Effect of laser remelting on microstructure and immersion corrosion of cold–sprayed aluminum coating on S355 structural steel

Abstract

A cold–sprayed aluminum (Al) coating was processed on S355 structural steel using a laser remelting (LR). The surface and interface morphologies, chemical composition, and phases of obtained Al coating were analyzed using a field emission scanning electronic microscope (FESEM), energy dispersive spectrometer (EDS) and X–ray diffractometer (XRD), respectively, and its residual stress was analyzed using a X–ray diffraction residual stress tester. The corrosion behavior of Al coating was investigated using an immersion corrosion test, in 3.5% NaCl solution for 720 h, the electrochemical corrosion was tested on a PS268A type of electrochemical workstation, and the mechanism of LR on the corrosion behavior of Al coating was also discussed. The results show that the porosity on the cold–sprayed Al coating reduced and its compactness increased after LR, the phase of Al coating after LR is composed of Al, with no other oxides. The residual compressive stress of cold–sprayed Al coating after LR is −69.0 MP, increased by 25% than the cold–sprayed Al coating, improving its bonding strength. The corrosion potential of cold–sprayed Al coating after LR shifts positively, showing that the electrochemical corrosion resistance of cold–sprayed Al coating is improved after LR.