Transcrystalline Corrosion

Definition - What does Transcrystalline Corrosion mean?

Transcrystalline corrosion is a type of corrosion cracking that can cause breakdown of alloys without residual or applied stress. In this, the cracking may take place due to the combined action of hydrogen embrittlement.

Thus, this happens in the presence of corrosive environments and factors other than tensile stress. Being able to control the causes of transcrystalline corrosion can help industries prevent the occurrence of cracking and other forms of corrosion patterns that can impact their operations negatively.

Corrosionpedia explains Transcrystalline Corrosion

Transcrystalline corrosion is a result of the combined actions of various components, including a specific environment or chemical species and a vulnerable material. For instance, alloys of copper as well as copper itself are susceptible compounds of ammonia, while stainless steels are vulneralbe to chlorides and mild steels are vulnerable to alkalis.

Transcrystalline corrosion is associated with various models and mechanisms such as adsorption, where certain species of chemical is adsorbed in the cracked areas. At times, transcrystalline corrosion is also produced when passive films split apart and form an active-passive cell. The newly formed cell undergoes breakage the second time and the cycle goes on until it leads to corrosion cracking or total failure.

It is also a result of preexisting grain boundaries and other paths where compounds are developed. Lastly, it can be the outcome of hydrogen embrittlement where the atoms of hydrogen diffuse to the tip of the crack, which weakens the metal, leading to cracking corrosion.

Because transcrystalline corrosion can be so damaging, industries implement measures to prevent it from occurring, such as:

  • Avoiding environments that cause corrosion
  • Utilizing materials that are resistant to corrosion under a certain environment
  • Controlling electrochemical potential and operating temperatures of alloys
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