What is stainless steel plate?
Generally speaking, the stainless steel plates we mention every day often refer to 1219*2438 plates, which is often referred to as four or eight feet. But many people don’t know what kind of medium-thick plate is?
In fact, not all stainless steel plates can be called medium-thick plates. Only steel plates that meet certain thickness requirements can be called so.
So what is the specific thickness of medium-thick plate?
Stainless steel medium-thick plates refer to steel plates with a thickness of 4~25.0mm, those with a thickness of 25.0~100.0mm are called thick plates, and those with a thickness exceeding 100.0mm are called extra-thick plates. Widely used to make various containers, furnace shells, furnace plates, bridges and automobile static steel plates, low alloy steel plates, bridge steel plates, general steel plates, boiler steel plates, pressure vessel steel plates, patterned steel plates, automobile girder steel plates, tractors Some parts and welded components.
Defects in stainless steel medium and thick plates
During the use of stainless steel medium and thick plates, attention should be paid to the occurrence of defects. Small longitudinal cracks, peak cracks, edge cracks, inclusions, and scars on the surface of the steel plate will affect the surface quality, cause changes in judgment, and reduce product quality.
Manifestations of defects in stainless steel medium and thick plates
1. Small longitudinal cracks. The shape of small longitudinal cracks on the surface of the steel plate is less than 200mm in length, less than 3mm in width, and less than 0.3mm in depth.
2. Peak-shaped cracks. These cracks all occur at 5-60mm from the edge of the lower surface of the steel plate. The macro direction is perpendicular to the rolling direction and is in the shape of a "peak".
3. Edge cracks. This crack mainly occurs at 20-80mm from the edge of the steel plate. It takes the form of multiple parallel longitudinal cracks of different sizes. The rule is that the thicker and wider the steel plate is, the more serious such defects will be.
4. Inclusions and scarring are regularly distributed, and the phenomenon is obvious after finishing operations such as edge flame peeling crack inspection or billet scratch flame cleaning.
Cause of defect
Small longitudinal cracks are formed when small impurities are mixed into the crystallizer.
The cause of peak cracks is mainly caused by transverse cracks in the subsurface corners of the outer arc skin of the cast slab.
Edge cracks are caused by the edges of the billet turning sideways to the surface during the rolling process.
Inclusions and scabs are caused by the surface oxide slag not being cleaned during finishing.
Measures to prevent defects
1. Check the crystallizer regularly, especially water samples, to see if there are small impurities mixed in that may cause changes in water quality.
2. Strictly control the overage service of the equipment to ensure timely maintenance of the sector section and avoid deep scratches on the cast slab due to local roller failure in the sector section.
3. Implement zoning control of water distribution in the bending section and dynamically control the corner temperature of the end face slabs with different widths to prevent the corner temperature of the slab from entering the brittle zone during the bending process.
4. Use wide-end cast billets as much as possible to produce large-width steel plates to reduce the amount of broadening during rolling, thereby reducing the uneven deformation of the edges during rolling of wide steel plates and weakening the width of edge cracks in the steel plates.
5. Improve the uniformity of the temperature of the slab in the heating furnace, optimize the slab heating process, reduce the temperature difference between the upper and lower sides of the slab, and reduce the difference in deformation resistance between the upper and lower sides of the rolled piece, thereby reducing the uneven deformation of the edge of the rolled piece.
6. Improve the finishing ability of the cast slab to avoid the occurrence of secondary defects such as incomplete cleaning of oxide slag and local deep burn marks after finishing the cast slab.
