Direct Metal Laser Re-Melting of 316L Stainless Steel Powder Part 2: Analysis of Cubic Primitives

Date
2001
Authors
Morgan, Rhys
Papworth, Adam
Sutcliffe, Chris
Fox, Pete
O'Neill, Bill
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Direct Metal Laser Re-Melting is a process variant of Selective Laser Sintering, whereby 316L stainless steel powder fractions are melted by a high power Nd:YAG laser. Layers are built up as a series of single lines to produce thin walled structures in the range »0.3-1.0mm thick. The structures exhibit a periodic, angular roughness to the wall surfaces. The samples also display a wave-like pattern on their upper surfaces. Further investigations reveal the angled ‘wave’ pattern exists on a macroscopic level in the microstructure. The pattern is fully formed by the third or fourth layer. Fern-like grain structures follow the orientation of the surface roughness and exist across many layers. This is believed to be the effect of grain orientation within the samples. The microstructure reveals long, needle, cell structures. The uni-axial needles grow epitaxially from previous layers. The samples have been shown to exhibit very little or no thermally induced residual stresses. Introduction

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