Corrosion fetigue features of carbon 35 (0.35c) steel in presence of oak chips extract
Journal Title: Вісник Тернопільського національного технічного університету - Year 2015, Vol 80, Issue 4
Abstract
It is established that corrosion protection efficiency of medium carbon steel in water inhibited by oak chip extract grows with increasing of inhibitor concentration. The degree of corrosion protection reaches 85 – 97% under inhibitor concentration of 0.8 – 2.0 g/l respectively. It is testified electrochemically, that extract is a mixed type action inhibitor, which inhibited both electrode reactions by forming chemisorptions film on steel surface. An increase of activation energy Еасt, calculated from temperature dependence (25 – 40ºC) of corrosion rate, is observed in the presence of extract. Calculated Еасt respectively is: 3500 g/mol•grad in water; 9170 g/mol•grad in presence of 0.8 g/l of extract. Thus, formed as a result of inhibitor adsorption protective film increases activation energy of corrosion process and slows its rate. The corrosion fatigue resistance of steel in the presence of inhibitor (0.8 – 2 g/l) is increased in average of 3 – 4 times and the mechanism of corrosion fatigue is changed. The macrofractographic analysis showed that oak chip extract affects crack initiation: it occurs by the intergranular mechanism from specimen surface in water and by the more energy transgranular one in the inhibited environment. The energy of corrosion fatigue under its final step of fracture is higher in inhibited environment than in water and the typical elements of ductile fracture on air namely, round holes tearing, are observed. Thus, environmental safe inhibitor based on oak chip extract provides medium carbon steel reliable corrosion protection and effectively slows corrosion fatigue in water.
Authors and Affiliations
Zvenomyra Slobodyan, Yaroslav Khabursky, Olga Maksymiv
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