Corrosion; It is based on the degradation of the material as a result of other chemical effects, as well as the oxidation of iron, non-ferrous alloys and other elements. If we give a simple example; rusting of iron is the oxidation of aluminum. The surfaces of the materials cannot be properly protected and corrosion can occur when it is under the influence of various elements around it (such as galvanic series, electro-chemical interactions).
Corrosion basically; In nature, all compounds except gold and platinum are found in oxidized form. This is because it is in contact with air too much. The Earth’s atmosphere contains about 78% nitrogen and 21% oxygen. The remaining about 1% is made up of other elements and molecules (for example, argon, carbon dioxide, methane).
Metals and metal alloys have a very high tendency to return to steady state. Steady state means that the compounds are oxidised in nature. As a result, metals can react with the elements in the environment, first turning into ions and then into other compounds. In other words, they decompose by undergoing chemical composition. Oxidized states of some elements are more stable (higher strength) and some have less strength. For example, Alumina oxide compound has greater strength than FeO (iron oxide, wüstite) compound.
CAUSES OF CORROSION
The environment in which the material is located, its interactions with the materials around it, and materials that are not isolated and protected are at risk of corrosion. Metals are the most corrosive substances in nature. If iron and steel products are not protected, they will corrode instantly. Corrosive sensitivity of iron products is very important. Because, considering its costs and physical properties, it can cause a huge amount of material damage.
In the subject of resistance to corrosion in parts manufactured by welding method, besides the properties of the material, welding designs are also of great importance. Economically, it causes great losses to every country. Apart from this, damages incurred due to corrosion;
As it is known, the corrosion products of copper adversely affect human health. That’s why copper vessels have been used for centuries by coating them with tin. Another example; crashes of aircraft are predominantly the result of corrosion. Types such as corrosion fatigue and strain corrosion cracking are frequently encountered in aircraft.
Corrosion is the biggest waste of important metal resources in the world. About one-third of the metallic materials produced each year will corrode by the end of the year. As a result, these metals become unusable.
As a result of corrosion, there is a loss of “capital-labor-energy and information” as well as material loss. In addition, dirty environment accelerates corrosion. For example, turning, milling, grinding machines are exposed to high corrosion. Because they are found too much in polluted environment. In case of accumulation of machine oils, the interaction of the elements in the oil with the active metals around it causes corrosion. Corrosion progresses rapidly by taking advantage of the polluted environment and is likely to cause serious damage.