Effect of Heat Treatment on Dynamic Tensile Strength and Damage Behavior of Medium-Fine-Grained Huashan Granite

Abstract

In order to investigate the dynamic behavior of medium-fine-grained Huashan granite treated by different temperatures, the splitting tests on the granite specimens are carried out using an improved split Hopkinson pressure bar (SHPB). The dynamic force equilibrium condition in the specimen is basically satisfied. The results show that with increasing treatment temperature, the ultrasonic P-wave velocity decreases, while thermal damage accordingly increases. The damage evolution follows the logistic curve model. For a temperature at or below 500 °C, all the specimens break diametrically into two halves at relatively low impact velocities. As the impact velocity rises, the triangular crushed zones are observed at the two loading ends of the specimen. When the temperature exceeds 500 °C, the damage of the specimen becomes severe, and even completely pulverized under high impact velocity. There are good correlations between the splitting strength and the treatment temperature, the ultrasonic P-wave velocity as well as the thermal damage. In addition, the splitting strength is slightly abnormal at 100 °C, namely the strength becomes lower than that at room temperature with increasing impact velocity. Overall, the decay of the splitting strength with thermal damage for the treatment temperatures over 100 °C accords with the power function. Moreover, the splitting strength of specimen is sensitive to strain rate at high temperature, but the increasing rates are different under different ranges of temperature.