Punchability and Punching Fracture Behavior of High Silicon Steel Sheets

The 0.2–0.3 mm thick cold-rolled sheets and annealed sheets of high silicon steel were produced by rolling process, then punching tests were carried out at room temperature to 150 °C. The punchability and punching fracture behavior were investigated by means of scanning electron microscope (SEM) and electron back-scattered diffraction (EBSD). It is found that cold-rolled sheets of high silicon steel show good punchability under the condition of 0. 01 mm punch-die clearance and at the temperature of 100 °C; the punchability of annealed sheets with fine grain size is better than that of annealed sheets with coarse grain size; the punching temperature of 150 °C is suitable for annealed high silicon steel sheets especially with coarse grain size on account of punching edge quality. The major cleavage planes of annealed high silicon steel sheets are {100} crystallographic planes on which brittle fracture occurs at low temperatures. The cleavage systems include {100}<110> and {100}<100>, and cleavage fracture is completed by one or both of them. The punchability of high silicon steel sheets is related with punching temperature, grain size and ordering degree. Reducing ordering degree, increasing punching temperature, as well as refining grain size can improve the ductility and punchability of high silicon steel sheets.