Several typical defect forms of stainless steel plate
Stainless steel plate refers to a steel plate with a thickness of 4 to 25.0 mm. Thick plates with a thickness of 25.0~100.0mm are called thick plates, and thick plates with a thickness of more than 100.0mm are extra thick plates. It is widely used in the production of various containers, furnace shells, furnace plates, bridges and automotive static steel plates, low alloy steel plates, bridge steel plates, steel plates, boiler steel plates, pressure vessel steel plates, pattern steel plates, automotive beam steel plates, tractors. Certain parts and welded components. During the use of stainless steel plate, it should be paid attention to the occurrence of defects. Small longitudinal cracks, peak cracks, edge cracks, inclusions and crusting on the surface of the steel plate will affect the surface quality, resulting in a change of judgment, resulting in a decline in product quality.
The following focuses on the typical forms of several defects:
1.Small longitudinal crack. The small longitudinal crack shape of the steel sheet surface is less than 200 mm in length, less than 3 mm in width, and less than 0.3 mm in depth.
2.Peak-shaped cracks. The cracks all occur at a distance of 5-60 mm from the edge of the steel sheet, and the macro direction is perpendicular to the rolling direction, and is in the form of a "mountain peak".
3.Edge cracks. The crack mainly occurs in the steel plate 20-80mm from the edge, and the shape is a plurality of parallel longitudinal cracks of different sizes. The rule is that the thicker and wider the steel plate is, the more serious such defects are.
4.Inclusions, crusting. inclusions, crusted in a regular distribution, after the edge of the flame suede crack inspection or slab scratching flame cleaning and other finishing operations after the obvious phenomenon.
The small longitudinal crack is formed by mixing fine impurities into the crystallizer. The cause of the peak crack is mainly caused by the transverse crack of the outer arc of the casting blank. The edge crack is caused by the side turn of the caster to the surface during the rolling process. Inclusion and crusting are caused by the surface oxidized slag not being cleaned during finishing.
In order to reduce the above situation, the following measures should be taken actively:
1. Regularly check the crystallizer, especially the water sample, to see if there are small impurities mixed in, causing water quality changes.
2. Strictly control the equipment overage service, ensure the timely maintenance of the segment, and avoid the deep scratch of the slab due to the non-rotation of the partial roller in the segment.
3. Implement the control of the water distribution zone of the curved section to dynamically control the corner temperature of the cast slabs of different widths to avoid the corner temperature of the slab entering the brittle zone during the bending process.
4. Produce large-width steel plates with wide-faced slabs as much as possible to reduce the amount of widening of the steel plates during rolling, thereby reducing the degree of uneven deformation of the edges during rolling of the wide steel plates, and weakening the width of the edge cracks in the steel plates.
5. Increasing the uniformity of the temperature of the slab in the heating furnace, optimizing the slab heating process, reducing the temperature difference between the upper and lower sides of the slab, reducing the difference in deformation resistance between the upper and lower parts of the slab, thereby reducing the uneven deformation of the edge of the slab.
6. Improve the finishing ability of the casting blank, and avoid the occurrence of secondary defects such as incomplete cleaning of the oxidized slag after the slab finishing and local deep burn marks.
The following focuses on the typical forms of several defects:
1.Small longitudinal crack. The small longitudinal crack shape of the steel sheet surface is less than 200 mm in length, less than 3 mm in width, and less than 0.3 mm in depth.
2.Peak-shaped cracks. The cracks all occur at a distance of 5-60 mm from the edge of the steel sheet, and the macro direction is perpendicular to the rolling direction, and is in the form of a "mountain peak".
3.Edge cracks. The crack mainly occurs in the steel plate 20-80mm from the edge, and the shape is a plurality of parallel longitudinal cracks of different sizes. The rule is that the thicker and wider the steel plate is, the more serious such defects are.
4.Inclusions, crusting. inclusions, crusted in a regular distribution, after the edge of the flame suede crack inspection or slab scratching flame cleaning and other finishing operations after the obvious phenomenon.
In order to reduce the above situation, the following measures should be taken actively:
1. Regularly check the crystallizer, especially the water sample, to see if there are small impurities mixed in, causing water quality changes.
2. Strictly control the equipment overage service, ensure the timely maintenance of the segment, and avoid the deep scratch of the slab due to the non-rotation of the partial roller in the segment.
3. Implement the control of the water distribution zone of the curved section to dynamically control the corner temperature of the cast slabs of different widths to avoid the corner temperature of the slab entering the brittle zone during the bending process.
4. Produce large-width steel plates with wide-faced slabs as much as possible to reduce the amount of widening of the steel plates during rolling, thereby reducing the degree of uneven deformation of the edges during rolling of the wide steel plates, and weakening the width of the edge cracks in the steel plates.
5. Increasing the uniformity of the temperature of the slab in the heating furnace, optimizing the slab heating process, reducing the temperature difference between the upper and lower sides of the slab, reducing the difference in deformation resistance between the upper and lower parts of the slab, thereby reducing the uneven deformation of the edge of the slab.
6. Improve the finishing ability of the casting blank, and avoid the occurrence of secondary defects such as incomplete cleaning of the oxidized slag after the slab finishing and local deep burn marks.
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