Corrosion resistance in chloride solution of the AlSi10Mg alloy obtained by means of LPBF

Abstract

The paper deals with the corrosion resistance in chloride solutions of an AlSi10Mg alloy obtained by laser powder bed fusion (LPBF) process. The potentiodynamic tests were carried out in solutions having different chloride contents. The results emphasize the role of chloride concentration on localized corrosion. The increase of concentration reduces pitting potential. In addition, the influence of the post‐processing heat treatment temperature was recognized. Penetrating attacks occurred either on after low temperatures stress relieving or specimens without any treatment, promoted by selective dissolution of the α‐Al phase stimulated by galvanic coupling with noble silicon precipitates at the border of the melt pool. Such penetrating morphology was not observed after heat treatments at high temperature.

Effect of Heat Treatment on Microstructure and Selective Corrosion of LPBF-AlSi10Mg by Means of SKPFM and Exo-Electron Emission

“…SKPFM data are in agreement with the corrosion behavior previously reported for the AlSi10Mg manufactured by LPBF [ 6 , 7 ] UT and 2h-300 specimens are susceptible to selective attack along the melt pool boundaries, as showed by the yellow dotted line in Figure 7 ; the white dotted line in ( Figure 7 c) evidences a porosity in the correspondence of the prior edge of the melt pool, whereas the melt pools disappeared after the heat treatment. The selective attack of the edge of the melt pool is promoted by galvanic coupling due to the high Volta potential difference between the Si and α-Al phases [ 7 ].…”

“…In the last few years many studies have investigated the effect of heat treatment on the corrosion behavior of AlSi10Mg alloy obtained by means of laser powder bed fusion (LPBF) [ 6 , 7 ], also known with trade names as direct metal laser sintering (DMLS) [ 8 , 9 , 10 , 11 ] or selective laser melting (SLM) [ 10 , 12 , 13 , 14 , 15 ]. The corrosion resistance of the LPBF alloys is affected by different factors including the effect of the 3D printed surface [ 16 , 17 ] and that of the microstructure [ 18 , 19 ].…”

Corrosion of metallic materials fabricated by selective laser melting

“…The SLM of the following aluminium alloys has been investigated: Al-Cu, [156][157][158] Al-Zn, 159 AlSi12, [160][161][162][163] AlSi50, 164 and AlSi10Mg, 70,115,[165][166][167][168][169][170][171][172] with AlSi10Mg receiving the most attention.…”

Corrosion of Cast Aluminum Alloys: A Review

“…The negative consequence of this issue is prevented by a shoot peening applied to surface [38]. Cabrini et al [82] performs potentiodynamic tests on a AlSi10Mg alloy obtained by LPBF process, observing that an increase of chloride solution concentration provokes a reduction of the pitting potential, with a logarithmic correlation, as indicative of a prone localized corrosion. The authors also detail the positive effect of high temperature post-processing heat treatment to selective dissolution of the α-Al phase stimulated by galvanic coupling with noble silicon precipitates wherein the corrosion morphology of localized attack modifies due to the different distribution and size of silicon phases induced by the heat treatment.…”