The effect of a Cu addition on the corrosion behavior of 304 austenitic stainless steel in a solution was elaborately investigated through salt spray tests, FeCl₃ immersion tests and characterization analyses. The corrosion behavior was further analyzed by optical microscopy, scanning electron microscopy, inductively coupled plasma mass spectrometry and an X-ray photoelectron spectroscopy analysis. 304Cu showed a higher corrosion resistance than 304 after the salt spray tests in a 5 wt.% NaCl solution for 168 h; the beneficial effect of Cu was not obvious after exposure for 480 h. Penetrating (stripped morphology in 304 and fishbone morphology in 304Cu) and non-penetrating dish-shaped pits were both observed on 304 and 304Cu after immersion in a 6 wt.% FeCl₃ solution for 72 h; the corrosion rates of 304Cu were much higher than 304. Cu and Cu²⁺ were the main existing forms in the as-received 304Cu and Cu⁺ formed with the corrosion in chloride solutions. The results indicated a good corrosion resistance of 304Cu in service. The use of steel in an aggressive environment for a long exposure time should be cautiously considered.

In this work, 316L stainless steel samples were prepared by selective laser melting (SLM) and the effects of the bulk laser energy density on the resulting density and mechanical properties were evaluated. The results show that the density and mechanical properties of SLM 316L stainless steel first improved and then deteriorated with increasing bulk laser energy density. When the bulk laser energy density was 70.2 J/mm³, the obtained tensile strength and yield strength vertical to the building direction were 720 and 546 MPa, respectively, which surpass the design requirements for forged 316L stainless steel. The influence of the microstructure on the mechanical properties of SLM 316L stainless steel is also discussed. The purpose of this research was to provide experimental data and a theoretical basis for high-performance 316L stainless steel fabricated by SLM.