Thermal Relaxation of Residual Stresses in Shot Peened Surface Layer on TiB_2/Al Composite at Elevated Temperatures

摘要

The residual stresses and work hardening relaxations of the shot peened layer on the TiB2/6351Al composite during thermal exposure were investigated. The results showed that the residual stresses were relaxed in the whole deformation layers especially under higher temperatures. The relaxation processes during isothermal annealing can be described using a Zener-Wert-Avrami function. The thermal stability of work hardening is higher than that of residual stresses. And both the activation enthalpies of the residual stresses and work hardening relaxations are higher than the enthalpy of aluminum self diffusion. For residual stresses relaxation, the enthalpy increment was caused by the hindrance effects of reinforcements. While for the work hardening relaxation, the increment was caused by the combination of hindrance effects of the reinforcements and the precipitates.