Microstructure, microhardness, composition, and corrosive properties of stainless steel 304 II. Low-pressure laser spraying with silicon.

Clad layers of silicon on a SUS 304 substrate were obtained by low-pressure laser spraying (LPLS) to investigate their microstructure, microhardness, composition, and corrosive properties. When an impinged energy density was adjusted to be 32 to 95 W mm-2, the silicon concentration of the surface of clad layers was estimated as 5 to 8 wt.%. For as-prepared layers, their crystal structure was a single phase of alpha-ferrite with no distinct corrosion resistance, because partially segregated Si atoms along the grain boundaries and inside the grains were selectively dissolved in the etching process. After solution-annealing for 2 h, the corrosion resistance was greatly improved in hydrochloric acid solution.