Prestressing steel wires are made from hot rolled high carbon wire rods with fine pearlitic structure. The wire rods after the hot finish rolling are subjected to accelerated cooling on a Stelmor cooling conveyor in the wire rod mill to obtain fine pearlitic structure essential for cold wire drawing operation. Prestressing steel wires are used to put concrete structure e.g. prestressed concrete cylinder pipe (PCCP) in compression by pre-tensioning the wires in the range of 70-75 percent of the specified minimum tensile strength. These high strength high carbon steel wires are prone to environmental degradation during service life because of complex corrosive processes in the presence of aggressive environmental conditions, which lead to general corrosion, surface pitting and hydrogen embrittlement stress cracking (HESC) resulting in premature failures of the wires embedded in concrete. The high carbon content and severe deformation due to cold drawing operation in wire manufacturing from the hot rolled wire rods also affect their corrosion resistance. The alloying elements e.g. chromium, vanadium, etc. are used to enhance the mechanical properties of the wire. The effects of these elements on corrosion behaviour of wire have been studied. Along with the standard electrochemical tests FIP tests were also carried out to assess the Hydrogen Embrittlement Stress Cracking of the micro alloyed steel wires. The V-alloyed wire showed excellent pitting corrosion resistance. FIP tests results showed that microalloyed wire with vanadium has excellent resistance to hydrogen embrittlement stress cracking (HESC) in comparison to other wires with different chemistry. Extensive Scanning and Transmission Electron Microscopy reinforced the study of corrosion evaluation of the wires. The findings of this research work have been used to manufacture prestressing steel wires for manufacturing of concrete structures for various applications.
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