The demands for constructions with high mechanical performance, located in seismic areas, expressed through EC2 and EC8- part3, were importantly satisfied mainly with the use of Tempcore dual phase steel bars. High mechanical performance of dual phase steel comes from the combination of the mechanical properties of each individual phase. However, several times have been reported problems concerning their structural cohesion.

In the present study four different technical classes (DP) of reinforcing steel bars were used: B500c, B450c, B400c and B500b. SEM and EDX analyses were used, focusing not only on the internal defects regions of the materials (before and after corrosion), but also on the external areas affected by pitting corrosion. Moreover, in terms of the experimental procedure, mechanical tensile tests were conducted, on both corroded and non corroded reinforcing steel bar specimens and the pertinent results are analyzed.

The conclusion from the present study is that both internal and external defects constitute a major problem for constructions, by diminishing their mechanical performance and resulting in their premature failure.