| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a non-tempered steel bar, which can manufacture steel bars of a small to large size in the same rolling process. SOLUTION: The non-tempered steel bar includes less than 0.05 mass% C, 0.005-2.0 mass% Si, 0.5-5.0 mass% Mn, 0.1-10.0 mass% Ni, more than 1.0 to 4.0 mass% Cu, 0.0002-1.0 mass% Al, 0.005-0.50 mass% S, 0.010-0.0200 mass% N, and the balance Fe with unavoidable impurities. The method for manufacturing the non-tempered steel bar is performed by hot rolling a cast steel piece of the above composition into a bar, and then simply cooling it with a cooling rate of 5-20 deg.C/hour, while keeping the surface of the bar in the temperature range of 900 deg.C-200 deg.C.
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