Correlation between selective laser melting parameters, pore defects and tensile properties of 99.9 % silver

Abstract

In this study the relationship between Selective Laser Melting (SLM) process parameters, associated pore defects and resulting tensile properties of additively manufactured (AM) pure (99.9 %) silver structures are investigated using X-ray Computed Tomography (XCT) and 3D visualisation analysis. Yield strength, Young’s Modulus, failure strain and ultimate tensile strength of AM pure silver are reported. Furthermore, fracture surfaces of the samples are analysed using optical microscopy and Scanning Electron Microscopy (SEM) to investigate fracture surface porosity content and surface roughness is analysed using digital microscopy. Pore defect distribution, morphology and resultant pore surface area are reported, and average pore size calculated in relation to SLM process parameters variations. It was found that sample yield and ultimate tensile strengths of pure silver have a direct correlation with energy density at the powder bed related to SLM process parameters selected. However, Youngs Modulus values were found to be dependent on the average porosity pore size rather than sample density or number of pores. SLM pure silver bulk density was evaluated using XCT comparative analysis while varying SLM parameters and the resultant pore defect morphology and distribution discussed. The results reported in this work serve as a basis for further material development and mechanical property predictions utilising XCT analysis for pure silver and other nonstandard SLM materials.