Dynamic Mechanical Behavior at Elevated Temperatures and High Strain Rates of Low Yield Point Steels

Abstract

The goal of this study is to investigate the dynamic mechanical properties of low yield (LY) point steels (LY100, LY160, and LY225) under high strain rates and elevated temperatures. The separate Hopkinson pressure bar system was used to conduct dynamic compression tests on LY steels at temperatures ranging from 25°C to 800°C and strain rates ranging from 1,000 s−1 to 5,000 s−1. The quasi-static compression tests (0.001 s−1) were conducted at the same temperatures. The stress-strain relationship of the presented three materials under various temperatures and strain rates was acquired. The test results demonstrated that LY100, LY160, and LY225 steels have an obvious temperature-softening effect. The three materials show low strain rate sensitivity under the strain rate is not more than 3,000 s−1. For a given strain rate, the flow stresses of LY100 and LY160 steel are consistent at 400°C and 600°C, respectively, and both materials exhibit dynamic strain aging. Besides, LY225 steel exhibits dynamic strain aging when the temperature is above 400°C. According to the test results, a modified Johnson–Cook model of the LY point steels was established, which can reflect the material properties well. The results of this study may provide a basis for studying LY steels’ dynamic mechanical properties.