CN104713759A - Method for detecting surface oxidized scale sample of hot rolled steel plate - Google Patents

Abstract

Aiming at the defects in the current sample preparation method and inspection method of hot-rolled metal oxide scale, a detection method for the surface oxide scale sample of hot-rolled steel plate is provided, which belongs to the field of backscattered image analysis of the surface structure of metal high-temperature oxidation. Specifically, the metal sample after high temperature oxidation is placed in a non-metallic pipe, and the liquid epoxy resin and its curing agent are used for cold mounting, and then after grinding, polishing, nitric acid ethanol mixed solution corrosion and surface carbon plating, etc., finally obtained A metal oxide scale sample suitable for field emission electron probe observation. This method is relatively simple to prepare the oxide scale samples of metal high temperature oxidation, and the epoxy resin in the cold state can effectively protect the outer layer of loose Fe ₂ O ₃ , Fe ₃ O ₄ , and FeO phases, preventing surface oxidation during hot mounting. The shedding of the iron sheet. Etching with a mixed solution of nitric acid ethanol can clearly corrode the surface oxide scale structure and the metallographic phase of the metal matrix, which can make the imaging effect clearer.

Description

A method for detecting iron oxide scale samples on the surface of hot-rolled steel plates

technical field

The invention belongs to the field of backscattering image analysis of the surface structure of metal high-temperature oxidation, and in particular relates to a detection method for a sample of iron scale on the surface of a hot-rolled steel plate.

Background technique

At present, as more and more hot-rolled products are gradually replacing cold-rolled products of the same specification, users have higher and higher requirements for the surface quality of hot-rolled strip steel. In recent years, although my country's iron and steel enterprises have gradually paid attention to the surface quality of hot-rolled products, surface defects also appear frequently, resulting in the reduction of the surface and internal quality of steel products, causing the subsequent deep processing scrap rate to seriously exceed the standard, and the surface finish of the rolled slab is extremely poor. Therefore, in order to enhance the competitiveness of hot-rolled slabs in our country, the surface quality control of hot-rolled steel is the direction we are focusing on now. The main problem of the surface quality of hot-rolled strip steel is that the structure of the oxide scale is not properly controlled, and the iron scale is pressed in due to the peeling of the oxide scale, resulting in partial or large areas of red rust, pitting, pitting and other surface defects on the surface of the strip steel. Problems that plague the surface quality of hot-rolled slabs. Therefore, it is necessary to study the structure and thickness of iron oxide scale under different conditions, grasp the formation mechanism of different iron oxide scale structures, and then control its formation.

At present, the sample preparation method of hot-rolled metal oxide scale mainly adopts hot-mounting, as shown in the patent CN-101856669-A, the disadvantage of hot-mounting is that it needs to be heated at 50-130°C and formed at 80-300bar during the heating process. Due to the loading force, the iron oxide scale sample generates partial stress during the hot mounting process, and the iron oxide scale is easily broken and tilted, which creates great difficulties for the detection of iron oxide scale. Secondly, the current corrosive solution is a mixed solution of hydrochloric acid and ethanol. Its disadvantage is that it can only corrode the iron oxide scale structure but cannot corrode the metal matrix structure, which is not conducive to the detection of the iron oxide scale matrix. At present, the metallographic microscope is mainly used in the detection equipment of iron oxide scale. Its shortcoming is that the imaging effect of light microscope is not clear, and it cannot meet the detection requirements for the precise structure and thickness of iron oxide scale.

Contents of the invention

The object of the present invention is to provide a detection method for a hot-rolled steel sheet surface oxide scale sample aiming at the defects existing in the sample preparation method and inspection method of the hot-rolled metal oxide scale. The method is simple and convenient to operate, and can also protect the oxide scale sample after high temperature, and can obtain clearer structure and tissue pictures of the oxide scale and metal matrix.

A method for detecting iron oxide scale samples on the surface of hot-rolled steel plates, comprising the following steps:

(1) Sampling

Take a sample of hot-rolled steel plate, the better specification is thickness 2-4.5mm;

(2) pipe cutting

Since what needs to be observed is the section on the long side of the oxide scale sample, a non-metallic pipe with a diameter greater than the length of the sample is selected, and the length of the intercepted pipe is close to the width of the sample, and the preferred length is the sample width ± 5mm;

The non-metallic pipe is a pipe that does not contain metal components, does not react with epoxy resin, and has a melting point higher than 50°C, such as PVC pipes, PPR pipes, PE pipes, etc.;

(3) Mosaic

Mix and stir the liquid epoxy resin and curing agent evenly, place on an incline until the air bubbles in the medium disappear;

Seal one side of the pipe, put the sample into the pipe cavity, make one long side of the sample touch the sealing surface, multiple samples can be placed in the pipe; then add the epoxy resin medium into the pipe cavity, the medium depends on The fluidity of its own liquid evenly wraps the sample until it completely covers the sample; then put the tube in an oven at 40-50°C to solidify for 3-6 hours to obtain a fixed sample;

(4) Grinding

Grind the cross-section of the fixed sample with sandpaper from low to high granularity in turn. The better sandpaper from low to high granularity is SiC sandpaper of 800#, 1000#, 1200# and 1500#. The scratches are the size of the sandpaper of the last specification; the grinding is done by manual water grinding, using free-flowing pure water as the medium, and the grinding and washing are carried out at the same time;

(5) Polishing

Polish the section of the polished sample on a polishing machine with an abrasive paste with a specification of W2.5-3.5 to remove scratches from sandpaper; then polish with an abrasive paste with a specification of W0.5-1.5 for 5 to 15 minutes; finally use clean water Or alcohol polishing for 5-15 minutes to obtain a sample of the polished iron oxide scale on the surface of the hot-rolled steel plate; the speed of the polishing machine is preferably 800-1000r/min;

(6) chemical corrosion

Mix nitric acid with a mass concentration of 50-70% and ethanol to make a corrosion solution, the volume percentage of nitric acid in the corrosion solution is 3-7%; drop the corrosion solution on the polished sample section, corrode the sample for 3-10s Soak in alcohol or acetone solution for 5-10 minutes, then air dry or blow dry;

(7) Microscope inspection

Use the Field Emission Electron Probe (EPMA) to observe the cross-section of the oxide scale sample and complete the detection;

In order to increase the conductivity of the sample, the corroded sample can be placed in a high vacuum evaporation apparatus for carbon plating before testing.

Technical characteristics of the present invention:

(1) The present invention adopts the cold mounting method, solidifies in a baking oven at 40-50 °C, and the liquid epoxy resin has good fluidity, which avoids extrusion deformation or shedding of the iron oxide scale of the sample during the high-temperature mounting process, and The inclination of the sample is prevented, and the inclination of the sample can be adjusted as long as the epoxy resin is cured, and the outer layer of loose Fe ₂ O ₃ , Fe ₃ O ₄ , and FeO phases can be effectively protected by the cold epoxy resin. The cured epoxy resin has excellent mechanical properties, chemical resistance, excellent electrical properties and excellent heat resistance.

(2) What the corrosion solution among the present invention adopts is that nitric acid and ethanol are mixed and made mixed solution, and the volume percentage of nitric acid is 3-7% in the mixed solution, and the weight concentration of nitric acid is 50-70%; Drop the corrosion solution onto the surface of the polished sample, and after corrosion for 3-10 seconds, fully soak the sample in alcohol or acetone solution, and then quickly dry it with hot air from a hair dryer. It can corrode the oxide scale structure and the metallographic structure of the metal matrix to facilitate detection.

(3) The present invention uses the backscattered electrons in the field emission electron probe (EPMA) to detect the sample. Backscattering is the use of electron backscattering elastically. The number of backscattered electrons escaping from the sample surface increases with the increase of the average atomic mass in the solid and the increase of the inclination angle of the sample with respect to the incident beam. Thus, a clearer picture of the structure and organization of iron oxide scale and metal collective can be obtained.

Description of drawings

Fig. 1 is the cross-section schematic diagram of the surface oxide scale sample of hot-rolled steel plate that the present invention makes;

Among them, 1. Pipe material, 2. Epoxy resin, 3. Metal substrate, 4. Iron oxide scale;

Fig. 2 is the physical figure of the hot-rolled steel plate surface oxide scale sample that the embodiment of the present invention 1 makes;

Fig. 3 is the EPMA backscatter detection figure of the surface oxide scale sample section structure of the hot-rolled steel plate that the embodiment 1 of the present invention makes;

Among them, a, Fe ₂ O ₃ layer, b, Fe ₃ O ₄ layer, c, FeO layer, d, FeO eutectoid product, e, metal matrix;

Fig. 4 is the EPMA backscatter detection diagram of the metal matrix structure of the hot-rolled steel plate surface oxide scale sample section detection that the embodiment 1 of the present invention makes;

Fig. 5 is the EPMA backscatter detection diagram of the cross-sectional structure of the oxide scale sample on the surface of the hot-rolled steel plate obtained in Example 2 of the present invention;

Among them, f, Fe ₃ O ₄ layer, g, FeO layer, h, metal matrix;

Fig. 6 is the EPMA backscatter detection diagram of the metal matrix structure of the iron oxide scale sample section on the surface of the hot-rolled steel plate obtained in Example 2 of the present invention;

Fig. 7 is the EPMA backscatter detection diagram of the cross-section structure of the oxide scale sample on the surface of the hot-rolled steel plate prepared in Example 3 of the present invention;

Among them, i, Fe ₂ O ₃ layers, j, Fe ₃ O ₄ layers, k, FeO layer, l, FeO eutectoid product, m, metal matrix;

Fig. 8 is the EPMA backscatter detection diagram of the cross-sectional structure of the oxide scale sample on the surface of the hot-rolled steel plate obtained in Example 4 of the present invention;

Among them, n, Fe ₂ O ₃ layers, o, Fe ₃ O ₄ layers, p, FeO layer, q, FeO eutectoid product, x, metal matrix.

Detailed ways

The liquid epoxy resin and curing agent adopted in the embodiment of the present invention are chemical products, ethanol is an industrial product, nitric acid is an industrial product, PVC, PE and PPR pipes are common construction pipes, the sandpaper is SiC sandpaper, and the abrasive paste is artificial diamond Abrasive paste.

The field emission electron probe (EPMA) model is JXA-8530F.

The high vacuum carburizer is 208C High produced by British Cressington Company.

Example 1

1. Heat the sample Fe-Cr alloy to 1100°C, keep it warm for 2 hours, and then cool it to room temperature with the furnace, and then use the wire cutting method to cut a section on the hot-rolled strip steel, with a length of 8mm, a width of 10mm, and a thickness of 2.2mm. Acetone is the cleaning solution to remove surface oil;

2. Take a PVC pipe with a diameter of 15mm, and use a cutter to cut a section with a length of 12mm;

3. Cut a piece of oil paper of 30×30mm, seal the oil paper on one side of the PVC pipe with solid glue; then weigh the liquid epoxy resin and curing agent in proportion, pour it into a beaker, stir it evenly with a glass rod, and place it at an angle 25min, until the bubbles in the medium disappear;

Put the sample vertically into the tube, so that one long side of the sample is in contact with the sealing surface, and the other long side is facing outward, as shown in Figure 1 and Figure 2, the section of the sample seen is the long side facing outward ; Dip the epoxy resin medium with a glass rod, drop it into the PVC pipe along the pipe wall, and the epoxy resin medium will wrap the sample evenly by its own liquid fluidity until it covers the sample; after standing still for 10 minutes, put The mounted sample was placed in a drying oven at 50°C for 4 hours, then the heating power was turned off and the sample was cooled to room temperature in the drying oven to obtain a fixed sample;

4. Use 800#, 1000#, 1200# and 1500# SiC sandpaper to grind the cross-section of the long side of the sample in sequence. The grinding is done by manual water grinding, using free-flowing water as the medium, and grinding and washing are carried out at the same time. Before the next level of sandpaper, the sample needs to be ground until the wear depth caused by the previous level of sandpaper is completely removed;

5. Polish the section of the polished sample, using abrasive paste with a particle size of W2.5, and polish it on a metallographic polishing machine with a rotation speed of 900r/min to remove the scratches of the SiC sandpaper; then use an abrasive paste with a particle size of W1.0 , polished on a metallographic polishing machine at the same speed for 15 minutes; finally, polished with water for 15 minutes on a metallographic polishing machine at the same speed;

6. Mix nitric acid with a mass concentration of 50% and ethanol to make a mixed solution. The volume percentage of nitric acid in the mixed solution is 3.5%. Use a rubber dropper to drop the corrosion solution onto the polished sample section, and corrode the sample for 8 seconds. Soak in ethanol for 7 minutes, and then dry quickly with hot air of a hair dryer;

7. Put the corroded sample into the high vacuum evaporation apparatus for carbon plating;

8. Observe the cross-section of the scale sample with the field emission electron probe (EPMA) on the sample after carbon plating, and complete the detection of the structure of the oxide scale oxidized at high temperature.

It can be seen from Figure 2 that the inlaid Fe-Cr alloy sample is complete, and there is no cracking and tilting; it can be seen from the field emission electron probe (EPMA) backscattering detection diagrams in Figure 3 and Figure 4 that under EPMA Observing the overall appearance of the oxide scale, the overall structure of the oxide scale is well preserved without cracks, and the outer layer is completely wrapped in epoxy resin. The Fe ₂ O ₃ layer, Fe ₃ O ₄ layer, FeO layer and the pro-eutectoid Fe ₃ O ₄ structure in the FeO layer can be identified one by one by observing the backscattered images of iron oxide scale. At the same time, the metallographic morphology of the metal matrix can also be observed.

Example 2

1. Heat the sample Fe-Cr alloy to 800°C, keep it warm for 2 hours, and then cool it to room temperature with the furnace; use the wire cutting method to cut a section on the hot-rolled strip steel, with a length of 11mm, a width of 8mm, and a thickness of 2.3mm. Remove surface oil for cleaning fluid;

2. Take a PE pipe with a diameter of 20mm, and use a cutter to cut a section with a length of 13mm;

3. Cut a piece of oil paper, seal the oil paper on one side of the PE pipe with solid glue; weigh the liquid epoxy resin and curing agent in proportion, pour it into a beaker, stir it evenly with a glass rod, and place it at an angle for 10-30 minutes , until the bubbles in the medium disappear;

Put the sample vertically into the pipe, so that one long side of the sample is in contact with the sealing surface, and the other long side faces outward; use a glass rod to dip in the epoxy resin medium, drop it into the PE pipe along the pipe wall, and the epoxy resin The medium evenly wraps the sample by its own liquid fluidity until it covers the sample; put the inlaid sample in a drying oven at 40°C for 6 hours, then turn off the heating power and let the sample stay in the drying oven Cool to room temperature to prepare a fixed sample;

4. Use 800#, 1000#, 1200# and 1500# SiC sandpaper to grind the section in turn. The grinding is done by manual water grinding, using free flowing water as the medium, grinding and rinsing at the same time, and grinding to the scratches of the sample is the grain size of the sandpaper of the last specification;

5. Polish the section of the polished sample, and use the abrasive paste with a particle size of W3.5 to polish on a metallographic polishing machine with a rotation speed of 1000r/min to remove the scratches of the SiC sandpaper; then use an abrasive paste with a particle size of W1.5 , polished on a metallographic polishing machine at the same speed for 5 minutes; finally, polished with alcohol for 10 minutes on a metallographic polishing machine at the same speed;

6. Mix nitric acid with a mass concentration of 50% and ethanol to make a mixed solution. The volume percentage of nitric acid in the mixed solution is 5%; use a rubber dropper to drop the corrosion solution onto the polished sample section, and corrode the sample for 5 seconds. Soak in acetone solution for 5 minutes, and then dry quickly with hot air from a hair dryer;

7. Put the sample into the high-vacuum evaporation apparatus, and coat the section of the corroded sample with a layer of carbon;

8. Use the field emission electron probe (EPMA) to observe the cross-section of the iron oxide scale sample, and complete the detection of the oxide scale structure oxidized at high temperature.

The field emission electron probe (EPMA) backscattering detection diagram of the cross-sectional structure of the sample can be seen from Fig. 5 and Fig. 6 .

Example 3

1. Heat the sample Fe-Cr alloy to 900°C, keep it warm for 2 hours, and then cool it to room temperature with the furnace; use the wire cutting method to cut a section on the hot-rolled strip steel, with a length of 10mm, a width of 12mm, and a thickness of 2.35mm. Remove surface oil for cleaning fluid;

2. Take a PPR pipe with a diameter of 15mm, and use a cutter to cut a section with a length of 12mm;

3. Cut a piece of oil paper, seal the oil paper on one side of the PPR tube with solid glue; weigh the liquid epoxy resin and curing agent in proportion, pour it into a beaker, stir it evenly with a glass rod, and place it at an angle for 10-30 minutes , until the bubbles in the medium disappear;

Put the sample vertically into the pipe, so that one long side of the sample is in contact with the sealing surface, and the other long side faces outward; use a glass rod to dip in the epoxy resin medium, drop it into the PPR tube from the tube wall, and the epoxy resin The medium evenly wraps the sample by its own liquid fluidity until it covers the sample; place the inlaid sample in a drying oven at 45°C for 3.5 hours, then turn off the heating power and let the sample stay in the drying oven Cool to room temperature to prepare a fixed sample;

4. Use 800#, 1000#, 1200# and 1500# SiC sandpaper to grind the section in turn. The grinding is done by manual water grinding, using free flowing water as the medium, grinding and rinsing at the same time, and grinding to the scratches of the sample is the grain size of the sandpaper of the last specification;

5. Polish the section of the polished sample, using abrasive paste with a particle size of W2.5, and polish it on a metallographic polishing machine with a rotation speed of 800r/min to remove the scratches of the SiC sandpaper; then use an abrasive paste with a particle size of W0.5 , polished on a metallographic polishing machine at the same speed for 15 minutes; finally, polished with water for 5 minutes on a metallographic polishing machine at the same speed;

6. Mix nitric acid with a mass concentration of 60% and ethanol to make a mixed solution. The volume percentage of nitric acid in the mixed solution is 5%; use a rubber dropper to drop the corrosion solution onto the polished sample section, and corrode the sample for 10 seconds. Soak in the alcohol solution for 10 minutes, and then dry quickly with hot air from a hair dryer;

7. Put the corroded sample into the high vacuum evaporation apparatus for carbon plating;

8. Use the field emission electron probe (EPMA) to observe the cross-section of the iron oxide scale sample, and complete the detection of the oxide scale structure oxidized at high temperature.

The field emission electron probe (EPMA) backscattering detection diagram of the cross-sectional structure of the sample can be seen from FIG. 7 .

Example 4

1. Heat the sample Fe-Cr alloy to 1000°C, keep it warm for 2 hours, and then cool it to room temperature with the furnace; use the wire cutting method to cut a section on the hot-rolled strip steel, with a length of 8mm, a width of 12mm, and a thickness of 2.2mm. Remove surface oil for cleaning fluid;

2. Take a PVC pipe with a diameter of 15mm, and use a cutter to cut a section with a length of 10mm;

3. Cut a piece of oil paper, seal the oil paper on one side of the PVC pipe with solid glue; weigh the liquid epoxy resin and curing agent in proportion, pour it into a beaker, stir it evenly with a glass rod, and place it at an angle for 10 to 30 minutes , until the bubbles in the medium disappear;

Put the sample vertically into the pipe, so that one long side of the sample is in contact with the sealing surface, and the other long side faces outward; use a glass rod to dip into the epoxy resin medium, drop it into the PVC pipe from the pipe wall, and the epoxy resin The medium wraps the sample evenly by its own liquid fluidity until it covers the sample; place the mounted sample in a drying oven at 50°C for 3 hours, then turn off the heating power and let the sample stay in the drying oven Cool to room temperature to prepare a fixed sample;

4. Use 800#, 1000#, 1200# and 1500# SiC sandpaper to grind the cross section in turn. The grinding is done by manual water grinding, using free flowing water as the medium, grinding and rinsing at the same time, before entering the next level of sandpaper Before, the sample needs to be ground until the depth of wear caused by the previous level of sandpaper is completely removed;

5. Polish the section of the polished sample, and use the abrasive paste with a particle size of W3.5 to polish on a metallographic polishing machine with a rotation speed of 900r/min to remove the scratches of the SiC sandpaper; then use the abrasive paste with a particle size of W1.0 , polished on a metallographic polishing machine at the same speed for 10 minutes; finally, polished with water for 15 minutes on a metallographic polishing machine at the same speed;

6. Mix nitric acid with a mass concentration of 70% and ethanol to make a mixed solution. The volume percentage of nitric acid in the mixed solution is 7%; use a rubber dropper to drop the corrosion solution onto the surface of the polished sample, and corrode the sample for 3 seconds. Soak in acetone solution for 5 minutes, and then dry quickly with hot air from a hair dryer;

7. Put the corroded sample into the high vacuum evaporation apparatus for carbon plating;

8. Use the field emission electron probe (EPMA) to observe the cross-section of the iron oxide scale sample, and complete the detection of the oxide scale structure oxidized at high temperature.

The field emission electron probe (EPMA) backscattering detection diagram of the cross-sectional structure of the sample can be seen from FIG. 8 .

Example 5

1. Heat the sample Fe-Mn alloy to 1000°C, keep it warm for 2 hours, and then cool it to room temperature with the furnace; use the wire cutting method to cut a section on the hot-rolled strip steel, with a length of 8mm, a width of 10mm, and a thickness of 4.5mm. Remove surface oil for cleaning fluid;

2. Take a PVC pipe with a diameter of 15mm, and use a cutter to cut a section with a length of 10mm;

3. Cut a piece of oil paper, seal the oil paper on one side of the PVC pipe with solid glue; weigh the liquid epoxy resin and curing agent in proportion, pour it into a beaker, stir it evenly with a glass rod, and place it at an angle for 10 to 30 minutes , until the bubbles in the medium disappear;

Put the sample vertically into the pipe, so that one long side of the sample is in contact with the sealing surface, and the other long side faces outward; use a glass rod to dip into the epoxy resin medium, drop it into the PVC pipe from the pipe wall, and the epoxy resin The medium wraps the sample evenly by its own liquid fluidity until it covers the sample; put the mounted sample in a drying oven at 50°C for 4 hours, then turn off the heating power and let the sample stay in the drying oven Cool to room temperature to prepare a fixed sample;

4. Use 800#, 1000#, 1200# and 1500# SiC sandpaper to grind the cross section in turn. The grinding is done by manual water grinding, using free flowing water as the medium, grinding and rinsing at the same time, before entering the next level of sandpaper Before, the sample needs to be ground until the depth of wear caused by the previous level of sandpaper is completely removed;

5. Polish the section of the polished sample, and use the abrasive paste with a particle size of W3.5 to polish on a metallographic polishing machine with a rotation speed of 800r/min to remove the scratches of the SiC sandpaper; then use the abrasive paste with a particle size of W1.0 , polished on a metallographic polishing machine at the same speed for 15 minutes; finally, polished with water for 15 minutes on a metallographic polishing machine at the same speed;

6. Mix nitric acid with a mass concentration of 60% and ethanol to make a mixed solution. The volume percentage of nitric acid in the mixed solution is 5%; use a rubber dropper to drop the corrosion solution onto the surface of the polished sample, and corrode the sample for 8 seconds. Soak in acetone solution for 5 minutes, and then dry quickly with hot air from a hair dryer;

7. Use the field emission electron probe (EPMA) to observe the cross-section of the iron oxide scale sample, and complete the detection of the structure of the iron oxide scale oxidized at high temperature.

Claims (8)

1. a detection method for hot rolled steel plate surface oxidation iron sheet sample, is characterized in that, comprises the following steps:

(1) sample

One piece of sample is extracted from hot rolled steel plate;

(2) Pipe Cutting

Choose the non-metal pipe that diameter is greater than sample length, intercept one section; Described non-metal pipe is not containing metal ingredient, do not react with epoxy resin, fusing point is higher than the tubing of 50 DEG C;

(3) inlay

By the epoxy resin of liquid state and hardening agent mixing and stirring, slant setting is until bubble collapse in medium;

Seal up tubing side, sample is put into tubing cavity; Then joined by epoxy resin medium in tubing cavity, medium wraps sample, until cover sample completely uniformly by the liquid fluidity of self; Heat in the baking oven again tubing being placed in 40 ~ 50 DEG C, epoxy resin medium is solidified, the obtained sample fixed;

(4) polish

Polish with by the section of sand paper to the sample fixed of low granularity to high granularity successively, the cut of polishing to sample is the granularity of last specification sand paper;

(5) polishing

With abrasive pastes 1, the sample section of having polished is carried out polishing on buffing machine, remove the cut of sand papering; Use abrasive pastes 2 polishing again; Finally with clear water or alcohol polishing, obtain polished hot rolled steel plate surface oxidation iron sheet sample;

(6) chemical corrosion

Corrosive liquid is dripped to polished sample section, after corrosion 3 ~ 10s, sample is immersed in 5 ~ 10min in alcohol or acetone soln, then air-dry or dry up;

(7) microscopic examination

Adopt field emission electron probe to observe the section of iron scale sample, complete detection.

2. the detection method of a kind of hot rolled steel plate surface oxidation iron sheet sample according to claim 1, is characterized in that, in described step (3), it is 3 ~ 6 hours that tubing is placed in heating setting time in baking oven.

3. the detection method of a kind of hot rolled steel plate surface oxidation iron sheet sample according to claim 1, is characterized in that, the polishing mode described in step (4) is manual water mill, and with free-pouring pure water for medium, polishing is carried out with flushing simultaneously.

4. the detection method of a kind of hot rolled steel plate surface oxidation iron sheet sample according to claim 1, is characterized in that, the SiC sand paper being followed successively by 800#, 1000#, 1200# and 1500# by low granularity to the sand paper of high granularity described in step (4).

5. the detection method of a kind of hot rolled steel plate surface oxidation iron sheet sample according to claim 1, is characterized in that, the specification of the abrasive pastes 1 described in step (5) is W2.5-3.5; The specification of described abrasive pastes 2 is W0.5-1.5.

6. the detection method of a kind of hot rolled steel plate surface oxidation iron sheet sample according to claim 1, is characterized in that, in described step (5), the polishing time of abrasive pastes 2 is 5 ~ 15min; Clear water or alcohol polishing time are 5 ~ 15min.

7. the detection method of a kind of hot rolled steel plate surface oxidation iron sheet sample according to claim 1, it is characterized in that, corrosive liquid described in step (6) is: be make corrosive liquid after the nitric acid of 50-70% and ethanol mixing by mass concentration, in corrosive liquid, the percent by volume of nitric acid is 3-7%.

8. the detection method of a kind of hot rolled steel plate surface oxidation iron sheet sample according to claim 1, is characterized in that, in described step (7), before employing field emission electron probe in detecting, the sample corroded is put into high vacuum vapor deposition instrument and plates carbon.