| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel in which the problem of hydrogen embrittlement caused by the defect of cavities is evaded, and which has excellent internal defect quality, and to provide a method for producing the same. SOLUTION: The steel having excellent internal defect quality has a composition comprising, by mass, 0.001 to 0.20% C,≤0.5% Si, 0.5 to 2.0% Mn, 0.007 to 0.030% S, 0.005 to 0.03% Ti and 0.0015 to 0.006% O, and the balance Fe with inevitable impurities. In an inspection test at a sensitivity of 100%+1.5dB using a test piece STB-N1 according to architectural institute standards (ultrasonic crack inspection standards for the weld zone of a steel structure building), flaw echo height is≤30%. COPYRIGHT: (C)2007,JPO&INPIT |
