PSI - Issue 59

Igor Stadnyk et al. / Procedia Structural Integrity 59 (2024) 672–678 Igor Stadnyk et al./ Structural Integrity Procedia 00 (2023) 000 – 000

676

5

, R 2 =0.9043

Table 1. Comparative evaluation of reagents anti-corrosive protective properties

Inhibitor consumption, g/l

Corrosion rate, mm/h

Protective action effect, %.

sample No. 1

sample No. 2

sample No. 1

sample No. 2

25 30 35 40 50 70

0.071 0.033

0.058 0.038 0.013 0.015 0.01 0.36

55.2 82.0 82.4 91.3 94.0

51.5 70.0 84.4 91.3 94.0

0

023

0.015 0.01

A graphical representation of the process with optimum within the 40-45 g/l inhibitor concentration range is shown by dashed lines in Fig. 2.

Fig. 2. Change in corrosion rate due to inhibitor consumption.

3. Results and discussion The evaluation of the method of technological equipment protection is taken into account based on a number of factors: simplicity of protection, ease of maintenance, and possible availability of plant raw materials. Evaluation of the steel St 20 corrosion rate by the developed inhibitors in drinking water is related to the change in the level of the metal surface in the protection and to the impact on the kinetics of corrosion process reactions. In the presence of all two extracts, the increase in the level of protection and braking coefficient are observed with the exposure time increase. The corrosion potential E st of steel 20 in water (is -483 mV (Slobodyan et al., 2021; Kityk et al. 2021) under the action of the developed inhibitors (extracts (0.8 g/l) has different value (Fig. 2). Therefore, the initial mechanism of protective action is slightly different due to the different composition. According to the results of corrosion inhibitors investigations (samples 1 and 2) carried out in laboratory conditions, high inhibitory ability of the obtained samples for the formation of protective film on the metal surface is determined. Analysis of fracture features at the investigation stage shows (Fig. 3) that the inhibitor in the samples fracture areas of has almost equal tear-off holes - elements typical of viscous destruction in the air (Fig. 3b). In fresh water, only parabolic shear holes (high fracture propagation rate) are observed (Fig. 3a). Thus, according to fractographic features, steel in inhibited water, compared to tap water, shows higher fracture resistance even at the stage of uncontrolled crack propagation. After all, water, discretely wetting the samples surface, reduces steel resistance to fatigue fracture compared to air. The extract of samples No. 1 and No. 2 (2 g/l) increases steel 20 resistance in comparison with water and changes the corrosion nature.