THE EFFECT OF THERMOMECHANICAL TREATMENT ON THE PITTING CORROSION OF REINFORCING CARBON-STEEL BARS

Steel reinforcing rods with varying amounts of cold work and carbon co ncentrations (0.06 to 0.45% C) exposed in soil embankments has shown v arious degrees of pitting corrosion. To understand this pitting proces s, laboratory investigations on residual stresses, microstructures and potentiodynamic cyclic polarization were undertaken. Analysis of resi dual stresses in the steels indicated low value of compressive stresse s in hot rolled steels and high value of tensile stresses in the cold worked counterparts. Hot rolled steels displayed a slightly better pit ting corrosion resistance than cold worked samples which is consistent with the above internal stress pattern. No definite correlation was o btained between the percentage of carbon in the steels and pitting sus ceptibility. An attempt has been made to define the role of the comple x steel-soil system for pitting corrosion behavior.