CrFeCoNi and CrMnFeCoNi coatings were prepared by laser remelting method. The grain boundary characteristics distribution of both coatings was investigated by electron backscattered diffraction technique. The results showed that the CrFeCoNi coating exhibited higher fraction of low angle grain boundaries and S3 boundaries compared to the CrMnFeCoNi coating. The corrosion properties of the CrFeCoNi and CrMnFeCoNi coatings in 3.5 wt% NaCl solution were identified by electrochemical method and localized electrochemical impedance spectroscopy technique. The results indicated that the CrFeCoNi coating had a higher corrosion resistance than the CrMnFeCoNi coating. The better corrosion resistance of the CrFeCoNi coating could be attributed to the high fraction of S3 boundaries and low fraction of the high angle boundaries.

The passivation behavior of selective laser melting 316L stainless steel (SLM 316L SS) on different building planes is studied in 3.5% NaCl solution. The results show that the XOZ and YOZ planes have a semicircular molten pool structure, and the XOY plane shows a columnar molten pool structure. Meanwhile, the XOZ planes have relatively smaller grain sizes and higher low-angle grain boundaries (LAGBs) proportionate than that of YOZ and XOY planes. The electrochemical testing results illustrate that the XOZ plane has a lower corrosion tendency than that of YOZ and XOY planes, as the thicker passive film with higher content of Cr 2 O 3 is detected on the XOZ plane. The XOZ plane, which has a higher Cr ox þ hy /(Fe ox þ hy þ Cr ox þ hy ) ratio, has excellent passivation performance and better electrochemical properties than the other two planes.

Owing to the versatility without expanding the machine’s size, thin-wall has been widely used in high-value parts. The investigation of laser additive manufacturing (LAM), which has advantages such as high powder density, easy controllability, and excellent stability, on the fabrication of thin-wall has drawn much attention. In this paper, the research status of macroscopic and microstructural features of metal thin-wall fabricated by LAM has been reviewed. The deposition quality was mainly focused on the effect of process parameters and especially the matching of z-increment and single deposition height. Based on the grain size and growth of columnar, the characteristics of microstructures were analyzed. Considering the structural feature of thin-wall, the effect of grain size and phases on the hardness and distribution of hardness were discussed. The effect of grain size, phases and loading direction on the tensile properties were reviewed. The distribution and modification of thermal stress were presented.