How to distinguish the corrosion of the galvanized steel coil caused by Soaking?
2020年5月7日
Rusting of steel materials, especially cold-rolled/galvanized plate rust, is a very common defect. Not only steel mills, steel traders, processing plants, end-users, and even insurance companies will suffer a loss.
The white rust of the galvanized plate is usually caused by water contamination.
Water is a common source of pollution in the supply chain links such as the production, processing, storage, transportation and use of galvanized plate rolls. How to distinguish between the source of pollution, and thus the classification of white rust, for the confirmation of liability, insurance claims, follow-up improvement and other work has a very realistic significance.
The classification of white rust can be roughly divided into: production pollution and storage and transportation pollution.
Production pollution refers to white rust caused by water contamination during the production process. Typical cases such as:
1.galvanized line flat flat machine flat liquid residue caused by white rust;
2.galvanizing wire or shear processing line dew caused by white rust;
The image above is two more typical production contaminations that lead to white rust, characterized by a bit or blockshape, usually with a complete outline, and sometimes there may be tailors or streaks along the rolling direction.
The characteristics of white rust caused by production pollution are strongly related to the two process characteristics of “steel belt movement” and “Fully expanded”
Storage and transportation pollution is caused by water contamination of steel rolls/steel plates after packing. Typical cases such as:
1. steel roll / steel plate in the transport without a rain cloth, resulting in packaging into the water
2. steel roll / steel plate in the cabin immersion, or the southern summer rainstorm, warehouse immersion caused;
The figure above is a typical white rust-shaped appearance caused by storage and transportation pollution, its characteristics are related to the “roll” state, usually intermittent appearance, the upper and lower surface position is similar in shape, and the outer diameter has correspondence, the end may not necessarily have a clear white rust, but sometimes see the residual appearance of water agent.
The confirmation point of the white rust caused by the storage and transportation pollution is somewhat similar to the friction black spot, and the confirmation point of the friction black spot is also the confirmation point of the storage and transportation white rust. (Friction black spot)
After the end is contaminated, the water will be gradually inhaled to both sides of the strip steel, and then when the water is removed from water pollution, the water on the side will continue to inhale, and the end contact with the environment, close to the endofs of the part of the moisture will evaporate.
In the end, this kind of off-end is a bit of a gap but the outline is obvious.
Rust is one of the main causes of the failure of steel materials, causing many losses to our traders and terminals. Frankly speaking, only the rust of the galvanized plate roll has many practical cases, such as passivation sea white rust, cut line in the middle of the white rust, white rust after the mulch, rust after making parts, rust after welding and so on.
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