Wear in cold rolling milling rolls: A methodological approach

As a major steel production technology, cold rolling processes have a strong influence on the final quality of rolled products. Traditionally, cold rolling mill rolls present a controlled surface topography that is imprinted onto the sheet during forming and are often coated, particularly using hard chrome deposition. However, wear of cold rolling rolls can affect tribological performance during rolling. Since the nature of tribological phenomena is highly systemic and evolve with sliding time, it is very challenging to reproduce wear in cold rolling rolls using laboratory tests. This work aimed to establish a methodology to reproduce wear mechanisms found in real cold rolling rolls. Due the high cost and dimensions of the rolls, the replication technique was used. Replicas were obtained from four major rolling mill Brazilian companies before and after a normal rolling campaign. The wear mechanisms in the replicas were evaluated using SEM and laser interferometry. To reproduce these mechanisms in laboratory, reciprocating sliding tests were used, which mimic well the change in the direction of friction force that occurs during rolling. The tests used spherical and cylindrical counter bodies under different normal loads and test times to verify which tribological conditions allowed to reproduce the wear mechanisms found in the replicas. These tests indicated the use of reciprocating sliding tests with cylindrical counter bodies in a line contact, where the evolution in wear can be assessed by tests with different test times. This methodology has a great potential to evaluate the tribological performance of different surface modifications used in cold rolling mill rolls. •Wear mechanisms were identified in industrial practice.•The replication technique was used to copy the roll worn surfaces.•Simple methodology using sliding reciprocating tests.•The laboratory tests reproduced the wear mechanisms in real cold rolling rolls.