蠕墨铸铁疲劳特性的研究

对在四种热处理方法下的蠕墨铸铁试样进行门槛值和裂纹扩展速率的测试,并对其进行分析和比较.其结果表明,不同的基体组织对蠕墨铸铁的门槛值和低速区的裂纹扩展速率有比较明显的影响,门槛值随相对韧度增大而增大.不同的石墨形态对门槛值的变化影响不大,且仍然可以维持在较高的水平.不同载荷比下的低速区裂纹扩展速率区别较大,但随着平均载荷的升高,载荷比的影响有减小的趋势,中速区载荷比的影响较小.文中给出不同载荷比下的蠕墨铸铁门槛值和裂纹扩展速率经验公式.

STUDY ON FATIGUE CHARACTERISTICS OF VERMICULAR GRAPHITE CAST IRON

The threshold values and crack growth rates of vermicular graphite cast iron specimen subjected to four heat treatment methods are tested, analyzed and compared.The results show that the base structures of vermicular graphite cast iron specimen affect markedly the threshold value and crack growth rate of within low speed growth rate region.The threshold value increases with the relative toughness coefficient.However,different graphite forms hardly affects the threshold value little,which is maintained at higher level.The crack growth rates of within low speed region vary greatly under different load ratio vary greatly,but with the increase of the averaged load,the influence of load ratio tends to decrease,the influence of load ratio and becomes lower under within medium speed region is lower.Moreover,The empirical formulaes ofor threshold value and crack growth rate of vermicular graphite cast iron under different load ratio are given.