CN111811912A - Metallographic corrosion method for high-carbon martensitic stainless steel grain boundary - Google Patents
Metallographic corrosion method for high-carbon martensitic stainless steel grain boundary Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 56
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 42
- 238000000227 grinding Methods 0.000 claims abstract description 33
- 239000003599 detergent Substances 0.000 claims abstract description 28
- OXNIZHLAWKMVMX-UHFFFAOYSA-N picric acid Chemical compound OC1=C([N+]([O-])=O)C=C([N+]([O-])=O)C=C1[N+]([O-])=O OXNIZHLAWKMVMX-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000003518 caustics Substances 0.000 claims abstract description 22
- 238000001035 drying Methods 0.000 claims abstract description 16
- 238000005530 etching Methods 0.000 claims abstract description 14
- 238000004140 cleaning Methods 0.000 claims abstract description 13
- 238000005498 polishing Methods 0.000 claims abstract description 13
- 239000007788 liquid Substances 0.000 claims abstract description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 26
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 17
- 239000000203 mixture Substances 0.000 claims description 10
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 4
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- 239000011651 chromium Substances 0.000 claims description 4
- 229920000742 Cotton Polymers 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 3
- 238000007598 dipping method Methods 0.000 claims description 2
- 230000003628 erosive effect Effects 0.000 claims 1
- 239000013078 crystal Substances 0.000 abstract description 21
- 229910001220 stainless steel Inorganic materials 0.000 abstract description 10
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- 230000000694 effects Effects 0.000 abstract description 7
- 238000001514 detection method Methods 0.000 abstract description 4
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- 229910000831 Steel Inorganic materials 0.000 description 10
- 239000010959 steel Substances 0.000 description 10
- 229910000734 martensite Inorganic materials 0.000 description 9
- 238000003756 stirring Methods 0.000 description 9
- 239000011159 matrix material Substances 0.000 description 8
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- 229910003460 diamond Inorganic materials 0.000 description 7
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- 230000000052 comparative effect Effects 0.000 description 5
- 238000009472 formulation Methods 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 4
- 238000004851 dishwashing Methods 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Substances N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 229910052698 phosphorus Inorganic materials 0.000 description 4
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- ORTQZVOHEJQUHG-UHFFFAOYSA-L copper(II) chloride Chemical compound Cl[Cu]Cl ORTQZVOHEJQUHG-UHFFFAOYSA-L 0.000 description 3
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- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 238000004881 precipitation hardening Methods 0.000 description 2
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- GJCXHYNLSNVSQZ-UHFFFAOYSA-L [Cu](Cl)Cl.Cl Chemical compound [Cu](Cl)Cl.Cl GJCXHYNLSNVSQZ-UHFFFAOYSA-L 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229960003280 cupric chloride Drugs 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000000265 homogenisation Methods 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229910001562 pearlite Inorganic materials 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 description 1
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- 239000004094 surface-active agent Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/32—Polishing; Etching
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/20—Metals
- G01N33/204—Structure thereof, e.g. crystal structure
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Abstract
The invention belongs to the field of stainless steel metallographic analysis and detection, and particularly relates to a metallographic corrosion method for a high-carbon martensitic stainless steel grain boundary. Aiming at the problem that a metallographic etching method aiming at high-carbon martensitic stainless steel and simple and convenient to operate and low in cost is lacked, the invention provides a metallographic etching method of a high-carbon martensitic stainless steel grain boundary, which comprises the following steps: carrying out coarse grinding, fine grinding, polishing, cleaning and drying on the high-carbon martensitic stainless steel metallographic specimen to obtain a bright and scratch-free polished surface; corroding the polished surface for 5-30 s at room temperature by adopting a metallographic corrosive agent, cleaning and drying; the metallographic corrosive agent comprises the following components: 1-4 g picric acid, 5ml concentrated hydrochloric acid, 100ml alcohol and 2-5 ml liquid detergent. The invention aims at the high-carbon martensitic stainless steel, has good crystal boundary display effect, short corrosion time, simple operation and easy popularization and use, and adopts normal-temperature corrosion without preheating a sample.
Description
Technical Field
The invention belongs to the field of stainless steel metallographic analysis and detection, and particularly relates to a metallographic corrosion method for a high-carbon martensitic stainless steel grain boundary.
Background
The high-carbon martensitic stainless steel belongs to hypereutectoid steel, is stainless steel which is mainly used for improving the wear resistance of materials by increasing the carbon content of steel, has stronger corrosion resistance and wear resistance and is widely used in the fields of bearing rings, bearing rolling bodies, precision shafts, measuring tools, surgical instruments and the like. The matrix of the stainless steel material contains high carbon content, the quenched metallographic structure generally comprises a martensite matrix, eutectic carbide, retained austenite, secondary carbide and a metal compound, the undissolved secondary carbide is uniformly distributed on the matrix and a crystal boundary after quenching due to the high carbon content, a common chlorinated high-iron hydrochloric acid alcohol etching agent is difficult to clearly corrode the crystal boundary of original austenite grains and grade the grain size, and in the actual metallographic analysis process, the grain size is often graded by observing the quenched martensite structure trend, so that the grading result has deviation. The grade of the grain size has an important effect on the strength, hardness and plasticity of the material, and scientific and accurate evaluation of the grade of the grain size is the main content of gold phase analysis. Therefore, a metallographic etching method for grain boundaries of high-carbon martensitic stainless steel (carbon content ≥ 0.6%) must be explored.
Patent CN110926912A discloses a metallographic etchant for low-carbon super martensitic stainless steel, wherein the carbon content of the steel is 0.01-0.04%, and the metallographic etchant is mainly aimed at low-carbon steel and cannot suggest metallographic corrosion of high-carbon steel.
Patent CN109295456A discloses a dendrite corrosive for precipitation-strengthened martensitic stainless steel, which uses a chemical corrosion method to corrode the dendrite category of continuous casting samples of precipitation-hardened martensitic stainless steel, and is used for evaluating the effect of homogenization heat treatment on the dendrite elimination of precipitation-hardened stainless steel. Similarly, the steel grade in the patent is 0Cr17Ni4Cu4Nb, the carbon content is required to be less than or equal to 0.07 percent, the low-carbon martensite precipitation hardening stainless steel belongs to low-carbon martensite precipitation hardening stainless steel, and cannot bring inspiration to the metallographic corrosion of high-carbon steel.
The patent CN107014661A discloses a method for displaying metallographic corrosion of high-nitrogen martensitic stainless steel, wherein the carbon content of the steel is 0.2-0.6%, the nitrogen content is 0.25-0.5%, the principle of an oxidation method is adopted, and a sample is subjected to heating oxidation and then is subjected to corrosion treatment by a chemical reagent so as to display prior austenite. The method is a display method aiming at the metallographic corrosion of the high-nitrogen martensitic stainless steel, needs heating oxidation and is complex to operate.
Patent CN105908186A discloses a metallographic corrosive agent for martensitic stainless steel, which comprises HCl20ml, alcohol 500ml, picric acid/trinitrophenol 7g and sodium dodecyl benzene sulfonate 2 g. The method is used for corroding the heated metallographic polished sample, the metallographic sample needs to be subjected to pre-heating treatment on the metallographic phase, the sample needs to be continuously wiped in the corrosion process, and the corrosion time is about 1 min.
Therefore, the existing research can only corrode medium-carbon martensitic stainless steel or adopt an oxidation method or a special process of multiple corrosion and polishing, the operation is complex, the cost is high, and a metallographic corrosion method specially aiming at a high-carbon martensitic stainless steel crystal boundary is not provided, so that the urgent development is needed.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: a gold phase corrosion method aiming at the high-carbon martensitic stainless steel and having simple and convenient operation and low cost is lacked.
The technical scheme for solving the problems comprises the following steps: provides a metallographic corrosion method of a high-carbon martensitic stainless steel grain boundary. The method comprises the following steps:
coarse grinding, fine grinding, polishing, cleaning and drying the high-carbon martensitic stainless steel metallographic specimen to obtain a bright and scratch-free polished surface; corroding the polished surface for 5-30 s at room temperature by adopting a metallographic corrosive agent, cleaning and drying; the metallographic corrosive agent comprises the following components: 1-4 g picric acid, 5ml concentrated hydrochloric acid, 100ml alcohol and 2-5 ml liquid detergent.
In the metallographic corrosion method for the grain boundary of the high-carbon martensitic stainless steel, the high-carbon martensitic stainless steel is martensitic stainless steel with the carbon content of more than 0.6 percent and the chromium content of more than 12 percent.
Furthermore, in the metallographic etching method for the grain boundary of the high-carbon martensitic stainless steel, the high-carbon martensitic stainless steel is 6Cr18Mo, 9Cr18, 9Cr18Mo or 9Cr18 MoV.
In the metallographic etching method for the grain boundary of the high-carbon martensitic stainless steel, the preparation method of the metallographic etchant comprises the following steps: the picric acid and the concentrated hydrochloric acid with the formula amount are poured into alcohol, dissolved and mixed evenly, and then the common tableware detergent with the phosphorus-free formula is dripped into the mixture.
Further, in the metallographic corrosion method of the high-carbon martensitic stainless steel grain boundary, the picric acid is analytically pure with the mass fraction of more than 99%; the concentrated hydrochloric acid is concentrated hydrochloric acid with mass concentration more than 30%; the alcohol is analytically pure with the mass fraction of more than 99%; the tableware detergent is a common household tableware detergent with a phosphorus-free formula.
In the metallographic corrosion method of the high-carbon martensitic stainless steel grain boundary, the corrosion method comprises the following steps: and immersing the polished surface into the corrosive agent, or dipping the polished surface into the corrosive agent by using a cotton swab to wipe.
In the metallographic corrosion method of the high-carbon martensitic stainless steel grain boundary, the cleaning is firstly carried out by using clean water and then is carried out by using alcohol.
Compared with the prior art, the invention has the beneficial effects that:
the invention mainly provides a metallographic corrosion method for steels with carbon content higher than 0.6%, such as 6Cr18Mo, 9Cr18, 9Cr18Mo, 9Cr18MoV and the like, and by adopting a proper corrosive agent, the grain boundary of martensitic stainless steel can be clearly and completely displayed, the color and the morphology of the structure do not influence the grain size evaluation of a sample, the grain boundary obtained by the corrosion method has good display effect, the sample is not required to be preheated, the normal temperature corrosion is adopted, the corrosion time is short (5-30 s), and the method is simple to operate and easy to popularize and use. The invention fills the blank of the high-carbon martensite non-light absorption grain boundary corrosion method, provides a quick, simple and effective grain boundary corrosion method, and can accurately finish the metallographic grain size rating.
Drawings
FIG. 1 is a 9Cr18Mo metallographic specimen which has been quenched and has a magnification of 200 times, and has been attacked by 4g of picric acid, 5ml of concentrated hydrochloric acid, 100ml of alcohol and 5ml of dishwashing detergent (ordinary phosphorus-free formulation);
FIG. 2 is a 9Cr18Mo metallographic specimen, which was quenched and magnified 500 times, and was attacked by 4g of picric acid, 5ml of concentrated hydrochloric acid, 100ml of alcohol, and 5ml of dishwashing detergent (ordinary non-phosphate formulation).
FIG. 3 is a diagram of the 6Cr18Mo gold phase corroded by 1g of picric acid, 5ml of concentrated hydrochloric acid, 100ml of alcohol reagent and 2ml of tableware detergent (ordinary non-phosphorus formulation) reagent, wherein the sample is quenched and has a magnification of 200 times;
FIG. 4 is a photograph of a 6Cr18Mo gold phase etched by 1g of picric acid, 5ml of concentrated hydrochloric acid, 100ml of an alcohol reagent, and 2ml of a dishwashing detergent (ordinary phosphorus-free formulation) reagent, wherein the sample is quenched and has a magnification of 500 times;
FIG. 5 is a diagram of 9Cr18Mo gold phase corroded by chlorinated ferric hydrochloric acid reagent, the sample is quenched and has a magnification of 200 times;
FIG. 6 is a diagram of 9Cr18Mo gold phase etched by a cupric chloride chlorohydrate reagent, the sample being quenched at 200 times magnification;
FIG. 7 is a 9Cr18Mo metallographic specimen that was subjected to quenching treatment at 200 times magnification and was attacked by 1g picric acid, 5ml concentrated hydrochloric acid and 100ml alcohol reagent;
FIG. 8 is a photograph of 6Cr18Mo gold phase corroded by 1g of picric acid, 5ml of concentrated hydrochloric acid, 100ml of alcohol reagent and 20ml of dish washing detergent (ordinary non-phosphorus formulation), and the sample is quenched and has a magnification of 200 times.
Detailed Description
The invention provides a metallographic corrosion method of a high-carbon martensitic stainless steel grain boundary, which comprises the following steps of:
coarse grinding, fine grinding, polishing, cleaning and drying the high-carbon martensitic stainless steel metallographic specimen to obtain a bright and scratch-free polished surface; corroding the polished surface for 5-30 s at room temperature by adopting a metallographic corrosive agent, cleaning and drying; the metallographic corrosive agent comprises the following components: 1-4 g picric acid, 5ml concentrated hydrochloric acid, 100ml alcohol and 2-5 ml liquid detergent.
In the metallographic corrosion method for the grain boundary of the high-carbon martensitic stainless steel, the high-carbon martensitic stainless steel is martensitic stainless steel with the carbon content of more than 0.6 percent and the chromium content of more than 12 percent.
Furthermore, in the metallographic etching method for the grain boundary of the high-carbon martensitic stainless steel, the high-carbon martensitic stainless steel is 6Cr18Mo, 9Cr18, 9Cr18Mo or 9Cr18 MoV.
Because the high-carbon martensitic stainless steel contains a large amount of carbon, after quenching treatment, a large amount of carbides are dispersed and distributed at a matrix and a crystal boundary, particularly because the carbides exist at the crystal boundary, a common picric acid hydrochloric acid alcohol reagent, ferric chloride or copper chloride hydrochloric acid alcohol reagent can simultaneously corrode the matrix and the crystal boundary, and the crystal boundary contrast of a corroded sample is not obvious. Therefore, the conventional method is difficult to perform metallographic corrosion on high-carbon martensitic stainless steel.
The formula of the metallographic corrosive agent is obtained through a large number of experiments, because the characteristics of the polycrystalline metal material and the corrosion resistance of crystal grains are different from those of crystal boundaries, the basic principle of metallographic corrosion is that the corrosion resistance is different, and the suitable corrosive agent is selected to improve the corrosion of the crystal boundaries as much as possible and reduce the corrosion of the crystal grains, so that the large optical contrast is achieved, and the observation, comparison and distinction of detection personnel under an optical microscope are facilitated. According to the invention, a certain amount of tableware detergent is particularly added into the metallographic corrosive agent, so that the surface activity of a solvent can be improved, the surface tension of a sample is reduced, and the surface effect of a corrosion inhibition matrix is achieved, thereby improving the optical contrast between crystal grains and crystal boundaries after the sample is corroded. Phosphorus is an element with certain corrosion performance, and the addition of the phosphorus can cause the reduction of the contrast of crystals, so that the tableware detergent needs to adopt the phosphorus-free tableware detergent. .
After the corrosion agent disclosed by the invention is used for corrosion, the contrast between a metallographic structure and a grain boundary is improved, and the quenched martensite prior austenite grains and the annealed pearlite prior austenite grains can be clearly displayed.
In the metallographic etching method for the grain boundary of the high-carbon martensitic stainless steel, the preparation method of the metallographic etchant comprises the following steps: the picric acid and the concentrated hydrochloric acid with the formula amount are poured into alcohol, dissolved and mixed evenly, and then the common tableware detergent with the phosphorus-free formula is dripped into the mixture.
Further, in the metallographic corrosion method of the high-carbon martensitic stainless steel grain boundary, the picric acid is analytically pure with the mass fraction of more than 99%; the concentrated hydrochloric acid is concentrated hydrochloric acid with mass concentration more than 30%; the alcohol is analytically pure with the mass fraction of more than 99%; the tableware detergent is a common household tableware detergent with a phosphorus-free formula.
In the metallographic corrosion method of the high-carbon martensitic stainless steel grain boundary, the cleaning is firstly carried out by using clean water and then is carried out by using alcohol.
Because the invention aims at the steel grade with high carbon content, the corrosion resistance is lower when the carbon content is higher according to the characteristics of the steel grade, the carbon content of the high-carbon martensite stainless steel generally exceeds 0.6 percent, a large amount of carbon can be precipitated in the form of carbide at the grain boundary and can be dispersed in crystal grains, the carbide has limited corrosion during corrosion, if the corrosion is not carried out by a common corrosive agent added with a corrosion inhibitor, the grain boundary of a metallographic phase is not obvious from the crystal grains, and the detection personnel can hardly distinguish the grain boundary from the crystal grains. Since different heat treatment conditions also affect the overall corrosion resistance of the material, the quenched material is less prone to intergranular chromium depletion due to the large amount of carbon being dissolved in the matrix than the annealed material, and the specific corrosion time is determined by the color of the sample surface during corrosion.
In the metallographic corrosion method for the grain boundary of the high-carbon martensitic stainless steel, the rough grinding, the fine grinding, the polishing, the cleaning and the drying of the metallographic specimen of the high-carbon martensitic stainless steel can be carried out by adopting a common method in the field. The rough grinding adopts water sand paper, the grain diameter is below 400 meshes after the rough grinding, then the metallographic sand paper is adopted for fine grinding, the grain diameter is 600/800/1000 meshes after the fine grinding, the diamond grinding paste is adopted for polishing, and the bright polished surface without scratches is obtained after the ultrasonic cleaning agent and the alcohol washing are carried out and then the drying treatment is carried out by electric blowing.
The following examples are intended to illustrate specific embodiments of the present invention without limiting the scope of the invention to the examples.
In the embodiment, two kinds of high-carbon martensitic stainless steels with different carbon contents are respectively selected and treated by the corrosive agent and the corrosion method shown in the invention, and the compositions of the two kinds of high-carbon martensitic stainless steels with different carbon contents are shown in table 1.
TABLE 1 composition of different steels
Example 1 high carbon martensitic stainless steel 9Cr18Mo was etched using the method of the present invention
(1) Sample treatment: the metallographic phase of the 9Cr18Mo high-carbon martensitic stainless steel is subjected to coarse grinding (400 meshes) by using water sand paper, fine grinding by using 600/800/1000 meshes of metallographic sand paper and polishing by using diamond grinding paste, and is cleaned by using an ultrasonic cleaning agent and washed by using alcohol, and then is dried by using electric blowing to obtain a scratch-free bright polished surface.
(2) Weighing 4g of picric acid on an electronic balance by adopting a 200ml beaker, pouring 100ml of analytically pure alcohol into the beaker by using a measuring cylinder, dropping 5ml of concentrated hydrochloric acid with the mass fraction of 30% into the beaker by using another measuring cylinder, stirring by using a glass rod, adding 5ml of a solution of detergent after dissolution, continuously stirring uniformly, pouring the prepared reagent into a volumetric flask, and standing for 30 min;
(3) pouring a certain amount of prepared corrosive solvent (only the observation surface of the sample can be corroded) into a glass culture dish, and clamping the prepared metallographic sample by using tweezers to corrode for 5-10 s (only the surface of the sample becomes grey);
(4) taking out the corroded sample, washing the corroded sample with clear water, washing the washed sample with analytical pure alcohol for the second time, and then drying the washed sample by blowing;
(5) the grain boundary and the grain matrix are further improved in contrast by being placed on a metallographic microscope for metallographic observation, and the brightness and the contrast of the shot metallographic picture can be properly adjusted, as shown in figures 1 and 2.
Example 2 high carbon martensitic stainless steel of 6Cr18Mo was etched using the method of the present invention
(1) Sample treatment: the metallographic phase of the 6Cr18Mo high-carbon martensitic stainless steel is subjected to coarse grinding (400 meshes) by using water sand paper, fine grinding by using 600/800/1000 meshes of metallographic sand paper and polishing by using diamond grinding paste, and is cleaned by using an ultrasonic cleaning agent and washed by using alcohol, and then is dried by using electric blowing to obtain a scratch-free bright polished surface.
(2) Weighing 1g of picric acid on an electronic balance by adopting a 200ml beaker, pouring 100ml of analytically pure alcohol into the beaker by using a measuring cylinder, dropping 5ml of concentrated hydrochloric acid with the mass fraction of 30% into the beaker by using a glass rod, stirring by using a glass rod, adding 2ml of a solution of a detergent after dissolution is finished, continuing stirring uniformly, pouring a prepared reagent into a volumetric flask, and standing for 30 min;
(3) pouring a certain amount of prepared corrosive solvent (only the observation surface of the sample can be corroded completely) into a glass culture dish, and clamping the prepared metallographic sample by using forceps for corrosion for 30s (because the proportion of picric acid is adjusted, the corrosion time is properly increased, and the grey surface of the sample is judged according to the color of the corroded actual sample);
(4) taking out the corroded sample, washing the corroded sample with clear water, washing the washed sample with analytical pure alcohol for the second time, and then drying the washed sample by blowing;
(5) the product is placed on a metallographic microscope for metallographic observation, and the contrast between crystal boundaries and crystal grains is reduced due to the reduction of the formula amount of the detergent with the surfactant, as shown in figures 3 and 4.
Comparative example 3 a 9Cr18Mo high carbon martensitic stainless steel was etched using the methods of the prior art references
(1) Sample treatment: the metallographic phase of the 9Cr18Mo high-carbon martensitic stainless steel is subjected to coarse grinding (400 meshes) by using water sand paper, fine grinding by using 600/800/1000 meshes of metallographic sand paper and polishing by using diamond grinding paste, and is cleaned by using an ultrasonic cleaning agent and washed by using alcohol, and then is dried by using electric blowing to obtain a scratch-free bright polished surface.
(2) Weighing 5g of ferric trichloride on an electronic balance by adopting a 200ml beaker, pouring 25ml of analytically pure alcohol into the beaker by using a measuring cylinder, dropping 25ml of concentrated hydrochloric acid with the mass fraction of 30% into the beaker by using another measuring cylinder, stirring by using a glass rod, uniformly dissolving, pouring the prepared reagent into a volumetric flask, and standing for 30 min;
(3) pouring a certain amount of prepared corrosive solvent (which can completely corrode the observation surface of the sample) into a glass culture dish, and clamping the prepared metallographic sample by using tweezers to corrode or wiping the prepared metallographic sample by using a degreasing cotton swab until the surface of the sample becomes grey;
(4) taking out the corroded sample, washing the corroded sample with clear water, washing the washed sample with analytical pure alcohol for the second time, and then drying the washed sample by blowing;
(5) the sample was placed on a metallographic microscope for metallographic observation, and the photographed metallographic picture was as shown in fig. 5.
Comparative example 4 a 9Cr18Mo high carbon martensitic stainless steel was etched using the methods of the prior art references
(1) Sample treatment: the metallographic phase of the 9Cr18Mo high-carbon martensitic stainless steel is subjected to coarse grinding (400 meshes) by using water sand paper, fine grinding by using 600/800/1000 meshes of metallographic sand paper and polishing by using diamond grinding paste, and is cleaned by using an ultrasonic cleaning agent and washed by using alcohol, and then is dried by using electric blowing to obtain a scratch-free bright polished surface.
(2) Weighing 1.5g of copper chloride on an electronic balance by adopting a 200ml beaker, pouring 25ml of analytically pure alcohol into the beaker by using a measuring cylinder, then taking 33ml of distilled water into the beaker by using a measuring cylinder, further taking 33ml of concentrated hydrochloric acid with the mass fraction of 30% from the measuring cylinder, dripping the concentrated hydrochloric acid into the beaker, stirring by using a glass rod, uniformly dissolving, pouring the prepared reagent into a volumetric flask, and standing for 30 min;
(3) pouring a certain amount of prepared corrosive solvent (which can completely corrode the observation surface of the sample) into a glass culture dish, and clamping and corroding the prepared metallographic sample by using tweezers until the surface of the sample is grayed;
(4) taking out the corroded sample, washing the corroded sample with clear water, washing the washed sample with analytical pure alcohol for the second time, and then drying the washed sample by blowing;
(5) the sample was placed on a metallographic microscope for metallographic observation, and the photographed metallographic picture was as shown in fig. 6.
Comparative example 5 high carbon martensitic stainless steel 9Cr18Mo was etched using the prior art literature
(1) Sample treatment: the metallographic phase of the 9Cr18Mo high-carbon martensitic stainless steel is subjected to coarse grinding (400 meshes) by using water sand paper, fine grinding by using 600/800/1000 meshes of metallographic sand paper and polishing by using diamond grinding paste, and is cleaned by using an ultrasonic cleaning agent and washed by using alcohol, and then is dried by using electric blowing to obtain a scratch-free bright polished surface.
(2) Weighing 1g of picric acid on an electronic balance by adopting a 200ml beaker, pouring 100ml of analytically pure alcohol into the beaker by using a measuring cylinder, dropping 5ml of concentrated hydrochloric acid with the mass fraction of 30% into the beaker by using a measuring cylinder, uniformly stirring by using a glass rod, pouring the prepared reagent into a volumetric flask, and standing for 30 min;
(3) pouring a certain amount of prepared corrosive solvent (which can completely corrode the observation surface of the sample) into a glass culture dish, and clamping and corroding the prepared metallographic sample by using tweezers until the surface of the sample is grayed;
(4) taking out the corroded sample, washing the corroded sample with clear water, washing the washed sample with analytical pure alcohol for the second time, and then drying the washed sample by blowing;
(5) the sample was placed on a metallographic microscope for metallographic observation, and the photographed metallographic picture is shown in fig. 7.
Comparative example 6 high carbon martensitic stainless steel of 6Cr18Mo was etched by the method of the present invention
(1) Sample treatment: the metallographic phase of the 6Cr18Mo high-carbon martensitic stainless steel is subjected to coarse grinding (400 meshes) by using water sand paper, fine grinding by using 600/800/1000 meshes of metallographic sand paper and polishing by using diamond grinding paste, and is cleaned by using an ultrasonic cleaning agent and washed by using alcohol, and then is dried by using electric blowing to obtain a scratch-free bright polished surface.
(2) Weighing 1g of picric acid on an electronic balance by adopting a 200ml beaker, pouring 100ml of analytically pure alcohol into the beaker by using a measuring cylinder, dropping 5ml of concentrated hydrochloric acid with the mass fraction of 30% into the beaker by using another measuring cylinder, stirring by using a glass rod, adding 20ml of a solution of a detergent after dissolution is finished, continuing stirring uniformly, pouring a prepared reagent into a volumetric flask, and standing for 30 min;
(3) pouring a certain amount of prepared corrosion solvent (which can completely corrode the observation surface of the sample) into a glass culture dish, and clamping and corroding the prepared metallographic sample by using tweezers for 30-180s (as the proportion of the detergent is adjusted, the detergent serving as a corrosion inhibitor can weaken the corrosion efficiency of picric acid and hydrochloric acid on the sample, greatly increase the corrosion time to 180s, and then the sample still presents a bright surface and is a metallographic image corroded for 30 s);
(4) taking out the corroded sample, washing the corroded sample with clear water, washing the washed sample with analytical pure alcohol for the second time, and then drying the washed sample by blowing;
(5) the sample is placed on a metallographic microscope for metallographic observation, and a photographed metallographic picture is shown in fig. 8, and only part of the outline of the eutectic carbide in the sample is corroded.
From the results of the examples and comparative examples, it can be seen that: the invention provides a special metallographic corrosion method for steel with carbon content higher than 0.6%, and a certain amount of detergent is specially added into the corrosive agent, so that the surface activity of a solvent of the corrosive agent is changed, the surface tension of a sample is reduced, the crystal boundary of martensitic stainless steel can be clearly and completely displayed, and the color and the morphology of the structure do not influence the grain size evaluation of the sample.
Claims (7)
1. The metallographic corrosion method of the high-carbon martensitic stainless steel grain boundary is characterized by comprising the following steps of:
carrying out coarse grinding, fine grinding, polishing, cleaning and drying on the high-carbon martensitic stainless steel metallographic specimen to obtain a bright and scratch-free polished surface; corroding the polished surface for 5-30 s at room temperature by adopting a metallographic corrosive agent, cleaning and drying; the metallographic corrosive agent comprises the following components: 1-4 g picric acid, 5ml concentrated hydrochloric acid, 100ml alcohol and 2-5 ml liquid detergent.
2. The metallographic etching method for grain boundaries of high-carbon martensitic stainless steel according to claim 1, characterized in that: the high-carbon martensitic stainless steel is martensitic stainless steel with the carbon content being more than 0.6 percent and the chromium content being more than 12 percent.
3. The metallographic etching method for grain boundaries of high-carbon martensitic stainless steel according to claim 1, characterized in that: the high-carbon martensitic stainless steel is 6Cr18Mo, 9Cr18, 9Cr18Mo or 9Cr18 MoV.
4. The metallographic etching method for grain boundaries of high-carbon martensitic stainless steel according to claim 1, characterized in that: the preparation method of the metallographic corrosive agent comprises the following steps: the picric acid and the concentrated hydrochloric acid with the formula amount are poured into alcohol, dissolved and mixed evenly, and then the common tableware detergent with the phosphorus-free formula is dripped into the mixture.
5. The metallographic etching method for grain boundaries of high-carbon martensitic stainless steel according to claim 1, characterized in that: the picric acid is analytically pure with the mass fraction of more than 99 percent; the concentrated hydrochloric acid is concentrated hydrochloric acid with mass concentration more than 30%; the alcohol is analytically pure with the mass fraction of more than 99%; the tableware detergent is a common household tableware detergent with a phosphorus-free formula.
6. The metallographic etching method for grain boundaries of high-carbon martensitic stainless steel according to claim 1, characterized in that: the erosion method comprises the following steps: and immersing the polished surface into the corrosive agent, or dipping the polished surface into the corrosive agent by using a cotton swab to wipe.
7. The metallographic etching method for grain boundaries of high-carbon martensitic stainless steel according to claim 1, characterized in that: the cleaning is that the cleaning is firstly carried out by clean water and then is carried out by alcohol.
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| CN115505687A (en) * | 2022-09-02 | 2022-12-23 | 泰州市佳乐金属制品有限公司 | Solid solution heat treatment process for stainless steel standard part |
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Application publication date: 20201023 |