What quality problems will A36 steel plates encounter 1

As a common structural steel, A36 steel plate is widely used in construction, shipbuilding, bridge construction, machinery manufacturing and other fields. However, during the production process, A36 steel plates may have some quality defects that affect their performance and safety. Frequently asked questions are of the following types:

1. Radiation printing of hot rolled plate
Hot-rolled plate radiation printing is a group of periodic concave and convex defects with basically the same size and shape, and irregular appearance. Causes may include pits caused by fatigue or insufficient hardness of the spokes, as well as bulges caused by foreign matter stuck to the surface of the spokes.

2. Surface inclusions
Surface Inclusions: There are irregular point-shaped block or strip-shaped non-metallic inclusions on the surface of A36 steel plates. The color is usually reddish-brown, yellow-brown, gray-white or gray-black. These inclusions may originate from subcutaneous inclusions in the slab, non-metallic objects such as heating furnace refractory materials and sediment falling on the surface of the slab, or being pressed into the surface of the A36 steel plate during the rolling process.

3. Iron oxide scale
Oxide scale usually adheres to the surface of A36 steel plates, distributed on part or all of the plate surface, and is black or reddish brown. The generation of iron oxide scale depends on the heating conditions of the slab. The longer the heating time, the higher the temperature, and the stronger the oxidizing atmosphere, the more iron oxide scale is generated, and it is not easy to fall off.

4. Uneven thickness
The inconsistent thickness of each part of the A36 steel plate is called uneven thickness, which usually manifests as excessive deviation, and the thickness of the local A36 steel plate exceeds the specified tolerance range. This may be caused by factors such as improper adjustment of the spoke gaps and improper configuration of the spoke shape, different wear of the rolling spokes and the bearing bushes on both sides of the rolling spokes, uneven heating temperature of the slab, etc.

5.Pits
There are local or continuous pits called pitting on the surface of A36 steel plate. The reason is that the slab is severely oxidized during the heating process. The iron sheet is pressed into the surface during rolling and falls off to form small pits. The bubbles vary in size and depth.

6. Circular convex hull
There are irregularly distributed circular convex hulls on the surface of the A36 steel plate, sometimes in the shape of an earthworm-like straight line. Its outer edge is relatively smooth and there is gas inside. When the bubbles burst, irregular fine cracks appear. Some bubbles are not raised, the surface is bright after smoothing, and the sheared section shows scratches.

7. Cold rolling damage
Defects caused by A36 steel strips being scratched by hard objects during cold rolling are usually strip-shaped and parallel to the rolling direction. In severe cases, the grooves caused can be felt with your hands. The gouge weld bead marks on the surface of the A36 steel strip have sharp, short, meteor-shaped defects that penetrate deeply into the steel strip. They are unevenly distributed and rough, with protrusions.

Pre: Common surface defects and treatment methods of A36 hot-rolled steel plates

Next: What quality problems will A36 steel plates encounter 2