The main types of corrosion of stainless steel

You are interested in, what types of corrosion can be stainless steel from the supplier Alekhlas? Here you will find the necessary information on the topic.

Fundamentals of corrosion resistance of stainless steels

Carbon steel suffer from General corrosion, when affected large areas of the surface. Stainless steels in passive state is usually protected from this form of attack, however, local forms of attack may occur and lead to corrosion problems.

Therefore, the evaluation of corrosion resistance in any particular environment is usually associated with consideration of specific corrosion mechanisms. These mechanisms are the following:

Surface corrosion;

Pitting;

Intergranular (or intercrystalline) corrosion;

Corrosion mechanical stress;

Electrochemical (galvanic) corrosion.

In the course of corrosion processes, the mechanism of erosion, which is accompanied by fatigue of the material: if duplicate, but non-critical load bearing capacity of the metal is gradually reduced.

Localised corrosion is often associated with chloride ions in aqueous media.

Acidic conditions (low pH) and temperature rise contribute to localized mechanisms of splitting and pitting. Adding tensile stress, regardless of whether you download them from the outside, or from the internal residual stresses, provides the conditions for stress corrosion cracking under tension.

All these mechanisms are associated with localized destruction of the surface protective layer of metal. A good supply of oxygen to all surfaces of the steel required for maintaining the passive layer but higher levels of chromium, Nickel, molybdenum and nitrogen help in their individual ways to prevent these forms of attack.

Supplier — the company Alekhlas — offers to purchase assortimente metal, made of different grades of stainless steels. Products can be purchased at a price formed on the basis of European and world standards. Possible, wholesale and retail, for regular customers a flexible system of discounts.

What forms of corrosion can occur in stainless steels?

The most common forms of corrosion of stainless steel are:

Pitting. The passive layer of stainless steel may be exposed to certain chemicals. The most common of these is the chloride ion Cl-.

Surface corrosion. Stainless steel requires oxygen in order to ensure that the passive layer can be formed on the surface. In a very tight contact is not always possible for the oxygen to access the surface of stainless steel.

Crystalline corrosion is prevented by sealing gaps flexible sealant or by using a more corrosion resistant grade of steel.

General corrosion. Usually, stainless steel does not corrode uniformly as ordinary carbon and alloy steels. However, with some chemical substances, especially acids, the passive layer may be subjected to uniform exposure, depending on concentration and temperature and the metal loss is distributed over the entire surface of the steel. Hydrochloric acid and sulphuric acid at some concentrations are particularly aggressive towards stainless steel.

The stress cracking. This is a relatively rare form of corrosion which requires a very specific combination of tensile stress, temperature and environment. Typical applications, which may be the SCC, are reservoirs for hot water and pools.

Another form, known as sulphide stress corrosion cracking under tension, is associated with hydrogen sulfide in the exploration and production of oil and gas.

Intergranular corrosion is a rare form of corrosion. If the level of carbon in steel is too high, chromium can combine with carbon with the formation of chromium carbide. This occurs at temperatures between about is between 450−850 ° C. the Process typically occurs during welding.

Galvanic corrosion — if two dissimilar metals are in contact with each other and with an electrolyte, such as water.

Supplier — the company Avecho offers various types of stainless steel domestic and foreign production. Products are offered at affordable prices from the manufacturer. Supplier guaranteed timely delivery at any address specified by the consumer.