The Corrosion Resistance Of Steel Tube Rectangular

Corrosion resistance refers to the ability of a material to resist the corrosive effects of the surrounding medium. The corrosion resistance of the metal is related to many factors, such as the chemical composition of the metal, processing properties, heat treatment conditions, organizational state, medium, temperature, etc. Chemical corrosion is the result of the direct chemical action between the metal and the surrounding medium. It includes two forms of gas corrosion and corrosion of metals in non-electrolytes. Its characteristics are: the corrosion process does not generate current, and the corrosion products are deposited on the surface of the Q345B steel tube rectangular. To deeply understand the corrosion resistance of the Q345B steel tube rectangular, we should first grasp the following points:

General corrosion: This kind of corrosion is evenly distributed on the entire inner and outer surfaces so that the cross-section is continuously reduced, and finally the stressed parts are damaged.

Pitting corrosion: Corrosion is concentrated in the small area on the surface of the Q345B steel tube rectangular, develops rapidly to the depths, and finally penetrates the metal, which is a kind of corrosion damage with greater harm.

Corrosion fatigue: refers to the damage caused by the material in the corrosive medium under the action of alternating stress.

Corrosion rate: The depth of the metal material corroded in unit time is called the corrosion rate.

Electrochemical corrosion: The corrosion caused by the contact of the Q345B steel tube rectangular with acid, alkali, salt, and other electrolyte solutions is called electrochemical corrosion. It is characterized by current generation during the corrosion process, and its corrosion product (rust) is not covered on the metal surface as the anode, but at a certain distance from the anode metal.

Intergranular corrosion: Corrosion is carried out inside the metal along the edge of the grain, which usually does not cause any change in the shape of the metal, and often causes sudden damage to equipment or parts.

Stress corrosion: refers to the damage caused by the metal in the corrosive medium under the action of static stress. The damage caused by this corrosive medium is also transgranular corrosion. Scratches: Scratches and other rough surfaces must be mechanically cleaned (eg dry blasting, glass beads for abrasives) to prevent the accumulation of process lubricants or products and/or dirt.

Rust spots: According to the analysis of Q345B steel tube rectangular manufacturers, rust is sometimes seen on stainless steel products or equipment before or during the production process, which indicates that the surface is seriously polluted. Rust must be removed before equipment is put into service, and thoroughly cleaned surfaces should be inspected by iron and/or water tests.

Welding arc striking: When the welder strikes the arc on the metal surface, it will cause surface roughness defects. The protective film is damaged, leaving a potential source of corrosion. The welder should strike the arc on the bead that has been welded or on the side of the weld joint. The arc strike is then fused into the weld.

Flux: The welding process of galvanized pipe using flux includes manual welding, flux-cored arc welding, and submerged arc welding. These welding processes will leave fine flux particles on the surface, which cannot be removed by ordinary cleaning methods. This particle will be a source of crevice corrosion, and mechanical cleaning methods must be used to remove this residual flux.

When the coating of the galvanized pipe is intact, the corrosion resistance of the galvanized layer is not good, because the product after corrosion is very loose, and a dense oxide film protective layer cannot be formed to protect the internal organization, but it can basically meet the requirements. The needs of various uses, especially after passivation treatment, the anti-corrosion performance of the zinc coating has been greatly improved.