SEAMLESS STEEL PIPE AND METHOD FOR PRODUCING SAME

Provided is a seamless steel pipe which has excellent SSC resistance, while being suppressed in strength variation in the circumferential direction and in the axial direction. A seamless steel pipe according to one embodiment of the present invention contains, in mass%, 0.21-0.35% of C, 0.10-0.50% of Si, 0.05-1.00% of Mn, 0.025% or less of P, 0.010% or less of S, 0.005-0.100% of Al, 0.010% or lessof N, 0.05-1.50% of Cr, 0.10-1.50% of Mo, 0.010-0.050% of Nb, 0.0003-0.0050% of B and 0.002-0.050% of Ti, with the balance made up of Fe and impurities. With respect to the main body region of this seamless steel pipe, the crystal grain size number of prior austenite crystal grains in accordance with ASTM E112 is 7.0 or more; the difference between the maximum value and the minimum value of the crystal grain size number is 1.0 or less; the yield strength is 655 MPa or more but less than 862 MPa; and the difference between the maximum value and the minimum value of the tensile strength is 27.6MPa or less. 提供具有优异的耐SSC性