Stainless steel wire mesh is generally not corroded, but nothing is absolute. Corrosion cracking of stainless steel wire mesh is a corrosive fracture that occurs under the action of stress and corrosive environment. Generally speaking, in the corrosive environment, stainless steel wire mesh will accelerate the rate of corrosion damage after being subjected to external stress. The simplest case is the result of the superposition of these two factors. In a specific corrosive environment, when the metal material is not stressed, the corrosion damage is minimal, and when subjected to a certain stress, although the stress is sometimes far lower than The strength limit of the stainless steel wire mesh itself, after a period of time, even the ductile stainless steel wire mesh will also break. This kind of damage is often without any warning, and the damage caused is very serious.
There are three essential conditions for stress corrosion cracking:1. Special environment; 2. Must be subjected to tensile force; 3. Stainless steel mesh itself is of poor quality.
Stress corrosion cracking is the result of the interaction of stress and corrosive medium. Corrosive medium is often unselectable. Stress is the dominant regulation of stress corrosion. In general, the three conditions that cause stress corrosion cracking are: one is the tendency of the metal material to have stress corrosion cracking in the environment; the other is that the structure composed of the material is in contact with or in a selective corrosive medium; It is necessary to have a tensile stress above a certain level. The absence of any of them is a condition in which stress corrosion cracking is unlikely to occur.
There is usually no uniform corrosion in the stress corrosion fracture site. The fracture often starts from pitting corrosion and crevice corrosion, and occurs from the metal surface of the contact medium and develops deep. The shape of the crack is macroscopically observed, and the crack is relatively straight. There are often branches, patterns or cracks. From the microscopic observation of the cross section of the crack, it is found that the crack generally has branching characteristics, the crack tip is sharp, and the root is slightly wider. From the analysis of fracture morphology, generally no obvious signs of plastic deformation are completely brittle fractures. From the macro fracture, the fracture is rough and the fracture always starts from the surface in contact with the medium, so the fracture near the surface of the crack is always the darkest. The fracture has a multi-layered crystal shape, a lamellar shape, a radial shape, and a mountain shape. From the microscopic analysis, the austenitic stainless steel is mostly transgranular fracture, which is a transgranular quasi-cleavage fracture, showing river patterns, fan-shaped patterns and feather-like patterns. Chromium stainless steel is mostly broken along the crystal, showing the sugar candy pattern.
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