In the use of stainless steel plate, in order to ensure that the results meet the requirements, need to pay attention to board surface defects may occur, such as small crack, crack, crack, edge peak shaped inclusions and scabs all will have a negative impact on the surface quality of stainless steel plate, and ultimately reduce product quality.
Below is the shape of the surface defect of the lower stainless steel plate.
The shape of small longitudinal crack is on the surface of stainless steel plate, which has a length less than 200mm, the width is less than 3mm, and the depth is lower than 0.3mm. The peak crack will only appear at the 5-60mm of the surface of the surface of the stainless steel plate, which is perpendicular to the rolling direction, and the shape is similar to the “mountain peak”. The side line cracks mainly occur in the 20-80mm area at the edge of stainless steel plate, and the shape is multiple longitudinal cracks with different sizes. The feature is that the thicker the stainless steel plate is, the more serious the defect is. The distribution of inclusions and scarring of the comparative law, and by the side of the crack of billet inspection or flame peeling scratch flame cleaning and finishing operation after the presentation is very obvious.
The formation of these defects is not a small, which is in the crystallizer longitudinal small impurities caused; peak shaped crack is more outer arc slab transverse corner crack cause subcutaneous; edge cracks are in rolling billet surface to form edges due to rollover; inclusion and scarring is finishing when the surface oxide slag do not clean up the cause.
There are many ways to avoid the surface defects of the stainless steel plate, and the following are the following points.
One is to regularly check the mould, especially water, there is no need to check into the small impurities, resulting in change of water quality. The second is to strictly control the equipment to ensure the maintenance of overage service, the segment in a timely manner, to prevent the occurrence of local segment does not turn to produce a deep scratch roll billet. The third is to carry out the zoning control of bending section water distribution, and dynamically control the corner temperature of the slab with different widths, so as to prevent the corner temperature from being brittle in the course of bending.
It is also necessary to use the wide end face slab to produce large width steel plate and reduce the width of the stainless steel plate when rolling, so as to reduce the uneven deformation extent of the wide plate when rolling, and weaken the wide extent of the side line cracks produced by the stainless steel plate.
It can also increase the temperature uniformity of the billet in the heating furnace, improve the heating process of the slab, reduce the temperature difference between the bottom and the bottom of the billet, and reduce the difference of the deformation resistance between the stainless steel workpiece and the lower part, so as to reduce the uneven deformation degree of the edge of the rolled piece.
Finally, the finishing ability of the billet can be improved to prevent the two defects, such as incomplete cleaning of the slag, and the local depth burn.
Source: China Stainless Steel Plates Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)