KRAWCZYK Janusz AGH University of Science and Technology

Spoluautoři PAWLOWSKI Bogdan, BALA Piotr

Wear mechanism of equipment rolls for fine section mills was investigated. The rolls were made of three different steels: X165CrV12 cold work steel, X40CrMoV5-1 hot work steel and C55 plain carbon steel. The banded microstructure, parallel to the roll axis, was observed for each tested roll. The microstructure of roll made of X165CrV12 consists of primary and secondary carbides bands in tempered martensite matrix. In the case of X40CrMoV5-1 steel, in tempered martensite microstructure fine grain bright etching bands with high volume fraction of dispersed vanadium carbides precipitations was observed. The microstructure of roll made of C55 steel consists of martensite and pearlite bands with fine ferrite grains. The different wear mechanisms were observed for investigated rolls: erosive, adhesive and abrasive wear, surface oxidation, spalling, thermal fatigue and white layer formation. The major factors determining the dominant wear mechanism and roll service life are steel chemical composition and microstructure. The presence of primary carbides in microstructure decreasing adhesive wear and thick white layer formation. The roll made of plain C55 steel, despite hardness level similar to hardness of investigated rolls made of hot and work alloy steels, has the worst wear resistance. Then, application of cheap plain steel for such equipment rolls has no economical reason because of the need for frequent replacement with new one. The X165CrV12 cold work steel showing the best wear resistance among the investigated steels.