Bendability and failure mechanisms of dual phase steel under air-bending at elevated temperatures

Industrial Engineering Department, Faculty of Engineering, King Mongkut’s Institute of Technology Ladkrabang, Bangkok, Thailand

^* Corresponding author: kkkannac@kmitl.ac.th

Abstract

In this study, process parameters such as the bending angle and bending temperature of the metal sheets for pure bending of advanced high strength steel sheet DP980 were investigated using the air-bending method. This investigation focused on bendability and failure mechanisms. Experimental studies were carried out with various bending temperatures and the bending angle parameters to identify effect on springback angle, initial crack, and the evolution of the microstructure. Prior to testing, the DP steel sheets were heattreated at different temperatures (room temperature, 200 °C, 400 °C, and 600 °C) with a heating rate of 2 °C/S and 5 minutes of holding time in an electric furnace. As a result of the experiments performed at different temperature values and bending angle values, it was determined that an increase in the bending angle reduces the size of the springback angle. It was also determined that an increase in air-bending-temperature reduces the amount of springback. Air-bending-temperature also affected the microstructure evolution and slowed the cracking of the bent surface.