Strip steel continuous hot galvanizing method

Abstract

The invention discloses a strip steel continuous hot galvanizing method. The strip steel continuous hot galvanizing method sequentially comprises the following steps of washing and pre-heating strip steel, adopting short flame to heat the strip steel to be at the temperature of 550-700 DEG C in a strip steel directly contacted mode, adopting a radiant tube heating method to continue to heat the strip steel to be at the temperature of 700-850 DEG C, sequentially soaking and slowly cooling the strip steel, adopting nitrogen and hydrogen mixed gas with 5-70% of hydrogen volume to quickly cool the strip steel to be at the temperature of 150-550 DEG C, heating the strip steel again to be at the temperature of 450-550 DEG C, performing secondary soaking to the strip steel and performing hot galvanizing treatment to the strip steel. By means of the method, the platability of ultrahigh strong steel can be obviously improved, various annealing curves can be achieved flexibly, and annealing processes which cannot be achieved by a traditional hot galvanizing unit can be achieved. In addition, the 'zinc scale' detect in starting of the unit can be obviously overcome.

Description

technical field [0001] The invention relates to a strip steel continuous annealing heat treatment method, in particular to a strip steel continuous hot-dip galvanizing method. Background technique [0002] Hot-dip galvanized strip steel is a common metallurgical product, which is a strip steel that reacts molten metal with an iron matrix to produce an alloy layer, thereby combining the matrix and the coating. Hot-dip galvanized steel strip has the advantages of uniform coating, strong adhesion and long service life. [0003] There are two main methods of traditional strip continuous hot-dip galvanizing: [0004] A: Cleaning→preheating→heating→soaking→slow cooling→quick cooling (cooling to 450-500°C)→hot-dip galvanizing→air knife injection→cooling in the upward cooling section→cooling again in the downward cooling section→water cooling. [0005] B: Cleaning→preheating→heating→soaking→slow cooling→quick cooling (cooling to 450~500℃)→soaking again (soaking temperature 450~500...

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Problems solved by technology

[0007] Aiming at the deficiencies of the above-mentioned traditional hot-dip galvanizing method, the purpose of the present invention is to provide a continuous hot-dip galvanizing method for strip steel. Using this hot-dip galvanizing method can not only significantly improve the galvanization of ultra-high-strength steel such as dual-phase steel and TRIP steel. Moreover, it can realize the heat treatment of all existing hot-dip galvanized products. At the same time, using this method can also reduce the waste of strip steel and zinc liquid caused by the unit opening the furnace cover for maintenance, belt threading and other operations and then starting to run, thereby avoiding Or reduce the "zinc skin" defect

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