CN113073256A

CN113073256A - Rare earth corrosion-resistant steel plate and preparation method thereof

Info

Publication number: CN113073256A
Application number: CN202110265158.1A
Authority: CN
Inventors: 吴刚; 姜学锋; 文小明; 韩宇; 陈红远; 李霞; 王丽铭; 董志鹏; 彭飞; 吕建勋
Original assignee: Bengang Steel Plates Co Ltd
Current assignee: Bengang Steel Plates Co Ltd
Priority date: 2021-03-11
Filing date: 2021-03-11
Publication date: 2021-07-06

Abstract

The invention belongs to the field of metallurgy, and particularly relates to a rare earth corrosion-resistant steel plate and a preparation method thereof. The technical scheme of the invention is as follows: the rare earth corrosion-resistant steel plate comprises the following chemical components in percentage by mass: c: 0.05 to 0.25%, Si: 0.07 to 0.37%, Mn: 0.90-1.65%, S: 0.001-0.008%, P: 0.003-0.015%, Al: 0.015 to 0.055%, Cu: 0.10 to 0.50%, Cr: 0.20 to 0.50%, RE: 0.01-0.05%, N: 0.0010-0.0060% and the balance of Fe and other inevitable impurities. The rare earth corrosion-resistant steel plate provided by the invention has the characteristics of high strength, thin thickness, good corrosion resistance and long service life.

Description

Rare earth corrosion-resistant steel plate and preparation method thereof

Technical Field

The invention belongs to the field of metallurgy, and particularly relates to a rare earth corrosion-resistant steel plate and a preparation method thereof.

Background

With the continuous increase of infrastructure construction and factory building, steel structure buildings are popularized and continuously developed, and steel structures are widely applied to the aspects of buildings, railways, bridges, houses and the like. Both extensive plain carbon steel (about 70%) and low alloy steel (about 20%) face serious corrosion problems. According to statistics, the annual loss caused by corrosion in China accounts for about 3-4% of GDP, and the loss is huge. The harm of steel corrosion is spread throughout daily life and almost all industries, particularly, steel for basic facilities faces atmospheric corrosion day after day, and the key problem of how to obviously improve the atmospheric corrosion resistance of building steel at low cost is to develop, popularize and apply novel corrosion resistant steel.

Disclosure of Invention

The invention provides a rare earth corrosion-resistant steel plate and a preparation method thereof, and the rare earth corrosion-resistant steel plate has the characteristics of high strength, thin thickness, good corrosion resistance and long service life.

The technical scheme of the invention is as follows:

the rare earth corrosion-resistant steel plate comprises the following chemical components in percentage by mass: c: 0.05 to 0.25%, Si: 0.07 to 0.37%, Mn: 0.90-1.65%, S: 0.001-0.008%, P: 0.003-0.015%, Al: 0.015 to 0.055%, Cu: 0.10 to 0.50%, Cr: 0.20 to 0.50%, RE: 0.01-0.05%, N: 0.0010-0.0060% and the balance of Fe and other inevitable impurities.

The preparation method of the rare earth corrosion-resistant steel plate comprises the following steps: molten iron pretreatment → converter smelting → LF refining → continuous casting → heating → 2300mm hot continuous rolling → controlled cooling → coiling.

Further, according to the preparation method of the rare earth corrosion-resistant steel plate, the heating temperature of the heating process is controlled to be 1200-1260 ℃, and the heat preservation time is controlled to be 25 minutes.

The corrosion resistance mechanism of the present invention: by researching the segregation of rare earth macro atoms to the interface of the rust layer and the matrix, after the rust layer is formed on the surface of the steel, a protective rare earth atomic layer is formed on the matrix close to the rust layer, so that the rust layer is prevented from expanding to the inside of the matrix, the corrosion rate is effectively slowed down, and the function of rust prevention by rust is achieved. The effective segregation effect of the rare earth interface can obviously improve the corrosion resistance by the corrosion tests such as the weekly immersion, the salt spray and the like. It can be seen from the corrosion test that the rust thickness increases with the increase of the corrosion time, while the rust particles change. The rusty layer particles before rare earth alloying are larger on the whole, different areas of the surface rusty layer have height difference and are distributed unevenly, the rusty layer of some areas is more compact, and the rusty layer of some areas is relatively loose, which is caused by the fluctuation of water flow in the infiltration process. The rust layer after the rare earth alloying is relatively flat, the thickness of the rust layer is much thinner than that of the rust layer before the rare earth alloying, and the rust layer has smaller particles and better compactness. By analyzing the element distribution of the cross section of the rust layer, the rust layer is thicker before rare earth alloying, and the surface rust layer is loose and falls off seriously. Because the content of the alloy elements is low, no obvious element enrichment phenomenon exists in the rust layer, wherein an Al peak at the joint of the epoxy resin and the rust layer, which is obviously higher than the content of the matrix, is brought in by the external environment. After the rare earth element is added, the inner rust layer and the outer rust layer are well combined, the falling degree is light, and the compactness is good. The addition of the rare earth improves the enrichment of elements such as P, Cr, Ni and the like in the rust layer and promotes the redistribution of various weather-resistant elements in the rust layer. In addition, the content of rare earth elements La and Ce is relatively high at the joint of the rust layer and the matrix, which indicates that the rare earth is subjected to segregation, so that the property of the rust layer is improved, the expansion of the rust layer to the interior of the matrix is effectively hindered, and the corrosion resistance is improved.

The invention has the beneficial effects that:

1. compared with the traditional plain carbon steel and low alloy, the rare earth corrosion-resistant steel plate disclosed by the invention has the advantage that the atmospheric corrosion resistance can be improved by 2-5 times in an atmospheric environment, and the corrosion loss of steel in a transportation process can be avoided. The rare earth corrosion-resistant steel structure can avoid coating and galvanizing, the service life of the prior steel after galvanizing is about 15 years, the service life of the rare earth corrosion-resistant steel can be prolonged to more than 20 years, the environmental protection burden is reduced, and the reasonable application of resources is facilitated.

2. The rare earth corrosion-resistant steel plate is low-carbon, energy-saving, green and environment-friendly and can be repeatedly used; the mechanical property fluctuation is small and uniform; the forming performance and the welding performance are good; the corrosion resistance is good; coating is avoided, and flexibility is good; the construction is convenient, and the material is environment-friendly; the service life is long.

Detailed Description

The production process comprises the following steps:

1. pre-desulphurisation of molten iron

Heavy scrap steel is adopted, the slag is required to be completely removed, and S in molten iron fed into a furnace is less than or equal to 0.005 percent.

2. Converter steelmaking

The converter steelmaking process requires that the carbon is drawn for one time to hit and avoid point blowing; tapping adopts high manganese and ferrosilicon; controlling a steel tapping hole before tapping to avoid flow scattering, purging a steel ladle by argon, and controlling Als in the steel ladle according to 0.015-0.050%; the N of the steel ladle is required to be less than or equal to 20ppm, and copper, ferrochrome and the like are added in the tapping process for alloying, so that the Cu and Cr in the steel meet the requirement of internal control standard.

3. Refining procedure

The LF ladle furnace is adopted for treatment, and the contents of nitrogen and oxygen in steel are strictly controlled.

4. Continuous casting procedure

Before continuous casting, argon is adopted to purge the tundish, protective casting is carried out in the whole process, no molten steel is exposed in the casting process, and the increase of N is controlled to be less than or equal to 5 ppm; in the continuous casting process, double-machine double-flow feeding is adopted for feeding rare earth wires, the reference addition amount of the rare earth wires is 0.3kg/t of steel, and slag is wrapped in high alkalinity, so that floating of inclusions in the steel is facilitated; the soft reduction function is put into the steel casting process; keeping the constant drawing speed at 1.0-1.2 m/min in the steel casting process; the control target of the superheat degree of continuous casting is not more than 30 ℃.

5. Hot rolling

1) Heating furnace section

The heating temperature is 1220-1260 ℃, and the target tapping temperature is 1200-1240 ℃. The furnace atmosphere of the heating furnace is controlled, the generation of the iron oxide scale of the casting blank is reduced, the uniform heating temperature is ensured, and a foundation is provided for ensuring the plate shape.

2) Rolling and coiling part

The rough rolling is controlled by selecting a 3+3 mode; load distribution of a finish rolling model is well done, and stability of a rolling process is guaranteed; the finishing temperature is as follows: more than or equal to 860 ℃; coiling temperature: the temperature is 520-620 ℃, after F7 is discharged in a cooling mode, the front section is immediately cooled, and the front section cooling mode fully ensures the accurate control of the final rolling and coiling temperature; selectively throwing the steel strip into an F1 machine and an F2 machine according to the actual condition of the surface of the steel strip, and then carrying out small descaling; optimizing and adjusting the control of the cooling water quantity between the frames.

The mechanical properties of the rare earth corrosion-resistant steel plate are shown in Table 1, and the results of accelerated corrosion experiments are shown in Table 2:

TABLE 1

TABLE 2

Claims

1. The rare earth corrosion-resistant steel plate is characterized by comprising the following chemical components in percentage by mass: c: 0.05 to 0.25%, Si: 0.07 to 0.37%, Mn: 0.90-1.65%, S: 0.001-0.008%, P: 0.003-0.015%, Al: 0.015 to 0.055%, Cu: 0.10 to 0.50%, Cr: 0.20 to 0.50%, RE: 0.01-0.05%, N: 0.0010-0.0060% and the balance of Fe and other inevitable impurities.

2. The method of manufacturing a rare earth corrosion-resistant steel plate according to claim 1, comprising the steps of: molten iron pretreatment → converter smelting → LF refining → continuous casting → heating → 2300mm hot continuous rolling → controlled cooling → coiling.

3. The method for preparing the rare earth corrosion-resistant steel plate according to claim 2, wherein the heating temperature in the heating process is controlled to be 1200-1260 ℃, and the heat preservation time is controlled to be 25 minutes.