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All metals and certain polymers and ceramics are susceptible to corrosion, that is typically produced by the existence of moisture in the air or direct connection with water. In metals this technique is oxidation: the alteration of electrostatic charge whereby oxides or salts are created, resulting in damage to the metal's structure. Rusting, the production of red oxide within an iron structure, is a very common demonstration of this. The phrase 'degradation' is applied to the corrosion of non-metals, even so the process is the same: the corroding material surrenders electrons in a chemical reaction and loses its structural integrity. Corrosion testing does apply for the following kinds of damage.

Galvanic corrosion takes place when two metals come into contact inside an electrolytic medium or one metal is encountered with two different electrolytes. Microbiologically Influenced Corrosion is attributable to micro-organisms assaulting a metallic or non-metallic material either with or without the presence of oxygen; as an example Accelerated Low Water Corrosion damages steel piles round the low-water mark, leaving behind an orange sludge as a deposit. Aerospace materials, engines or power-generation materials are typical cases of substances at risk from High Temperature Corrosion. Metal Dusting happens in high-carbon-dioxide contexts, developing a tell-tale film of graphite on metal and reducing the metal to powder.

Corrosion testing necessitates the promotion of deterioration in test samples to find out the extent and rate of any damage by corrosion in the environment. Accelerated Corrosion Testing is an approach created to calibrate the long-term effects on the system of alternating wet and dry cycles, creating the output of partially dry corrosion agents that exacerbate degradation within the system. Typical will be the ISO 11474 test, which employs an outside intermittent salt-water spray.

Weld testing for corrosion damage or other structural compromise can be done via Dye Penetrant Inspection. Penetrant is applied to a test surface and left for 5-30 minutes. Developer, such as dry powder or Non-Aqueous Wet Developer (e.g. acetone), draws penetrant from defects in a visible ‘bleed-out’ process. Additional weld testing methods consist of Magnetic Particle Testing, X-rays, 3D X-rays and microscopy: all classified as Non-Destructive Inspection procedures. mechanical testing materials