Experimental study on high strain rate behavior of high strength 600–1000 MPa dual phase steels and 1200 MPa fully martensitic steels

As one of high grade advanced high strength steels (AHSSs), dual phase (DP) steel sheets and fully martensitic (MS) steel sheets have been successfully used in automotive crash-resistance components for its great benefit in reducing vehicle weight while improving car safety as well as their advantage in cost saving through cold forming instead of hot forming. The strain rate sensitivity of 600/800/1000 MPa DP and 1200 MPa MS were studied in this paper through a split Hopkinson tensile bar (SHTB) setup and compared with each other. The experiments showed that all dual phase (DP) AHSS ranging from 600 MPa to 1000 MPa are of positive strain rate sensitivity. While for the tested 1200 MPa MS, negative strain rate sensitivity has been found. Possible reason for the difference has been investigated through metallographical observation and their microstructures.

► High strain behavior is evaluated for 600/800/1000 MPa DP AHSS and 1200 MPa MS. ► 600–1000 MPa DP AHSS are of positive strain rate sensitivity. ► Negative strain rate sensitivity has been found with 1200 MPa MS. ► Microstructure evolution under quasi-static and high strain rate has been presented.