Electropolishing of re-melted SLM stainless steel 316L parts using deep eutectic solvents: 3x3 full factorial design
This three-level three-factor full factorial study describes the effects of electropolishing using deep eutectic solvents on the surface roughness of re-melted 316L stainless steel samples produced by the selective laser melting (SLM) powder bed fusion additive manufacturing method. An improvement in the surface finish of re-melted stainless steel 316L parts was achieved by optimizing the processing parameters for a relatively environmentally friendly electropolishing process using a Choline Chloride ionic electrolyte. The results show that further improvement of the response value-average surface roughness (Ra) can be obtained by electropolishing after re-melting to yield a 75% improvement compared to the as-built Ra. The best Ra value was less than 0.5 lm, obtained with a potential of 4 V, maintained for 30 min at 40 C. Electropolishing has been shown to be effective at removing the residual oxide film formed during the remelting process. The material dissolution during the process is not homogenous and is directed preferentially toward the iron and nickel, leaving the surface rich in chromium with potentially enhanced properties. The re-melted and polished surface of the samples gave an approximately 20% improvement in fatigue life at low stresses (approximately 570 MPa). The results of the study demonstrate that a combination of re-melting and electropolishing provides a flexible method for surface texture improvement which is capable of delivering a significant improvement in surface finish while holding the dimensional accuracy of parts within an acceptable range.
The authors acknowledge the significant support provided by researchers from the Materials Centre, Department of Chemistry, University of Leicester (Dr Harris, Robert C., Dr Juma, Jamil and particularly Karl S. Ryder, Professor of Physical Chemistry). The affiliation of co-author A.A.Al-Barzinjy at time of submission of the article and duration of the experimental work, was the Materials Centre, Department of Chemistry, University of Leicester. The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.
Citation : Alrbaey, K., Wimpenny, D.I., Al-Barzinjjy, A.A. and Moroz, A. (2016) Electropolishing of re-melted SLM stainless steel 316L parts using deep eutectic solvents: 3x3 full factorial design. Journal of Materials Engineering and Performance, 25 (7), pp. 2836-2846
ISSN : 1059-9495
Research Group : Engineering and Physical Sciences Institute (EPsi)
Peer Reviewed : Yes