Technological method and equipment for improving corrosion resistance of surfaces of reinforced bars

Abstract

The invention relates to the field of steel rolling, in particular to a technological method and equipment for improving the corrosion resistance of the surfaces of reinforced bars. The technologicalmethod comprises the following steps of: step one. improving a heating technology, dividing a heating zone into a preheating segment, a heating segment and a soaking segment, automatically controllingthe temperature of each zone, and specially, controlling the temperature of the preheating segment to be less than 850 DEG C, the temperature of the heating segment to be in the range of 1060-1080 DEG C and the temperature of the soaking segment to be in the range of 1130-1180 DEG C; step two. controlling the initial rolling temperature, and controlling the rough rolling temperature to be in therange of 1030 DEG C-1050 DEG C; step three. entering an intermediate rolling system, carrying out intermediate rolling, and cooling by using a pre-through water system, and ensuring that the finish rolling temperature is controlled in the range of 930-950 DEG C; step four. entering a finish rolling system, and carrying out finish rolling; and step five. entering a through water cooling and back blow wash system, and carrying out through water cooling and back blow wash. The technological method and equipment can prevent air bubbles on the surfaces of the reinforced bars and improve the corrosion resistance and mechanical properties of the surfaces of the reinforced bar.

Description

technical field [0001] The invention relates to the field of steel rolling equipment, in particular to a process and equipment for improving the corrosion resistance of steel bar surfaces. Background technique [0002] There are many reasons why the surface of steel bars is easy to be corroded. It is mainly caused by surface foaming during the steel rolling process in the rolling mill. The specific reasons are as follows: [0003] 1. The thermal conductivity and physical properties of the oxide film on the surface of the steel bar are quite different from those of the steel bar matrix. When the steel bar is subjected to a large temperature change, the greater the thickness of the oxide film on the surface layer, the easier it is to generate a large internal stress and rupture. α-Fe2O3 is particularly high, and α-Fe2O3 itself is relatively loose, and it is easy to absorb water or be corroded by other chemical substances, so that the corrosion of the steel surface is greatly a...

AI Technical Summary

Problems solved by technology

[0003] 1. The thermal conductivity and physical properties of the oxide film on the surface of the steel bar are quite different from those of the steel bar matrix. When the steel bar is subjected to a large temperature change, the greater the thickness of the oxide film on the surface layer, the easier it is to generate a large internal stress and rupture. α-Fe2O3 is particularly high, and α-Fe2O3 itself is relatively loose, and it is easy to absorb water or be corroded by other chemical substances, so that the corrosion of the steel surface is greatly accelerated;

[0004] 2. Because the bar factory generally adopts the weak water penetration process, the temperature of the upper cooling bed is above 1000 degrees. When the steel passes through each cooling ring, the steel will be in contact with the air again, and at the same time, the surface of the steel will inevitably carry water and attachments, especially when the water contains oil, this phenomenon will be more serious, and the water brought out by the steel Under the action of gravity, there will be uneven distribution on the surface of the steel, which will cause bubbling on the surface of the steel. For example, the longitudinal ribs and the roots of the transverse ribs of the rebar are more likely to accumulate water, and these parts are most likely to produce larger and more water. bubbling

[0005] 3. The pressure of the cooling water in the rolling mill is low, only 0.3-0.5MPa, which is not enough to break the steam film on the surface of the steel and take away the heat. At the same time, this pressure is also difficult to remove the secondary oxide film on the surface of the steel, so that the steel is tempered again. A new oxide film is formed during the process, and the resulting temperature drop is also very small. In addition, the water-cooled steel only cools the steel surface during the water-through process, and the steel surface temperature will rise rapidly after leaving the cooler. The larger the steel specification , the higher the surface temperature rises, so large-scale steel is more prone to bubbling

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