

Department

Materials Science and Engineering

Degree Program

Materials Science and Engineering

Format

application/pdf

Identifier

CFE0008509

Language

English

Release Date

May 2021

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

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