LAUSR

The study explored the influence of various technological factors, namely the application of absorbent coatings, laser radiation incidence conditions, the roughness of the roll body surface, and the active layer characteristics, on the laser hardening process of rolls of multi-roll mills. Various light-absorbing coatings were investigated. The use of mandarin ochre as an absorbing coating resulted in the highest laser heat treatment efficiency. The coating application technology was fairly simple and involved applying a 0.1 mm-thick layer of ochre with a sprayer to the pre-degreased surface of the roll body and drying at + 50°C for 30 min. Analysis of the effect of the laser radiation incidence conditions showed that the laser hardening process was most effective when the lens focus was deepened inside the treated surface while the magnitude of the focus shift was 0.04–0.06 of the focal distance of the lens. Under various processing schemes, the hardened layer depth depended on the incidence angle of the laser beam on the roll surface and was maximum at angles of 10–20°. The surface quality of the laser-hardened samples increased with increasing rotational speed, and a decrease in the translational movement speed of the laser beam led to an increase in the height of profile irregularities. Analysis of experimental data showed that the higher the initial hardness of the roll material, the higher the hardness of the laser-hardened steel. Moreover, it was established that a distinctive characteristic of laser-hardened rolls is the presence of a constant-hardness active layer along the roll radius, which allows for maintaining uniform body hardness during the service life of the roll.