Inspection and specificity of the intactness of multi-layer and small-size parts like copper-Clad steel rod is a hard task and requires high accuracy. The intactness of these parts is crucial due to their importance. One of the inspection methods for these parts is using ultrasonic waves. The scattering phenomenon occurs when these waves impact curved shape bodies under a special condition. The ultrasonic scattering waves contain a lot of information from the physical conditions and mechanical properties of the part. However, using these waves requires high accuracy and attention due to their complexity. One result of the ultrasonic scattering waves is the far-field backscattered frequency spectrum, form function. For the first time in this research, the form function of a copper-Clad steel rod that is immersed in water is calculated using the finite element method (FEM) available in the commercial ABAQUS software. For validating the proposed model, the simulation results are compared with analytical and experimental results in the normalized frequency range of 4 £ Ka £ 10. A good agreement is observed between the three methods at the resonance frequencies, and in the overall form of obtained form function. Furthermore, the effects of the two most common defects in these rods, i.e., the corrosion and interfacial disbond between the Clad and steel rod, is studied. Results show that this method can properly specify the corrosion percentage and location, and also the length and location of the interfacial disbond defect.