On the basis, there is little a difference between the chemical analyses of ductile and gray cast irons that the corrosion resistance of the two materials also would be similar. However, there is disagreement as to whether or not ductile iron should have better corrosion resistance than has gray cast iron because of the spheroidal morphology of the graphite nodules.

Microbiologically influenced corrosion (MIC) is caused by the presence and activities of microorganisms in biofilms on the surface of the corroding material. Most materials, including metals, polymers, glass and ceramics can be degraded in this manner.

Without properly characterizing the failure attributes, corrosion debris, or environment involved in the failure, the root cause of the failure may be coming from an unexpected source, and may remain to cause the replacement components to fail.

Closed water systems are carefully designed to create precise and adaptable environmental conditions within buildings or process plant.

An unusual and perhaps unexpected corrosion problem can be caused by bacteria. As one of the oldest groups of organisms on the planet, bacteria have evolved to survive even in extreme environments.

When two dissimilar metals are in contact, or in close proximity with a conducting fluid in between, an electrochemical cell can be formed that leads to the more reactive metal becoming an anode and the less reactive metal a cathode. This kind of corrosion is known as galvanic corrosion. It is not uncommon, since metals are often coated with others of different E0, and different metals are often in close contact with a common electrolyte.

Structural materials can be attacked by environments. Although they do have specific connotations, they are frequently used as blanket terms for material deterioration. They are degradation, dissolution and corrosion. 

• Degradation: loss of strength of non-metals such as wood, rope or textile.
• Dissolution: removal of material in solution owing to the attacking medium.
• Corrosion: attack of metallic materials.

Many failures occur after a product has been in service for some time: such as the wear of a car tyre, or corrosion of the car body itself. It is also possible for components to fail because of a combination of a manufacturing defect with the applied loading or with the environmental conditions during use.

In many cases component failure is because something has reached the end of its working life due to a slow-acting failure mechanism: car tyres wear slowly and will eventually burst if not replaced; the filament in a light bulb slowly loses material until it cannot sustain the applied voltage and melts.

Microbial influenced corrosion can be caused for various microorganisms. Under humid conditions, Thiobacillus bacteria (microorganism) absorb hydrogen sulphide (H2S) gas on the sewer walls and excrete the corrosive acid which attacks concrete.

Zinc has been used as a sacrificial anode to cathodically protect ship’s hulls for more than a century now. It has become a common practice to use cathodic protection either alone or in combination with coatings for buried pipelines, storage tanks and offshore structures.

Highly cracked, delaminated cover
When reinforcements are strongly corroded, their corrosion products can expand, and deteriorate the concrete cover, by cracking, delamination and spalling. Then, the first action to be undertaken is to eliminate these geometrical defects, by replacing concrete cover, or sometimes injecting cracks.

The reinforced concrete structures are designed and built for a service life, which is defined by the designer and is controlled by the manufacturer. For this period of time, the structure should not be so deteriorated that it does not fulfill any more its functions. Reinforcements corrode when they are in contact with a high amount of aggressive agents. This is the reason why, the prevention of reinforcement corrosion, in structures to be built, is obtained mainly by controlling the thickness and the quality of the concrete cover.

The presence of microbial cells on a metal surface, as well as their metabolic activities, can cause Microbiologically Influenced Corrosion (MIC). The forms of corrosion caused by bacteria are not unique. Biocorrosion results in pitting, crevice corrosion, selective dealloying, stress corrosion cracking, and under-deposit corrosion. There are some mechanisms of the causes of biocorrosion as follows.