عنوان مقاله [English]
Friction has an important role in both plastic flow of workpiece material and the determination of the required force during the forging process. Therefore, in order to increase the accuracy of the numerical simulation results in the process of die designation as well as predicting the required force, it is necessary to perform suitable tests to estimate the friction coefficient of the process. In this research, a new testing method called open die compression of a cylindrical rod has been presented and the calibration curves have been developed. Then, this test and the well-known ring compression test have been used to predict the friction coefficient in the isothermal forging of a gas turbine compressor Ti-6Al-4V blade sample. The friction coefficient determined by the ring compression test has been applied for the root region and the coefficient determined by the rod compression test was employed for the airfoil region of the blade. Finally, the forging process was numerically and experimentally investigated. Comparison of the maximum forces from the numerical and the experimental results showed an acceptable agreement. The results showed that the open die compression of cylindrical rod test is a reliable method for evaluating the friction. The difference between the friction coefficients determined by the two mentioned testing methods showed the dependence of friction coefficient value on the deformation condition of the workpiece.