Segmented gas-sealed heat treatment process for hot-dip galvanized strip and its alloying furnace

Abstract

The invention discloses a segmented gas seal type heat treatment process of hot-galvanized strip steel and an alloying furnace thereof. The process comprises the following steps: the heating, the heat insulation and the cooling are sequentially performed for strip steel output from a zinc pot online; and finally, the alloying of the strip steel is realized; the key is to control the heat insulation temperature within 500-550 DEG C and the heat insulation time within 10-15 s at a middle heat insulation section of the alloying furnace; meanwhile, a gas injection manner and a gas extraction manner are respectively performed on the two side surfaces of the strip steel, so that at least one high-temperature gas curtain perpendicular to the strip steel conveying direction is formed in the middle heat insulation section, heat is centralized and controlled in a partition area formed by the high-temperature gas curtain, and a chimney effect in the middle heat insulation section is stopped. The alloying furnace comprises a bottom heating section, the middle heat insulation section and an upper cooling section, wherein at least one set of high-temperature gas curtain generator is arranged on the middle heat insulation section. The process and the alloying furnace can restrain the generation of the chimney effect, reduce the heat emission of the heat insulation section, and improve the heat treatment efficiency.

Description

technical field [0001] The invention relates to the field of hot-dip galvanized strip steel manufacturing, in particular to a hot-dip galvanized strip steel subsection air-sealed heat treatment process and an alloying furnace thereof. Background technique [0002] Due to its low production cost, good corrosion resistance, coating performance, welding performance and impact resistance, hot-dip galvanized steel sheet is very suitable for high-end hot-dip galvanized product consumption industries such as automobiles and home appliances, and can meet the needs of users. The quality requirements of high-quality surface characteristics and good internal performance of products. [0003] The hot-dip galvanized steel strip output from the zinc pot usually needs to complete multi-stage heat treatment in the alloying furnace. The internationally accepted process is the annealing process of "first high temperature and then low temperature". There is also a slight difference in timing....

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Problems solved by technology

[0005] However, affected by the "chimney effect" of the vertically arranged alloying furnace, even if the furnace is sealed as a whole, the heat is easily dissipated from the lower end of the middle heat preservation section to the upper end, and the lower end is supplemented by cold air. The temperature at the upper end of the central insulation section is higher than that at the lower end, and the harm is mainly reflected in four aspects: 1. The entire process cannot meet the requirements of "high temperature first and then low temperature", resulting in unstable quality control; 2. The rapid dissipation of heat cannot be guaranteed. The central heat preservation section is kept at a process temperature of 530-550°C. Sometimes the heat preservation temperature is only 480°C, and the alloying process cannot even be completed smoothly; 3. The heat dissipated from the middle heat preservation section is relatively large, and the temperature at the upper end of the strip is high, which will The cooling capacity of the upper cooling section puts forward higher requirements, which further affects the product quality; 4. The heat loss also has an adverse effect on other equipment after plating, reducing the service life of these equipment

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