Effects of powder characteristics and processing conditions on the corrosion performance of 17-4 PH stainless steel fabricated by laser-powder bed fusion

Abstract

Powder characteristics and processing conditions are known to strongly influence the densification of parts fabricated by the laser-powder bed fusion (L-PBF) process. However, the influence of powder and L-PBF process parameters on corrosion performance of parts has not been studied extensively. In this paper, the effects of processing conditions (energy density) and powder characteristics (shape and size) on the corrosion performance of 17-4 PH stainless steel parts produced by L-PBF were investigated. The corrosion performance of the L-PBF parts was evaluated using corrosion current, polarization resistance and corrosion rate values from the potentiostatic polarization curves. It was observed that the density and consequently corrosion performance of L-PBF parts using coarser water-atomized (D50 = 24 and 43 µm) powders increased when the energy density was increased from 64 to 104 J/mm3. However, the density and subsequent corrosion performance of the L-PBF parts was relatively higher for the finer gas (D50 = 13 µm) and water-atomized (D50 = 17 µm) powders when fabricated using the same range of energy densities. At an energy density of 104 J/mm3, the corrosion performance of L-PBF parts fabricated using water-atomized 17-4 PH stainless steel powders all powders exhibited higher polarization resistance (28,000 ± 500 Ω) than the wrought sample (25,000 ± 1000 Ω) in the 0.5 M NaCl environment, indicative of better corrosion properties.