The strip steel after pickling with hydrochloric acid may have various defects. The reasons for various defects and how to prevent them are analyzed below. HUNGTHAI METAL has a complete quality supervision system and makes every effort to provide you with high-quality steel coil products.
- Excessive pickling
Black spots composed of associated elements appear on the surface of the strip during pickling. To prevent excessive pickling, pay attention to reducing the stoppage of the process section, and pay attention to the acid release in time when the process section is stopped. The common method is to add a corrosion inhibitor to the acid solution, and the effect is good.
- Insufficient pickling
Because the pickling is not fully completed, the surface of the strip steel becomes black and there is residual iron oxide scale, which is the most common defect in the pickling production process. In order to prevent this phenomenon, the temperature of the acid liquid should be guaranteed, and the vapor pressure of the paint should be guaranteed.
- Water Stains
The cause of the water stains: the damage of the squeeze roller causes the residual rinsing water, or the ferric hydroxide is formed on the surface of the strip to form the trace of water. Such defects have an impact on the surface quality of the high-quality cold-rolled sheet.
In order to prevent this problem, it is necessary to insist on using demineralized water for production, and replace the squeeze rollers regularly to ensure good working conditions.
- Corrosion holes
After pickling, a little acid solution remains on the surface of the strip, or the strip is not completely dry after cleaning, or it stays in the high-temperature cleaning water for too long, causing the pickling solution to corrode locally, thus causing this defect.
When such a defect occurs, the console needs to be notified in time to reduce the speed and prevent the strip from breaking.