Steel strip continuous annealing method, steel strip continuous annealing device, hot dip galvanized steel strip manufacturing method and hot dip galvanized steel strip manufacturing device

摘要

Annealing atmosphere with low dew point with few problems of pickup defects and furnace wall damage, oxidizable elements such as Si and Mn in steel are concentrated on the steel strip surface, and oxides of oxidizable elements such as Si and Mn Is provided, and a continuous annealing method for a steel strip that can realize an annealing atmosphere suitable for annealing a steel strip containing an easily oxidizable element such as Si and Mn at a low cost is provided. A heating zone for conveying the steel strip in the vertical direction, a soaking zone, a partition wall for separating the atmosphere in the furnace is provided in the heating zone to the soaking zone, and an atmosphere gas is supplied into the furnace from the outside of the furnace. While exhausting the inner gas from the steel strip introduction part at the lower part of the heating zone, part of the gas in the furnace is sucked and discharged to a refiner having a deoxygenator and a dehumidifier provided outside the furnace, and oxygen and moisture in the gas When the steel strip is annealed in a vertical annealing furnace configured to reduce the dew point and reduce the dew point into the furnace, the steel strip temperature at the partition wall passing position is 550 to 700 ° C. Control to become.