## 2 Materials and Experimental Procedure  
In this research, the SBPR 930/1080 Type B No. 1 medium carbon high-strength steel was investigated, and its chemical composition is presented in Table 1 (in wt%). The material used for the manufacturing of the specimens was supplied by a local company according to JJS G 3109 [15], in 450 mm \(\times\) 32 mm cylindrical pieces out of which the dog-bone type specimens were manufactured using a manual lathe. Geometrical details can be seen in Figure 2, for cylindrical specimens used throughout this research for both quasi-static and dynamic tensile tests, with smooth as well as notched gauge lengths. For the tensile tests, MTS 244.11 servo-hydraulic actuator (Figure 3) was used. Acceleration, velocity, displacement, and excitation frequency characteristics are represented in Figure 4. Despite the dynamic characteristics of the experimental procedure, experimental parameters were well within the capability envelope of the utilized actuator. The actuator was mounted on a loading frame using ball-joints for both fixed and extendable part of the piston to allow for increased mobility and flexibility under various testing conditions and requirements. For this research, both specimens and actuator were positioned and fixed in a vertical orientation to ensure an inline application of pulling force (Figure 5). Furthermore, to ensure constant pulling rate, the loading end of the specimens were constructed in such a way as to allow for initial retraction of the actuator's piston without exerting force onto the specimen. Once required velocity is achieved, and after that stage, contact between the top of the specimen and the mounting fixture (plate) at the movable end of the actuator is initiated, transferring the resulting load onto the specimen body. As can be seen in Table 2, for dynamic loading cases, three specimens were tested for each required strain rate, and the resulting force-displacement data were converted into true stress-strain data using standard equations for uniaxial tensile tests. To further aid the calibration of the initial part of flow stress-strain curves, 2 mm strain gauges were attached using adhesive onto the specimens, and strain data were captured for values up to 20,000 \(\upmu\)m, before the adhesive failure resulting in detachment of the strain gauges positioned in the middle of the respective gauge lengths. From the flow stress-strain data of smooth (no notch) specimens (Figure 6a), it can be seen that for the same strain rate, similar stress-strain curves were obtained. For quasi-static strain rate (0.001 s\({}^{-1}\)), this specific material showed the most ductile behavior fracturing, on average at 0.127 strain. In uniaxial dynamic tensile (Figure 6b) tests, it can be seen that for the case of 0.5 s\({}^{-1}\) strain rate, material showed a more brittle behavior while fracturing, on average at 0.092 strain. In comparison to the 0.5 s\({}^{-1}\) strain rate case, specimens tested at 1 s\({}^{-1}\) showed an increase in the ductility fracturing, on average at 0.099 strain, as well as showing the highest ultimate stress values overall. Finally, for the case of 2 s\({}^{-1}\) strain rate, specimens presented most brittle behavior out of all cases, while not showing any significant increase in their ultimate stress value when compared to the slowest dynamic case. In Figure 7, engineering stress-strain (initial cross-sectional area is used for the strain calculations) and converted true stress-strain (strain calculations are performed based on the actual cross-sectional area, which changes with time) data can be seen for quasi-static \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**C** & **Si** & **Mn** & **P** & **S** & **Cu** \\ \hline
0.60–0.65 & 0.12–0.32 & 0.30–0.60 & \(\leq\)0.030 & \(\leq\)0.035 & \(\leq\)0.30 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Chemical composition of SBPR 930/1080 Type B No. 1 medium carbon steel (in wt%).