Friction Coefficient in Hot Compression of Cylindrical Sample

Abstract

In order to analyze the evolution behavior of friction coefficients during large strain hot forging processes, compression tests were carried out on IHS38MSV hypoeutectoid steel samples at a stroke rate of 1.2 mm/s and temperatures ranging from 1073 to 1473 K. The simulation results of the geometrical change in the sample during the compression process obtained by using various friction coefficients were compared with experimental results in order to verify the validity of the “instantaneous friction coefficient”. The results showed that the friction coefficient was a constant at lower strain level, and the instantaneous friction coefficient, m_s, showed an approximately exponential relationship at higher strain level. The simulation results obtained by using m_s showed better results as compared to those obtained by using average friction coefficients (m_c and m_a). It was also found from the simulation results that at a certain strain level, the variation of friction coefficient did not have a strong effect on the shape of deformed sample; however, the radius of the top surface of the sample, R_t, changed greatly due to friction.