The variation of damping behavior with vibration amplitude

frequency and temperature in grey cast iron HT250 dense bar produced by horizontal continuous casting was measured by dynamic mechanical analyzer to understand the damping mechanism of the alloy. The results show that the damping behavior is increased with increasing in amplitude and frequency. An internal friction peak occurs at about 40 ℃ and is extrapolated by Snoek relaxation. The damping temperature curve shows inverse tendencies at higher temperature range and lower temperature range as a result of the occurrence of Snoek peak. There exists a critical amplitude range

and the damping behavior at higher amplitude is much higher than that at lower amplitude. The temperature-dependent damping capacity mainly is resulted from point-defect damping

while dislocation damping is predominant in the frequency-dependent damping and amplitude-dependent damping

which controls the damping behavior of the alloy.