## 2 Ultrasonic Testing of Materials
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Parameter/Head Name** & **MB2S** & **KD1-6** & **KD0.8-3** & **MB4S** & **KD4-12** & **KD6-16** & **GE20** \\ \hline
**Number of Ultrasonic** & **1** & **2** & **3** & **4** & **5** & **6** & **7** \\ \hline frequency MHz & 2.00 & 2.40 & 2.75 & 4.00 & 12.5 & 14.00 & 20.00 \\ transducer diameter mm & 10.00 & 12.00 & 12.00 & 10.00 & 6.00 & 3.00 & 3.00 \\ effective diameter of the beam mm & 9.70 & 11.64 & 11.64 & 9.70 & 5.82 & 2.91 & 2.91 \\ mean wave velocity in & 5513 & 5513 & 5513 & 5513 & 5513 & 5513 & 5513 \\ wavelength mm & 2.80 & 2.30 & 2.00 & 1.40 & 0.40 & 0.40 & 0.30 \\ near field mm & 7.80 & 14.20 & 16.40 & 16.70 & 19.10 & 5.30 & 7.60 \\ decibel drop ratio K & 0.87 & 0.87 & 0.87 & 0.87 & 0.87 & 0.87 & 0.87 \\ sin beam divergence angle & 0.25 & 0.17 & 0.15 & 0.12 & 0.07 & 0.12 & 0.08 \\ divergence angle\({}^{\circ}\) & 14.31 & 9.89 & 8.62 & 7.10 & 3.78 & 6.76 & 4.73 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Characteristics of the ultrasonic heads used in the study of basic acoustic parameters of Ti6 Al4V-AM produced by additive manufacturing technology. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & \multicolumn{2}{c}{**Ti6 Al4V–Bear**} & \multicolumn{2}{c}{**Ti6 Al4V-AM—Bear**} \\  & & \multicolumn{2}{c}{**Diameter mm**} & \multicolumn{2}{c}{**Diameter mm**} \\
**Sample** & **10** & **25** & **40** & **10** & **25** & **40** \\ \hline MB2S & 5.0 & 12.5 & 20.0 & 5.1 & 12.8 & 20.4 \\ KD1-6 & 3.4 & 8.6 & 13.7 & 3.5 & 8.7 & 13.9 \\ KD0.8-3 & 3.0 & 7.4 & 11.9 & 3.0 & 7.6 & 12.1 \\ MB4S & 2.4 & 6.1 & 9.8 & 2.5 & 6.2 & 10.0 \\ KD4-12 & 1.3 & 3.2 & 5.2 & 1.3 & 3.3 & 5.3 \\ KD6-16 & 2.3 & 5.8 & 9.3 & 2.4 & 5.9 & 9.5 \\ GE20 & 1.6 & 4.1 & 6.5 & 1.7 & 4.1 & 6.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The diameter of the ultrasonic wave beam B at the bottom of the tested samples. The tests were carried out using the echo technique, applying the head to the material, and generating a beam of ultrasonic waves that propagated through the material. The beam is then reflected from the bottom of the sample and returned to the ultrasonic head. The image of the wave was visualized on the screen of the ultrasonic flaw detector as a sequence of reflections with decreasing amplitude (Figure 1). GE Krautkramer's USM 35 XS ultrasonic flaw detector during the study was used. Ultrasonic testing was preceded by measurements and calibration performed on reference samples. Calibration included settings for ultrasonic wave gain, ultrasonic wave speed, pulse width, head and delay matching. The ultrasonic wave pulse amplification parameters were selected experimentally in such a way as to obtain at least two reflections from the bottom of the sample or the boundary of the adhesion joint. In addition, it is shown later in the article that the gain of the ultrasonic wave pulse has no significant effect on the obtained measurement results. The obtained values of the mean ultrasonic wave velocity in two different materials (shown in Tables 1 and 2) were determined from 10 measurements for each ultrasonic head. A summary of the individual wave velocity values for each head is shown in Figure 2. Higher values of ultrasonic wave velocity can be seen for the material produced by additive manufacturing technology. The difference in wave velocity is equal to around 2%. It may be caused by the different densities of the material and the more compact structure for Ti6 Al4V-AM, which is formed due to the melting of individual layers during the manufacturing process. Figure 1: Ultrasonic testing—scheme; h = 10, 25 and 40 mm, d = 25 mm, B—beam diameter in mm, H\({}_{1}\), H\({}_{2}\), H\({}_{3}\)—amplitude of pulses from the bottom of the specimen. Figure 2: Average ultrasonic wave velocity values for the material Ti6 Al4V and Ti6 Al4V-AM. In the next stage of the research, the effect of ultrasonic longitudinal wave pulse gain on the damping coefficient values in the tested materials was verified.