What causes intergranular attack?
What causes intergranular attack?
An intergranular attack is caused by the segregation of impurities at the grain boundaries or by enrichment or depletion of one of the alloying elements in the grain boundary areas.
How does intergranular corrosion occur?
Intergranular corrosion (IGC) It is as a result of chromium depletion, mainly due to the precipitation of chromium carbides in the grain boundaries. Chromium carbides can be precipitated if the stainless steel is sensitized in the temperature range 550–850°C (1020–1560°F), for example during heat treatment or welding.
What is intergranular corrosion example?
Stainless steels and weld decay sensitization are the best examples of intergranular corrosion. Grain boundaries that are rich in chromium elements will precipitate lead. This makes the boundaries very vulnerable to corrosion attacks in various electrolytes.
What is INCONEL 718 used for?
INCONEL alloy 718 is ideal for use in these circumstances. For example, it has been used in jet engine and high-speed airframe parts, including wheels, fasteners, instrumentation parts, bolts, spacers and buckets.
How is an intergranular attack measured?
Similar to the Streicher test, the Huey test method uses a nitric acid solution and subjects the specimen to five 48-hour boiling intervals. The samples are weighed at each interval to determine mass loss and degree of susceptibility to intergranular attack.
What is the most common material attacked by intergranular corrosion?
Intergranular corrosion attack is mainly prevalent in certain types of stainless steel rather than in carbon steel.
How can we prevent 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.
How do we prevent intergranular corrosion?
Is Inconel stronger than steel?
Corrosion Resistance This is because Inconel is stronger than stainless steel at high temperatures, while being more resistant to oxidation and scaling as well. However, there are specific chemicals that the stainless steel might be better at resisting than Inconel—such as sulfuric acid.