A stainless steel seamless pipe is provided that is a stainless steel comprising, in mass %, Cr: 11.5 to 35.0%, and Mo: 0.5 to 6.0%, and including ferrite and austenite, the stainless steel seamless pipe having a ferrite grain boundary and/or a ferrite-austenite grain boundary with a Mo concentration (mass %) that is at most 4.0 times the intragranular Mo concentration (mass %) of ferrite, or an austenite grain boundary with a Mo concentration (mass %) that is at most 4.0 times the intragranular Mo concentration (mass %) of austenite, the stainless steel seamless pipe having an axial tensile yield strength of 689 MPa or more, and an axial compressive yield strength/axial tensile yield strength ratio of 0.85 to 1.15.

A stainless steel seamless pipe is provided that is a stainless steel comprising, in mass %, Cr: 11.5 to 35.0%, and Mo: 0.5 to 6.0%, and including ferrite and austenite, the stainless steel seamless pipe having a ferrite grain boundary and/or a ferrite-austenite grain boundary with a Mo concentration (mass %) that is at most 4.0 times the intragranular Mo concentration (mass %) of ferrite, or an austenite grain boundary with a Mo concentration (mass %) that is at most 4.0 times the intragranular Mo concentration (mass %) of austenite, the stainless steel seamless pipe having an axial tensile yield strength of 689 MPa or more, and an axial compressive yield strength/axial tensile yield strength ratio of 0.85 to 1.15.

A preferable aspect of the present invention provides: a hot-rolled steel sheet with excellent impact resistance containing, by weight, 0.35-0.55% of C, 0.7-1.5% of Mn, 0.3% or less (excluding 0%) of Si, 0.03% or less (including 0%) of P, 0.004% or less (including 0%) of S, 0.04% or less (excluding 0%) of Al, 0.3% or less (excluding 0%) of Cr, 0.3% or less (excluding 0%) of Mo, one or two of 0.1-1.0% of Ni and 0.1-1.0% of Cu, 0.4% or more of Cu+Ni, 0.006% or less (excluding 0%) of N, and the balance Fe and other impurities, the alloy elements satisfying relational formulas 1 to 3 below, wherein a microstructure of the hot-rolled steel sheet comprises, by volume, 10% or more of ferrite and 90% or less of pearlite; a steel pipe and a member each using the same; and manufacturing methods therefore.

(Mn/Si)≥3 (weight ratio)  [Relational formula 1]

(Ni+Cu)/(C+Mn)≥0.2 (weight ratio)  [Relational formula 2]

(Ni/Si)≥(weight ratio)  [Relational formula 3].

A preferable aspect of the present invention provides: a hot-rolled steel sheet with excellent impact resistance containing, by weight, 0.35-0.55% of C, 0.7-1.5% of Mn, 0.3% or less (excluding 0%) of Si, 0.03% or less (including 0%) of P, 0.004% or less (including 0%) of S, 0.04% or less (excluding 0%) of Al, 0.3% or less (excluding 0%) of Cr, 0.3% or less (excluding 0%) of Mo, one or two of 0.1-1.0% of Ni and 0.1-1.0% of Cu, 0.4% or more of Cu+Ni, 0.006% or less (excluding 0%) of N, and the balance Fe and other impurities, the alloy elements satisfying relational formulas 1 to 3 below, wherein a microstructure of the hot-rolled steel sheet comprises, by volume, 10% or more of ferrite and 90% or less of pearlite; a steel pipe and a member each using the same; and manufacturing methods therefore.

(Mn/Si)≥3 (weight ratio)  [Relational formula 1]

(Ni+Cu)/(C+Mn)≥0.2 (weight ratio)  [Relational formula 2]

(Ni/Si)≥(weight ratio)  [Relational formula 3].

A lumen stent preform is provided using a plasma nitriding technology, a preparation method thereof, a method for preparing a lumen stent by using the preform, and a lumen stent obtained according to the method. The preform is manufactured by using pure iron or an iron alloy containing no strong nitrogen compound, has a hardness of 160-250HV0.05/10, and has a microstructure that is a deformed structure having a grain size scale greater than or equal to 9 or a deformed structure after cold machining. Alternatively, the preform is an iron alloy containing a strong nitrogen compound, and has a microstructure that is a deformed structure having a grain size scale greater than or equal to 9 or a deformed structure after cold machining. The lumen stem preform meets the requirements of a conventional stent for radial strength and plasticity, so that plasma nitriding is applicable to commercial preparation of a lumen stent.

The seamless pipe in which a thin-walled portion in a pipe circumferential direction is formed in a pipe axial direction, in which a line segment formed by connecting one end and the other end of the thin-walled portion along a pipe surface with a shortest distance in a formation direction of the thin-walled portion is inclined at an angle α of 5.0° or more with respect to the pipe axial direction. It is preferable that one end and the other end of the thin-walled portion are set from a region in a pipe selected with a shorter length between a length of 1.0 m in the pipe axial direction and 90% of a length in the pipe axial direction where the thin-walled portion turns once in the pipe circumferential direction.

A high temperature iron-chromium-aluminium (FeCrAl) alloy tube extending along a longitudinal axis, wherein the tube is formed from a continuous strip of a high temperature FeCrAl alloy and comprises a helical welded seam. The high temperature FeCrAl alloy tube is manufactured by feeding a continuous strip of the high temperature FeCrAl alloy toward a tube shaping station, helically winding the strip such that long edges of the strip abut each other and a rotating tube moving forward in a direction parallel to its longitudinal axis is formed, and continuously joining said abutting long edges together in a welding process directly when the tube is formed, whereby a welded tube comprising a helical welded seam is obtained.

Embodiments of the disclosure relate to a ferritic alloy having excellent ability to withstand nuclear power plant accidents and a method of manufacturing a nuclear fuel cladding tube using the same. The alloy includes iron (Fe), aluminum (Al), chromium (Cr), and nickel (Ni). The nickel (Ni) may be included 0.5 to 10 wt % based on a total amount of the alloy. The chromium may be included 13 to 18 wt % based on the total amount of the alloy. The aluminum may be included 5 to 7 wt % based on the total amount of the alloy.

The present invention relates to steel used for a sash component and the like of a vehicle and, more specifically, to a hot-rolled steel sheet for a high-strength electric resistance welded steel pipe having excellent expandability and a method for manufacturing same, the hot-rolled steel sheet having a smaller decrease in the strength of a welding heat-affected zone (HAZ) formed during electric resistance welding, in comparison with a base material.

A high-strength stainless steel seamless pipe for oil country tubular goods has a composition that comprises, in mass%, C : 0.002 to 0.05%, Si: 0.05 to 0.50%, Mn: 0.04 to 1.80%, P: 0.030% or less, S: 0.002% or less, Cr: more than 14.0% and 17.0% or less, Ni: 4.0 to 8.0%, Mo: 1.5 to 3.0%, Al: 0.005 to 0.10%, V : 0.005 to 0.20%, Co: 0.01 to 1.0%, N : 0.002 to 0.15%, and O: 0.006% or less, and that satisfies the predetermined formulae, and in which the balance is Fe and incidental impurities, the high-strength stainless steel seamless pipe having a microstructure containing prior austenite having an average grain size of 40 .Math.m or less, the high-strength stainless steel seamless pipe having a yield strength of 758 MPa or more.