Corrosion susceptibility of an X-120 experimental microalloyed steel subjected to tempering treatment

This study evaluated the corrosion rate of an experimental microalloyed steel subjected to tempering heat treatments in aqueous environments containing 3.5% NaCl, 0.5 M NaOH, and 0.5 M H₂SO₄. The microhardness values decreased after the tempering treatment, which was attributed to material softening caused by the reduction of internal stresses and the possible redistribution of precipitates. Despite this change, the microstructures in both the as-received and tempered conditions retained the same martensite–bainite morphology. However, tempering resulted in a greater quantity and improved the distribution of precipitates. The corrosion rate was measured to evaluate the charge transfer kinetics and material degradation mechanisms, and it was concluded that the tempered steel exhibited improved corrosion resistance.