Study on Formability and Microstructure Evolution of Usibor<sup>®</sup>2000 Sheet Under Different Forming Temperatures in Deep Drawing Process.

Abstract

Due to the need for weight reduction in the automobile structure, effective and accurate forming is demanded to take advantage of ultrahigh-strength steels. Research on the deep-drawing formability of Usibor^®2000 has an important impact on the application of lightweight automotive bodies. The microstructure and formability of Usibor^®2000 sheets at different temperatures were investigated by the Swift test. The positive effects of increasing the temperature on improving the forming limit and forming quality of Usibor^®2000 were demonstrated by LDR results, thickness, and hardness measurement. The microstructure evolution of Usibor^®2000 steel plates under warm forming and hot forming conditions was discussed in terms of microstructure characterization and precipitate morphology. The phase composition of the sample deformed at 860 °C is analyzed by two-step etching metallographic analysis and numerical simulation, which provides a reference for the application of Usibor^®2000 ultrahigh-strength steel in automotive lightweight.