| 摘要 |
PURPOSE:To obtain a hot rolled soft steel plate having superior workability, carburizability and hardenability by reducing the C content of a steel to the utmost and by adding a specified amount of O. CONSTITUTION:A molten steel for a hot rolled steel plate is refined by a vacuum degassing method such as an RH method or a PH method to remove C as CO up to an extremely low carbon grade such as <0.0050% C, and <=0.8% Mn and 0.016-0.035% O are added to the steel. When N contained in the steel causes a problem, it is fixed as BN by adding <=0.0050% B. The resulting molten dead soft steel is continuously cast into a slab, and the slab is hot rolled to obtain a hot rolled soft steel plate having high elongation and bore-expandability as well as superior carburizability and hardenability.
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