STEEL PIPE

• Main Authors: NAKAMURA HIDEYUKI, KIYOTA YOSUKE, FUKUSHI TAKAAKI
• Format: Patent
• Language: English; Korean
• Published: 03.08.2016
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

본 발명에서는, 질량％로, C: 0.06％∼0.25％, Si: 0.50％ 이하, Mn: 1.00％∼1.80％, P: 0.030％ 이하, S: 0.020％ 이하, Al: 0.08％ 이하, N: 0.008％ 이하, 및 Nb: 0.080％ 이하를 함유하고, 잔부가 Fe 및 불가피적 불순물로 이루어지고, 외표면에 있어서의 X선 법으로 측정된 압축 잔류 응력이, 250㎫ 이상이고, 외표면으로부터 깊이 1㎜의 위치에 있어서의 X선 법으로 측정된 압축 잔류 응력이, 상기 외표면에 있어서의 X선 법으로 측정된 압축 잔류 응력의 70％ 이상인 강관이 제공된다. The present invention provides a steel pipe, consisting of, in terms of mass%: from 0.06% to 0.25% of C, 0.50% or less of Si, 1.00% to 1.80% of Mn, 0.030% or less of P, 0.020% or less of S, 0.08% or less of Al, 0.008% or less of N, 0.080% or less of Nb, and a remainder consisting of Fe and unavoidable impurities, wherein a compressive residual stress at an outer surface measured by an X-ray method is 250 MPa or more, and a compressive residual stress at a position at a depth of 1 mm from the outer surface measured by the X-ray method is 70% or more of the compressive residual stress at the outer surface measured by the X-ray method.