Patent ID: 11959159
Assignee: POSCO CO., LTD
Field: Materials, metallurgy (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. An austenitic stainless steel comprising, in percent (%) by weight of the entire composition,
C: 0.01 to 0.04%,
Si: 0.1 to 1.0%,
Mn: 0.1 to 2.0%,
Cr: 16 to 20%,
Ni: 6 to 10%,
Cu: 0.1 to 2.0%,
Mo: 0.2% or less,
N: 0.035 to 0.07%, and
the remainder of iron (Fe) and other inevitable impurities,
wherein the C+N satisfies 0.06 to 0.1%,
wherein an Md30 value in equation (1) is −10° C. or less, and an average grain size is 45 μm or more,

Md30=551−462*(C+N)−9.2*Si−8.1*Mn−13.7*Cr−29*(Ni+Cu)−18.5*Mo  (1)

where, C, N, Si, Mn, Cr, Ni, Cu, and Mo represent the content, % by weight, of each element,
wherein a product of the Md30 (° C.) value represented by the equation (1) and the average grain size (μm) satisfies less than −500,
wherein a work-hardening exponent n value in a range of true strain 0.3 to 0.4 satisfies the range of 0.45 to 0.5,
wherein an aging crack limited drawing ratio of the stainless steel is 2.97 or more, and
wherein a hole expansion rate (HER) represented by equation (2) is 72% or more

HER=(Dh−D0)/D0×100  (2)

where Dh is an inner diameter after fracture and D0 is an initial inner diameter.