What causes the dendritic grooves to appear on the surface of carbon steel heads after hot pressing?
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May I ask who understands that after hot pressing of carbon steel heads, tree-like grooves appear on the surface, as shown in the attached diagram. After removing the oxide scale, the depth can sometimes be 0.2 millimeters or 0.3 millimeters. Is it due to the sheet material itself? It’s still due to the profiling process
Preheating of the oxide layer on the steel plate surface and compressive deformation are the causes of its detachment. You can use flame cutting to heat the raw steel plate of this head and see for yourself
The peeling of the oxide layer is similar to skin cracking; it’s a normal phenomenon
Check whether there are any issues with the surface of the head mold, and also see if it was cleaned properly during the pressing process.
The old material stuck to the edges of the mold was scraped off
There are no mold scratches on the outer part of this end cap; this phenomenon is caused by the shedding of oxide scale during heating and pressing.
For hot-pressing head seals, after heating the seal but before pressing it, a lubricant is applied to its surface; the most common one is coal dust, which helps the mold to slide smoothly over the surface of the steel plate. Are the grooves on the surface indentations left by the lubricant remaining on the surface during the pressing process?
If this occurs frequently, it is likely indentations left by the peeling off of the mold lubricant powder; it has no impact on the head