| 摘要 |
<p>A seamless steel pipe, characterized in that it contains, in mass %, 0.30 to 0.50 % of C, 0.5 % or less of Si, 0.3 to 2.0 % of Mn, 0.025 % or less of P, 0.005 % or less of S, 0.15 to 1.0 % of Cr, 0.001 to 0.05 % of Al, 0.005 to 0.05 % of Ti, 0.02 % or less of N, 0.0005 to 0.01 % of B, and 0.0050 % or less of O (oxygen), and Beff defined by the following formula (a) or (b) takes a value of 0.0001 or more, where Beff = B-10.8??(N-14??Ti/47.9)/14 --- (a) when Neff = N-14??Ti/47.9 >= 0, and Beff = B --- (b) when Neff = N-14??Ti/47.9 < 0. The above seamless steel pipe is excellent in all of cold workability, hardenability, toughness and torsional fatigue strength, and thus is optimum as a material for a hollow axis for use in a hollow driveshaft being formed in one piece.</p> |
