CN102095671B - Analytical method of small-size impurities in steel - Google Patents

Abstract

The invention discloses an analytical method of small-size impurities in steel. The technical scheme adopted by the method comprises the steps of: (1) electrolyzing a sample in neutral organic electrolyte under constant current and voltage; (2) filtering a solution rich in a large amount of impurity particles after electrolysis by a filter membrane with superfine aperture so as to settle the small-size impurity particles on the membrane; (3) taking off the filter membrane, bonding the membrane on a supporting table and putting the filter membrane on a scanning electron microscope for observation, taking morphology photos and analyzing energy spectrum components; and (4) processing data, and conducting three-dimensional statistic analysis to all impurities in the sample or statistic analysis to specified type of impurities. The analytical method of small-size impurities in steel solves the problems that the electrolysis extraction method of bulk sample is not applicable to the traditional analysis method of small-size impurities, the impurities cannot be displayed completely in the analysis of impurities on a two-dimensional polishing surface, and the analysis of components is interfered with a matrix.

Description

The middle-size and small-size inclusion analysis method of steel

Affiliated technical field

The present invention relates to a kind of Analysis of Metallic Materials method, especially small-sized non-metallic inclusion below the 5 μ m in the steel is carried out the analytical approach of spatial statistics.

Background technology

At present; The analytical approach that many research steel inclusions are arranged both at home and abroad for example with the cutting of steel samples cross section, is put into after grinding, polishing under optical microscope or the ESEM; The pattern of snotter on the observation sample polished surface; The size of statistics inclusion particle adopts the method for this cutting section can probably understand distribution, quantity, form and the size of nonmetallic inclusionsin steel, but still receives the restriction of metal flour milling about Research on Inclusion; Because a certain snotter that shows on the polished surface is the part of real inclusion particle in fact, is inaccurate so represent whole snotter with this snotter throwing face.In addition, when a certain small-sized snotter on the polished surface being carried out constituent analysis with ESEM, because the resolution of power spectrum is limited, the often serious interference that quantitatively receives matrix of composition of inclusions, accuracy is lower.

Electrolytic process is from steel, to extract another important method of snotter, and electrolytic process can be come out nonmetal inclusion electrolytic separation such as the oxide in the steel, sulfide, then observation analysis under Electronic Speculum.What use at present domestic is the bulk sample electrolysis method more, and it utilizes the more tiny characteristics of carbonide particle diameter ratio, eluriates carbonide with elutriation method or water elutration method; Bulky grain is mingled with ferriferous oxide stays bottom land; With the magnetic separation reduction, separate snotter at last, test samples weighs 3～5 kilograms; Specimen size φ 60 * 150mm, about about 20 days of electrolysis time.

Because acidic electrolysis baths such as bulk sample electrolysis method employing hydrochloric acid come snotter in the electrolysis separation of steel; Acidic electrolysis bath is prone to unsettled snotter dissolved corrosions such as sulfide in the steel; Incomplete the remaining of some large-scale snotteres possibilities; Small-sized snotter then possibly dissolve fully, and elutriation process subsequently also can eluriate tiny inclusion particle, so the detected inclusion particle of bulk sample electrolysis method is bigger; Slightly little Particulate Inclusion diameter has five or six ten microns; Bigger particle diameter reaches two or three hundred microns, is generally used for the large-scale Research on Inclusion of continuous casting billet, and not too is applicable to the clean steel product snotter check and analysis that contain less less snotter.

The production of clean steel at present is an important topic of steel industry development; Clean steel has been applied to many industries such as automobile, household electrical appliances, food industry and even acidproof pipeline, is extended to the wide spectrums from the ultra-low-carbon steel to high-carbon steel such as deep-drawing sheet, IC lead-in wire pivot, tire meridian, ball-bearing steel, rail.Steel inclusion is very big to the production performance and the usability influence of steel, and therefore the Control Study of clean steel inclusion is significant.The degree of purity of molten steel is higher in the clean steel; The size of snotter is tending towards tinyization; Reaching submicron order or nanoscale, how quantity, form and the Size Distribution of the middle-size and small-size non-metallic inclusion of steel are estimated exactly, is the key factor of the cleanliness factor of research and control steel.

Summary of the invention

Deficiency to prior art; The present invention provides a kind of steel middle-size and small-size snotter statistical analysis technique; Can the small-sized non-metallic inclusion below the 5 μ m in the steel be extracted and separate; Carry out the spatial statistics analysis of form, quantity, composition and Size Distribution then, effectively reflect truly that there is situation in snotter in steel products.

The technical scheme that the present invention adopted comprises the steps:

1. under the continuous current voltage in neutral organic electrolyte the electrolysis sample;

2. with the membrane filtration of the solution that is rich in inclusion particle after the electrolytic reaction through superfine aperture, the filter membrane aperture size is 0.05～0.5 micron, and small-sized inclusion particle is deposited on the film;

3. clip part filter membrane also is bonded at the carbonaceous conductive adhesive tape and puts into scanning electron microscopic observation on the brace table, takes the pattern photo and also makes energy spectrum composition analysis;

4. data processing is carried out the three dimensions statistical study to all snotteres in the sample and perhaps the snotter of particular type is carried out statistical study.

According to the middle-size and small-size inclusion analysis method of steel of the present invention; Step 1. in electrolytic solution for being the neutral organic solution of solvent with methyl alcohol; Proportioning is: 5～15% diacetones-0.5～1.5% chlorination tetramethylammonium-methanol solution; Wherein: 5～15% is the percent by volume of diacetone and the total solution of methyl alcohol, 0.5～1.5% percentage by weight for chlorination tetramethylammonium and the total solution of methyl alcohol.

According to the middle-size and small-size inclusion analysis method of steel of the present invention; The quantity that step adopts formula

to come different size inclusion particle in the statistical unit volume in is 4. drawn the bulk distribution plan of snotter then.Wherein Nv is the quantity of different size rank particle in the unit volume; n _(j)Quantity for j size class particle in the certain observation zone; A _FilArea for the snotter filter membrane; ρ _MeDensity for test button; A _ObsBe the observed filter membrane area of ESEM; W _DisFor test button is dissolved into the weight in the electrolytic solution, i.e. the loss in weight before and after the test button electrolytic experiment.

The present invention provides a kind of analysis mode accurately and effectively for the middle-size and small-size Research on Inclusion of steel; This method relates to the small-sized non-metallic inclusion extraction and separation technology below the 5 μ m in the steel; And the inclusion particle that extracts carried out the spatial statistics analysis of form, quantity, composition and Size Distribution; There is situation in true reflection snotter in steel products; Especially satisfied the active demand of the middle-size and small-size snotter statistical study of present clean steel, the technology controlling and process of cleanliness factor provides the active data support in the steel thereby can be.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the present invention is described further.

Fig. 1 is the electrolytic experiment installation drawing;

Fig. 2 is for filtering extraction element figure;

Fig. 3 is filter membrane brace table figure;

Fig. 4 is the inclusion particle shape appearance figure under the ESEM;

Fig. 5 is the snotter bulk scatter chart of various sample;

Fig. 6 is the bulk scatter chart of globular inclusion and square snotter;

Fig. 7 is MgO, Al ₂O ₃, MgO+Al ₂O ₃The bulk scatter chart of inclusion particle.

Among the figure:

1---electrolytic solution 2---platinum filament 3---sample 4---KCl saturated solution 5---KCl gel

6---mercurous chloride electrode 7---controlled potential appearance 8---coulombmeter 9---voltage table 10---reometer

11---is rich in the solution 12---filter membrane 13---vacuum pump 14-inclusion particle of inclusion particle

15-part filter membrane 16-carbonaceous conductive adhesive tape 17-brace table

Embodiment

Below in conjunction with description of drawings embodiment of the present invention, be example with the statistical study of certain low-carbon (LC) steel inclusion.

Small-sized snotter in the steel is analyzed and researched, and comprises several steps such as the preceding preparation of experiment, electroextraction experiment, ESEM grain size analysis, data statistic analysis, and is specific as follows:

1. prepare before the experiment

At first be ready to the electrolysis bridge, configuration electrolytic solution 1, mix proportion scheme is as shown in table 1:

The mix proportion scheme of table 1 electrolytic solution

Mix proportion scheme	Diacetone/ml	Chlorination tetramethylammonium/g	Total solution/the ml of methyl alcohol
				A
	8	0.9	100
				B	10	1	100
C	13	1.2	100

The analysis of this example is adopted mix proportion scheme B configuration electrolytic solution 1, and preparation size is the clean sample 3 of 15 * 10 * 3mm then, and weighing sample 3, record numerical value.Clean up all glasswares respectively with light water, distilled water, methyl alcohol,, set parameters such as electric current, voltage and coulomb number by the experimental provision that is ready to shown in Figure 1.

2. electrolytic experiment

Opening power, the experiment beginning.The distance that slight adjustment electrolysis bridge and sample are 3 to be measured, whether holding current is constant, whenever normally carry out at a distance from checking experiment in ten minutes.Experiment stops automatically when arriving the enclosed pasture number of setting after a period of time, then turns off power supply.

The beaker that electrolytic solution 1 is housed is taken out from experimental provision; At this moment many inclusion particles can suspend in the electrolytic solution 1; Use washed with methanol sample 3, platinum filament 2 and tweezers surface then; And cleaning fluid also poured in the beaker that electrolytic solution 1 is housed, the inclusion particle that electrolysis is come out all gets in the electrolytic solution.The sample that cleans up 3 is dried up weighing once more, record numerical value.

3. extract experiment

Be ready to the vessel that clean up are as shown in Figure 2, afterwards the solution that is rich in inclusion particle in the beaker 11 all poured in the filter cup, control the filter velocity of electrolytic solution, remain a constant speed as far as possible and filter slowly through the pressure of regulating bottom vacuum pump 13.After filter finishing, the inclusion particle 14 that electrolysis is come out from sample promptly is deposited on the film, and the filter membrane 12 of 0.05～0.5 micron of aperture size is taken off gently, and clip part filter membrane 15 utilizes carbonaceous conductive adhesive tape 16 to be bonded on the brace table 17 then, sees Fig. 3.

4. scanning electron microscopic observation

Brace table 17 put under the ESEM snotter on the part filter membrane 15 is carried out observation analysis; Whether the distribution of at first checking inclusion particle is even; Whether the particle back of the body end is clean; Have only clean, the equally distributed filter membrane of inclusion particle in the back of the body of the employing end, the statistical study work of particle size distribution is just meaningful.

Then * 1000, * 2000 or * diverse location of getting filter membrane 15 under the different magnifications such as 5000 takes electromicroscopic photograph respectively, and is as shown in Figure 4.For the statistical study of all snotteres in the sample, the total quantity of particle statistic should be more than 200～300; For a certain type impurity such as TiN in the sample, the statistical study of MnS etc., the total quantity of particle statistic should be no less than 500-1000.According to the needs that particle statistic is analyzed, other part of clip filter membrane 12 is put into and is observed and take electromicroscopic photograph under the Electronic Speculum again.

5. data statistic analysis

After utilizing the inclusion particle 14 on the scanning electron microscopic observation filter membrane 12 and taking pictures, the inclusion particle on can comparison film carries out statistical study, adopts the quantity of different size inclusion particle in the formula 1 unit of account volume.Can adopt different analytical approachs that NULL is carried out in the bulk distribution of snotter then.

1) computing formula

$N_V=\frac{n_{\left(j\right)}\×A_{\mathrm{Fil}}\×{\mathrm{\ρ}}_{\mathrm{Me}}}{A_{\mathrm{Obs}}\×W_{\mathrm{Dis}}}$ (formula 1)

Nv: the quantity of different size rank particle in the unit volume;

n _(j): the quantity of j size class particle in the certain observation zone;

A _Fil: the area of snotter filter membrane;

ρ _Me: the density of test button;

A _Obs: the filter membrane area that ESEM is observed;

W _Dis: test button is dissolved into the weight in the electrolytic solution, i.e. the loss in weight before and after the test button electrolytic experiment.

2) analysis-by-synthesis of all inclusion particles

Under ESEM, take the inclusion particle photo; Measure the equivalent diameter of all particles; Utilize formula 1 to calculate the quantity of j size class particle in the per unit volume; Draw out the bulk distribution plan of all snotteres on the filter membrane, shown the snotter bulk distribution curve of sample 1,2,3 like Fig. 5.

3) classification analysis of inclusion particle

Inclusion particle can be divided into by form:

is square, like TiN...

Spherical, like MgO, Al ₂O ₃...

Group's bunch shape like Al ₂O ₃...

strip like MnS...

other form ...

For example; Under ESEM, take pictures; Calculate the mean diameter of square inclusion particle; The quantity of square inclusion particle in the 1 unit of account volume by formula can be drawn out the size distribution plot of filter membrane top clevis foreign material, has shown the bulk distribution curve of globular inclusion and square snotter like Fig. 6.

Inclusion particle can be divided into by forming:

Simple oxide or composite oxides, like MgO, Al ₂O ₃, MgO+Al ₂O ₃

The oxide of

different content; Like 10～30%CaO; 30～60%CaO,＞60%CaO...

oxide, nitride, oxynitrides

sulfide, oxysulfide, oxysulfide+nitride ...

For example, under ESEM, take pictures, use the energy spectrometer analysis composition of inclusions; Calculate the mean diameter of MgO inclusion particle; The quantity of MgO inclusion particle in the 1 unit of account volume by formula can be drawn out the size distribution plot of MgO snotter on the filter membrane, has shown MgO, Al like Fig. 7 ₂O ₃, MgO+Al ₂O ₃The bulk distribution curve of inclusion particle.

Claims (2)

1. middle-size and small-size inclusion analysis method of steel is characterized in that may further comprise the steps:

1. under the continuous current voltage in neutral organic electrolyte (1) the electrolysis sample; Described electrolytic solution is for being the neutral organic solution of solvent with methyl alcohol; Proportioning is: 5～15% diacetones-0.5～1.5% chlorination tetramethylammonium-methanol solution; Wherein: 5～15% is the percent by volume of diacetone and the total solution of methyl alcohol, 0.5～1.5% percentage by weight for chlorination tetramethylammonium and the total solution of methyl alcohol;

2. the solution that is rich in inclusion particle after the electrolytic reaction (11) is filtered through filter membrane (12); Filter membrane (12) aperture size is 0.05～0.5 micron; The pressure of vacuum pump (13) is controlled the filter velocity of electrolytic solution bottom regulating, and small-sized inclusion particle (14) is deposited on the film;

3. clip part filter membrane (15) also is bonded on the brace table (17) with carbonaceous conductive adhesive tape (16) and puts into scanning electron microscopic observation, takes the pattern photo and also makes energy spectrum composition analysis;

4. data processing is carried out the three dimensions statistical study to all snotteres in the sample and perhaps the snotter of particular type is carried out statistical study.

2. the middle-size and small-size inclusion analysis method of steel according to claim 1; It is characterized in that: the quantity that step adopts formula to come different size inclusion particle in the statistical unit volume in 4., draw the bulk distribution plan of snotter then;

Wherein: Nv is the quantity of different size rank particle in the unit volume;

n _(j)Quantity for j size class particle in the certain observation zone;

A _Fi1Area for the snotter filter membrane;

ρ _MeDensity for test button;

A _ObsBe the observed filter membrane area of ESEM;

W _DisFor test button is dissolved into the weight in the electrolytic solution, i.e. the loss in weight before and after the test button electrolytic experiment.

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