Common Defects and Correction Methods of Re-rolling Stainless Steel Sheets

Stainless Steel Sheet Defects and Corrections

Stainless steel sheet is a kind of commonly used product. Its surface can produce a variety of excellent performance. Due to its excellent resistant to corrosion property and its excellent performance in heat resistance, stainless steel sheet has been widely used in various fields, such as chemical engineering, medicine, electronics, etc.

However, during the production process, such as hot rolling, cold rolling, coil rolling and other processes, some defects will occur. In order to ensure the production of qualified products, the inspection of the steel plates should be conducted in each process and the defective products should be corrected in time.

1. Roll mark processing

In the cold rolling process, when stainless steel plates pass through the roller gap, uneven pressure of the roller will cause rolls mark to appear on the surface of the stainless steel plates, which reduces the surface quality.

For the roll marks, polish can be used to repair. The repair procedure is as follows. First, the depth of the roll marks should be evaluated. If the depth is not too deep, it can be finished with a polishing wheel. In this way, the roll marks can be removed. However, when the roll marks are particularly deep, it is necessary to conduct polishing after grinding.

2. Cracks and cracks processing

Cracks usually appear in hot rolling and cold rolling process. Such cracks can be caused by rough manufacture or uneven force. In addition, the unstable microstructure of steel also can cause cracks.

Cracks can be repaired by welding, If it is a small crack, it can be filled and repaired with manual welding, and then treated with grinding wheel to make it smooth and uniform.

3. Pitted treatment

Pitting, also known as concave spots, is common in hot rolling process, which is mainly caused by rusty roller and deposition of alloy elements on the surface of stainless steel sheet.

Pitting repair is usually accomplished by polishing or grinding and polishing. First, light grinding can be used to remove oxidation of rust spots on the surface of stainless steel sheet. Then a grinding wheel can be used to polish and smooth the surface. Finally, polishing can be conducted to make the surface flat and smooth and with a reflective appearance.

4. Coil slitting

During the coil slitting process, some defects often occur, such as burrs, uneven thickness, corner cracks, etc. Therefore, coil slitting should also be inspected for defects.

To repair the defects caused by coil slitting, the first step is to generally remove all possible dimensional faults, slag, cracks and burrs in the slit edge of the strip. Then, it must be checked that the strip must have no burrs and traces of slag to ensure the quality of the slit strip.

5. Straightening processing

The straightening process is also important to stainless steel sheets. The straightening process is generally conducted after a cold rolling process to make the plate more straight and smooth. However, if there are bumps on the straightened plates, it can also cause serious defects.

To repair such deformations, manual straightening should be adopted. Firstly, the deformed part of the plate should be placed on an anvil. Then a flat hammer should be used to pound the plate to make it smooth. Finally, the surface should be ground with a grinding wheel to make it smooth and straight.

To sum up, stainless steel sheet has been widely used due to its excellent performance. Defects will occur during the production process, so it is necessary to conduct inspection in each process, as well as in-time correction to ensure the quality of products. To repair the defects, there are various ways, such as polishing, grinding, welding, etc. With the above methods and in-time repair, the quality of the sheet will be greatly improved.

Common defects in the cold rolling of stainless steel thin plates and the corresponding rectification methods:

1.Offset defect: should be checked first to confirm whether the gap between the upper roller and the top roller of the rolling mill is appropriate. The upper roller should be raised slightly and the lower roller should be lowered slightly to improve the offset.

2.Oval head defect: adjust the roll gap to a certain extent to reduce the irregularity of the rolling pressure.

3.Rolling crack defect: be careful when rolling, pay attention to monitoring and reduce the rolling speed when passing through the part with cracks.

4.Wrinkle defect: should adjust the roll gap to ensure that the pitch of the pressure line is consistent and pay attention to checking the wrinkle in time.

5.Surface defect: If the surface defect is serious, the rolling speed should be reduced appropriately, and the number of passes should be increased.

Above are the common defects and corresponding rectification methods for the cold rolling of stainless steel thin plates. It is necessary to pay attention to the controlling of roll gap and the monitoring of rolling speed during the rolling process.