Effects of Build Angle on Additively Manufactured Aluminum Alloy Surface Roughness and Wettability

Abstract

Laser Powder Bed Fusion (LPBF) was utilized to create a series of aluminum alloy (i.e., AlSi10Mg) 5-mm-diameter support pillars with a fixed height of 5 mm containing varying filet angles and build orientations (i.e., 0°, 10°, 20°, 30°, 40°, 50°, and 60° from the normal surface) to determine their effects on surface roughness and water wettability. From experiments, anisotropic wetting was observed due in part to the surface heterogeneity created by the LPBF process. The powder-sourced AlSi10Mg alloy, typically hydrophobic, exhibited primarily hydrophilic behavior for build angles of 0° and 60°, a mix of hydrophobic and hydrophilic behavior at build angles of 10° and 20°, and hydrophobic behavior at 30°, 40°, and 50° build angles. Measured surface roughness, Ra, ranged from 5-36 micrometers and varied based on location. 3D-topography maps were generated and arithmetic mean heights, Sa, of 15.52-21.71 micrometers were observed; the anisotropy of roughness altered the wetting behavior, thereby prompting some hydrophilic behavior. Build angles of 30° and 40° provided for the smoothest surfaces. A significantly rougher surface was found for the 50° build angle. This abnormally high roughness is attributed to the melt pool contact angle having maximal capillarity with the surrounding powder bed. In this study, the critical melt pool contact angle was near-equal to the build angle suggesting a critical build angle exists which gives rise to pronounced melt pool wetting behavior and increased surface roughness due to enhanced wicking followed by solidification.

Ongoing Challenges of Laser-Based Powder Bed Fusion Processing of Al Alloys and Potential Solutions from the Literature—A Review

“… Plot of surface roughness as a function of the main categories of commercially available materials for PBF-LB/M production [ 130 , 131 , 132 , 133 , 134 , 135 , 136 , 137 , 138 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146 , 147 , 148 , 149 , 150 , 151 , 152 , 153 , 154 , 155 , 156 , 157 , 158 , 159 , 160 , 161 , 162 , 163 ]. …”

Surface Properties and Tribological Behavior of Additively Manufactured Components: A Systematic Review

“…Furthermore, all the articles dealing with the effect of printing and process parameters on roughness were gathered into another category. In this category, eleven articles focusing on metal AM processes [30][31][32][33][34][35][36][37][38][39][40] and three articles, which focus on polymer parts in FFF [41][42][43] were identified. For instance, Panahizadeh et al [35] investigated laser powder bed fusion and optimized the parameters of laser power, scanning speed, hatch space, scanning pattern angle, and heat treatment temperatures, using the multiobjective non-dominant sorting genetic algorithm, to obtain parameter combinations that lead to maximum relative density and minimum roughness on Ti6Al4V samples.…”

“…Predicting or measuring the roughness Metal LPBF, WAAM [10][11][12][13][14][15][16][17][18][19] Polymer SLS, FFF [20][21][22][23][24][25][26][27] Methods for reducing roughness Metal LBF, DMLS [29,50,[56][57][58][59][60][61][62][63][64][65][66] Polymer [28] Effects of printing and process parameters on roughness Metal LBF, WAAM, GMAW [30][31][32][33][34][35][36][37][38][39][40] Polymers FFF [41][42][43] Effects of roughness on part properties Corrosion LPBF-M [49,67] Mechanical LPBF-M, Arbitrary [44]…”

Surface Roughness Studies on F357 Aluminum Alloy Fabricated Using Laser Powder Bed Fusion Process

“…Thus, it is important to understand the variations in as-fabricated surface roughness and its influences on the performance of components. Previous studies [15][16][17][18][19][20] investigated the different aspects related to the surface roughness evolution of LPBF-processed AlSi10Mg aluminum alloy. The factors studied involved the influence of processing parameters such as laser power, scanning speed, scanning strategies, and overlap between tracks.…”