Production method of high-strength hot-dip galvanizing steel strip

[0011] Please refer to the attached drawings. In an embodiment of the present invention, the steel strip (1) enters the heating furnace along the steel strip running direction (2) for annealing treatment. First, it is heated to about 700-700 in the heating section (3) of the heating furnace. 800°C, and after being kept at the above temperature for a period of time in the heating furnace insulation section (4), it enters the heating furnace cooling section (5), which is the relevant area of ​​the present invention. The invention adopts several nozzles (6) and other additional devices arranged on the upper and lower sides of the steel belt (1) in the cooling section (5) of the heating furnace, which can spray the steel belt (1) from the upper and lower directions without causing the steel The cooling medium for belt oxidation. The cooling medium selected in the present invention is liquid at ambient temperature. After spraying on the surface of the steel belt (1) and contacting the high-temperature steel belt (1), it will immediately vaporize, directly from the steel belt (1) The surface absorbs a large amount of heat, so that the steel strip (1) is cooled at a very fast speed, and the recrystallization transformation occurs in a short time, generating very fine internal structure grains to achieve the effect of improving the strength. At the same time, the liquid cooling medium used will not oxidize the steel strip, and then the steel strip (1) enters the zinc pot (8) through the turning roller (7) in a state of no oxidation on the surface, and the zinc at a temperature of about 455-475 ℃ Hot-dip galvanizing is carried out in the solution (9), leaving the zinc pot (8) after the sinking roller (10), to produce a high-strength hot-dip galvanized steel strip. The selected cooling medium can be, but is not limited to, combustible substances such as hydrocarbons. The gas running direction in the heating furnace is opposite to the steel strip running direction (2), that is, the gas in the cooling section (5) of the heating furnace flows to the holding section (4) and the heating section (3) of the heating furnace in turn, if it is Combustible substances such as hydrocarbons (such as industrial ethanol, methyl ethyl ketone, etc.) can be burned in the heating section of the steel belt to release chemical heat and assist the heating of the steel belt without causing environmental pollution and energy waste.

[0012] In a commercial application example of this application, the ordinary steel strip continuous galvanizing production line was modified, and four rows of nozzles were added on both sides of the steel strip in the cooling section, with a flow rate of 30-35kg/min. Spray industrial methanol on the surface of the steel strip. When the industrial methanol encounters high temperature, the steel strip will immediately vaporize and take away a lot of heat, so that the steel strip will drop from 700-800°C to 455-475°C within 4-5 seconds and then galvanized. Produced high-strength hot-dip galvanized sheets. Compared with before the transformation, when using the same raw materials, the grain level of the product structure increased from 6-7 to 9-10, the mechanical properties and yield strength increased from 260-300Mpa to 420-500Mpa, and the elongation after breaking was A 50 It has risen from 36%-40% to 40%-44%. Through the process transformation of this application, ordinary raw materials are used to stably produce galvanized sheets of S350GD+Z grade. Compared with the use of high-strength raw materials, although the production cost has increased by 38-45 yuan/ton, the raw material cost is saved. 120-150 yuan/ton, the actual production cost has been reduced by 82-105 yuan/ton, and the annual economic benefit exceeds 8.5 million yuan, which is a complete commercial success.

[0013] It can be seen that the method of the present invention is simple and easy to implement, has a good and stable commercial application effect, and is an exquisite processing method.