为降低制造轴承材料的成本，决定采用球墨铸铁来代替黄铜作为轴承保持架的材料。因为首次生产这种材料，为保证产品的质量，采用无损检测的方法对球墨铸铁材料的生产工艺过程进行技术及质量把关。１　铸铁的声特性１．１　单一材料中的声速在单一组织的“无限大”固体材料中，? In order to reduce the cost of manufacturing bearing materials, ductile iron was chosen instead of brass as the bearing cage material. Because of the first production of this material, in order to ensure the quality of the product, nondestructive testing methods are adopted to check the technology and quality of the production process of ductile iron material. Acoustic properties of cast iron 1.1 The velocity of sound in a single material In a single tissue “infinite” solid material,