球墨铸铁与灰口铸铁的超声衰减鉴别

为了找到快速准确鉴别球墨铸铁件与灰口铸铁件的现场检测方法，采用不同频率的超声波对不同厚度的球墨铸铁和灰口铸铁试样进行了超声衰减测试，发现灰口铸铁件超声衰减明显，而球墨铸铁件超声衰减微乎其微。分析认为在通常采用的波长范围内，产生超声衰减的主要原因是灰口铸铁中石墨晶体的构造以及石墨组织的形状、大小和分布。利用这一原理可以十分方便地鉴别球墨铸铁件和灰口铸铁件。

Ultrasonic Attenuation Discrimination between Nodular Iron and Gray Iron

In order to find a quick and accurate test method for discriminating the nodular iron from the gray iron on the production spot, ultrasonic attenuation tests were conducted on both the nodular iron and gray iron specimens with different thicknesses by adopting the ultrasonic waves with different frequencies. It was found that the ultrasonic attenuation action of the gray iron was very obvious, however the ultrasonic attenuation action of nodular iron was next to nothing. It was believed according to the analysis that, in the wavelength range normally adopted, the ultrasonic attenuation is caused mainly by the graphite crystal structure as well as the graphite morphology, size and distribution. Based on this principle, it is very easy to discriminate the nodular irons from the gray irons.