Influence of Annealing Modes in Bell Furnaces on the Stress–Strain State of Rolls of Cold Rolled Steel

Formation mechanisms of the stress-strain state (SSS) of rolls of the cold-rolled strips during heating, isothermal tempering and cooling during annealing in bell furnaces have been studied. Detailed analysis of the influence of annealing temperature ramping conditions on the appearance of critical inter-windings pressures in the rolls resulting in the strips surface “kinks” (“breaks”) and other types of defects have been provided. Shown here are the possibilities of influencing the roll' SSS during annealing by controlling the duration of isothermal exposure and the rate of subsequent roll cooling under the furnace muffle. Thus, the influence of the cold rolling on the rolls’ SSS is considered as well. Optimized temperature ramps regimes are recommended for the thin strips’ roll annealing in the production of the cold-rolled steel intended for highly complex stretching, providing prevention of adhesion-welding of the adjacent windings of the rolls and delivering high quality finished products.