CN117587409A - Metallographic corrosive liquid for as-cast duplex stainless steel, and preparation method and use method thereof - Google Patents
Metallographic corrosive liquid for as-cast duplex stainless steel, and preparation method and use method thereof Download PDFInfo
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- CN117587409A CN117587409A CN202311595778.7A CN202311595778A CN117587409A CN 117587409 A CN117587409 A CN 117587409A CN 202311595778 A CN202311595778 A CN 202311595778A CN 117587409 A CN117587409 A CN 117587409A
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- 229910001039 duplex stainless steel Inorganic materials 0.000 title claims abstract description 58
- 239000007788 liquid Substances 0.000 title claims abstract description 45
- 238000000034 method Methods 0.000 title claims abstract description 25
- 238000002360 preparation method Methods 0.000 title abstract description 11
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 77
- 239000000203 mixture Substances 0.000 claims description 69
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 claims description 44
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 31
- 229910017604 nitric acid Inorganic materials 0.000 claims description 31
- ORTQZVOHEJQUHG-UHFFFAOYSA-L copper(II) chloride Chemical compound Cl[Cu]Cl ORTQZVOHEJQUHG-UHFFFAOYSA-L 0.000 claims description 22
- 238000005530 etching Methods 0.000 claims description 20
- 238000003756 stirring Methods 0.000 claims description 15
- 238000005406 washing Methods 0.000 claims description 15
- 229920000742 Cotton Polymers 0.000 claims description 14
- 238000001035 drying Methods 0.000 claims description 12
- 238000005303 weighing Methods 0.000 claims description 12
- 230000003287 optical effect Effects 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 7
- 238000007598 dipping method Methods 0.000 claims description 7
- 238000002156 mixing Methods 0.000 claims description 3
- QUQFTIVBFKLPCL-UHFFFAOYSA-L copper;2-amino-3-[(2-amino-2-carboxylatoethyl)disulfanyl]propanoate Chemical compound [Cu+2].[O-]C(=O)C(N)CSSCC(N)C([O-])=O QUQFTIVBFKLPCL-UHFFFAOYSA-L 0.000 claims 1
- 239000003153 chemical reaction reagent Substances 0.000 abstract description 5
- 230000000007 visual effect Effects 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 24
- 238000005260 corrosion Methods 0.000 description 22
- 230000007797 corrosion Effects 0.000 description 22
- 239000000463 material Substances 0.000 description 16
- 239000013078 crystal Substances 0.000 description 15
- 229910000859 α-Fe Inorganic materials 0.000 description 13
- 239000007864 aqueous solution Substances 0.000 description 11
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 9
- 229910001566 austenite Inorganic materials 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 9
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 9
- 238000001514 detection method Methods 0.000 description 8
- 239000003086 colorant Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- HRZFUMHJMZEROT-UHFFFAOYSA-L sodium disulfite Chemical compound [Na+].[Na+].[O-]S(=O)S([O-])(=O)=O HRZFUMHJMZEROT-UHFFFAOYSA-L 0.000 description 7
- 229940001584 sodium metabisulfite Drugs 0.000 description 7
- 235000010262 sodium metabisulphite Nutrition 0.000 description 7
- QZPSXPBJTPJTSZ-UHFFFAOYSA-N aqua regia Chemical compound Cl.O[N+]([O-])=O QZPSXPBJTPJTSZ-UHFFFAOYSA-N 0.000 description 6
- 239000007769 metal material Substances 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 150000001450 anions Chemical class 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000004043 dyeing Methods 0.000 description 2
- 238000011010 flushing procedure Methods 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 230000000877 morphologic effect Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 241001270131 Agaricus moelleri Species 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229910000885 Dual-phase steel Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000003556 assay Methods 0.000 description 1
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 229960003280 cupric chloride Drugs 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F1/00—Etching metallic material by chemical means
- C23F1/10—Etching compositions
- C23F1/14—Aqueous compositions
- C23F1/16—Acidic compositions
- C23F1/28—Acidic compositions for etching iron group metals
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
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Abstract
The invention provides a metallographic corrosive liquid for as-cast duplex stainless steel, a preparation method and a use method thereof, wherein the metallographic corrosive liquid comprises the following components: the metallographic corrosive liquid for the as-cast duplex stainless steel has the advantages that the metallographic color contrast of a metallographic photograph is good, and the grain combination characteristics are visual and vivid; the reagent is common and convenient to prepare; and has the advantage of extremely high success rate.
Description
Technical Field
The invention relates to the technical field of metallographic examination of metal materials, in particular to a metallographic corrosive liquid for as-cast duplex stainless steel, and a preparation method and a use method thereof.
Background
The duplex stainless steel is obtained by increasing the content of elements forming ferrite such as chromium, molybdenum, titanium and the like on the basis of 18-8 austenitic stainless steel, reducing the content of elements forming austenite such as nickel, manganese and the like, and then carrying out solution treatment. Among them, austenite phase (Austenitic) is a phase having high corrosion resistance and high toughness, usually formed at high temperature, and is characterized by a face-centered cubic structure; ferrite phase (ferrite) is another phase, which has lower corrosion resistance but generally higher strength, and ferrite phase is formed at a lower temperature and has a structure of body-centered cubic. The metallographic structure of the duplex stainless steel is that island austenite is distributed on a ferrite matrix, and the ferrite content is generally about 50-70%. The as-cast duplex stainless steel is prepared by a casting process, and because the structure of the duplex stainless steel contains both an austenite phase and a ferrite phase, the duplex stainless steel combines the corrosion resistance of the austenite phase and the strength of the ferrite phase, so that the duplex stainless steel is excellent in some special applications, particularly in environments requiring higher strength and corrosion resistance, such as chemical engineering, ocean engineering and some special high-temperature and high-pressure environments.
In the prior art, the common metallographic corrosive liquid for the duplex stainless steel is aqua regia, sodium metabisulfite hydrochloric acid aqueous solution and the like; the metallographic corrosive liquid used for the stainless steel material also comprises ferric chloride aqueous solution, hydrochloric acid and nitric acid aqueous solution and the like. The aqua regia, sodium metabisulfite and hydrochloric acid solution is mainly used for corroding the metallographic structure of the duplex stainless steel so as to display and distinguish two phases in the duplex steel; the test shows that the ferric chloride aqueous solution and the hydrochloric acid ferric chloride aqueous solution can not corrode the duplex stainless steel, and the test surface is still bright after long-time corrosion.
Grain size detection is a conventional detection item in metallographic detection, grain size is a characteristic of a crystal size or a crystal structure in a material, and the size of the grain size can influence physical and mechanical properties of the material, so that the performance of the material can be predicted and understood through grain size detection and knowledge of a microstructure of the material, and the selection of a proper material for a specific application scene is facilitated; the method can help to optimize the processing technology and improve the processing performance and formability of the material, which is important for the processing processes of forging, rolling, quenching and the like of the metal material; in addition, grain size and grain boundaries have an effect on the corrosion resistance of the material, smaller grains generally mean more grain boundaries, possibly leading to higher corrosion resistance, so that the behavior of the material in a corrosive environment can be understood by grain size detection; the grain structure also has an effect on the fatigue performance of the metal material, smaller grains are generally associated with a higher fatigue life, and the behavior of the material under fatigue loading can be better understood by detecting the grain size; the distribution and shape of the grains is also related to the fracture behaviour of the material, and grain size detection can provide information about the fracture toughness and fracture mode of the material. In general, grain size detection of metallic materials is a key step in understanding and optimizing material properties, helping to guide material design, processing, and application. However, the existing metallurgical corrosive liquids such as aqua regia, sodium metabisulfite hydrochloric acid solution and the like can only be used for corroding the metallurgical structure of the duplex stainless steel, and the two phases in the duplex steel are distinguished, so that the appearance characteristics of crystal grains of the metallurgical corrosive liquids can not be displayed, and the existing metallurgical corrosive liquids and corrosion methods for effectively detecting the grain size of the as-cast duplex stainless steel are lacking.
Disclosure of Invention
The invention designs a metallographic corrosive liquid for as-cast duplex stainless steel, a preparation method and a use method thereof, and aims to solve the technical problem that the existing metallographic corrosive liquid cannot display the crystal grain morphology characteristics of as-cast duplex stainless steel.
In order to solve the problems, the invention discloses a metallographic etching solution for as-cast duplex stainless steel, which comprises the following components:
a mixture A of hydrochloric acid and copper chloride,
and a mixture B of nitric acid and ferric nitrate.
Further, in the metallographic etching solution, the mass ratio of the mixture A to the mixture B is (0.7-1.3): 1.
further, in the metallographic corrosive liquid, the mass ratio of the mixture A to the mixture B is 1:1.
further, in the mixture A, the addition amount of copper chloride is 0.04 to 0.06g/ml.
Further, in the mixture B, the addition amount of ferric nitrate is 0.04-0.06 g/ml.
Further, the mass concentration of the hydrochloric acid is 35-40%, and the mass concentration of the nitric acid is 60-75%.
Further, the metallographic corrosive liquid comprises the following formula:
a mixture A of 10-12 ml hydrochloric acid and 0.5g copper chloride,
and, per 10ml to 12ml of a mixture B of nitric acid and 0.5g of ferric nitrate.
The preparation method of the metallographic corrosive liquid for the as-cast duplex stainless steel is used for preparing the metallographic corrosive liquid for the as-cast duplex stainless steel and comprises the following steps:
s1, preparing a mixture A: weighing a certain amount of hydrochloric acid into a container according to a weight ratio, adding a certain amount of copper chloride into the container according to the weight ratio, and uniformly stirring to obtain a mixture A;
s2, preparing a mixture B: weighing a certain amount of nitric acid in a container according to the weight ratio, adding a certain amount of ferric nitrate in the container according to the weight ratio, and stirring uniformly to obtain a mixture B;
s3, preparing metallographic corrosive liquid: and mixing the mixture A and the mixture B, and stirring uniformly to obtain the metallographic etching solution.
A method of using a metallographic etchant for as-cast duplex stainless steel, the method of using the metallographic etchant for as-cast duplex stainless steel comprising:
firstly preparing a metallographic sample to be corroded, dipping the metallographic corrosive liquid by using absorbent cotton, wiping the surface of the sample at normal temperature by using the absorbent cotton until the surface of the sample turns grey, and then washing and drying the surface of the sample to detect the grain size under an optical metallographic microscope.
Further, the process of rinsing and drying the surface of the sample is as follows: firstly, washing the surface of a sample by flowing water, then washing the surface of the sample by absolute ethyl alcohol, and finally drying the surface of a metallographic sample.
The metallographic corrosive liquid for the as-cast duplex stainless steel, the preparation method and the use method thereof have the advantages that the gray color contrast of metallographic photos is good, and the grain combination characteristics are visual and vivid; the reagent is common and convenient to prepare; and has the advantage of extremely high success rate.
Drawings
FIG. 1 is a metallographic photograph of as-cast duplex stainless steel obtained in example 1 of the present invention;
FIG. 2 is a metallographic photograph of as-cast duplex stainless steel obtained in example 2 of the present invention;
FIG. 3 is a metallographic photograph of as-cast duplex stainless steel obtained in example 3 of the present invention;
FIG. 4 is another metallographic photograph of as-cast duplex stainless steel obtained in example 3 of the present invention;
FIG. 5 is a metallographic photograph of as-cast duplex stainless steel obtained in comparative example 1 of the present invention;
FIG. 6 is another metallographic photograph of the as-cast duplex stainless steel of comparative example 1 of the present invention;
FIG. 7 is a metallographic photograph of as-cast duplex stainless steel obtained in comparative example 2 of the present invention;
FIG. 8 is another metallographic photograph of the as-cast duplex stainless steel of comparative example 2 of the present invention;
FIG. 9 is a metallographic photograph of as-cast duplex stainless steel obtained in comparative example 3 of the present invention.
Detailed Description
In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.
A metallographic etchant for as-cast duplex stainless steel comprising:
a mixture A of hydrochloric acid and copper chloride,
and a mixture B of nitric acid and ferric nitrate.
Further, in the metallographic etching solution, the mass ratio of the mixture A to the mixture B is (0.7-1.3): 1.
preferably, in the metallographic corrosive liquid, the mass ratio of the mixture A to the mixture B is 1:1.
further, in the mixture A, the addition amount of copper chloride is 0.04 to 0.06g/ml.
Preferably, in the mixture A, the addition amount of copper chloride is 0.05g/ml.
Preferably, in the mixture a, the mass concentration of the hydrochloric acid is 35 to 40%.
Further, in the mixture B, the addition amount of ferric nitrate is 0.04-0.06 g/ml.
Preferably, in said mixture B, the amount of ferric nitrate added is 0.05g/ml.
Preferably, in the mixture B, the mass concentration of the nitric acid is 60 to 75%.
As a preferred embodiment of the invention, the metallographic corrosive liquid comprises the following formula: 10ml to 12ml of hydrochloric acid, 0.5g of cupric chloride, 10ml to 12ml of nitric acid and 0.5g of ferric nitrate. Of course, the amount of each raw material in the formulation can be scaled up or down in equal proportions.
In addition, the invention also provides a preparation method of the metallographic corrosive liquid, which comprises the following steps:
s1, preparing a mixture A: weighing a certain amount of hydrochloric acid into a container according to a weight ratio, adding a certain amount of copper chloride into the container according to the weight ratio, and uniformly stirring to obtain a mixture A;
s2, preparing a mixture B: weighing a certain amount of nitric acid in a container according to the weight ratio, adding a certain amount of ferric nitrate in the container according to the weight ratio, and stirring uniformly to obtain a mixture B;
s3, preparing metallographic corrosive liquid: and mixing the mixture A and the mixture B, and stirring uniformly to obtain the metallographic etching solution.
Furthermore, the invention also provides a use method of the metallographic corrosive liquid, which comprises the following steps: firstly preparing a metallographic sample to be corroded, then dipping the metallographic corrosive liquid with absorbent cotton, wiping the surface of the sample with absorbent cotton at normal temperature for 40S-50S until the surface of the sample turns grey, firstly flushing the surface of the sample with running water, then flushing the surface of the sample with absolute ethyl alcohol, finally drying the surface of the metallographic sample with an electric hair drier, and then observing the grain characteristics under an optical metallographic microscope and detecting the grain size.
As some examples of the present application, the preparation process of the metallographic specimen to be corroded is: the cast duplex stainless steel metallographic specimen is subjected to coarse grinding, fine grinding, polishing, cleaning and drying to obtain a bright and scratch-free polished surface.
The metallographic etching liquid for the as-cast duplex stainless steel, the preparation method and the use method thereof are illustrated by the following specific examples:
example 1
The ratio of metallographic corrosive liquid:
mixture a:10ml hydrochloric acid +0.5g copper chloride,
mixture B:10ml nitric acid +0.5g ferric nitrate.
Preparing metallographic etching liquid: 10ml of hydrochloric acid with the concentration of 35% is measured and poured into a beaker, 0.5g of copper chloride is measured and poured into hydrochloric acid solution, and the mixture A is obtained after uniform stirring; then 10ml of nitric acid with the concentration of 60% is measured and poured into another beaker, 0.5g of ferric nitrate is measured and poured into the nitric acid solution, and the mixture B is obtained after uniform stirring; the mixture A and the mixture B are mixed to obtain the metallographic etching solution which is used at room temperature.
Use of metallographic etching solution: firstly preparing a metallographic sample to be corroded, dipping the metallographic corrosive liquid with absorbent cotton, wiping the sample surface 40S at normal temperature by using absorbent cotton until the sample surface turns grey, washing the sample surface with running water, washing the sample surface with absolute ethyl alcohol, and finally drying the metallographic sample surface by using an electric hair drier, and then placing the metallographic sample surface under an optical metallographic microscope to observe the grain characteristics and detect the grain size.
Fig. 1 is a graph of the morphology of the as-cast duplex stainless steel observed in example 1, and it can be seen from fig. 1: under an optical metallographic microscope, each grain of the as-cast duplex stainless steel presents different gray colors, the grain is clear and visible, and the corrosion effect is excellent.
Example 2
The ratio of metallographic corrosive liquid:
mixture a:12ml hydrochloric acid+0.5g copper chloride;
mixture B:12ml nitric acid +0.5g ferric nitrate.
Preparing metallographic etching liquid: weighing 12ml of hydrochloric acid with the concentration of 40% and pouring the hydrochloric acid into a beaker, weighing 0.5g of copper chloride and pouring the copper chloride into a hydrochloric acid solution, and uniformly stirring to obtain a mixture A; then, weighing 12ml of nitric acid with the concentration of 75% and pouring the nitric acid into another beaker, weighing 0.5g of ferric nitrate and pouring the ferric nitrate into a nitric acid solution, and uniformly stirring to obtain a mixture B; the mixture A and the mixture B are mixed to obtain the metallographic etching solution which is used at room temperature.
Use of metallographic etching solution: firstly preparing a metallographic sample to be corroded, dipping the metallographic corrosive liquid with absorbent cotton, wiping the sample surface 50S at normal temperature by using absorbent cotton until the sample surface turns grey, washing the sample surface with running water, washing the sample surface with absolute ethyl alcohol, and finally drying the metallographic sample surface by using an electric hair drier, and then placing the metallographic sample surface under an optical metallographic microscope to observe grain characteristics and detect grain size.
Fig. 2 is a graph of the morphology of the as-cast duplex stainless steel observed in example 2, and it can be seen from fig. 2: under an optical metallographic microscope, each grain of the as-cast duplex stainless steel presents different gray colors, the grain is clear and visible, and the corrosion effect is excellent.
Example 3
The ratio of metallographic corrosive liquid:
mixture a:10ml hydrochloric acid +0.4g copper chloride,
mixture B:12ml nitric acid +0.4g ferric nitrate.
Preparing metallographic etching liquid: 10ml of hydrochloric acid with concentration of 37% is measured and poured into a beaker, then 0.4g of copper chloride is measured and poured into hydrochloric acid solution, and mixture A is obtained after uniform stirring; then, weighing 12ml of nitric acid with the concentration of 70% and pouring the nitric acid into another beaker, weighing 0.4g of ferric nitrate and pouring the ferric nitrate into a nitric acid solution, and uniformly stirring to obtain a mixture B; the mixture A and the mixture B are mixed to obtain the metallographic etching solution which is used at room temperature.
Use of metallographic etching solution: firstly preparing a metallographic sample to be corroded, dipping the metallographic corrosive liquid with absorbent cotton, wiping the sample surface 45S at normal temperature by using absorbent cotton until the sample surface turns grey, washing the sample surface with running water, washing the sample surface with absolute ethyl alcohol, and finally drying the metallographic sample surface by using an electric hair drier, and then placing the metallographic sample surface under an optical metallographic microscope to observe grain characteristics and detect grain size.
FIGS. 3 to 4 are metallographic photographs of as-cast duplex stainless steel observed in example 3, as can be seen from FIGS. 3 to 4: under an optical metallographic microscope, each grain of the as-cast duplex stainless steel presents different gray colors, the grain is clear and visible, and the corrosion effect is excellent. This is because different crystal grain orientations are different, the corrosion degree to the crystal grain is different, and the crystal grain morphology is easier to identify due to rich contrast colors, so that the analysis of the crystal grain thickness degree is facilitated.
Comparative example 1
Corroding the as-cast duplex stainless steel by adopting a corrosive liquid of aqua regia (30 ml of hydrochloric acid with the concentration of 37 percent and 10ml of nitric acid with the concentration of 68 percent) for 1 minute, wherein the metallographic structure is ferrite and austenite, the ferrite is light gray, and the austenite is white and bright, and is shown in figure 5; the grain features are not visible, see fig. 6.
Comparative example 2
Corroding the as-cast duplex stainless steel for 40 seconds by adopting aqueous solution of sodium metabisulfite and hydrochloric acid (90 ml of water+10 ml of hydrochloric acid with concentration of 37 percent and 1g of sodium metabisulfite), wherein the corroding liquid is a colorful metallographic corroding agent which dyes ferrite phase into dark color and austenite phase is white and bright, thereby realizing the distinction of the two phases, and is shown in figure 7; but cannot show grain characteristics, see fig. 8.
Comparative example 3
As a result of corrosion of the as-cast duplex stainless steel with aqueous ferric chloride acid solution (50 ml of water+10 ml of 37% strength hydrochloric acid+5 g of ferric chloride) and aqueous hydrochloric acid/nitric acid chloride aqueous solution (20 ml of hydrochloric acid+5 ml of nitric acid+5 g of ferric chloride+100 ml of water) for 3 minutes, no corrosion of the duplex steel was possible, and a metallographic photograph of the corrosion of the aqueous ferric chloride acid solution was shown in FIG. 9.
In comparative examples 1 to 3, the etching method used was: firstly preparing a metallographic sample to be corroded, dipping the metallographic corrosive liquid with absorbent cotton, wiping the surface of the sample with absorbent cotton at normal temperature for a certain time until the surface of the sample turns grey, washing the surface of the sample with running water, washing the surface of the sample with absolute ethyl alcohol, and finally drying the surface of the metallographic sample and placing the metallographic sample under an optical metallographic microscope for detection.
It can be seen from the above that: the cast duplex stainless steel has stronger corrosion resistance, and the existing corrosive liquid:
(1) The aqueous solution of ferric chloride, hydrochloric acid, nitric acid, aqueous solution of ferric chloride and the like can not corrode the dual-phase steel;
(2) Hydrochloric acid and nitric acid are strong acids and have strong corrosiveness, and the ratio of hydrochloric acid to nitric acid is 3: the ratio of 1 forms aqua regia which can corrode the morphological characteristics of ferrite and austenite phases, but cannot display the morphological characteristics of crystal grains; the sodium metabisulfite hydrochloric acid aqueous solution is not very strong in corrosion, but has good dyeing effect, and can realize ferrite dyeing, so that the purpose of displaying two phases is achieved. However, the two kinds of corrosive liquids can not realize good display of crystal grains, the aqua regia and the aqueous solution of sodium metabisulfite hydrochloride are both relatively uniform to corrode the whole sample surface, and corrosion of different gray scales generated according to the crystal grain position does not occur.
In the etching solution adopted by the invention, copper chloride and hydrochloric acid have the same anions, and ferric nitrate and nitric acid have the same anions, so that the etching solution can generate special etching effects on grains in different directions, namely, different grains show different gray gradients, thereby realizing the identification of the grains and achieving the purpose of detecting the grain size. It should be noted that: the invention realizes the corrosion of different gray colors of the grain surface instead of the corrosion of the grain boundary, and realizes the observation and the grading of the grains through the different colors of the grains.
Therefore, the metallographic corrosive liquid for the as-cast duplex stainless steel is not difficult to obtain, and the preparation method and the use method of the metallographic corrosive liquid have the following advantages:
firstly, the gray color contrast of the metallographic photo is good, and the grain combination characteristics are visual and vivid; the corrosion method can enable the crystal grains of the as-cast duplex stainless steel to be presented in different gray scale colors, and enable the crystal grains to present gray scale with larger contrast under a microscope, and the high contrast is helpful for more clearly observing and analyzing the combination characteristics of the crystal grains, such as the boundary and the shape of the crystal grains;
secondly, the reagent is common and convenient to prepare; the reagents used in the invention are relatively common and convenient to prepare, which is an advantage for laboratory work, since it means that no complex or expensive reagents are required, thereby improving the feasibility and economy of the assay;
thirdly, the success rate is extremely high; the corrosion method disclosed by the invention is very reliable and has high success rate when treating an as-cast duplex stainless steel sample; the method has strong applicability to samples, and can stably generate clear grain microscopic images under various conditions.
Although the present invention is disclosed above, the present invention is not limited thereto. In the description of the present specification, reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention should be assessed accordingly to that of the appended claims.
Claims (10)
1. A metallographic etchant for as-cast duplex stainless steel, comprising:
a mixture A of hydrochloric acid and copper chloride,
and a mixture B of nitric acid and ferric nitrate.
2. The metallographic etchant for as-cast duplex stainless steel according to claim 1, wherein in the metallographic etchant, the mass ratio of the mixture a to the mixture B is (0.7-1.3): 1.
3. the metallographic etchant for as-cast duplex stainless steel according to claim 2, wherein in the metallographic etchant, the mass ratio of the mixture a to the mixture B is 1:1.
4. the metallographic etchant for as-cast duplex stainless steel according to claim 1, wherein the copper chloride is added in an amount of 0.04-0.06 g/ml in the mixture A.
5. The metallographic etchant for as-cast duplex stainless steel according to claim 1, wherein the amount of ferric nitrate added in the mixture B is 0.04-0.06 g/ml.
6. The metallographic etchant for as set forth in claim 1, wherein the mass concentration of hydrochloric acid is 35-40% and the mass concentration of nitric acid is 60-75%.
7. A metallographic etchant for as set forth in claim 1 or 3, wherein the metallographic etchant has the formula:
a mixture A of 10-12 ml hydrochloric acid and 0.5g copper chloride,
and, per 10ml to 12ml of a mixture B of nitric acid and 0.5g of ferric nitrate.
8. A method for preparing a metallographic etchant for as-cast duplex stainless steel, characterized in that the method is used for preparing the metallographic etchant for as-cast duplex stainless steel according to any one of claims 1 to 7, and the method comprises the steps of:
s1, preparing a mixture A: weighing a certain amount of hydrochloric acid into a container according to a weight ratio, adding a certain amount of copper chloride into the container according to the weight ratio, and uniformly stirring to obtain a mixture A;
s2, preparing a mixture B: weighing a certain amount of nitric acid in a container according to the weight ratio, adding a certain amount of ferric nitrate in the container according to the weight ratio, and stirring uniformly to obtain a mixture B;
s3, preparing metallographic corrosive liquid: and mixing the mixture A and the mixture B, and stirring uniformly to obtain the metallographic etching solution.
9. A method of using the metallographic etchant for as-cast duplex stainless steel according to any one of claims 1 to 7, comprising:
firstly preparing a metallographic sample to be corroded, dipping the metallographic corrosive liquid by using absorbent cotton, wiping the surface of the sample at normal temperature by using the absorbent cotton until the surface of the sample turns grey, and then washing and drying the surface of the sample to detect the grain size under an optical metallographic microscope.
10. The method of using a metallographic etchant for as-cast duplex stainless steel according to claim 9, wherein the process of washing and drying the surface of the sample is as follows: firstly, washing the surface of a sample by flowing water, then washing the surface of the sample by absolute ethyl alcohol, and finally drying the surface of a metallographic sample.
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