Improvement in Galvanising Line Productivity through Annealing Simulation

摘要

The continuous annealing section of five decades old galvanizing lines at Rourkela Steel Plant, consists of flame heating, reduction cum annealing and controlled cooling furnaces. Due to deterioration of flame heating furnace burners, the strip could be preheated to 150℃ instead of 450℃. Moreover, the temperature in reduction cum annealing furnace rarely went above 820℃. Inadequate heating was considered a deterrent for higher processing speed, while achieving the strip hardness below 65 HRB. Continuous annealing simulation was conducted in Gleeble-3500 to obtain desired strip property at different temperature and speed conditions. The difference between the strip soaking and furnace temperature was determined. Based on this study, plant trials at higher speeds and modified furnace temperature were conducted. Hardness and microstructure of finished product established the feasibility of higher speeds. The galvanizing line speed has increased by 16% for 0.5 and 0.63mm thick strip, the major production.