The chemical compositions of steels obtained using an optical emission spectrometer (OES) are provided in Table 1. Figure 1 shows the typical microstructure of G11 (Figure 1a), SCR (Figure 1b), LC (Figure 1c) and G12 (Figure 1d) along rolling direction obtained using light optical microscope. All photomicrographs consist of ferritic matrix (lighter phase) with pearlite (darker phase) at the grain boundary region. While uniform distribution of pearlite was noticed in G11, SCR and LC, the same is not found in the case of higher phosphorus content (0.42% P) G12. Furthermore, the ferrite grain size is significantly larger in G12 steel. Other microstructural feature is that the grain size is relatively smaller in the case of LC than that of G11 and SCR. These finding indicates that phosphorus increases grain size of ferrite and the effect is significant with higher phosphorus content. Tafel polarisation was carried out on freshly grounded samples and the behaviour of corresponding Tafel plots of G11, G12, SCR and LC steels in 3.5% NaCl solution is shown in Figure 2. The cathodic branch of all Tafel plots are diffusion controlled. This is expected as NaCl solution is aerated and neutral where the cathodic reaction consists of the oxygen reduction (O2 + 2H2O + 4e 4OH- ). This is also evident from Pourbaix diagram of Fe-H2O system. Here, diffusion controlled oxygen reduction is the only dominant reaction at ZCP, for which the linear cathodic Tafel region is absent.(19) The icorr and corrosion rate (mpy) obtained from the Tafel polarisation curves of samples under investigation are tabulated in Table 2. The Ecorr of the samples lies between -500 mV SCE to 600 mV SCE. The corrosion rate of all samples is in good agreement with the literature findings. The reported corrosion rate of samples of low alloy, C-Mn, and high phosphorus steel obtained by the Tafel extrapolation method after 1 hour immersion in 3.5% NaCl was in the range of 6 to 10 (mpy), where the alloying elements had no effect on corrosion rate. In the present study, the corrosion rate of all samples obtained by Tafel Extrapolation method after 45 minutes immersion in 3.5% NaCl is in the range of 9 to 12 mpy . Thus, the Tafel polarization study showed that the presence of the alloying elements like Cu: 0.30-0.35, Cr: 0.36-0.37, Ni: 0.20-0.31 and P: 0.15-0.42 has no effect on reducing corrosion rate in 3.5% NaCl although the contents of alloying element is higher than that of the low alloy steel used in the study of Sahoo and Balasubramaniam.