Steel defects: What is the effect of oxidation color on use?
What is oxidation color:
Oxidation color more complete name should be: steel surface annealing oxidation color difference, there is also directly called "annealing oxidation". In fact, put the soup spoon on the gas stove for a while, the blue film generated on the surface is a kind of oxidation color.
It should be noted that the existence of high temperature oxide film on the surface of annealed sheet is a common state. The different thickness of the oxide film on the surface of the strip, the different alloy elements of the strip and other factors will lead to the difference in the surface color of the steel plate. But this color difference is generally small, we will not notice.
However, when the oxidation color is serious to a certain extent, it will reflect the obvious color, such as the common yellow brown, gray black, gold and so on.
Of course, oxidation color can not be said with the word "oxidation", it is considered to be rust, and there is no research on surface oxidation color that will exacerbate environmental rust.
Morphology of oxidation color:
Due to the different annealing process, the appearance of oxidation color is also different.
The oxidation color of continuous annealing process is mainly based on the color change in the direction of length, such as the color difference between the inner ring and the outer ring of the steel coil.
The oxidation color of the furnace annealing process is the color difference between the edge and the middle of the strip.
Due to the different batches of steel coil production, the process and substrate state will have some slight differences, which may also lead to color differences between different steel coils.
What is the effect of oxidation color on use?
Oxidized color as an appearance part, of course, will lead to color differences in different batches of finished products. However, if it is used as an internal part, if it is not very dark in color or there is an obvious grayish black powder after the paper towel is wiped, it generally will not affect the use.
However, for some non-high alloy steel types (such as DC03, SPCC, etc.), if there is oxidation color on the surface, it means that the process parameters of the steel coil may fluctuate during the annealing process (such as the annealing temperature change). The fluctuation of annealing process parameters may lead to the fluctuation of steel coil properties.
An extreme example of this is the startup heating material after the continuous annealing production line is fixed, or the continuous annealing production line is changed from low temperature material to high temperature material, and the temperature is too fast. These steel coils will appear oxidation color defects, but also accompanied by performance fluctuations, serious will lead to subsequent use of stamping cracking, stamping orange peel and other defects.
Can the color be used to judge whether the material is suitable for use?
May not be accurate, for example, in the boot heating material, if the annealing temperature does not reach the required value, the board may still be white, but because the annealing is not complete, there will be stamping cracking.
15358968703