This work focuses on the influence of post-processing on microstructure and corrosion properties of additive manufactured (AM) super-duplex stainless steels (SDSS) 2507 consolidated via laser-powder bed fusion (L-PBF). Conventional heat treatment or hot isostatic press (HIP) with different cooling rates; 200 °C/min or 5 °C/min were carried out. The corrosion resistance was analyzed by critical pitting temperature (CPT) using ASTM G150 and immersion testing. Scanning Kelvin Probe Microscopy (SKPFM) was used to evaluate the electrochemical response.

The results suggest that different thermal cycles led to variation in the microstructure and corrosion properties. HIP with a fast cooling rate is recommended to ensure good corrosion resistance of L-PBF 2507. Use of a slow cooling rate after HIP processing can lead to appreciably lower corrosion resistance compared to conventional manufactured 2507 due to the presence of detrimental phases. A conventional heat treatment of the AM components can also give acceptable corrosion resistance. The conclusion is that with the right post-processing, the L-PBF material had similar or even higher corrosion resistance than conventional material and thus a high potential to be used in off-shore applications or other corrosive environments.

Subject
Sigma phase, Test methods, Materials, Corrosion rate, Microstructure, Additive manufacturing, Pitting, Corrosion resistance, Pitting resistance equivalent number, Ferrite, Electrochemical potential, Heat treatment, Austenite
Keywords:
duplex stainless steel, SDSS, additive manufactured, AM, L-PBF, corrosion, SKPFM, pitting, CPT
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2021
Association for Materials Protection and Performance (AMPP)
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