High-strength nonmagnetic austenitic stainless steel and manufacturing method therefor

A high strength non-magnetic austenitic stainless cold-rolled steel sheet comprising, in percent (%) by weight of the entire composition, C:

• 0.02 to 0.12%, Si:
• 1.2% or less, Mn:
• 0.5 to 2.0%, Cr:
• 17.0 to 22.0%, Ni:
• 11.0 to 15.0%, Mo:
• 3.0% or less, N:
• 0.25% or less, the remainder of iron (Fe) and other inevitable impurities,
• satisfying C+N:
• 0.25% or more, and
• satisfying following Formulas (1) and (2).
• [{Cr+Mo+1.5*Si+18}/{Ni+30*(C+N)+0.5*Mn+36}+0.262]*161−161−log(cooling rate)<0 (1)
• 551−462*(C+N)−9.2*Si−8.1*Mn−13.7*Cr−29*Ni−18.5*Mo≤−200 (2)
• (Here, Cr, Mo, Si, Ni, C, N, Mn mean the content (% by weight) of each element, and the cooling rate means the cooling rate (° C./s) of the cast slab solidified from molten steel)

A manufacturing method of a high strength non-magnetic austenitic stainless steel, the manufacturing method comprising,

• manufacturing a hot-rolled annealed steel sheet by performing hot rolling and annealing heat treatment on a slab comprising, in percent (%) by weight of the entire composition, C:
• 0.02 to 0.12%, Si:
• 1.2% or less, Mn:
• 0.5 to 2.0%, Cr:
• 17.0 to 22.0%, Ni:
• 11.0 to 15.0%, Mo:
• 3.0% or less, N:
• 0.25% or less %, C+N:
• 0.25% or more, the remainder of iron (Fe) and other inevitable impurities;
• and
• manufacturing a cold-rolled steel sheet by cold rolling the hot-rolled annealed steel sheet at a reduction ratio of 80% or more, and
• wherein the slab satisfies following Formulas (1) and (2),
• a permeability μ of the cold-rolled steel sheet is 1.02 or less.
• [{Cr+Mo+1.5*Si+18}/{Ni+30*(C+N)+0.5*Mn+36}+0.262]*161−161−log(cooling rate)<0 (1)
• 551−462*(C+N)−9.2*Si−8.1*Mn−13.7*Cr−29*Ni−18.5*Mo≤−200 (2)
• (Here, Cr, Mo, Si, Ni, C, N, Mn mean the content (% by weight) of each element, and the cooling rate means the cooling rate (° C./s) of the cast slab solidified from molten steel)