... -890°c,keep temperature 2-4H,furnace cold below ,out and air cold.2.Steel isothermal technology:heat temperature840-860° ... to 720-740°c,keep 4H,furnce cold below 550°c,out and air cold ,tempering hardness207-255HBS. Characteristic1.Good quenching ... treatment deformation. Application1.Make cold die,tool ,measure tool cold extrusion mold,precison mould,Thread roller wheel Cold shear knife,etc. Campangy ...