| 摘要 |
PURPOSE: A method for manufacturing a duplex stainless steel of which a surface crack is reduced is provided to control a rolling temperature by rationalizing an extracting temperature at a heating furnace, and control the reduction rate in accordance with the final thickness of a product in order to minimize the generation of a surface crack during rolling. CONSTITUTION: A method for manufacturing a duplex stainless steel comprises: a step of heating and extracting a duplex stainless steel slab in a heating furnace; and a step of obtaining a desired target thickness of a steel plate by rolling the slab. The temperature of the slab, which is extracted from the heating furnace, is controlled between the temperatures of 1230±30°C. The reduction rate or reduction amount of the steel plate per each pass in a rolling step is determined by the references below: In case a target plate thickness is more than the reference value of the target plate thickness, 1) inlet side plate thickness ≥ reference value 1 of the inlet plate thickness: reduction rate < reference value 1 of the reduction rate. 2) inlet side plate thickness < reference value 1 of the inlet plate thickness: reduction rate < reference value 2 of the reduction rate. In case a target plate thickness is less than the reference value of the target plate thickness, first inlet side plate thickness ≥ reference value 3 of the inlet plate thickness: reduction rate < reference value 4 of the reduction rate. second inlet side plate thickness < reference value 3 of the inlet plate thickness: reduction rate < reference value 5 of the reduction rate or reduction amount < reference amount 1 of the reduction amount. [Reference numerals] (AA) Target plate thickness >= Target plate thickness reference value ?; (B1,B2,B3,B4) No; (C1,C2,C3,C4) Yes; (DD) Inlet side plate thickness >= Inlet plate thickness reference value 1; (EE) Inlet side plate thickness >= Inlet plate thickness reference value 3; (FF) Reduction rate < Reduction rate reference value 1; (GG) Reduction rate < Reduction rate reference value 4; (HH) Inlet side plate thickness >= Inlet plate thickness reference value 2; (II) Reduction rate < Reduction rate reference value 5 or Reduction amount < Reduction rate reference value 1; (JJ) Reduction rate < Reduction rate reference value 2; (KK) Reduction rate < Reduction rate reference value 3; |
