## 3 Test Results and Analysis  
Table 4 shows the life of steel wires in group A-G under different stress ranges. It can be seen that the life of steel wire with machine-cut notches increases as the stress range decreases. When the stress range decreases from 720 MPa to 360 MPa, the service life increases by more than 10 times. Comparing steel wire in group A with those in other groups, it can be seen that the corrosion significantly reduces the life of the steel wire. Comparing the wire in group B with that in group C (3.5 wt% NaCl with a pH value of 7 and 3, respectively), it can be seen that with the increase of acidity, the life of steel wire decreases significantly, and by more than 12.0% under all stress ranges. Comparing wire in group D with that in group E (0.5 wt% NaCl of pH 7 and 3, respectively), it can also be seen that the life of steel wire is significantly decreased by acid. Compared with the neutral solution, the acidic solution reduces the life to a greater extent. The life of steel wire subjected to acid solution is 14% lower than that of the neutral solution. When the stress range is low (such as 480 MPa and 360 MPa), the life of steel wire in the acid solution is reduced by more than 25% with respect to that in neutral solution. Comparing wire in group B with that in group D (0.5 wt% and 3.5 wt% NaCl with pH of 7, respectively), it can be seen that the increase of concentration actually increases the lifetime. Especially under the high-stress range (such as 720 MPa and 600 MPa), the life increases by 23% and 24%. By comparing the wires in two groups C and E (0.5 wt% and 3.5 wt% NaCl with pH of 3, respectively), it can also be seen that the increase of concentration still increases the life of steel wire. By comparing the wires in two groups F and G (Fatigue tests were carried out after 15 and 30 days of corrosion, respectively), it can be found that corrosion reduces the life of steel wire. Under a stress range of 720 MPa, the life of steel wire that corroded for 15 days is reduced by 27% compared with that of steel wire that has not been corroded; and under a stress range of 360 MPa, it is reduced by 20%. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Specimen** & **Specimen** & \begin{tabular}{c} **Maximum** \\ **Stress** \\ **\(\sigma_{\text{max}}\)/MPa** \\ \end{tabular}  & \begin{tabular}{c} **Minimum** \\ **Stress** \\ **\(\sigma_{\text{min}}\)/MPa** \\ \end{tabular}  & \begin{tabular}{c} **Stress Range** \\ **\(\sigma_{\text{min}}\)/MPa** \\ \end{tabular}  & \begin{tabular}{c} **Mean Stress** \\ **\(\sigma_{\text{a}}\)/MPa** \\ \end{tabular}  & \ \begin{tabular}{c} **Stress** \\ **\(\sigma_{\text{am}}\)/MPa** \\ \end{tabular}  & \begin{tabular}{c} **Leading** \\ **Frequency** \\ _f_/**Hz** \\ \end{tabular}  \\ \hline \multirow{4}{*}{A} & A-1 & 643 & 283 & 360 & 463 & 0.44 & 0.5 \\  & A-2 & 857 & 377 & 480 & 617 & 0.44 & 0.5 \\  & A-3 & 1071 & 471 & 600 & 771 & 0.44 & 0.5 \\  & A-4 & 1286 & 566 & 720 & 926  
A large number of tests have proved that the fatigue life and stress range of components under constant load conform to a linear relationship in the log-log coordinates. The equation of stress range \(S_{a}\) and fatigue life \(N\) is usually in the form of a power exponent, as shown in Equation (1):  
\[S_{a}^{m}N=C \tag{1}\]  
where \(m\) and \(C\) are the material constants.