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.

• 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。