Is there a semi regular component at first? This effect called brinelling (indentations) results when the roll material's elastic limit is exceeded. How can that happen? Most people would say excessive temperature and or poor coolant delivery. I think its because of overloading on material rolled prior to the campaign where you are now finally noticing it.

Once the brinelling Indentations in rolls starts, it can result in increased vibration and then small particles can be abraded off adjacent to the brinelled area

Once the initial brinell indentations are established they would create the opportunity for additional spalling to occur, which would then accelerate the failure causing the rough texture. Also the brinell indentations would increase vibration.

Usually on roll sets the rough texture is a result of overloads, or as you mentioned poor descaling practice, but this is probably not the case in the situation that you describe.

I would also ask you to look at the location on the rolls this could be a clue to bearing issues.

Why does it occur only on horizontal and not verical rolls?

two other things to keep in mind:

1) does your rolling schedule run the lighter wt per foot items after the heaviest? The roll damage from ooverload or brinelling may have occurred on the heavier weight per foot material.

2) In a mill where there are substantial differences in weight per foot of product rolled, mileage of product rather than mass of product is a better indicator for preventive maintenance a nd roll dressing issues.

Finally what was surface finish on rolls when initially put into service

Surface finish is easy for the roll shop to poo-poo ("they are only roughers why put the extra finish pass for surface finish on ?")

Just like sharpeneing a cutting tool followed by honing results in longer life, so does getting a smooth finish on the rolls. Even roughers.

Look for locational or tracking clues and brinelling indentations for clues as to bearing issues or vibration. Track miles rolled not tons. look for brinelling during/after rolling heavoier weight per foot items.

milo

We do run "heavy" to "light" and it is understood that linear feet are what cause pass wear as opposed to tons. The incident that prompted me to ask this question happened after a roll change of both horizontal universals because of the pass wear on the first set. Finished bar length was 200' and the mill started up on w18x46lbs. Our roll sets are turned down from wider products to extend roll life. I will ask our set up person how many times these particular roll sets have been in the mill and if they were wider at one time. I will also ask if the 2 high rougher was turned before this rolling. Again sometimes they are not, thanks for your observations and ideas.

Zeepiler

Yes you could be down into tougher core material rather than harder OD material on old rolls.

milo