Mechanical Properties and Microstructural Variation of Fe–Mn–Al–Cr–Ni–C Dual-Phase Lightweight Steel at Different Strain Rates

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发表日期：

2026年4月13日

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Mingkun Jiang,
Zhensheng Han,
Weiwei Zhu,
Guoqing Zu,
Ying Han,
Xu Ran

摘要

This article conducts uniaxial tensile tests at room temperature on Fe–Mn–Al–Cr–Ni–C dual-phase lightweight steel at a strain rate of 10⁻⁴ to 0.5 s⁻¹ to investigate the effect and mechanism of strain rate on the microstructure and properties of dual-phase lightweight steel for automobiles . The results show that when the strain rate is higher than 10⁻³ s⁻¹, the yield strength of the experimental steel gradually decreases with the decrease of the strain rate. When the strain rate is lower than 10⁻³ s⁻¹, the yield strength of the experimental steel increases with the decrease of the strain rate. During the plastic deformation, the ferrite phase mainly forms the $\left\langle {110} \right\rangle$ $〈110〉$ //X0 fiber texture, and the austenite phase mainly forms the $\left\langle {111} \right\rangle$ $〈111〉$ //X0 fiber texture. The difference in hardness between the two phases and the formation of twins lead to the preferential accumulation of dislocations at the phase boundary, resulting in higher strain accumulation. The deformation mechanism of BCC phase is dislocation slip, and as the strain rate decreases, the density of dislocations and spacing of slip lines decrease, and the dislocation motion mode changes from plane slip to wavy slip. The deformation mechanism of FCC phase is twinning and dislocation slip. When the content of Σ3 twins is higher, its entanglement ability for moving dislocations is stronger, and the resulting enhancement increment is also greater. This research is conducive to understanding the response of dual-phase lightweight steel to different strain rates, which can provide a strong guarantee for the sustainable development of the automotive industry.