METHOD FOR ROLLING/DRAWING NICKEL-FREE HIGH-NITROGEN STAINLESS STEEL MATERIAL, THIN SEAMLESS TUBE OF NICKEL-FREE HIGH-NITROGEN STAINLESS STEEL, AND METHOD OF MANUFACTURING THE SAME
Provided is a method of rolling/drawing a nickel-free high-nitrogen stainless steel material, the method including: an intermediate annealing process S11 in which a nickel-free high-nitrogen stainless steel material made of a fine grain structure having a maximum crystal grain size of 30 μm or less is annealed at a temperature of 900° C. or higher and 1000° C. or lower and then is air-cooled to room temperature a rolling/drawing process S12 in which the nickel-free high-nitrogen stainless steel material is extended while being thinned or being reduced in diameter and a final solution treatment process S13 in which the nickel-free high-nitrogen stainless steel material is heated to a temperature of 1200° C. or higher and 1400° C. or lower and then is air-cooled to room temperature. A nickel-free high-nitrogen stainless steel raw tube made of a fine grain structure 11 having a maximum crystal grain size of 30 μm or less is subjected to plastic working according to the method of rolling/drawing the nickel-free high-nitrogen stainless steel material to obtain a thin seamless tube 10 for the nickel-free high-nitrogen stainless steel stent. The thin seamless tube for the nickel-free high-nitrogen stainless steel stent is made of a fine grain structure having a maximum crystal grain size of 30 μm or less.
