1. A method for measuring the corrosion rate of a steel member by using an electromagnet is characterized in that the electromagnet connected with a power supply is placed on the opposite back surface of a corrosion surface of the steel member to be measured, after the electromagnet is powered on, an iron powder is used for filling the corrosion area of the corrosion surface of the steel member to be measured, so that the corrosion area is filled with the iron powder, the iron powder is scraped to remove the redundant iron powder, then the electromagnet is powered off, the filled iron powder is collected, the volume of the iron powder is calculated, namely the volume of a rust pit, and then the local corrosion rate of the measured part is calculated.

2. The method for measuring the rust rate of the steel member by using the electromagnet as recited in claim 1, wherein the rusted area of the rusted surface of the steel member is subjected to surface loose rust removal before the test.

3. The method for measuring the corrosion rate of the steel member by using the electromagnet as claimed in claim 1, wherein a film is applied to the corroded area of the steel member before the iron powder is filled in the corroded area of the steel member, and the iron powder is coated on the corroded area of the steel member to fill the film opening.

4. The method for measuring the corrosion rate of a steel member using an electromagnet as claimed in claim 1, wherein the iron powder is filled and then the excessive iron powder at the opening of the excessive rust pit is scraped in the same direction by an antistatic plastic plate, which is placed at an angle of 60-80 ° to the reference surface of the member.

5. The method for measuring the corrosion rate of a steel member using an electromagnet as claimed in claim 1, wherein another electromagnet connected to a power supply is used when the charged iron powder is collected.

6. The method of claim 1, wherein the iron powder is calculated by scraping the obtained iron powder, stacking the iron powder on an electronic scale, and weighing to obtain the mass of the iron powder, wherein the iron powder volume is calculated according to a formulaCalculation of where p_sIs the bulk density of the iron powder.

7. The method of measuring the corrosion rate of a steel member using an electromagnet according to claim 6, wherein the corrosion rate of a steel member is calculated according to the following formula:

wherein eta is the corrosion rate of the steel member, m_cMass lost by rusting, m₀Is the original mass of the component, rho is the density of the steel component, V_cVolume lost by corrosion, i.e. volume of iron powder, V₀Is the original volume of the component.

8. The method for measuring the rusting ratio of a steel member using an electromagnet according to claim 1, wherein the iron powder has a particle size of 200 mesh.

9. The method for measuring the corrosion rate of the steel member by using the electromagnet as claimed in claim 1, wherein the electromagnet is a 12V sucker type electromagnet, and a 12V lithium battery is used as a power source.

10. The method for measuring the corrosion rate of the steel member by using the electromagnet according to claim 3, wherein the thin film is an antistatic thin film which is a PE tensile winding film with a thickness of 0.02mm, and the antistatic plastic plate is an acrylic plate with a thickness of 3 mm.

Background

In the field of civil engineering, a steel member is one of the most widely used building materials in the world at present, but the corrosion of the steel member in various environments weakens the section area of the steel member, reduces the tensile strength of the steel member, and easily causes stress concentration and reduces the fatigue strength of the member due to uneven depth distribution caused by pitting corrosion. The direct economic loss caused by the corrosion of steel in China is up to hundreds of billions of yuan every year, so the durability influence caused by the corrosion of steel components is a problem to be solved urgently by the current engineering.

At present, a laboratory method for measuring the corrosion rate of a steel member mainly adopts ISO 8407: 2009 by: and brushing the rusted steel member with a steel wire brush to remove the surface rust, cleaning the test piece with dilute hydrochloric acid, hexamethylenetetramine and distilled water, drying, and weighing the rusted mass of the test piece, so that the rust rate of the steel member is obtained, and the rust rate of the measured member cannot be taken down by the member to be measured in the actual structure.

Under the condition that the accurate corrosion rate cannot be known, a grid-drawing method is usually selected to calculate the corrosion rate of the surface of the component, wherein the grid-drawing method is to draw 10 × 10 grids on the surface of a sample to be estimated, and the corrosion rate is estimated according to the number of grids with corrosion areas occupying the grids, but the method cannot estimate the depth of a rust pit at all while the corrosion rate is not accurate enough.

Disclosure of Invention

The invention aims to overcome the difficulties in the prior art, provides the device and the method for measuring the local corrosion rate, which are accurate, simple and convenient, can be directly detected on site, are applicable to most of steel member surfaces, can be applied to the measurement of corrosion rates in various scenes, and can also improve the accuracy of the measurement of the local corrosion rate.

The purpose of the invention is realized by the following technical scheme:

a method for measuring the rust rate of a steel member by using an electromagnet comprises the steps of placing the electromagnet connected with a power supply on the opposite back of a rust surface of the steel member to be measured, filling a rust area of the rust surface of the steel member with iron powder after the electromagnet is electrified so as to fill the rust area, leveling the rust area, removing redundant iron powder, then powering off the electromagnet, collecting the filled iron powder, calculating the volume of the iron powder, namely the volume of a rust pit, and further calculating to obtain the local rust rate of the measured part.

According to the invention, the rust pit volume is conveniently and accurately obtained by using the mode that the electromagnet adsorbs the iron powder, so that the calculation of the rust rate is determined.

Further, the rusted area of the rusted surface of the steel member is subjected to surface loose rust removal before testing.

Further, a thin film is laid on a rusted area of the rusted surface of the steel member before the iron powder is filled, and the iron powder is coated on the rusted area of the steel member to fill the thin film opening. The film opening can control the area and the shape of the measured area, and can ensure that no iron powder permeates into the rust pit outside the measured area, thereby ensuring the accuracy of the measuring method.

Further, the film can be attached to the surface of the measured member by dipping water to prevent the iron powder in the measured area from penetrating into the outside of the measured area.

Further, after the iron powder is filled, the excessive iron powder at the position of the excessive rust pit is scraped off by an antistatic plastic plate along the same direction, and the placing direction of the plastic plate and the reference surface of the component is 60-80 degrees, and is preferably 70 degrees.

And further, another electromagnet connected with a power supply is adopted when the filled iron powder is collected. After the magnet is communicated, the iron powder in the rust pit is adsorbed to the magnet, the power supply of the upper-end electromagnet is disconnected at the moment, and the measured component can be patted for several times to ensure that all the iron powder can be adsorbed to the lower-end electromagnet.

Further, the method for calculating the volume of the iron powder comprises the steps of scraping the obtained iron powder, stacking the iron powder on an electronic scale, and weighing to obtain the mass of the iron powder, wherein the volume of the iron powder is calculated according to a formulaCalculation of where p_sIs the bulk density of the iron powder.

Further, the corrosion rate of the steel member is calculated according to the following formula:

wherein eta is the corrosion rate of the steel member, m_cMass lost by rusting, m₀Is the original mass of the component, rho is the density of the steel component, V_cVolume lost by corrosion, i.e. volume of iron powder, V₀Is the original volume of the component.

The original volume of the component can be obtained by the design size of the component, and the device is used for obtaining the volume lost by corrosion of the component. The electromagnet is placed on the back of the component after being electrified, magnetic powder can be adsorbed inside the rust pit, and the opening anti-static film can determine the area S of the measured area_sOn the other hand, the adsorption range of the iron powder can be limited, and the iron powder is prevented from permeating into the measured area. And the iron powder at the rust pit is scraped along the surface of the member by using the acrylic plate, so that redundant iron powder can be removed, and the measurement accuracy is improved. The other electromagnet is used for adsorbing the iron powder in the rust pit, the electromagnet on the back is powered off, it can be ensured that the iron powder in the rust pit is completely adsorbed on the electromagnet on the front side, and after the electromagnet is taken down, the mass of the iron powder in the rust pit is measured to be m_s。

Local corrosion rateWhere t is the component measurement area thickness.

Further, the iron powder has a particle size of 200 meshes.

Furthermore, the electromagnet is a 12V sucker type electromagnet, and a 12V lithium battery is adopted as a power supply.

Further, the film is an anti-static film and is a PE tensile winding film with the thickness of 0.02mm, and the anti-static plastic plate is an acrylic plate with the thickness of 3 mm.

The patent CN 102621056A discloses a method for measuring the corrosion rate of the surface of a steel member by using a metallographic image analyzer, the method uses a computer to process a binary image of the surface of the member so as to obtain the estimation of the corrosion rate of the surface, the method is simple, but effective data in a corrosion depth direction cannot be obtained, so the corrosion rate estimation value has only reference significance.

Patent CN 104964918B discloses a method for measuring the corrosion rate of steel bar along the axial length direction by using the buoyancy of water, which measures the corrosion rate of steel bar by continuously injecting water into the device and using the difference between liquid level and gravity of steel bar. But the device has limitation on the use place and cannot be used in actual components; in addition, the method is more convenient to measure the component with the straight axis and is more difficult to process the component with the curved axis.

Compared with the prior art, the invention is time-saving and efficient, can ensure the test accuracy, can adapt to the measurement of the corrosion degree of the steel member at various angles because the electromagnet is arranged at any position, does not need to take down the member, and is suitable for field measurement. Meanwhile, the method for filling the rust pit with the iron powder is independent of the shape of the member, and can be suitable for measuring the corrosion degree of steel members with various shapes and curvatures.

Drawings

FIG. 1 is a schematic diagram of the apparatus of the present invention;

FIG. 2 is a schematic front view of the steel member after iron powder is added in the embodiment;

FIG. 3 is a flowchart of a measurement method in the embodiment;

in the figure, 1 is a back electromagnet, 2 is a front electromagnet, 3 is iron powder, an anti-static plastic film 4 and an anti-static plastic thin plate 5.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

A method for measuring the corrosion rate of a steel member by utilizing an electromagnet is disclosed, and as shown in figure 1, a back electromagnet 1, a front electromagnet 2, iron powder 3, an anti-static plastic film 4 and an anti-static plastic thin plate 5 are used in the test.

Before measurement, according to the corrosion degree of a steel member and the operation difficulty of a measurement position, an anti-static plastic film 4 with a proper opening size is selected, after surface rust of a region to be measured is scraped by a steel wire brush, the back electromagnet 1 is adsorbed on the surface of the member at the center of the back of the region to be measured, the anti-static plastic film 4 with the opening is attached to the region to be measured after being wetted, and air in a gap is discharged as much as possible. The iron powder 3 is evenly smeared on the area to be measured, the excessive iron powder at the rust pit opening is scraped off by an anti-static plastic thin plate 5 as shown in figure 2, and then the anti-static plastic thin film 4 is taken off. The front electromagnet 2 is energized to adsorb the remaining iron powder 3 in the measurement area. And turn off the back electromagnetThe power supply of the iron 1 is used for ensuring that all iron powder 3 in the rust pit is adsorbed to the front electromagnet 2. Then, the electromagnet 2 on the front side is powered off, the iron powder 3 is taken down and weighed to obtain the mass of the iron powder in the rust pit, so that the volume of the rust pit is obtained by a formula, and the local corrosion rate eta of the measured area is obtained by utilizing the thickness of the component and the opening area of the selected opening anti-static plastic film 4_sFig. 3 is a flowchart of a measurement method in the embodiment.

The specific principle is as follows:

calculating the corrosion rate of the steel member:

where eta is the corrosion rate of the steel member, m_cMass lost by rusting, m₀Is the original mass of the component, rho is the density of the steel component, V_cVolume lost by corrosion, V₀Is the original volume of the component.

The original volume of the component can be obtained by the design size of the component, the electromagnet is placed on the back of the component after being electrified, magnetic powder can be adsorbed inside the rust pit, and the opening anti-static film can determine the area S of the measured area_sOn the other hand, the adsorption range of the iron powder can be limited, the iron powder is prevented from permeating into the measured area, the iron powder at the rust pit is scraped along the surface of the member by using the acrylic plate, the redundant iron powder can be removed, and the measurement accuracy is improved. The other electromagnet is used for adsorbing the iron powder in the rust pit, the electromagnet on the back is powered off, it can be ensured that the iron powder in the rust pit is completely adsorbed on the electromagnet on the front side, and after the electromagnet is taken down, the mass of the iron powder in the rust pit is measured to be m_s。

Volume of rust pitWhere ρ is_sTaking the bulk density of the iron powder as 2.4g/cm³。

Local corrosion rateWhere t is the component measurement area thickness.

In this embodiment, the electromagnet is an ELE-P13/27 suction cup type electromagnet manufactured by Irelaceae, the voltage is 12V, the power is 1.2W, and the maximum suction force is 1 kg.

In this example, the iron powder was 200 mesh medium powder, the particle diameter was 0.074mm, and the loose bulk density was 2.4g/cm³。

In this embodiment, the antistatic plastic film is a PE tensile winding film made of low density linear polyethylene with a thickness of 0.02 mm.

In this embodiment, the antistatic plastic plate is a 3mm acrylic plate.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.