水平连铸灰铁HT250型材的阻尼行为

Damping Behavior of Grey Cast Iron HT250 Dense Bar Fabricated by Horizontal Continuous Casting

选用直径为55mm的水平连铸灰铁HT250棒材,利用动态热机械分析仪测试型材的阻尼性能随振幅、频率和温度的变化关系,探讨灰铸铁型材的阻尼机制。研究表明,灰铸铁型材的阻尼性能随振幅和频率的提高而增加。在40℃附近出现斯诺克温度内耗峰。斯诺克峰的出现,使型材的阻尼性能随温度的变化在高低温时表现出完全不同的趋势。存在一临界应变振幅范围,大应变振幅下的阻尼性能远高于小应变振幅下的阻尼性能。灰铸铁型材的阻尼温度效应主要来源于点缺陷阻尼。位错阻尼在阻尼频率效应和阻尼振幅效应中起了主导作用,决定了型材的阻尼-频率行为和阻尼振幅行为。

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.