Energy Absorption Mechanism of High-Strength Q&P and DP Steel Thin-Walled Structures

In order to research the energy absorption characteristics of high-strength steels in vehicles, the single-hat thin-walled structural components were made from quenching and partitioning (Q&P) steel and dual-phase (DP) steel so as to understand the differences and superiority in the energy absorption characteristics of various types of steel in the energy-absorbing box of current vehicles. Crushing experiments were performed with a testing machine equipped with a high-speed camera. The energy absorption mechanism of the two steels was investigated by means of transmission electron microscopy and electron back-scattered diffraction. The results showed that the energy absorption capacity of Q&P steel is better than that of DP steel, which can be observed from the different compression distances of the single-hat thin-walled structure. The major contribution in energy absorption of Q&P steel comes from the internally retained austenite-to-martensite transformation. The amount of retained austenite substantially reduces at the crushed part with large deformation. On the other hand, while there is a large amount of dislocation and quantity of plug in the crushed DP steel part, the energy stays inside the material without dissipating.