What is intergranular stress corrosion cracking?
Intergranular stress corrosion cracking (IGSCC) is the progressive nucleation and growth of cracks by localized corrosion along the grain boundaries in metals in the presence of stress or strain. Thermal sensitization is due to chromium carbide precipitation at the grain boundaries (2).
What is the mechanism of stress corrosion cracking?
Stress corrosion cracking (SCC) is defined as the growth of cracks due to the simultaneous action of a stress (nominally static and tensile) and a reactive environment [1]. SCC is the result of the combined and synergistic interactions of mechanical stress and corrosion/oxidation reactions [2].
What is the mechanism of intergranular corrosion?
Intergranular corrosion is caused by Microsegregation of impurities and alloying elements on the grains boundaries. The driving force of intergranular corrosion is the difference between the Electrode potentials of the grain boundary and the grain itself, which form a galvanic cell in presence of an electrolyte.
Is stress corrosion cracking Transgranular?
Stress corrosion of austenitic steels is usually transgranular. Stress corrosion cracking can proceed in one of two ways: Intergranular stress corrosion cracking (IGSCC) – Cracks propagate along the grain boundaries.
How do you fix intergranular corrosion?
Intergranular corrosion can be prevented through:
- Use low carbon (e.g. 304L, 316L) grade of stainless steels.
- Use stabilized grades alloyed with titanium (for example type 321) or niobium (for example type 347). Titanium and niobium are strong carbide- formers.
- Use post-weld heat treatment.
What causes intergranular stress corrosion cracking ( igscc )?
Intergranular stress corrosion cracking (IGSCC) highly relates to the nucleation of cracks in the heat affected zone (HAZ) or cold-worked zone of austenitic stainless steels, especially in the cases of aged nuclear pressure reactor components [1 ].
What are the mechanisms of stress corrosion cracking?
Stress-corrosion cracking (SCC) is a term used to describe service failures in engineering materials that occur by slow, environmentally induced crack propagation. The observed crack propaga tion is the result of the combined and synergistic interaction of mechanical stress and corrosion re actions.
What kind of corrosion can occur in intergranular tank?
Inset (at a higher magnification) shows shallow dimples/flutes on the macroscopically brittle area [ 73, 120 ]. Intergranular stress corrosion cracking of cold-formed or welded steel tanks in which liquid or gaseous ammonia was stored under a pressure of 1.75 MN/m2 has been reported [ 128 ].
What is the pH of transgranular corrosion cracking?
In contrast to intergranular cracking, transgranular SCC is associated with a near-neutral pH, around pH 7, typically in areas of the pipeline that cathodic protection has not reached, such as under disbonded coatings that shield the underlying pipe from cathodic protection.