Assessment of Hot Corrosion in Molten Na2SO4 and V2O5 of Inconel 625 Fabricated by Selective Laser Melting versus Conventional Technology

Teodor Adrian Badea; Dan Batalu; Nicolae Constantin; Alexandru Paraschiv; Delia Pătroi; Laurentiu Constantin Ceatra

doi:10.3390/ma15124082

Assessment of Hot Corrosion in Molten Na₂SO₄ and V₂O₅ of Inconel 625 Fabricated by Selective Laser Melting versus Conventional Technology

Materials (Basel). 2022 Jun 8;15(12):4082. doi: 10.3390/ma15124082.

Authors

Teodor Adrian Badea^{1

2}, Dan Batalu², Nicolae Constantin², Alexandru Paraschiv¹, Delia Pătroi³, Laurentiu Constantin Ceatra¹

Affiliations

¹ Romanian Research and Development Institute for Gas Turbines COMOTI, 220D Iuliu Maniu Av., 061126 Bucharest, Romania.
² Materials Science and Engineering Faculty, University Politehnica of Bucharest, 060042 Bucharest, Romania.
³ R&D National Institute for Electrical Engineering ICPE-CA Bucharest, 313 Splaiul Unirii, 030138 Bucharest, Romania.

Abstract

Inconel 625 samples, obtained by Selective Laser Melting (SLM) and conventional technology, were tested for hot corrosion resistance against a molten mixture of Na₂SO₄ and V₂O₅. The assessments were performed in air, at 900 °C with exposure time of up to 96 h, and at 1000 °C for 8 h. Weight gain was higher for samples obtained by SLM, with 37.4% after 8 h, 3.98% after 24 h, 4.46% after 48 h, and 5.8% after 96 h at 900 °C (22.6% at 1000 °C, 8 h). Three stages of corrosion were observed, the first and last with a high corrosion rate, while the second one showed a slower corrosion rate. Corrosion behaviour depends on the morphology of the grain boundary, which can influence the infiltration of corrosive salts, and on the formation of Cr₂NiO₄ compound, which acts as a temporary barrier.

Keywords: Inconel 625; hot corrosion; selective laser melting; sodium sulphate (Na2SO4); vanadium pentoxide (V2O5).

Grants and funding

This research was performed within the “Nucleu” Program, Grant no. 2N/2019 and 25PFE/30.12.2021—Increasing R-D-I capacity for electrical engineering-specific materials and equipment with reference to electromobility and “green” technologies within PNCDI III, Programme 1, funded by Romanian Ministry of Education, Research and Digitalization.