Failure under Service of High-strength Steel

Failure under Service of High-strength Steel 

Crack initiation is promoted by corrosion and, particularly, by pitting or crevice attack, even of low depth, which can cause local conditions of acidity and thus the development of hydrogen. The duration of this stage depends both on the characteristics of the steel and the environment (e. g. the surface finishing of the steel bars, the pH and chemical composition of the environment, etc.) and the time required to initiate the preliminary pitting or crevice attack. However, it does not depend on the stress applied to the steel. 

A material with low fracture toughness - high applied stress B tough material - low applied stress 

If steel is passive and is embedded in non-carbonated and chloride-free concrete, the first stage does not take place and, consequently, also the others do not. Conversely, it can take place if concrete is carbonated or chloride contaminated. Similarly, it can occur if part of the steel surface is not embedded in concrete and is in contact with soil, aqueous solutions with neutral or acid pH or simply with moist atmosphere. 

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Failure under Service of High-strength Steel 149... 

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