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In this study, seven 316L stainless steel (316L SS) bulks with different angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°) relative to a build substrate were built via selective laser melting (SLM). The influences of different angles on the metallography, microstructure evolution, tensile properties, and corrosion resistance of 316L SS were studied. The 0° sample showed the morphology of corrugated columnar grains, while the 90° sample exhibited equiaxed grains but with a strong <101> texture. The 60° sample had a good strength and plasticity: the tensile strength with 708 MPa, the yield strength with 588 MPa, and the elongation with 54.51%. The dislocation strengthening and grain refinement play a vital role in the mechanical properties for different anisotropy of the SLM-fabricated 316L SS. The 90° sample had greater toughness and corrosion resistance, owing to the higher volume fraction of low-angle grain boundaries and finer grains., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Li, Yi, Wu, Zhang, Yang, Zhao, Wang, Liu and Bai.)

• 316L SS was fabricated by laser powder bed fusion (L-PBF) process. • L-PBF processed steel showed fine cellular/columnar structure due to rapid cooling. • The formation of passive layer on the L-PBF processed steel is favored in the alkaline media. • Better corrosion performance was observed for L-PBF processed steel. This study investigates the microstructure and electrochemical behavior of 316 L processed through laser powder bed fusion (L-PBF) and the related commercial wrought counterpart in the concrete pore solution (0.9 M NaOH + 0.9 wt% NaCl). Analyses showed that the L-PBF method did not decline the corrosion resistance of 316L SS in the alkaline solution. Even in some cases, L-PBF processed alloy showed better electrochemical behavior compared the wrought alloy. Microscopy evaluation indicated that L-PBF processed specimen showed an ultrafine cellular/columnar structure with the more uniform morphology at the higher magnifications compared to the wrought sample, possibly because of the excessive cooling rate of the L-PBF process. Besides, electrochemical studies revealed that corrosion current density related to the L-PBF processed sample reported about one-third of wrought counterpart. Also, L-PBF processed alloy identified the lower defect density compared to the wrought one. The better corrosion performance of the L-PBF processed 316L SS could be related to the fabrication method of the additively manufactured samples, which hindered the presence of detrimental phases and more stability of the passive film. [ABSTRACT FROM AUTHOR]

• New water-soluble PAni–SNF NCs were successfully synthesized by a one-step in-situ polymerization method at room temperature. • SNF not only acts as a dopant but also plays the main role in the formation of nanocomposites. • The highest inhibition efficiency of 99% was observed for PANS-10 at 50 ppm concentration. • The adsorption of the PAni–SNF NCs on 316L SS surface obeys the Langmuir adsorption isotherm. • This study revealed that PAni–SNF NCs act as an excellent corrosion inhibition behavior for 316L SS in 1 M HCl solution. In this paper, water-soluble conducting polyaniline–sulfonated naphthalene formaldehyde nanocomposites (PAni–SNF NCs) were successfully synthesized by a one-step in-situ polymerization method. The structural characterization of the synthesized PAni–SNF NCs was confirmed by Fourier transform-infrared spectroscopy (FT–IR), Ultraviolet-visible spectroscopy (UV–Vis), Proton nuclear magnetic resonance spectroscopy (1H NMR), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), Dynamic light scattering (DLS), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Conductivity measurements, Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), and Cyclic voltammetry (CV). The corrosion protective behavior of 316L stainless steel (316L SS) in 1 M HCl was examined using electrochemical measurements and weight loss methods at various PAni–SNF NCs. The inhibition efficiency of PAni–SNF NCs was found to 97.9% and 99.3% in the case of PANS-3 and PANS-10 NCs at the optimum concentration of 50 ppm. The potentiodynamic polarization method demonstrated that PAni−SNF NCs acted as a mixed-type inhibitor in both studied NCs. Moreover, adsorption of PAni−SNF NCs inhibitor on the 316L SS surface followed the Langmuir isotherm model. The present report provides extremely significant findings in preparing and designing novel and sustainable corrosion inhibitors with high inhibition efficiency. [ABSTRACT FROM AUTHOR]

In this study, single-layer and three-layer nickel-based coatings were fabricated on 316L SS by laser additive manufacturing. The phase characterization, microstructure observation, and microhardness analysis of the coatings were carried out by X-ray diffraction (XRD), scanning electron microscope (SEM), and microhardness tester. And the wear resistance of the coatings was analyzed through dry sliding friction and wear test. The results show that the cross-section microstructure of the three-layer nickel-based coating is different from that of the single-layer one under the influence of heat accumulation; the dendrite structure in the central region of the former is equiaxial dendrite, while that of the latter still remains large columnar dendrites. The existence of solid solution phase γ-(Fe, Ni) and hard phases of Ni17Si3, Cr5B3, Ni3B in the coating significantly improve the wear resistance of the coating, and the microhardness is nearly 2.5 times higher than that of the substrate. However, the average microhardness of multilayer cladding coating is about 48 HV0.2 higher than that of the single-layer cladding coating. In addition, the fine surface structure of the three-layer nickel-based coating improves the wear resistance of the coating, making this coating with the best wear resistance. [ABSTRACT FROM AUTHOR]

Effect of microstructure on the crack initiation and early propagation mechanism in the very high cycle fatigue (VHCF) regime was studied in 316L stainless steel (316L SS) by atomic force microscope (AFM) and electron back scattered diffraction (EBSD). The results show that small fatigue cracks initiate from the slip band near the grain boundaries (GBs) or the twin boundaries (TBs). Early crack propagation along or cross the slip band is strongly influenced by the local microstructure such as grain size, orientation, and boundary. Besides, the gathered slip bands (SBs) are presented side by side with the damage grains of the run-out specimen. Finally, it is found that dislocations can either pass through the TBs, or be arrested at the TBs. [ABSTRACT FROM AUTHOR]

• Interactions of the Hastelloy N-316 L SS couple affect the corrosion of material. • Corrosion of 316 L SS is accelerated while that of Hastelloy N is impeded. • Interactions of the Hastelloy N-316 L SS couple lead to the mass transfer of Fe. • Mass transfer relies on whether dissolved element can be alloyed by Hastelloy N. • Interactions of the couple depend on galvanic corrosion and Fe mass transfer. The corrosion behavior of a Hastelloy N-316 L stainless steel couple in molten LiF-NaF-KF salt at 700 °C was investigated using electrochemistry, immersion tests, and microstructure analyses. Hastelloy N exhibits better corrosion resistance than 316 L SS. Galvanic coupling between two metals accelerates the corrosion of 316 L SS but impedes the corrosion of Hastelloy N. Fe dissolved from 316 L SS was alloyed with Ni in Hastelloy N to form a concentration cell of Fe, which accelerated the mass transfer of Fe from 316 L SS to Hastelloy N. The interactions of the Hastelloy N-316 L SS couple depend on galvanic corrosion and the Fe transfer. [ABSTRACT FROM AUTHOR]