Now the
aluminium plate market mixed, some small factory production of
aluminium plate surface "black spots", for this phenomenon my company's professional and technical personnel after years of experience, summed up the following:
The phenomenon and law of "black pitting"
The so-called "black pockmark" is the surface of the finished product in the strip, after the user after further processing, erosion and polishing treatment, the surface of the exposed small, scattered black small pits; in the strip surface area Block) traces of the distribution of points; in the severe alkali after the black spots can be off on the addition; and hot-rolled milk leakage time, in the hot-rolled emulsion "aging" after the situation is more serious.
Analysis on the Causes of Defects in
According to the principle of "embedded in the surface or near surface of the processed product generally from the processing process", it can be determined that the "black pitting" is caused by foreign matter pressing during the rolling (main hot rolling) after the horizontal ingot. As the main component of this defect as the leading factor and contributing factors two aspects:
(1) the leading factor - hot-rolled lubrication emulsion emulsion "aging" and "dirty" caused by Wei emulsion "aging" refers to the use of time is too long, due to more than the reasons for the composition of the emulsion changes, lubrication Performance deterioration, the emergence of oil and water stratification, emulsion yellowing and surface contamination and other phenomena; "dirty" refers to the emulsion in the "dirt" increased, including dust, sand, pipe system corrosion, falling aluminium plate particles and Emulsions formed by the creamy substances.
As the emulsion "aging" and "dirty" will be hot plate when the bad surface of the formation of foreign body pressure to create the conditions. However, the "black pock" in terms of formation. More should be considered is the emulsion "aging", oil and water stratification, fuel residue caused by the impact. The following are the same as the "
(2) contributing factors - ingot bad surface roughness caused by bad.
In the horizontal continuous casting process, especially when the casting process is not properly controlled, the surface of the ingot is easy to form a clear "cold stripe pattern"; in the mold wear or damage will appear when the "groove." The presence of the "groove" is advantageous for the retention of oil or dirt, and the coverage of the "pattern" raised portion during hot rolling causes it to form a subcutaneous inclusion so that the defect is not directly exposed on the surface of the finished product.
Reduce the "black pock"
1, to reduce or eliminate the effect of hot-grouting fluid
2, the use of hot-rolled
aluminium plate with high-quality emulsion to ensure that its working conditions "aging" period is long, less prone to oil and water stratification;
3, in the temperature, bacteria, metal ions (especially Al +3 ") and so on the role of emulsion" aging "inevitable circumstances, can guarantee the amount of hot rolling required under the conditions of" appropriate amount of change ";