**3.1 Alloy composition**

**Table 1** shows the compositional analysis of the different types of TMT rebars (IS 1786: 2008 for Fe 600 and IS 12594:1988 for galvanized). It has been already reported that an increase in yield strength of reinforcing bars occurs by raising carbon as well as manganese content or by microalloying. It is also true that higher carbon content may cause lower weldability and ductility [13, 16, 23]. It is worth mentioning here that all the steel rebar samples selected in the present investigation contain a lower amount of carbon since a higher amount of carbon can cause harmful carbide formation and pearlite formation in the as-rolled steels thereby causing micro-galvanic corrosion [23, 33]. Major alloying elements other than carbon are manganese and silicon in the case of all the rebar samples. However, in the case of stainless steel rebar (IS 16651:2017), apart from these two elements, chromium and nickel are also present to enhance the 'stainless' property of this steel by forming a stable and protective oxide layer to make them corrosion-resistant [34–36]. In this context, it is imperative to mention here that the corrosion resistance of the stainless steel rebar depends on the formation of the chromium layer (≈5 nm thickness) and the content of chromium that keeps the rebar surface electrochemically passive in corrosive environments [37]. It is well known that manganese increases the hardenability and tensile strength of the steel [23, 33]. The addition of silicon is beneficial to increase the hardness and strength. It also acts as a deoxidizer during the casting of the rebar, thereby helps in reducing the casting defects and allows sound steel castings [23, 38].
