PSI - Issue 54

Ana Dantas et al. / Procedia Structural Integrity 54 (2024) 593–600

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AnaDantas / Structural Integrity Procedia 00 (2023) 000–000

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Fig. 5: Stress-strain diagrams:(a) stress-strain curves of corroded specimens and (b) comparison between tensile data of corroded and not corroded specimens.

Fig. 6: Specimens after testing: (a) pre-corroded and (b) not corroded

It is interesting to compare these results to the mechanical properties observed from three not corroded specimens, previously tested in similar condition: same geometry and also at displacement control and velocity of 1 mm / min. Analysing engineering curves of both conditions (Figure 5 (b)) and the values in Table 1, it can be concluded that the surface corrosion, correspondent to half a year, did not have a significant impact in the tensile properties. Furthermore, the not corroded specimens also presented necking and a similar fracture configuration as depicted in Figure 6. Table 1: Mechanical Properties obtained from quasi-static tensile tests of not corroded and pre-corroded specimens (half an year of corrosion): E: Young’s modulus; σ y : yield strength ; σ u : ultimate strength; El y : elongation at yield strength; El u : elongation at ultimate strength; El f : elongation after fracture; AV: average.

Speciemen

E [GPa]

σ y [MPa]

σ u [MPa] El y [%] El u [%] El f [%]

A.V. not-corroded 216.14

781 772 8.57 1.10

819 805

0.56 0.59 0.04 6.44

6.40 17.64 6.63 19.39 0.23 1.75 3.53 9.94

A.V. corroded

200.04

Absolute Deviation 16.10

13.31

Relative Deviation [%]

7.45

1.63

5. Conclusions

The work developed aimed to study the e ff ect of seawater pre-corrosion on the tensile behaviour of S690 steel. To achieve the pre-corrosion condition, a setup (three-electrode cell) and methodology was developed. As a result, the corrosion mass loss rate of the material immersed in a solution of 3.5 % NaCl was determined to be 4.00032 x 10 − 8 g / s. Based on this value, surface corrosion equivalent to half a year was induced, to quasi-static tensile specimens, in only 2.43 h by applying a current of 0.25 A. A consistent mass loss, averaging 0.674 g for all