## 4 Discussion  
In the case of the tensile strength measurements, all the obtained curves for hydrogenated alloys, as well as for unhydrogenated alloys, follows a three-stage scheme. The characteristics of the curves for hydrogenated alloys are similar to the one obtained for unhydrogenated alloys. Based on the obtained results, it was found that for each of the analyzed alloys, hydrogenation of the specimens increases the cracking rate, and thus weakens their mechanical resistance. The mean square error did not exceed 3% of the value in the entire measurements range. For the alloy 1050A (Figure 5), the nucleation of the crack propagation after hydrogenation (\(K_{1 SCCH}\)) of the specimen is lower by approx. 5% (for 10 min of hydrogenation) and 20% (for 25 min of hydrogenation) than the \(K_{1 SCC}\) value without hydrogenation. The critical value at which the specimen breaks is, in the case of a hydrogenated alloy (\(K_{1 CH}\)), lower by approx. 16% (for 10 min of hydrogenation) and by approx. 45% (for 25 min of hydrogenation) than the \(K_{1C}\) value of the non-hydrogenated alloy. For the alloy 5754 (Figure 6), the nucleation of the crack propagation after hydrogenation (\(K_{1 SCCH}\)) of the specimen is lower by approx. 3% (for 10 min of hydrogenation) \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Aluminum Alloy Designation**} & \multirow{2}{*}{**Impact Strength**} & **Impact Strength** & **Impact Strength** \\  & & **Impact Strength** & **after** & **after** \\  & & **[]-cm\({}^{-2}\)]** & **Hydrogenation** & **Hydrogenation** \\ \hline
**by Number** & **by Chemical** & **Symbols** & **(H\({}_{2}\)—10 min)** & **(H\({}_{2}\)—25 min)** \\  & & & **[]-cm\({}^{-2}\)]** & **[]-cm\({}^{-2}\)]** \\ \hline EN AW-1050A & EN AW-Al. 99.5 & 104 \(\pm\) 4 & 93 \(\pm\) 5 & 65 \(\pm\) 2 \\ \hline EN AW-5754 & EN AW-Al. Mg3 & 42 \(\pm\) 2 & 40 \(\pm\) 3 & 31 \(\pm\) 3 \\ \hline EN AW-6060 & EN AW-Al MgSi & 53 \(\pm\) 3 & 49 \(\pm\) 3 & 37\(\pm\) 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Experimental data on impact strength measurements, before and after hydrogenation. Figure 7: The dependence of the crack propagation rate on the value of the stress intensity factor \(K_{1}\) for not-hydrogenated and hydrogenated (H\({}_{2}\)) 6060 alloy—time of the hydrogenation: 10 and 25 min. \(K_{1 SCC}\)—nucleation and growth of a stress corrosion crack; \(K_{1 SCCH}\)—nucleation and growth of a stress corrosion crack after hydrogenation; \(K_{1C}\)—material separation; and \(K_{1 CH}\)—material separation after hydrogenation. and 15% (for 25 min of hydrogenation) than the \(K_{1 SCC}\) value without hydrogenation. The critical value at which the specimen breaks is, in the case of a hydrogenated alloy (\(K_{1 CH}\)), lower by approx. 12% (for 10 min of hydrogenation) and by approx. 40% (for 25 min of hydrogenation) than the \(K_{1C}\) value of the non-hydrogenated alloy. For the alloy 6060 (Figure 7), the nucleation of the crack propagation after hydrogenation (\(K_{1 SCCH}\)) of the specimen is lower by approx. 4% (for 10 min of hydrogenation) and 25% (for 25 min of hydrogenation) than the \(K_{1 SCC}\) value without hydrogenation. The critical value at which the specimen breaks is, in the case of a hydrogenated alloy (\(K_{1 CH}\)), lower by approx. 9% (for 10 min of hydrogenation) and by approx. 40% (for 25 min of hydrogenation) than the \(K_{1C}\) value of the non-hydrogenated alloy. It should be noted that fracture rate in full range for all the alloys considered is greater for the hydrogenated alloy measurements. The fracture strength value is in all considered cases lower after the hydrogenation of the aluminum alloys. In all cases, the value of the threshold stress intensity factor (the value of the stress intensity factor above which the crack propagation nucleation occurs) reaches a lower value after hydrogenation. In the case of the impact strength measurements, all specimens (non-hydrogenated and hydrogenated) were characterized by slip scrap (ductile material).