| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel plate for heat treatment excellent in strength stability under heat treatment conditions and in resistance to delayed fracture; and a production method thereof. SOLUTION: This steel plate comprises 0.05-0.09 mass% C, 1 mass% or lower Si, 1.6-2.4 mass% Mn, 0.02 mass% or lower P, 0.02 mass% or lower S, 0.01-0.1 mass% sol.Al, 0.005 mass% or lower N, 0.0003-0.003 mass% B, Ti in a content satisfying the inequality: (48/32)S+(48/14)N≤Ti≤2ä(48.32)S+(48/14)N} (wherein each atomic symbol denotes the mass% of each element), and the balance substantially being iron, with the proviso that the average particle size of iron carbide is 2μm or lower. The steel plate may further contain at least either 0.1-2 mass% Cr or 0.1-2 mass% Mo. COPYRIGHT: (C)2003,JPO
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