| 摘要 |
PURPOSE: A method is provided to improve delayed fracture resistance of a ultra-high strength retained Austenite contained steel sheet by diffusion coating or plating Ni content on the surface thereof when manufacturing the ultra-high strength retained austenite contained steel sheet by reverse transformation or Austempering. CONSTITUTION: In a method for manufacturing a retained Austenite contained steel sheet comprising the processes of manufacturing a hot rolled steel sheet by hot rolling Mn low carbon steel, pickling the hot rolled steel sheet and reverse transforming Martensite into Austenite by reannealing the pickled steel sheet, the method for manufacturing a ultra-high strength retained Austenite contained steel sheet having superior delayed fracture resistance is characterized in that a Ni layer is formed by dipping the steel sheet into an electroless plating solution containing Ni content for 5 to 30 seconds after the pickling process, thereby coating Ni on the surface of the steel sheet, and reannealing the Ni coated steel sheet so that Ni is diffused on the surface layer of the steel sheet. In a method for manufacturing a retained Austenite contained steel sheet comprising the processes of stabilizing Austenite by maintaining Si-Mn medium carbon steel in the Bainite temperature zone, hot rolling the carbon steel, finish rolling and coiling the hot rolled carbon steel, and picking the coiled steel sheet, the method for manufacturing a ultra-high strength retained Austenite contained steel sheet having superior delayed fracture resistance is characterized in that the surface of the steel sheet is electroless plated by dipping the pickled steel sheet into a Ni contained electroless plating solution for 5 to 30 seconds after the pickling process.
|
