Probability statistical analysis and data processing of low-temperature Charpy V-notch impact test results for 700L automobile frame steel

The results of pendulum impact test of 700L steel at -40 ℃ show a high degree of dispersion. Usually, the arithmetic mean of impact energy is used to characterize the impact test results of materials. However, the test influencing factors in low-temperature environment are complex and diverse, which makes the measured values often difficult to accurately reflect the impact resistance performance of materials. To obtain more reliable impact energy test results of materials, -40 ℃ low temperature Charpy V-notch impact tests on longitudinal and transverse samples were conducted by pendulum impact testing machine. During the test, the distribution characteristics of the impact energy test results of V-notch specimens with 2 mm pendulum blade were mainly discussed. The influence of the two sampling methods of longitudinal and transverse sampling on the dispersion of impact energy values of 700L steel was systematically investigated, and the corresponding safe impact energy with 90% confidence level was obtained to evaluate the corresponding impact resistance performance of materials. The results showed that the impact energies of both sampling methods conformed to the normal distribution characteristics. At the corresponding 90% confidence level, the safe impact energies of longitudinal and transverse specimens were 31.58 J and 38.83 J, respectively. This analysis result provides theoretical and practical guidance for the application of Charpy impact test of 700L steel and the accurate acquisition of results.