本實驗使用超音波檢測法（Ultrasonic testing）量測球墨鑄鐵經過拉伸試驗後，其微觀組織與超音波衰減率、音速的關係。配合光學顯微鏡(OM)觀察為結構改變，並嘗試以超音波評估球墨鑄鐵的衰減率對內耗能的變化來推測材料內部結構改變，結合基地組織來推測材料內部的微結構變化。使用頻率為5MH z的探頭時，衰減率與散射因素的主要影響為材料在在粗的顆粒多、細的顆粒少衰減率低，粗的顆粒少、細的顆粒多衰減率高 當石墨率高時， 其散射因素也會跟著提高。 以非破壞檢測法(超音波衰減率與散射因素變化)偵測球墨鑄鐵顆粒粗細變化的情形，晶粒尺寸(100~200顆)在20μm以下可發現當顆粒數越多衰減率會跟著增加。 The experiment uses ultrasonic detection method (Ultrasonic testing) after tensile test measurement ductile iron, its microstructure and ultrasonic attenuation rate, the relationship between the speeds of sound. With optical microscopy (OM) was observed for structural change and try to assess ductile iron ultrasonic attenuation rate changes in internal energy inside the material to infer structural changes, combined with martix to speculate micro-structural changes within the material. 5MHz frequency of use of the probe, the attenuation rate of the scattering factors, the main effect of the coarse particulate material in many low attenuation less fine particles, less coarse particles, fine particles much decay rate when graphite ratio high, will increase in the scattering factors. Non-destructive testing method (Ultrasonic attenuation and scattering factors change) detect changes in the case of ductile iron particle thickness, grain size (100 to 200) can be found in the following 20μm when the number of particles, the more attenuation rate increases will follow.
