What causes intercrystalline corrosion?
Intercrystalline corrosion occurs when steels are heated with a temperature of about 450°-800°C. Chromium carbides precipitate at the boundaries of the affected grains. This results in the weakening of the chromium protection on the peripheries of the grains at the zones of the weld.
How does intergranular corrosion occur?
Intergranular corrosion occurs when certain metals and alloys reach temperatures between 425°C and 870°C (887°F to 1598°F.) These temperatures are most common during welding, heat treatment, or operation in high-temperature environments.
What do you mean by inter granular corrosion?
Intergranular corrosion (IGC) is a form of localized corrosion characterized by preferential corrosion at grain boundaries or areas adjacent to them, with little or negligible attack on the grains. Similarly to other forms of localized corrosion, it mainly occurs on passive alloys exposed to specific corrodents.
How is an IGC test done?
Generally used for stainless steel and nickel alloys, the Streicher test involves boiling the specimen in a Ferric Sulfate – Sulfuric Acid solution for 24-120 hours and evaluating the results. The level of corrosion is determined by mass loss.
Where does intergranular corrosion occur?
grain boundaries
Intergranular corrosion is localized attack along the grain boundaries, or immediately adjacent to grain boundaries, while the bulk of the grains remain largely unaffected.
What is transgranular and intergranular corrosion?
Intergranular stress corrosion cracking (IGSCC) – Cracks propagate along the grain boundaries. Transgranular stress corrosion cracking (TGSCC) – Cracks run through the individual grains.
How do you remove corrosion from exfoliation?
The methods normally used to remove corrosion are mechanical and chemical. Mechanical methods include hand sanding using abrasive mat, abrasive paper, or metal wool, and powered mechanical sanding, grinding, and buffing, using abrasive mat, grinding wheels, sanding discs, and abrasive rubber mats.
What is intercrystalline corrosion?
Intercrystalline corrosion can also be referred to as intergranular corrosion or weld decay. Intercrystalline corrosion occurs when steels are heated with a temperature of about 450°-800°C. Chromium carbides precipitate at the boundaries of the affected grains.
What is intergranular corrosion?
Intergranular corrosion (IGC) is a form of localized corrosion characterized by preferential corrosion at grain boundaries or areas adjacent to them, with little or negligible attack on the grains. Similarly to other forms of localized corrosion, it mainly occurs on passive alloys exposed to specific corrodents.
How does corrosion affect the surface of a material?
This corrosion attacks the surface grain layers or crystallites and is known to penetrate metal objects along the grain boundaries. This results in destruction of the metal articles along the grain boundaries.
What is corrosion of the grain boundaries?
This corrosion attacks the surface grain layers or crystallites and is known to penetrate metal objects along the grain boundaries. This results in destruction of the metal articles along the grain boundaries. It arises from the precipitation of chromium carbide at the grain boundaries.