Microstructure and corrosion behavior of 10CrNi3MoV high-strength low-alloy steel coating via underwater wire-feed laser cladding

The underwater local dry wire-feed laser cladding was successfully used to prepare 10CrNi3MoV high-strength low-alloy steel coating for the first time and the influences of water environment on the surface morphology, cross section, microstructure and corrosion behavior of cladding layer were studied. Compared with the in-air cladding layer, the surface flatness of the underwater cladding layer was poor. There were no defects such as lack of fusion and cracks between the cladding layers and substrate. Besides, the heights of cladding zone and heat affected zone in underwater cladding layer were 94.8 % and 88.5 % that of in-air cladding layer, respectively. Due to the presence of more lath martensite, smaller grain size, higher kernel average misorientation and lower texture strength of (100) lattice plane, the electrochemical corrosion performance of underwater cladding layer was poor. The corrosion mechanisms of both underwater and in-air cladding layers were pitting corrosion, but corrosion degree of underwater cladding layer was more serious and corrosion rate was faster. There were less alpha-FeOOH, Cr2O3 and NiFe2O4 in underwater cladding layer, which reduced the compactness of corrosion products film. Therefore, the protection ability of the corrosion products film of the underwater cladding layer became weak.