Fabrication of Lotus-type porous stainless steel by continuous zone melting technique and mechanical property

Lotus-type porous stainless steel (SUS304L) rods were fabricated by the continuous zone melting technique under a pressurized mixed gas of hydrogen and inert gas such as argon or helium. Pores with cylindrical shape, whose growth direction is parallel to the solidification direction are observed in the rods. The dependence of the porosity and averaged pore diameter on the partial pressure of hydrogen or the total pressure and on the transference velocity of rods was investigated. It was found that the porosity increases with increasing partial pressure of hydrogen under a constant total pressure and the pore diameter decreases with increasing transference velocity. The maximum porosity was about 60 pct under the experimental conditions in the present work. The observation of the microstructure and the. measurement of the tensile strength were also carried out.