Enhanced corrosion resistance of 17-4 PH stainless steel fabricated by laser powder bed fusion in H₂SO₄ solution

The purpose of this study is to examine the microstructure and corrosion performance of martensitic stainless steel 17-4 PH produced by laser powder bed fusion (LPBF) and its corresponding rod specimen in sulfuric acid. Based on a microstructural analysis, the LPBF alloy contained melt pools with an ultrafine cellular structure and uniform distribution of elements, including Nb. The LPBF process significantly improved the corrosion resistance of the 17-4 PH stainless steel alloy in sulfuric acid. The alloy manufactured by LPBF had a charge transfer resistance of at least 7 times that of the Rod counterpart and a corrosion current density that was 4 times lower than Rod. The homogeneous distribution of elements during the solidification process improved the electrochemical performance of LPBF 17-4 PH stainless steel due to the development of gentle galvanic cells compared to Rod one.