Title: Investigating The Influence Of Surface Finishing Methods On Corrosion Of Additively Manufactured SS316L
Program: Master of Science in Materials Science and Engineering
Advisor: Dr. Mike Hurley, Materials Science
Committee Members: Dr. Brian Jaques, Materials Science and Engineering; and Dr. Donna P. Guillen, Engineering and Applied Science
Additive Manufacturing (AM), namely with metal, has seen a surge in growth and interest over recent years. A wide array of industries are developing new products to take advantage of this budding technology. In order to enable adoption of this technology, understanding of the differences of AM versus traditionally manufacturing on the resultant materials properties of printed components is important. The work done for this study fell into two separate categories of work.
The first effort of this work involved the installation, certification, and operation of the first laser powder bed fusion (LPBF) printer at the Center for Advanced Energy Studies (CAES). As this being the first of its kind at the center and for BSU, all new technical and engineering considerations were encountered, taking nearly two full years to complete all the documentation and certification. As a result, successful LPBF printing of SS316L has been established
The second effort aimed to gain a better understanding of the corrosion properties of AM SS316L and how the printing process and post-printing surface finish impacts relative corrosion rates and potentials. Using an Open Additive PANDA LPBF printer with typical parameters for stainless steel, twenty-five identical samples were produced. The samples were divided into groups of three. Each group tested with a different surface preparation method. The surface preparation methods included media blasting, machining, and polishing. A piece of wrought steel of the same variety was also included for a baseline comparison. Electrochemical testing was performed to provide accelerated corrosion conditions. Testing and post-test characterization results show that a better surface finish will lead to better corrosion properties, with select cases outside the expected trend. On average, AM SS316L showed a reduced corrosion rate to that of the wrought steel. Greater interest was found in how corrosion progressed on the AM samples with different surface finishes. Pitting corrosion on all of the AM parts led to irregular attack around the AM microstructural features and significant delamination between the individual print layers. Wrought samples showed no such damage. Further testing is required to fully understand this phenomenon. With newly established metal 3d printing capability, future research efforts will build on this work to support increased adoption of this manufacturing technology.