CN114232065B - Method for removing modified layer on surface of stainless steel - Google Patents
Method for removing modified layer on surface of stainless steel Download PDFInfo
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- CN114232065B CN114232065B CN202111303529.7A CN202111303529A CN114232065B CN 114232065 B CN114232065 B CN 114232065B CN 202111303529 A CN202111303529 A CN 202111303529A CN 114232065 B CN114232065 B CN 114232065B
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- 239000010935 stainless steel Substances 0.000 title claims abstract description 65
- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 65
- 238000000034 method Methods 0.000 title claims abstract description 28
- 238000005498 polishing Methods 0.000 claims abstract description 125
- 239000000243 solution Substances 0.000 claims abstract description 70
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims abstract description 54
- 239000012266 salt solution Substances 0.000 claims abstract description 51
- 239000000654 additive Substances 0.000 claims abstract description 37
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 36
- 230000000996 additive effect Effects 0.000 claims abstract description 36
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims abstract description 30
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 claims abstract description 24
- 229910052921 ammonium sulfate Inorganic materials 0.000 claims abstract description 24
- 235000011130 ammonium sulphate Nutrition 0.000 claims abstract description 24
- 238000001513 hot isostatic pressing Methods 0.000 claims abstract description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 18
- AEQDJSLRWYMAQI-UHFFFAOYSA-N 2,3,9,10-tetramethoxy-6,8,13,13a-tetrahydro-5H-isoquinolino[2,1-b]isoquinoline Chemical compound C1CN2CC(C(=C(OC)C=C3)OC)=C3CC2C2=C1C=C(OC)C(OC)=C2 AEQDJSLRWYMAQI-UHFFFAOYSA-N 0.000 claims abstract description 16
- WDIHJSXYQDMJHN-UHFFFAOYSA-L barium chloride Chemical compound [Cl-].[Cl-].[Ba+2] WDIHJSXYQDMJHN-UHFFFAOYSA-L 0.000 claims abstract description 16
- 229910001626 barium chloride Inorganic materials 0.000 claims abstract description 16
- 239000000176 sodium gluconate Substances 0.000 claims abstract description 16
- 235000012207 sodium gluconate Nutrition 0.000 claims abstract description 16
- 229940005574 sodium gluconate Drugs 0.000 claims abstract description 16
- 239000001103 potassium chloride Substances 0.000 claims abstract description 15
- 235000011164 potassium chloride Nutrition 0.000 claims abstract description 15
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000001488 sodium phosphate Substances 0.000 claims abstract description 6
- 229910000162 sodium phosphate Inorganic materials 0.000 claims abstract description 6
- 125000000383 tetramethylene group Chemical group [H]C([H])([*:1])C([H])([H])C([H])([H])C([H])([H])[*:2] 0.000 claims abstract description 6
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 claims abstract description 6
- 238000010438 heat treatment Methods 0.000 claims abstract description 5
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 7
- XOJITQHBMRQMRX-UHFFFAOYSA-M sodium;ethane-1,2-diamine;2-oxido-1,3,2$l^{5}-dioxaphosphepane 2-oxide Chemical compound [Na+].NCCN.[O-]P1(=O)OCCCCO1 XOJITQHBMRQMRX-UHFFFAOYSA-M 0.000 claims description 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 6
- 150000003841 chloride salts Chemical class 0.000 claims description 4
- 235000019270 ammonium chloride Nutrition 0.000 claims 1
- 239000002932 luster Substances 0.000 abstract description 2
- 239000010410 layer Substances 0.000 description 56
- 210000002381 plasma Anatomy 0.000 description 36
- 239000003792 electrolyte Substances 0.000 description 13
- 230000004048 modification Effects 0.000 description 12
- 238000012986 modification Methods 0.000 description 12
- 150000007524 organic acids Chemical class 0.000 description 11
- STNSYZSNIYTNMI-UHFFFAOYSA-N azane;[2-[bis(phosphonomethyl)amino]ethyl-(phosphonomethyl)amino]methylphosphonic acid Chemical compound N.OP(O)(=O)CN(CP(O)(O)=O)CCN(CP(O)(O)=O)CP(O)(O)=O STNSYZSNIYTNMI-UHFFFAOYSA-N 0.000 description 9
- 239000007788 liquid Substances 0.000 description 8
- 238000007517 polishing process Methods 0.000 description 8
- 238000002360 preparation method Methods 0.000 description 7
- 239000002994 raw material Substances 0.000 description 7
- 238000005406 washing Methods 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 6
- 239000008139 complexing agent Substances 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- 239000011159 matrix material Substances 0.000 description 6
- 239000007789 gas Substances 0.000 description 5
- 238000001746 injection moulding Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000002253 acid Substances 0.000 description 4
- 230000009471 action Effects 0.000 description 4
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000003912 environmental pollution Methods 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 238000004663 powder metallurgy Methods 0.000 description 4
- 239000004576 sand Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 229910000684 Cobalt-chrome Inorganic materials 0.000 description 3
- WAIPAZQMEIHHTJ-UHFFFAOYSA-N [Cr].[Co] Chemical compound [Cr].[Co] WAIPAZQMEIHHTJ-UHFFFAOYSA-N 0.000 description 3
- 239000010952 cobalt-chrome Substances 0.000 description 3
- 210000001519 tissue Anatomy 0.000 description 3
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000003486 chemical etching Methods 0.000 description 2
- 229910000423 chromium oxide Inorganic materials 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000000866 electrolytic etching Methods 0.000 description 2
- 229910000480 nickel oxide Inorganic materials 0.000 description 2
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 description 2
- 229910052939 potassium sulfate Inorganic materials 0.000 description 2
- 235000011151 potassium sulphates Nutrition 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- YASYEJJMZJALEJ-UHFFFAOYSA-N Citric acid monohydrate Chemical compound O.OC(=O)CC(O)(C(O)=O)CC(O)=O YASYEJJMZJALEJ-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229960002303 citric acid monohydrate Drugs 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 1
- 238000006864 oxidative decomposition reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 150000005837 radical ions Chemical class 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 238000003887 surface segregation Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 238000011179 visual inspection Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F3/00—Electrolytic etching or polishing
- C25F3/16—Polishing
- C25F3/22—Polishing of heavy metals
- C25F3/24—Polishing of heavy metals of iron or steel
Abstract
The application relates to a method for removing a modified layer on the surface of stainless steel, which relates to the technical field of polishing. The method is used for stainless steel after hot isostatic pressing treatment and comprises the following steps: preparing polishing solution, and pouring the polishing solution into a polishing groove; heating the polishing solution to a preset temperature, and placing the stainless steel part in the polishing groove and immersing the stainless steel part in the polishing solution; polishing the stainless steel part according to preset voltage and preset time; the polishing solution comprises a salt solution, an additive and water, wherein the salt solution is at least two of potassium chloride, barium chloride and ammonium sulfate, and the additive is at least one of phosphoric acid, acetic acid, ethylenediamine tetramethylene sodium phosphate and sodium gluconate. The polishing solution prepared from the salt solution, the additive and the water can effectively remove the metamorphic layer on the surface of the stainless steel part, so that the dimensional accuracy of the part subjected to hot isostatic pressing treatment can be accurately controlled, and the product has good surface finish, smoothness and luster.
Description
Technical Field
The application relates to the technical field of polishing, in particular to a method for removing a modified layer on the surface of stainless steel.
Background
Stainless steel products are widely used, for example, stainless steel powder metallurgy parts for gas turbines, and in order to meet various application requirements, it is necessary to ensure excellent material properties of the stainless steel powder metallurgy parts. For example, in order to improve the material properties of a 316L stainless steel product produced by injection molding technology, a hot isostatic pressing technology is required to be used for treatment, but after the product is subjected to hot isostatic pressing at high temperature and high pressure, a modified layer with a certain thickness (about 10-15 μm) appears on the surface of the product. On one hand, the metamorphic layer has complex components and is mainly oxide such as chromium oxide, nickel oxide and the like, and the interface of the metamorphic layer of the oxide has strong bonding force with a matrix and is difficult to remove; on the other hand, the parts have complex dimensions and high precision requirements such as circular arcs, chamfers, planes and the like.
At present, when a modified layer of stainless steel powder metallurgy parts and the like for a gas turbine is removed, the problems of dust pollution, inaccurate part size control and the like can be generated by adopting a polishing method such as mechanical grinding or abrasive particle flow and the like; by adopting the electrochemical polishing method, the strong acid solution used in the polishing process causes corrosion to the surface of the part, a large number of corrosion small points are generated, and the environment is polluted greatly.
Therefore, how to remove the surface deterioration layer on the premise of ensuring the dimensional accuracy of the parts, reducing the environmental pollution, ensuring the surface smoothness of the product, ensuring the luster and the like is a technical problem to be solved in the industry.
In the prior art, a method for polishing and processing the surface of a stainless steel part by plasma is disclosed in related patents. The patent application publication No. CN 105220218A discloses an electrolyte-plasma polishing process method for a stainless steel material precise structural member, and aims at removing tiny burrs on the surface and edge blunting of a servo valve of a core element of a certain spacecraft with high precision requirements, and provides an electrolyte plasma polishing process method, wherein the polishing solution comprises 2-4% of pure ammonium sulfate solution, and the plasma removal and chemical pitting corrosion of a base metal jointly act in the polishing process to remove tiny burrs on the surface of a part. However, the ionization and gasification of water molecules in the later polishing stage after the ionization of the pure ammonium sulfate solution lead to the increase of ion concentration, the decrease of electric field strength between two poles, serious chemical pitting behavior of matrix metal and damage to the surface flatness and precision of parts due to longer polishing time. The composition of the oxide modified layer on the surface of the 316L stainless steel piece after hot isostatic pressing is complex, the bonding force between the interface of the modified layer and a matrix is strong after high temperature and high pressure, the low-concentration salt solution cannot achieve synchronous plasma removal and electrolytic etching removal at the initial stage of polishing, and the modified layer is insufficiently removed; and the pure ammonium sulfate solution cannot uniformly remove the modified layer on the surface of the part in the later ionization stage, so that the pitting corrosion behavior is serious, and the flatness of the polished part cannot be ensured. Therefore, the patent has good application effect in removing the tiny burrs of the stainless steel precision part, but the surface quality requirement can not be met when the surface modification layer of the 316L stainless steel part after hot isostatic pressing is removed.
Patent grant publication number CN 110129872B discloses a polishing solution for cobalt-chromium metal electrolyte plasma polishing, the polishing solution component is developed for polishing the surface of medical cobalt-chromium metal workpieces, and comprises organic acid, sulfate and water in a proportion of 1: (6-9): (150-315). In order to avoid sand points on the surface of the workpiece after polishing, chloride and nitrate can trigger ionization to corrode the surface of the workpiece, and sulfate solutions are used as salt solutions; considering that cobalt-chromium metal crystals are regularly and densely arranged, ammonium sulfate and potassium sulfate are adopted as electrolyte; the organic acid enhances ionization effect in the solution, and enlarges the gas layer on the surface of the workpiece to generate more plasmas. When the electrolyte plasma polishing solution is applied to removing the surface modification layer of the 316L stainless steel piece after hot isostatic pressing, as the modification layer has complex components and strong bonding force between the interface and the matrix, the organic acid solution can not quickly cause the molecular structure change of the surface modification layer in the initial stage, the salt solution can not quickly trigger a plasma discharge channel and reach a certain scale, the phenomenon of uneven removal of the surface modification layer can occur in the later stage, sand points appear at the removed part of the modification layer, sand points exist on the surface of the final 316L stainless steel piece, and the brightness is uneven.
Accordingly, there is a need to improve one or more problems in the related art as described above.
It is noted that this section is intended to provide a background or context for the embodiments of the disclosure set forth in the claims. The description herein is not admitted to be prior art by inclusion in this section.
Disclosure of Invention
The present application is directed to a method of removing a modified layer of a stainless steel surface that, at least to some extent, overcomes one or more of the problems due to the limitations and disadvantages of the related art.
The application provides a method for removing a modified layer on the surface of stainless steel, which is used for stainless steel after hot isostatic pressing treatment and comprises the following steps:
preparing polishing solution, and pouring the polishing solution into a polishing groove;
heating the polishing solution to a preset temperature, and placing the stainless steel part in the polishing groove and immersing the stainless steel part in the polishing solution;
polishing the stainless steel part according to preset voltage and preset time;
the polishing solution comprises a salt solution, an additive and water, wherein the salt solution is at least two of potassium chloride, barium chloride and ammonium sulfate, and the additive is at least one of phosphoric acid, acetic acid, ethylenediamine tetramethylene sodium phosphate and sodium gluconate.
Preferably, the mass concentration of the salt solution is 4-6%, and the mass ratio of the salt solution to the additive is (7-10): 1, wherein the mass ratio of the salt solution to water is 1: (15-25).
Preferably, the mass ratio of chloride salt to sulfate in the salt solution is 1: (3-5).
Preferably, the preset temperature is 60-80 ℃.
Preferably, the preset voltage is 300-400V.
Preferably, the preset time is 8-12 min.
Preferably, the mass ratio of the ammonium sulfate to the potassium chloride in the salt solution is 4:1, and the additive contains 30 mass percent of phosphoric acid, 60 mass percent of acetic acid and 10 mass percent of ethylenediamine tetramethylene sodium phosphate.
Preferably, the mass ratio of the ammonium sulfate to the barium chloride in the salt solution is 4:1, and the additive contains 40 mass percent of phosphoric acid, 40 mass percent of acetic acid, 10 mass percent of sodium gluconate and 10 mass percent of sodium ethylenediamine tetramethylene phosphate.
Preferably, the mass ratio of the ammonium sulfate, the potassium chloride and the barium chloride in the salt solution is 8:1:1, and the additive contains 50% of phosphoric acid, 30% of acetic acid, 5% of sodium gluconate and 15% of sodium ethylenediamine tetramethylene phosphate by mass percent.
Preferably, the mass ratio of the ammonium sulfate, the potassium chloride and the barium chloride in the salt solution is 15:2:3, and the additive contains 50% of phosphoric acid, 30% of acetic acid, 5% of sodium gluconate and 15% of sodium ethylenediamine tetramethylene phosphate by mass percent.
The application can realize the following beneficial effects:
the polishing solution prepared from the salt solution, the additive and the water can effectively remove the metamorphic layer on the surface of the stainless steel part, so that the dimensional accuracy of the part after hot isostatic pressing treatment can be accurately controlled, and the product has good surface finish, smoothness and bright color.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the disclosure and together with the description, serve to explain the principles of the disclosure. It will be apparent to those of ordinary skill in the art that the drawings in the following description are merely examples of the disclosure and that other drawings may be derived from them without undue effort.
FIG. 1 is a flow chart of a method for removing a modified layer on a stainless steel surface in an embodiment of the application;
FIG. 2 shows an SEM photograph of a surface deterioration layer of a 316L stainless steel part prior to polishing, in one embodiment of the application;
fig. 3 shows SEM photographs of the surface modified layer of the part of fig. 2 after polishing.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. However, the exemplary embodiments may be embodied in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
The embodiment of the application provides a method for removing a modified layer on the surface of stainless steel, which is used for stainless steel after being subjected to hot isostatic pressing treatment and comprises the following steps of:
step S100, preparing polishing solution, and pouring the polishing solution into a polishing groove;
step S200, heating the polishing solution to a preset temperature, and placing the stainless steel part in the polishing groove and immersing the stainless steel part in the polishing solution;
step S300, polishing the stainless steel part according to preset voltage and preset time;
the polishing solution comprises a salt solution, an additive and water, wherein the salt solution is at least two of potassium chloride, barium chloride and ammonium sulfate, and the additive is at least one of phosphoric acid, acetic acid, ethylenediamine tetramethylene sodium phosphate and sodium gluconate.
According to the embodiment of the application, the polishing solution prepared from the salt solution, the additive and the water can effectively remove the modified layer on the surface of the stainless steel part, for example, the modified layer on the surface of a 316L stainless steel product produced by an injection molding technology, so that the dimensional accuracy of the 316L stainless steel part produced by the injection molding technology after hot isostatic pressing treatment can be accurately controlled, and the product has good surface finish, smoothness and bright color.
Specifically, the principle of action of the polishing liquid of the present application is described as follows. The solute component of the polishing solution prepared by the application comprises a salt solution and additives, for example, the salt solution contains sulfate and chloride. Because the ionization effect of the chloride salt is stronger than that of the sulfate, after polishing is started, a gas layer can be rapidly generated around a workpiece by electrolysis, and then a certain-scale plasma is released; the sulfate is ammonium sulfate, the oxidative decomposition capability is low, the added chloride is potassium chloride or barium chloride, and the chloride can enhance the chemical etching action on the 316L stainless steel surface modification layer with strong binding force after being dissolved in water, so that the removal speed of the surface modification layer is increased; after polishing for a period of time, barium sulfate precipitation is generated due to the added barium chloride, so that acid radical ions in the solution are reduced, and chemical erosion of the solution to the removed clean part of the modified layer in the later stage of polishing is reduced; the weak acid phosphoric acid and the organic acid acetic acid added into the additive have certain ionization effect, maintain the acid-base balance of the solution, enhance the plasma intensity, and cause the molecular structure change of the modified layer on the surface of the 316L stainless steel piece at the initial stage of polishing so as to reduce the binding force between the 316L stainless steel piece and the matrix. EDTMPS (ethylenediamine tetramethylene sodium phosphate) or sodium gluconate is added into the additive to ensure that the components of the solution in the polishing process are uniform; the EDTMPS has good chemical stability, can be decomposed into a plurality of positive ions and negative ions in water to form a plurality of macromolecular network complexes with monomer structures, and can damage the crystallization state of precipitated barium sulfate, so that each component of the polishing solution can be uniformly distributed, and the polishing process is uniformly carried out; the action of sodium gluconate is similar to that of EDTMPS and is also used as a complexing agent in solution, so that one or two of EDTMPS or sodium gluconate can be used in the additive.
Optionally, in some embodiments, the mass concentration of the salt solution is 4% -6%, for example, may be 4.5%, 5%, 5.5%, etc., and the mass ratio of the salt solution to the additive is (7-10): 1, for example, can be 8:1, 9:1, etc., and the mass ratio of the salt solution to the water is 1: (15 to 25) may be, for example, 1:18, 1:20, 1:22, 1:24, etc. The concentration of the inorganic acid solution adopted in the polishing solution is low, the environmental pollution is small, the cost is low, and the like.
In some embodiments, the mass ratio of chloride salt to sulfate salt in the salt solution is 1: (3 to 5) may be, for example, 1:3.5, 1:4, 1:4.5, etc. When the 316L stainless steel part is subjected to hot isostatic pressing, cr and Ni in the stainless steel are subjected to surface segregation at high temperature, a certain amount of oxygen is attached to the surface of the 316L stainless steel, an oxide layer with complex components is generated at high temperature, the thickness is about 10-15 mu m, the oxide layer mainly contains chromium oxide and nickel oxide, and the surface layer is dark green after the stainless steel is discharged from the furnace at room temperature. In addition, when the heat is preserved at high temperature and high pressure, element atoms have stronger diffusion activation energy and interface binding force, so that the binding force between the interface of the oxide modified layer and the matrix is stronger. In order to completely remove the oxides, the purposes of high surface smoothness and bright color are achieved, and compared with the prior art, the method disclosed by the application has the advantages that the concentration of the salt solution is properly increased, so that plasma removal and electrolytic etching are combined to act on a modified layer.
Alternatively, in some embodiments, the predetermined temperature is 60 to 80 ℃. The local boiling phenomenon of the polishing solution can be caused by the overhigh temperature, and bubbles are generated to make the polishing solution strongly surge, so that the polishing process can not be stably carried out, and the processing efficiency is reduced. Therefore, the limiting temperature is 60 to 80 ℃.
Optionally, in some embodiments, the preset time is 8-12 min, and too short a time may result in insufficient removal of the surface modification layer, and too long a time may result in poor surface roughness improvement of the part, sand points may occur, and electrical energy loss may be caused.
The method for removing the altered layer according to the present application will be described in detail below by taking a 316L stainless steel part produced by injection molding technology for a gas turbine as an example. The 316L stainless steel part is manufactured by adopting a powder metallurgy injection molding technology, and in order to reduce the pore volume in a tissue and optimize the tissue performance, after adopting a proper hot isostatic pressing process and high-temperature treatment, although the pore volume in the tissue of a product is reduced and the density and the tensile performance are improved to different degrees after the part is subjected to hot isostatic pressing treatment, a modified layer with a certain thickness is generated on the surface of the product, and in order to remove the modified layer of the product, the method disclosed by the application is adopted, and specifically comprises the following steps:
example 1
(1) The preparation proportion (weight ratio) of the polishing solution raw materials is that the additive is a salt solution and the water is=1:10:180; the salt solution is ammonium sulfate and potassium chloride in a ratio of 4:1; the additive contains 30% of phosphoric acid, 60% of organic acid acetic acid and 10% of complexing agent EDTMPS, so that electrolyte plasma polishing solution is obtained;
(2) Pouring the prepared and uniformly stirred electrolyte plasma polishing solution into a polishing tank, and heating the polishing solution to 70 ℃;
(3) According to the structural size of the 316L stainless steel part, a polishing fixture clamp and a pendant are utilized, and the 316L stainless steel part which is subjected to hot isostatic pressing treatment and generates a modified layer is arranged on the polishing pendant. Placing the polishing fixture and the parts on the hanging piece into the polishing groove, completely immersing the parts into the polishing liquid, connecting the fixture and the parts with a positive electrode of a power supply, connecting the polishing groove with a negative electrode of the power supply, and controlling the output voltage at 330V;
(4) Carrying out plasma processing treatment on the 316L stainless steel part subjected to the hot isostatic pressing treatment to generate a modified layer according to the technological parameters;
(5) And (3) carrying out plasma processing for 12min, and then taking out the part, washing and airing.
Example 2
(1) The preparation proportion (weight ratio) of the polishing solution raw materials is that an additive: salt solution: water = 1:7:170; the salt solution is ammonium sulfate and barium chloride in a ratio of 4:1; the additive comprises 40% of phosphoric acid, 40% of organic acid acetic acid, 10% of sodium gluconate and 10% of complexing agent EDTMPS;
(2) Pouring the prepared and uniformly stirred electrolyte plasma polishing solution into a polishing tank, and when the temperature of the polishing solution is 75 ℃;
(3) Placing the polishing fixture and the parts on the hanging piece into the polishing groove, and completely immersing the parts into polishing liquid; the tool clamp and the parts are connected with the positive electrode of the power supply, the polishing groove is connected with the negative electrode of the power supply, and the output voltage is controlled at 330V;
(4) Carrying out plasma processing treatment on the 316L stainless steel part subjected to the hot isostatic pressing treatment to generate a modified layer according to the technological parameters;
(5) And (3) carrying out plasma processing for 12min, and then taking out the part, washing and airing.
Example 3
(1) The preparation proportion (weight ratio) of the polishing solution raw materials is that an additive: salt solution: water=1:8:200; the salt solution contains 80% ammonium sulfate, 10% potassium chloride and 10% barium chloride; the additive comprises 50% of phosphoric acid, 30% of organic acid acetic acid, 5% of sodium gluconate and 15% of complexing agent EDTMPS;
(2) Pouring the prepared and uniformly stirred electrolyte plasma polishing solution into a polishing tank, and when the temperature of the polishing solution is 80 ℃;
(3) Placing the polishing fixture and the parts on the hanging piece into the polishing groove, and completely immersing the parts into polishing liquid; the tool clamp and the parts are connected with the positive electrode of the power supply, the polishing groove is connected with the negative electrode of the power supply, and the output voltage is controlled at 300V;
(4) Carrying out plasma processing treatment on the 316L stainless steel part subjected to the hot isostatic pressing treatment to generate a modified layer according to the technological parameters;
(5) And (5) carrying out plasma processing for 10min, and then taking out the part, washing and airing.
Example 4
(1) The preparation proportion (weight ratio) of the polishing solution raw materials is that an additive: salt solution: water=1:8:200; the salt solution contains 75% of ammonium sulfate, 10% of potassium chloride and 15% of barium chloride; the additive comprises 50% of phosphoric acid, 30% of organic acid acetic acid, 5% of sodium gluconate and 15% of complexing agent EDTMPS;
(2) Pouring the prepared and uniformly stirred electrolyte plasma polishing solution into a polishing tank, and when the temperature of the polishing solution is 80 ℃;
(3) Placing the polishing fixture and the parts on the hanging piece into the polishing groove, and completely immersing the parts into polishing liquid; the tool clamp and the parts are connected with the positive electrode of the power supply, the polishing groove is connected with the negative electrode of the power supply, and the output voltage is controlled at 300V.
(4) Carrying out plasma processing treatment on the 316L stainless steel part subjected to the hot isostatic pressing treatment to generate a modified layer according to the technological parameters;
(5) And (5) carrying out plasma processing for 10min, and then taking out the part, washing and airing.
Example 5
(1) The preparation proportion (weight ratio) of the polishing solution raw materials is that an additive: salt solution: water=1:8:180; the salt solution contains 85% of ammonium sulfate, 5% of potassium chloride and 10% of barium chloride; the additive contains 60% phosphoric acid, 30% organic acid acetic acid and 10% complexing agent EDTMPS;
(2) Pouring the prepared and uniformly stirred electrolyte plasma polishing solution into a polishing tank, and when the temperature of the polishing solution is 80 ℃;
(3) Placing the polishing fixture and the parts on the hanging piece into the polishing groove, and completely immersing the parts into polishing liquid; the tool clamp and the parts are connected with the positive electrode of the power supply, the polishing groove is connected with the negative electrode of the power supply, and the output voltage is controlled at 300V;
(4) Carrying out plasma processing treatment on the 316L stainless steel part subjected to the hot isostatic pressing treatment to generate a modified layer according to the technological parameters;
(5) And (3) carrying out plasma processing for 12min, and then taking out the part, washing and airing.
Comparative example 1
(1) The preparation proportion (weight ratio) of the polishing solution raw materials is that a salt solution is prepared: water = 1:49; the salt solution is ammonium sulfate;
(2) Pouring the prepared electrolyte plasma polishing solution into a polishing tank, and when the temperature of the polishing solution is 90 ℃;
(3) Placing the polishing fixture and the parts on the hanging piece into the polishing groove, and completely immersing the parts into polishing liquid; the tool clamp and the parts are connected with the positive electrode of the power supply, the polishing groove is connected with the negative electrode of the power supply, and the output voltage is controlled at 300V;
(4) Carrying out plasma processing treatment on the 316L stainless steel part subjected to the hot isostatic pressing treatment to generate a modified layer according to the technological parameters;
(5) And (3) plasma processing for 8min, and then taking out the part, washing and airing.
Comparative example 2
(1) The preparation proportion (weight ratio) of the polishing solution raw materials is organic acid: salt solution: water = 1:8:240; the salt solution contains 75% ammonium sulfate and 25% potassium sulfate; the organic acid is citric acid monohydrate;
(2) Pouring the prepared electrolyte plasma polishing solution into a polishing tank, and when the temperature of the polishing solution is 96 ℃;
(3) Placing the polishing fixture and the parts on the hanging piece into the polishing groove, and completely immersing the parts into polishing liquid; the tool clamp and the parts are connected with the positive electrode of the power supply, the polishing groove is connected with the negative electrode of the power supply, and the output voltage is controlled at 340V;
(4) Carrying out plasma processing treatment on the 316L stainless steel part subjected to the hot isostatic pressing treatment to generate a modified layer according to the technological parameters;
(5) And (5) carrying out plasma processing for 10min, and then taking out the part, washing and airing.
Evaluation of performance:
the surface conditions of the 316L stainless steel parts of examples 1 to 5 and comparative examples 1 to 2 after plasma polishing were tested, including the degree of removal of the altered layer, the surface finish, etc., by visual inspection. The thickness of the altered layer was measured by a precision gauge, and the results are shown in Table 1.
Table 1 results of removal of modified layers in examples and comparative examples
In addition, SEM analysis was performed on the modified layers before and after polishing, respectively, see fig. 2 to 3 (detection points are not less than three and uniformly distributed on the surface to be tested).
As can be seen from table 1 and fig. 2 to 3, the method of the example of the present application has significantly higher removal rate of the altered layer of stainless steel than the comparative example, and the surface finish is significantly better than the comparative example.
In summary, the beneficial effects of the application are as follows:
(1) By adopting the method, the surface modification layer of the 316L stainless steel piece after hot isostatic pressing can be effectively removed by adjusting the ion concentration in the electrolyte polishing solution and matching the corresponding parameters such as temperature, voltage, time and the like, the product surface is smooth and glossy, the glossiness is good, the dimensional accuracy of the product after plasma processing can be accurately controlled, the concentration of the used inorganic weak acid solution is lower, the environmental pollution is small, the cost is low and the like.
(2) The prepared polishing solution improves the plasma intensity in the polishing process, also causes the surface of the 316L stainless steel part to have certain chemical etching action, reduces the binding force between a surface modification layer and an interface by the additive component, can completely remove the oxide modification layer, and achieves the purposes of high surface smoothness and bright color.
(3) The process method has the advantages of high processing efficiency, low cost and less environmental pollution, and is suitable for industrial production.
It should be appreciated that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the embodiments of the present application, the meaning of "plurality" is two or more, unless explicitly defined otherwise.
In the embodiments of the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured" and the like are to be construed broadly and include, for example, either permanently connected, removably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the terms in this disclosure will be understood by those of ordinary skill in the art as the case may be.
In the description of the present specification, a description referring to terms "one embodiment," "some 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 present disclosure. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Further, one skilled in the art can engage and combine the different embodiments or examples described in this specification.
Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any adaptations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.
Claims (6)
1. A method for removing a modified layer on a surface of stainless steel for stainless steel after being subjected to hot isostatic pressing, comprising:
preparing polishing solution, and pouring the polishing solution into a polishing groove;
heating the polishing solution to a preset temperature, and placing the stainless steel part in the polishing groove and immersing the stainless steel part in the polishing solution;
polishing the stainless steel part according to preset voltage and preset time;
the polishing solution comprises a salt solution, an additive and water, wherein the salt solution is ammonium sulfate and chloride, the chloride is at least one of potassium chloride and barium chloride, and the additive is at least one of phosphoric acid, acetic acid, ethylenediamine tetramethylene sodium phosphate and sodium gluconate;
the mass concentration of the salt solution is 4-6%, and the mass ratio of the salt solution to the additive is (7-10): 1, wherein the mass ratio of the salt solution to water is 1: (15-25);
the mass ratio of the chloride salt to the sulfate in the salt solution is 1: (3-5);
the preset temperature is 60-80 ℃;
the preset time is 8-12 min.
2. The method of claim 1, wherein the predetermined voltage is 300-400V.
3. The method according to claim 1, wherein the mass ratio of ammonium sulfate to potassium chloride in the salt solution is 4:1, and the additive comprises 30% phosphoric acid, 60% acetic acid and 10% sodium ethylenediamine tetramethylene phosphate by mass percent.
4. The method according to claim 1, wherein the mass ratio of ammonium sulfate to barium chloride in the salt solution is 4:1, and the additive comprises 40% phosphoric acid, 40% acetic acid, 10% sodium gluconate, and 10% sodium ethylenediamine tetramethylene phosphate by mass percent.
5. The method according to claim 1, wherein the mass ratio of the ammonium sulfate, the potassium chloride and the barium chloride in the salt solution is 8:1:1, and the additive comprises 50% of phosphoric acid, 30% of acetic acid, 5% of sodium gluconate and 15% of sodium ethylenediamine tetramethylene phosphate by mass percent.
6. The method according to claim 1, wherein the mass ratio of ammonium sulfate, potassium chloride and barium chloride in the salt solution is 15:2:3, and the additive comprises 50% phosphoric acid, 30% acetic acid, 5% sodium gluconate and 15% sodium ethylenediamine tetramethylene phosphate by mass percent.
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