Comparison of springback value of the selected structure element for cold forming and hot forming methods

• Main Authors: Bałon, Paweł, Rejman, Edward, Kiełbasa, Bartłomiej, Smusz, Robert, Szostak, Janusz, Cieślik, Jacek
• Format: Conference Proceeding
• Language: English
• Subjects: Cold; Cold weather construction; Cold working; Construction materials; Construction methods; Heat treatment; Hot forming; Iron and steel plants; Mechanical properties; Metal sheets; Phase transitions; Process parameters; Recrystallization; Springback; Yield point; Yield strength
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/1.5112638

The problem of springback effect involves mostly cold forming processes, ie below the recrystallization temperature of steel. The springback effect occurs after relieving the force of the press ram and thus the punch of the forming tool. It mainly concerns the processes of forming and cutting construction materials which are processed by plastic forming. The mechanical parameters of those materials such as yield point and strength limit are essentially in the HSS, UHSS and AHSS steel groups. In this paper, the authors attempted to determine the springback value for two methods of the same construction element manufacturing, i.e., cold forming and hot forming methods. As a result, the same part was obtained which has different springback values for different blank materials, i.e., the cold formed material HCT 780x + Z140, and the hot formed material MBW 1500+AS150. The reason for the use of different materials as the blank for the forming process results from phase changes which take place during the hot forming process as a result of heating the steel sheet to about 700-800 °C and rapidly cooling it to about 200 °C in the forming tool for over several dozen seconds. During the heat treatment, the strength parameters are increased even to the level of several thousand MPa. Because of the fact that during the cold forming process, the mechanical parameters of the steel (yield strength and strength limit) do not change, as it occurs during the hot process, the cold forming blank should provide appropriate values of strength parameters as a blank supplied from the steelworks form of sheets or circles. Due to the significant compensation problem of large springback deviations during cold forming of steel, the hot forming process can be an alternative, eliminating significant springback values.