CN114585768A - Metal product and method for manufacturing same - Google Patents
Metal product and method for manufacturing same Download PDFInfo
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- CN114585768A CN114585768A CN202080071298.9A CN202080071298A CN114585768A CN 114585768 A CN114585768 A CN 114585768A CN 202080071298 A CN202080071298 A CN 202080071298A CN 114585768 A CN114585768 A CN 114585768A
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- 229910052751 metal Inorganic materials 0.000 title claims abstract description 103
- 239000002184 metal Substances 0.000 title claims abstract description 103
- 238000000034 method Methods 0.000 title claims abstract description 31
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 26
- 239000000463 material Substances 0.000 claims abstract description 141
- 150000001845 chromium compounds Chemical class 0.000 claims abstract description 99
- 238000001556 precipitation Methods 0.000 claims abstract description 54
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 92
- 238000005121 nitriding Methods 0.000 claims description 80
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 74
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 62
- 229910052757 nitrogen Inorganic materials 0.000 claims description 57
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 38
- 229910052742 iron Inorganic materials 0.000 claims description 37
- 238000005254 chromizing Methods 0.000 claims description 36
- 238000010438 heat treatment Methods 0.000 claims description 31
- 229910052759 nickel Inorganic materials 0.000 claims description 31
- 239000000956 alloy Substances 0.000 claims description 29
- 239000010953 base metal Substances 0.000 claims description 28
- 239000007789 gas Substances 0.000 claims description 28
- 229910000831 Steel Inorganic materials 0.000 claims description 27
- 229910045601 alloy Inorganic materials 0.000 claims description 27
- 239000010959 steel Substances 0.000 claims description 27
- 239000012298 atmosphere Substances 0.000 claims description 25
- 239000000843 powder Substances 0.000 claims description 19
- CXOWYMLTGOFURZ-UHFFFAOYSA-N azanylidynechromium Chemical compound [Cr]#N CXOWYMLTGOFURZ-UHFFFAOYSA-N 0.000 claims description 18
- 230000004048 modification Effects 0.000 claims description 17
- 238000012986 modification Methods 0.000 claims description 17
- 229910001220 stainless steel Inorganic materials 0.000 claims description 15
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 13
- 229910052799 carbon Inorganic materials 0.000 claims description 13
- 239000010935 stainless steel Substances 0.000 claims description 11
- 239000010410 layer Substances 0.000 abstract description 352
- 239000002344 surface layer Substances 0.000 abstract description 33
- 238000000151 deposition Methods 0.000 abstract description 20
- 230000007797 corrosion Effects 0.000 abstract description 18
- 238000005260 corrosion Methods 0.000 abstract description 18
- 230000008021 deposition Effects 0.000 abstract description 17
- 230000008646 thermal stress Effects 0.000 abstract description 16
- 238000005299 abrasion Methods 0.000 abstract description 7
- 239000002585 base Substances 0.000 description 117
- 239000011651 chromium Substances 0.000 description 105
- 239000000047 product Substances 0.000 description 54
- 229910052804 chromium Inorganic materials 0.000 description 35
- 230000000052 comparative effect Effects 0.000 description 21
- 238000009792 diffusion process Methods 0.000 description 20
- 125000004433 nitrogen atom Chemical group N* 0.000 description 13
- 229910001567 cementite Inorganic materials 0.000 description 9
- 238000005336 cracking Methods 0.000 description 9
- 238000003682 fluorination reaction Methods 0.000 description 9
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 9
- 239000002244 precipitate Substances 0.000 description 9
- 230000007423 decrease Effects 0.000 description 8
- 238000009826 distribution Methods 0.000 description 8
- 238000012360 testing method Methods 0.000 description 8
- 206010040844 Skin exfoliation Diseases 0.000 description 7
- 239000000919 ceramic Substances 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 7
- 230000026030 halogenation Effects 0.000 description 7
- 238000005658 halogenation reaction Methods 0.000 description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 6
- 229910001566 austenite Inorganic materials 0.000 description 6
- 239000003795 chemical substances by application Substances 0.000 description 6
- 230000001737 promoting effect Effects 0.000 description 6
- 239000002131 composite material Substances 0.000 description 5
- 238000001816 cooling Methods 0.000 description 5
- 229910001039 duplex stainless steel Inorganic materials 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 230000008595 infiltration Effects 0.000 description 5
- 238000001764 infiltration Methods 0.000 description 5
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen(.) Chemical compound [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 5
- 238000005480 shot peening Methods 0.000 description 5
- 239000002253 acid Substances 0.000 description 4
- UPHIPHFJVNKLMR-UHFFFAOYSA-N chromium iron Chemical compound [Cr].[Fe] UPHIPHFJVNKLMR-UHFFFAOYSA-N 0.000 description 4
- GVEHJMMRQRRJPM-UHFFFAOYSA-N chromium(2+);methanidylidynechromium Chemical compound [Cr+2].[Cr]#[C-].[Cr]#[C-] GVEHJMMRQRRJPM-UHFFFAOYSA-N 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 229910052731 fluorine Inorganic materials 0.000 description 4
- 239000011737 fluorine Substances 0.000 description 4
- 229910052736 halogen Inorganic materials 0.000 description 4
- 150000002367 halogens Chemical class 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 230000007935 neutral effect Effects 0.000 description 4
- 150000004767 nitrides Chemical class 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 230000001376 precipitating effect Effects 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- 239000013535 sea water Substances 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- 229910003470 tongbaite Inorganic materials 0.000 description 4
- 229910000599 Cr alloy Inorganic materials 0.000 description 3
- 229910017060 Fe Cr Inorganic materials 0.000 description 3
- 229910002544 Fe-Cr Inorganic materials 0.000 description 3
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 229910052786 argon Inorganic materials 0.000 description 3
- 238000005422 blasting Methods 0.000 description 3
- 239000011247 coating layer Substances 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 238000007542 hardness measurement Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 230000000116 mitigating effect Effects 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- 229910000640 Fe alloy Inorganic materials 0.000 description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- CKUAXEQHGKSLHN-UHFFFAOYSA-N [C].[N] Chemical compound [C].[N] CKUAXEQHGKSLHN-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 150000001805 chlorine compounds Chemical class 0.000 description 2
- 239000000788 chromium alloy Substances 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- XLJMAIOERFSOGZ-UHFFFAOYSA-N cyanic acid Chemical compound OC#N XLJMAIOERFSOGZ-UHFFFAOYSA-N 0.000 description 2
- 238000004512 die casting Methods 0.000 description 2
- 238000004453 electron probe microanalysis Methods 0.000 description 2
- 230000003628 erosive effect Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 229910001337 iron nitride Inorganic materials 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 229910000734 martensite Inorganic materials 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 238000002161 passivation Methods 0.000 description 2
- 239000012466 permeate Substances 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910001208 Crucible steel Inorganic materials 0.000 description 1
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
- 229910017112 Fe—C Inorganic materials 0.000 description 1
- 229910000760 Hardened steel Inorganic materials 0.000 description 1
- 101000993059 Homo sapiens Hereditary hemochromatosis protein Proteins 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- 229910000617 Mangalloy Inorganic materials 0.000 description 1
- 229910000792 Monel Inorganic materials 0.000 description 1
- 229910018487 Ni—Cr Inorganic materials 0.000 description 1
- 229910001315 Tool steel Inorganic materials 0.000 description 1
- LDDQLRUQCUTJBB-UHFFFAOYSA-N ammonium fluoride Chemical compound [NH4+].[F-] LDDQLRUQCUTJBB-UHFFFAOYSA-N 0.000 description 1
- -1 as shown in FIG. 1 Substances 0.000 description 1
- SJKRCWUQJZIWQB-UHFFFAOYSA-N azane;chromium Chemical compound N.[Cr] SJKRCWUQJZIWQB-UHFFFAOYSA-N 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- VNTLIPZTSJSULJ-UHFFFAOYSA-N chromium molybdenum Chemical compound [Cr].[Mo] VNTLIPZTSJSULJ-UHFFFAOYSA-N 0.000 description 1
- OGSYQYXYGXIQFH-UHFFFAOYSA-N chromium molybdenum nickel Chemical compound [Cr].[Ni].[Mo] OGSYQYXYGXIQFH-UHFFFAOYSA-N 0.000 description 1
- VNNRSPGTAMTISX-UHFFFAOYSA-N chromium nickel Chemical compound [Cr].[Ni] VNNRSPGTAMTISX-UHFFFAOYSA-N 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- YOCUPQPZWBBYIX-UHFFFAOYSA-N copper nickel Chemical compound [Ni].[Cu] YOCUPQPZWBBYIX-UHFFFAOYSA-N 0.000 description 1
- 125000001153 fluoro group Chemical group F* 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 229910000856 hastalloy Inorganic materials 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 229910001026 inconel Inorganic materials 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- DDTIGTPWGISMKL-UHFFFAOYSA-N molybdenum nickel Chemical compound [Ni].[Mo] DDTIGTPWGISMKL-UHFFFAOYSA-N 0.000 description 1
- 238000010606 normalization Methods 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011002 quantification Methods 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
Images
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
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
- C23C10/28—Solid state diffusion of only metal elements or silicon into metallic material surfaces using solids, e.g. powders, pastes
- C23C10/34—Embedding in a powder mixture, i.e. pack cementation
- C23C10/36—Embedding in a powder mixture, i.e. pack cementation only one element being diffused
- C23C10/38—Chromising
-
- 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
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
-
- 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
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/24—Nitriding
Abstract
A metal product having a heat-resistant, corrosion-resistant, and wear-resistant surface layer with high resistance to repeated thermal stress, and a method for manufacturing the same are provided. The surface-modified layer is configured to include a chromium compound layer present on a surface side and a deposition layer present between the chromium compound layer and the base material, the deposition layer depositing a chromium compound in the base material metal constituting the base material. The thermal expansion coefficient of each layer is greater than that of the chromium compound layer and less than that of the precipitation layer and greater from the surface to the deep part. In other words, the difference in thermal expansion coefficient between the layers becomes small. Thus, the surface layer has high resistance to repeated thermal stress, and the characteristics of heat resistance, corrosion resistance, and abrasion resistance possessed by the surface layer can be maintained. The environment and the application range of the use are wide.
Description
Technical Field
The present invention relates to a metal product and a method for manufacturing the same.
Background
There is known a technique of forming a surface layer made of chromium nitride on the surface of an iron-based metal to improve the wear resistance, oxidation resistance, corrosion resistance, and the like of the iron-based metal. Regarding such a technique, the present applicant has developed a technique shown in patent document 1 below. The present applicant also has grasped the following patent document 2 as a prior art relating to the related art.
Prior art documents
Patent document
Patent document 1: japanese patent laid-open publication No. 2016-74948
Patent document 2: japanese patent laid-open publication No. 2011-
In patent document 1, a surface layer made of chromium carbonitride is formed by nitriding an iron alloy material in advance and then chromizing the iron alloy material.
The patent document 1 mentioned above describes the following.
The method for modifying the surface of a metal according to claim 1 of the present invention is a method for preparing a base material of an iron-based metal or a nickel-based metal. The surface of the iron-based metal or the nickel-based metal is covered with an oxide film and a passivation film. When an oxide film or a passivation film is present on the surface, diffusion and permeation of nitrogen atoms are generally easily inhibited. The base material is subjected to nitriding treatment by heating and holding in an atmosphere containing a nitrogen source gas. By this nitriding treatment, nitrogen atoms are diffused and penetrated to the surface of the base material activated by the halogenation treatment. Thereafter, the nitrided base material is subjected to chromizing treatment in which the nitrided base material is present in a powder containing a metal chromium powder and is heated and held at a temperature of 850 to 1200 ℃. By this chromizing treatment, chromium atoms diffuse and penetrate to the surface layer portion diffused and penetrated with nitrogen atoms, and a surface-modified layer is formed.
Fig. 5(a) and 5(b) show the distribution of elements in the surface modified layer formed in the example. In the measurement, the concentration distribution of the cross section of the material was measured by EPMA (electron probe X-ray microanalysis).
Fig. 5(a) shows a surface-modified layer formed by applying a fluorination treatment, a soft-nitriding treatment, and a chromizing treatment to an SUS304 base material. The soft nitriding treatment was carried out at 570 ℃ for 2 hours.
Fig. 5(b) shows a surface modified layer formed by applying a fluorination treatment, a nitriding treatment, and a chromizing treatment to an SUS304 base material. Nitriding treatment was conducted at 570 ℃ for 30 minutes.
Both layers can be formed with a high Cr and N concentration and a low Fe concentration at a thickness of about 50 μm on the front surface side. Which can be considered as a chromium nitride layer. In this chromium nitride layer, about 82 wt.% chromium and about 11 wt.% nitrogen can be identified as Cr2And N is added. Further, a layer having a low nitrogen concentration and a high Fe and Cr concentration can be formed in a thickness of about 60 μm below the layer. This can be considered as a chromium-densified layer in which chromium is diffused and infiltrated in the base material.
Patent document 2 describes forming an intermediate layer composed of a carbide complex of an element to be coated and iron of a base material when forming a carbide coating layer on an iron-based base material, so as to prevent the coating layer from cracking due to a difference in thermal expansion coefficient between the base material and the coating layer.
Patent document 2 describes the following.
Taking a Cr coating as an example, a sliding member according to the present invention is characterized in that a chromium carbide layer is coated on a steel member via an intermediate layer composed of a composite carbide (Fe, Cr) C of iron and chromium. This layer structure is shown in fig. 1 (a). … … shown in FIG. 1(a) can prevent film cracking.
The present invention is also a method for manufacturing a sliding member in which a chromium carbide layer is coated on a steel part through an intermediate layer made of a composite carbide (Fe, Cr) C of iron and chromium by diffusion infiltration treatment, and the method includes the steps ofCharacterized in that the steel structure contains cementite in advance, and the diffusion and permeation treatment is carried out in an austenite + cementite area on a Fe-C phase diagram. If the structure of the surface of the steel member is in the austenite + cementite state, Fe is present in the austenite + cementite region3C is stably present, and therefore, Cr is supplied from the outside to react with Fe3The reaction of C can reliably produce an intermediate layer of (Fe, Cr) C as shown in FIG. 1 on the surface of the steel member.
Disclosure of Invention
Problems to be solved by the invention
In the metal product obtained by the technique of patent document 1, an austenitic metal is subjected to nitriding treatment and then chromizing treatment. Thereby forming Cr of the surface layer2N layer and chromium-densified layer inside the N layer. The parent material exists further inside.
The above Cr2The N layer is a ceramic with a small coefficient of thermal expansion of 9X 10－6V. C. The thermal expansion coefficient of the austenite base material existing at the innermost portion is 17X 10－6V. C if it is in combination with Cr as defined above2The N layer ratio is about 2 times. In addition, nitrogen is substantially absent in the chromium-enriched layer. Therefore, the thermal expansion coefficient of the chromium-densified layer does not significantly change from that of the austenite base material. Therefore, Cr is the outermost layer2The difference in thermal expansion coefficient between the N layer and the chromium-densified layer and the base material existing as the lower layer is large and significantly differs. In such a layer structure, when used at a high temperature of 1000 ℃ or higher, for example, Cr may occur under thermal stress caused by repeated alternation of heating and cooling2Peeling and cracking of the N layer. Therefore, the available metal products have limitations in terms of usable environment and use.
The iron-based sliding member obtained by the technique of patent document 2 is subjected to diffusion infiltration treatment of Cr or the like using an iron-based material as a base material, which is a steel structure containing cementite beforehand. This results in the formation of a carbide layer on the surface layer and an intermediate layer made of a composite carbide of iron, Cr, or the like on the inside thereof. The parent material exists further inside.
In this method, the base material needs to contain cementite in advance, that is, an iron-based material containing 0.6 wt% or more of carbon. Therefore, the intermediate layer cannot be formed in a material having high corrosion resistance and containing a small amount of carbon, such as stainless steel or heat-resistant steel. Therefore, there is a problem that it is not suitable for environments and uses where corrosion resistance is also required.
The compound precipitated in the intermediate layer is carbide such as Cr-based carbide, and is more easily decomposed when heated to a high temperature than Cr-based nitride. Therefore, there is also a problem that the performance is easily deteriorated when used in a high-temperature environment.
The present invention has been made to solve the above problems, and provides a metal product and a method for manufacturing the same, which have the following objects.
A metal product having a surface layer with high resistance to repeated thermal stress, heat resistance, corrosion resistance and wear resistance, and a method for producing the same are provided.
Means for solving the problems
The metal product according to invention 1 has the following configuration to achieve the above object.
The surface-modified steel sheet is provided with a base material of an iron-based metal or a nickel-based metal, and a surface-modified layer formed on the surface of the base material,
the surface modification layer includes:
a chromium compound layer present on the surface side;
a deposition layer which is present between the chromium compound layer and the base material and deposits a chromium compound in a base metal constituting the base material.
The metal product according to invention 2 has the following configuration in addition to the configuration according to invention 1.
In the deposition layer, the amount of the chromium compound deposited is increased as the chromium compound layer on the front surface side is closer.
The metal product according to invention 3 has the following structure in addition to the structure according to invention 1 or 2.
The base material is any one of stainless steel, heat-resistant steel, and nickel-based alloy having a carbon concentration of 0.6 wt% or less, and the chromium compound is chromium nitride.
In order to achieve the above object, the method for manufacturing a metal product according to invention 4 employs the following configuration.
For the base material of iron-based metal or nickel-based metal,
performing nitriding treatment by keeping and heating the base material in an atmosphere containing a nitrogen source gas,
performing a chromizing treatment in which the base metal subjected to the nitriding treatment is present in a powder containing chromium metal powder and is held by heating,
thus, a surface modification layer including the following layers is formed on the surface of the base material:
a chromium compound layer present on the surface side;
a deposition layer which is present between the chromium compound layer and the base material and deposits a chromium compound in a base metal constituting the base material.
The method for producing a metal product according to invention 5 employs the following configuration in addition to the configuration described in invention 4.
In the nitriding treatment, a nitrided layer having a thickness of at least 1.5 times or more the thickness of the chromium compound layer included in the surface modified layer to be finally formed is formed.
The method for producing a metal product according to invention 6 employs the following configuration in addition to the configuration described in invention 5.
The chromizing treatment is performed for a time period for the nitrided layer formed in the nitriding treatment to have a predetermined thickness.
Effects of the invention
The metal product according to invention 1 includes a base material of an iron-based metal or a nickel-based metal, and a surface-modified layer formed on a surface of the base material. The surface-modified layer includes a chromium compound layer present on the surface side and a precipitation layer present between the chromium compound layer and the base material. In other words, a precipitation layer is present between the chromium compound layer, which is a hard ceramic layer, and the base material, which is an iron-based or nickel-based metal. The deposition layer is formed by depositing a chromium compound in the base metal constituting the base material.
Therefore, the thermal expansion coefficient of each layer becomes larger from the surface to the depth in the order of chromium compound layer < precipitation layer < base material. Therefore, the difference in thermal expansion coefficient between the respective layers is smaller than in the conventional art in which the thermal expansion coefficient is greatly different between the chromium compound layer on the surface and the chromium-thickened layer and the base material. Thus, the surface layer has higher resistance to repeated thermal stress than conventional ones, and can maintain the characteristics of heat resistance, corrosion resistance and abrasion resistance of the surface layer. The environment and the application range of the product can be more extensive than before.
In the metal product according to invention 2, the precipitation amount of the chromium compound is larger in the chromium compound layer on the surface side of the precipitation layer.
Thus, the thermal expansion coefficient of the precipitation layer increases from the surface to the depth. Therefore, the thermal expansion coefficient continuously changes from the chromium compound layer on the surface side toward the base material in a non-stepwise manner. Thus, the surface layer has higher resistance to repeated thermal stress than conventional ones, and can maintain the characteristics of heat resistance, corrosion resistance and abrasion resistance of the surface layer. The environment and the application range of the product can be more extensive than before.
The metal product according to invention 3, wherein the base material is any one of stainless steel, heat-resistant steel and nickel-based alloy having a carbon concentration of 0.6 wt% or less.
With respect to such a base material, a metal product having excellent characteristics can be obtained by forming a surface modification layer including 2 layers of a chromium compound layer and a precipitation layer. Stainless steel, heat-resistant steel, and nickel-based alloy having a carbon concentration of 0.6 wt% or less do not include carbon having a high concentration such as cementite in the base metal. Therefore, when only the diffusion and infiltration treatment of chromium is performed, the carbide layer of the surface layer and the intermediate layer made of a composite carbide of iron, Cr, or the like cannot be formed. For example, a deposition layer in which chromium nitride is deposited in the base metal can be formed by performing nitriding treatment to diffuse and permeate nitrogen atoms and then performing chromium diffusion treatment to form a chromium nitride layer as a chromium compound layer on the surface and to alleviate a difference in coefficient of thermal expansion between the chromium nitride layer and the base metal.
The metal product has extremely high hardness, excellent heat resistance and corrosion resistance, and excellent performance in environments such as high-temperature oxidation, high-temperature corrosion, erosion, cavitation and the like. The metal product exhibits excellent performance even in an acid or alkali environment or a neutral environment, and also in a corrosive environment such as a chloride of seawater. The metal product can be applied to a part requiring heat resistance and wear resistance in a turbocharger, for example, if the metal product is an automobile part. In addition, for example, in a die for die casting of aluminum, magnesium, zinc, or the like, melting loss to the alloy can be prevented, and excellent performance can be maintained. Further, the present invention can be applied to a large number of parts such as leaf sheets, valves, and pumps in the chemical industry, thermal power generation, and alternative energy environments. In addition, the present invention can be applied to materials and parts used in corrosive environments such as acid, alkaline, neutral, and chlorides of seawater.
In the method for producing a metallic product according to invention 4, a nitriding treatment for heating and holding a base material of an iron-based metal or a nickel-based metal in an atmosphere containing a nitrogen source gas is performed, and a chromizing treatment for heating and holding the nitrided base material in a powder containing a metal chromium powder is performed. Thereby, a surface-modified layer is formed on the surface of the base material. The surface modification layer includes: a chromium compound layer present on the surface side; a deposition layer existing between the chromium compound layer and the base material. The precipitation layer is configured such that a chromium compound is precipitated in a base metal constituting the base material.
Therefore, the thermal expansion coefficient of each layer is chromium compound layer < precipitation layer < base material, and becomes larger from the surface to the depth. Therefore, the difference in thermal expansion coefficient between the respective layers is smaller than in the conventional technique in which the thermal expansion coefficient is greatly different between the chromium compound layer on the surface and the chromium-densified layer and the base material. Thus, the surface layer has higher resistance to repeated thermal stress than conventional ones, and can maintain the characteristics of heat resistance, corrosion resistance and abrasion resistance of the surface layer. The environment and the application of the device can be more extensive than the prior art.
The method for producing a metal product according to invention 5 is a method for producing a nitrided layer having a thickness of at least 1.5 times or more the thickness of the chromium compound layer included in the surface-modified layer to be finally formed, by the nitriding treatment.
This enables the deposition layer to be formed reliably.
The method for manufacturing a metal product according to invention 6, wherein the nitriding layer formed by the nitriding treatment is subjected to the chromizing treatment for a predetermined time.
This enables the deposition layer to be formed reliably.
Drawings
Fig. 1 is a schematic diagram illustrating the difference between the conventional article and the present invention.
FIG. 2 is a diagram showing the distribution of elements in a surface-modified layer, wherein (A) is comparative example 1 and (B) is example 1.
FIG. 3 is a photomicrograph of a cross-section of the surface layer, (A) shows comparative example 1, and (B) shows example 1.
Fig. 4 is a line graph showing the cross-sectional hardness distributions of comparative example 1 and example 1.
FIG. 5 is a photograph showing the appearance after the shot peening test, wherein (A) is comparative example 1 and (B) is example 1.
FIG. 6 is a photograph showing the appearance after repeating the test by heating and cooling, wherein (A) is comparative example 1 and (B) is example 1.
FIG. 7 is a photomicrograph of a cross-section of the surface layer portion of example 2.
FIG. 8 is a diagram showing the element distribution of the surface-modified layer of example 2.
Fig. 9 is a photograph showing an appearance after a shot peening test using duplex stainless steel SUS329J4L as a base material.
Fig. 10 is an appearance observation photograph of a duplex stainless steel SUS329J4L after a heating and cooling repeated test.
Detailed Description
Next, a mode for carrying out the present invention will be described.
Original Commission of exploitation
Surface Cr2The N layer is a ceramic layer, the chromium-densified layer and the base material inside the N layer are alloy layers, and the difference in thermal expansion coefficient is a problem at the interface between the ceramic layer and the alloy layer. In other words, in Cr2Nitrogen is not present in the chromium-enriched layer of the alloy layer present between the N layer and the base material. Therefore, the thermal expansion coefficients of the layer interfaces are deviated from each other, and the resistance to repeated thermal stress is insufficient.
Therefore, it is thought that Cr is interposed between2In the alloy layer between the N layer and the base material, a chromium compound as a ceramic is precipitated. In other words, in Cr2A thermal expansion coefficient layer of an intermediate level between the ceramic layer and the alloy layer is formed between the N layer and the base material. This alleviates the difference in thermal expansion coefficient between the layer interfaces, thereby solving the problem.
In addition, as the chromium compound, it is preferable to precipitate chromium nitride instead of carbide such as chromium carbide. This is because nitrides have a higher decomposition temperature than carbides, and are less likely to decompose even at high temperatures during heating, and therefore, when used in a high-temperature environment, the performance of mitigating the thermal expansion coefficient deviation of the precipitation layer is not deteriorated, but is effective.
Fig. 1 is a schematic view illustrating the difference between the above-described conventional product and the present invention. (A) Is an existing product, and (B) is the invention of the application.
As shown in FIG. 1(A), Cr is contained in the conventional products2The coefficient of thermal expansion of the N layer is very different from that of the chromium densified layer (high chromium alloy layer). Nitrogen is not present in the chromium-densified layer of the alloy layer, and a difference in thermal expansion coefficient occurs at the layer interface.
As shown in FIG. 1(B), in the present invention, nitrogen is present in the precipitate layer and Cr is removed from the precipitate layer2N layer via precipitation layer (Cr)2N precipitation layer) toward the base material, the thermal expansion coefficient gradually changes. The deviation of the thermal expansion coefficient at the layer interface is alleviated.
In the graph of the thermal expansion coefficient in fig. 1, the thermal expansion coefficient increases below the vertical axis.
Metal product
The metal product of the present embodiment includes a base material of an iron-based metal or a nickel-based metal, and a surface-modified layer formed on a surface of the base material.
[ parent metal ]
The base metal constituting the base material is an iron-based metal or a nickel-based metal.
As the iron-based metal, various iron and steel materials and iron-based alloys can be used. As the iron-steel material and the iron-based alloy, for example, various steel types such as carbon steel, alloy steel, nickel-chromium-molybdenum steel, chromium-molybdenum steel, manganese steel, tool steel, stainless steel, heat-resistant steel, nitriding steel, case-hardened steel, and the like can be applied.
As the nickel-based metal, a nickel-based alloy can be used. As the nickel-based alloy, for example, an alloy having a nickel content of 50 wt% or more can be used. Specifically, nickel-copper (Monel), nickel-chromium (inconel), and nickel-molybdenum (Hastelloy) are used.
As the base metal, any of stainless steel, heat-resistant steel, and nickel-based alloy having a carbon concentration of 0.6 wt% or less is particularly preferably used. For example, the following can be suitably used: ferritic stainless steel such as SUS410L and SUS 430; martensitic stainless steels such as SUS410 and SUS420J 2; duplex stainless steels such as SUS821L1, SUS323L, SUS329J31, SUS329J3L, SUS329J4L, and SUS327L 1; austenitic stainless steels such as SUS304, SUS316, and SUS310S, and ferritic heat-resistant steels such as SUH21 and SUH 409; martensitic heat-resistant steels such as SUH3 and SUH 11; austenitic heat-resistant steels such as SUH35 and SUH 660; heat-resistant cast steel such as SCH21 and SCH 22; nickel-based ALLOYs such as ALLOY625 and ALLOY 800H.
In such a stainless steel, a heat-resistant steel, and a nickel-based alloy having high corrosion resistance, which do not include cementite in the base metal, a chromium nitride layer is formed as a chromium compound layer on the surface by, for example, nitriding to diffuse and infiltrate nitrogen atoms and then diffusion and infiltration of chromium, and a difference in thermal expansion coefficient between the chromium nitride layer and the base metal is alleviated, so that a deposition layer in which chromium nitride is deposited in the base metal can be formed.
[ surface-modified layer ]
The surface-modified layer includes a chromium compound layer present on the surface side and a precipitation layer present between the chromium compound layer and the base material.
The surface-modified layer can be formed on the surface of the base material by nitriding and chromizing the base material, as will be described later. In this case, the halogenation treatment is carried out before the nitriding treatment as necessary.
[ chromium compound layer ]
The chromium compound layer is formed by combining nitrogen atoms of a nitrided layer formed on the surface of the base metal by the nitriding treatment and chromium atoms infiltrated into the nitrided layer by the nitriding treatment. The nitrided layer is an iron nitride layer on the surface and a nitrogen diffused layer in the depth thereof. The iron nitride layer on the surface may not be formed depending on conditions such as nitriding treatment.
The chromium compound constituting the chromium compound layer is preferably Cr2And N is added. The chromium compound layer can be formed to a thickness of about 5 to 50 μm from the viewpoint of performance and economy.
[ precipitation layer ]
The deposition layer is formed by depositing a chromium compound in the base metal constituting the base material.
The precipitate layer is formed as follows: in the nitrogen diffusion layer in which nitrogen atoms are diffused into the base metal by the nitriding treatment, chromium atoms are infiltrated by the chromizing treatment. In other words, the chromium atoms penetrating deeper than the chromium compound layer form a chromium compound with the nitrogen atoms present in the nitrogen diffusion layer and precipitate. Since the nitrogen atom concentration in the nitrogen diffusion layer is low on the deeper side of the surface, the chromium compound does not form a layer as in the case of the chromium compound layer, and a particulate chromium compound is precipitated.
By providing the precipitation layer between the chromium compound layer and the base material, the thermal expansion coefficient of each layer is made larger from the surface to the depth in the order of chromium compound layer < precipitation layer < base material. Therefore, the difference in thermal expansion coefficient between the layers becomes small. This increases the resistance of the surface layer to repeated thermal stress.
The precipitation layer is preferably such that the precipitation amount of the chromium compound is larger as the chromium compound layer on the front surface side is closer. In other words, the precipitation layer preferably has a smaller precipitation amount of the chromium compound as the base material is located deeper.
The chromium compound is not a carbide such as chromium carbide, but is preferably chromium nitride. This is because nitrides have a higher decomposition temperature than carbides, and are less likely to decompose even at high temperatures during heating, and therefore, when used in a high-temperature environment, the performance of mitigating the difference in the thermal expansion coefficient of the precipitation layer is less likely to deteriorate.
In other words, the precipitation layer preferably has a higher nitrogen concentration closer to the chromium compound layer on the front surface side and a lower nitrogen concentration closer to the base material in the deep part. Thus, the thermal expansion coefficient of the precipitation layer gradually increases from the surface to the depth. Therefore, the thermal expansion coefficient between the layers gradually increases from the chromium compound layer on the surface to the base material at a deep position. Thereby, the surface layer is more resistant to repeated thermal stresses. In other words, by absorbing the strain generated by the thermal stress, peeling and cracking can be prevented.
The deposited layer may have a thickness of about 5 to 100 μm in a portion having a nitrogen concentration of 5 atomic% or more from the viewpoint of performance and economy. A more preferable range of the thickness of the deposition layer is 8 to 50 μm. The intention is not to form a chromium compound layer (Cr) on the surface by making nitrogen permeated by nitriding treatment not penetrate2N layer) is completely consumed, and the remaining nitrogen concentration is 5 atomic% or more in the portion as the deposition layer. As a result, nitrogen combines with Cr whose concentration decreases toward the inside, and Cr whose precipitation amount decreases toward the inside is formed2And N, forming the precipitation layer of the invention. In such a precipitation layer, the hardness gradually decreases toward the inside.
[ Effect of the embodiment ]
The metal product of the above embodiment exhibits the following effects.
The metal product of the present embodiment includes a base material of an iron-based metal or a nickel-based metal, and a surface-modified layer formed on a surface of the base material. The surface-modified layer includes a chromium compound layer present on the surface side and a precipitation layer present between the chromium compound layer and the base material. In other words, a precipitation layer is present between the chromium compound layer, which is a hard ceramic layer, and the base material, which is an iron-based or nickel-based metal. The precipitation layer is formed by precipitating a chromium compound in a base metal constituting the base material.
Therefore, the thermal expansion coefficient of each layer is chromium compound layer < precipitation layer < base material, and becomes larger from the surface to the depth. Therefore, the difference in thermal expansion coefficient between the respective layers is smaller than in the conventional technique in which the thermal expansion coefficient is greatly different between the chromium compound layer on the surface and the chromium-densified layer and the base material. Thus, the surface layer has higher resistance to repeated thermal stress than conventional ones, and the properties of heat resistance, corrosion resistance and abrasion resistance possessed by the surface layer can be maintained. The environment and the application range of the product can be more extensive than before.
In the metal product of the present embodiment, the precipitation amount of the chromium compound is larger as the precipitation layer is closer to the chromium compound layer on the front surface side.
Thus, the thermal expansion coefficient of the precipitation layer increases from the surface to the depth. Therefore, the thermal expansion coefficient continuously changes from the chromium compound layer on the surface side to the base material in a non-stepwise manner. Thus, the surface layer has higher resistance to repeated thermal stress than conventional ones, and can maintain the characteristics of heat resistance, corrosion resistance and abrasion resistance of the surface layer. The environment and the application range of the product can be more extensive than before.
In the metal product of the present embodiment, the base material is any one of stainless steel, heat-resistant steel, and nickel-based alloy having a carbon concentration of 0.6 wt% or less.
By forming a surface modification layer including 2 layers of a chromium compound layer and a precipitation layer on such a base material, a metal product having excellent characteristics can be obtained. Stainless steel, heat-resistant steel, and nickel-based alloy having a carbon concentration of 0.6 wt% or less do not include carbon having a high concentration such as cementite in the base metal. Therefore, the carbide layer of the surface layer and the intermediate layer made of a composite carbide of iron, Cr, or the like on the inner side cannot be formed merely by performing diffusion infiltration treatment of chromium. For example, a deposition layer in which chromium nitride is deposited in the base metal can be formed by performing nitriding treatment to diffuse and permeate nitrogen atoms and then performing chromium diffusion treatment to form a chromium nitride layer as a chromium compound layer on the surface and to alleviate the difference in coefficient of thermal expansion between the chromium compound layer and the base metal.
The metal product has extremely high hardness, excellent heat resistance and corrosion resistance, and excellent performance in environments such as high-temperature oxidation, high-temperature corrosion, erosion, cavitation and the like. The metal product exhibits excellent performance even in an acid or alkali environment, a neutral environment, and a corrosive environment such as a chloride of seawater. The metal product can be applied to a part requiring heat resistance and wear resistance in a turbocharger, for example, if the metal product is an automobile part. In addition, for example, in a die for die casting of aluminum, magnesium, zinc, or the like, melting loss to the alloy can be prevented, and excellent performance can be maintained. Further, the present invention can be applied to a large number of parts such as leaf sheets, valves, and pumps in the chemical industry, thermal power generation, and alternative energy environments. In addition, the present invention can be applied to materials and parts used in corrosive environments such as acid, alkaline, neutral, and chlorides of seawater.
Method for producing metal product
In the method for manufacturing a metal product according to the present embodiment, a base material of an iron-based metal or a nickel-based metal is nitrided and chromized.
The nitriding treatment is performed by heating and holding the base material in an atmosphere containing a nitrogen source gas.
The chromizing treatment is performed by heating and holding the base metal subjected to the nitriding treatment in a powder containing the metal chromium powder.
In the method for producing a metal product according to the present embodiment, the nitriding treatment may be preceded by a halogenation treatment.
[ halogenation treatment ]
The halogenation treatment is performed by heating and holding the base material in an atmosphere gas containing halogen by using a heating furnace capable of controlling the atmosphere.
As the halogen used for the above-mentioned atmosphere gas, for example, F can be used2、Cl2、HCl、NF3And the like halogen gas or halide gas.
The atmosphere gas may be a mixed gas containing 0.5 to 20 vol% of halogen and the balance of nitrogen, hydrogen, an inert gas, or the like.
The halogenation treatment is carried out by heating the base material at 200 to 550 ℃ for about 10 minutes to 3 hours in the atmosphere gas to activate the surface.
[ nitriding treatment ]
The nitriding treatment is performed by heating and holding the halogenated base material in an atmosphere containing a nitrogen source gas, if necessary.
As the nitriding treatment, any of gas nitriding treatment, gas soft nitriding treatment, salt bath soft nitriding treatment, vacuum nitriding treatment, and ion nitriding (plasma nitriding) treatment can be applied.
The gas nitriding or gas soft nitriding can be carried out in a nitriding or soft nitriding atmosphere, i.e., NH3As a nitrogen source, and if necessary, N2、CO、CO2、H2And the base material after the halogenation treatment is heated and held in a mixed atmosphere.
The salt bath nitriding can be performed by heating and holding the base material in a salt bath containing cyanide or cyanic acid as a main component.
Ion nitriding (plasma nitriding) is performed by applying a dc voltage of several hundred volts to a workpiece as a cathode in a nitrogen mixed gas atmosphere of 0.1 to 10Pa to generate glow discharge, accelerating ionized gas components to a high speed, colliding the ionized gas components with the surface of the workpiece, heating the workpiece, and nitriding the workpiece by sputtering or the like.
The heating temperature and the holding time can be appropriately determined according to the nitriding method to be used and the properties of the target surface-modified layer. For example, the heating is carried out at a predetermined temperature in the range of 350 to 900 ℃ (preferably 350 to 650 ℃) and for a predetermined time.
By the nitriding treatment, a nitrogen diffusion layer having a high nitrogen concentration is formed on the surface layer portion of the base material. Thereafter, by performing the chromizing treatment, the chromium atoms diffused and permeated by the chromizing treatment are bonded to the nitrogen atoms existing in the nitrogen diffusion layer, and a chromium nitride layer is generated as a chromium compound layer.
When soft nitriding is performed as the nitriding treatment, a carbon-nitrogen diffusion layer having high nitrogen concentration and carbon concentration is formed on the surface layer portion of the base material. Thereafter, by performing the chromizing treatment, the chromium atoms diffused and permeated by the chromizing treatment are bonded to the nitrogen atoms and the carbon atoms existing in the carbon-nitrogen diffusion layer, and a chromium carbonitride layer is generated as a chromium compound layer.
In the method for modifying a metal surface according to the present embodiment, it is preferable that a diffusion layer in which nitrogen is diffused is formed by the nitriding treatment so that the nitrogen concentration is 10 atomic% or more and the thickness is 5 μm or more.
After the nitriding treatment, a treatment for normalizing the surface can be performed as necessary before the chromizing treatment. As the normalization process, for example, a process such as shot peening or barrel polishing can be employed.
The nitriding treatment is performed as follows: the chromium compound layer (Cr) contained in the finally formed surface-modified layer is formed2N layer) of at least 1.5 times or more the thickness of the nitride layer (compound layer + diffusion layer).
[ chromizing treatment ]
The chromizing treatment is a process of heating and holding the nitrided base metal in a powder containing a metal chromium powder. By the chromizing treatment, chromium atoms can be diffused and penetrated from the surface of the base material subjected to the nitriding treatment.
The chromizing treatment is performed for a time period until the nitrided layer (compound layer + diffusion layer) formed by the nitriding treatment reaches a predetermined thickness.
This enables the formation of Cr2The inside of the N layer has a precipitation layer having an inclined concentration gradient of N and Cr.
The chromizing treatment can be performed by a powder embedding method. The powder embedding method is performed as follows: a base material in which nitriding treatment is completed is embedded in a treatment agent powder filled in a heat-resistant container, and the heat-resistant container is placed in an atmosphere furnace and heated and held while a gas for promoting a reaction is circulated. By doing so, the following processing is performed: chromium atoms are diffused and penetrated from the surface of the base material subjected to the nitriding treatment.
As the treating agent powder, a powder containing metallic chromium or iron-chromium alloy, and Al for preventing sintering can be used2O3Powder and trace amount of NH added for promoting reaction4Cl or NH4F, powder agent.
As the gas for promoting the reaction, H can be used2Or Ar.
The heating is maintained at a predetermined temperature in the range of 850 to 1200 ℃ (preferably 900 to 1200 ℃) for a predetermined time. By doing so, chromium atoms are diffused and penetrated from the surface of the base material subjected to the nitriding treatment, and a surface modified layer is formed.
[ surface-modified layer ]
In the method for manufacturing a metal product according to the present embodiment, a surface-modified layer is formed on the surface of the base material by nitriding and chromizing the base material.
The surface-modified layer includes, as described above, a chromium compound layer present on the surface side and a precipitation layer present between the chromium compound layer and the base material. The precipitation layer is formed by precipitating a chromium compound in a base metal constituting the base material.
The chromium compound forming the chromium compound layer is preferably Cr2And N is added. Here, Cr2The inner precipitate layer of the N layer can be in other words Cr2N layers of oblique tissue. Such a precipitation layer can form Cr in a layer form in a thermodynamic state without reaching a nitrogen concentration2The degree of N. However, to make Cr2Nitrogen concentration to the extent that N is partially precipitated. Further, as the nitrogen concentration decreases, Cr is more concentrated2The amount of N deposited decreases. Moreover, Cr cannot be precipitated in the end2Nitrogen concentration of N. Thus, the precipitation layer becomes Cr2An inclined N precipitate layer. In addition, the above Cr2Since N has a higher decomposition temperature than carbide and is hardly decomposed even at high temperature during heating, the performance of mitigating the thermal expansion coefficient deviation of the precipitation layer is hardly deteriorated when used in a high-temperature environment.
[ Effect of the embodiment ]
The method for manufacturing a metal product according to the above embodiment exhibits the following effects.
In the method for manufacturing a metal product according to the present embodiment, a nitriding treatment for heating and holding a base material, which is an iron-based metal or a nickel-based metal, in an atmosphere containing a nitrogen-containing source gas is performed, and a chromizing treatment for heating and holding a base material subjected to the nitriding treatment in a powder containing a metal chromium powder is performed. Thereby, a surface modification layer is formed on the surface of the base material. The surface-modified layer includes a chromium compound layer present on the surface side and a precipitation layer present between the chromium compound layer and the base material. The precipitation layer is formed by precipitating a chromium compound in a base metal constituting the base material.
Therefore, the thermal expansion coefficient of each layer is chromium compound layer < precipitation layer < base material, and becomes larger from the surface to the depth. Therefore, the difference in thermal expansion coefficient between the layers is smaller than in the conventional art in which the thermal expansion coefficient of the chromium compound layer on the surface is greatly different from that of the chromium-densified layer and the base material. Thus, the surface layer has higher resistance to repeated thermal stress than conventional ones, and can maintain the characteristics of heat resistance, corrosion resistance and abrasion resistance of the surface layer. The environment and the application range of the product can be more extensive than before.
Examples
Hereinafter, examples will be described together with comparative examples.
[ comparative example 1]
Fig. 2(a) shows the element distribution of the surface-modified layer formed by performing the fluorination treatment, nitriding treatment, and chromizing treatment under the following conditions on the SUS304 base material.
Very good fluorination treatment
Atmosphere: fluorine-based gas (NF)3：10vol％+N2：90vol％)
Temperature: 300 deg.C
Time: 15 minutes
Very good nitriding treatment
Atmosphere: NH (NH)3：50vol％+N2：50vol％
Temperature: 570 ℃ C
Time: 30 minutes
Chromizing very good
Treating agent: adding Al for preventing sintering to powdered Cr or Fe-Cr alloy in required amount2O3And a small amount of NH for promoting the reaction4Powder of Clr
Airflow: hydrogen or argon flow
Temperature: 1050 deg.C
Time: 10 hours
[ example 1]
Fig. 2(B) shows the element distribution of the surface-modified layer formed by performing the fluorination treatment, nitriding treatment, and chromizing treatment under the following conditions on the SUS310S base material.
Very good fluorination treatment
Atmosphere: fluorine-based gas (NF)3：10vol％+N2：90vol％)
Temperature: 400 deg.C
Time: 60 minutes
Very good nitriding treatment
Atmosphere: NH3:H2:N2＝30:20:50
Temperature: 590 deg.C
Time: 20 hours
Chromizing very good
Treating agent: metal Cr particles or Fe-Cr alloy particles + Al for preventing sintering2O3+ small amount of NH for promoting the reaction4Cl
Airflow: hydrogen or argon
Temperature: 1050 deg.C
Time: 2 hours
The layers are formed with high Cr and N concentrations and low Fe concentrations at a thickness of about 10 to 20 μm on the surface side. This can be seen as a chromium nitride layer. The chromium nitride layer was about 80% by weight of chromium and about 10% by weight of nitrogen in the measurement of the weight concentration ratio in FIG. 2 (A). Also in the measurement of the atomic number concentration ratio in fig. 2(B), chromium was about 60 atomic% and nitrogen was about 30 atomic%. Thus, it can be identified as Cr2And N is added. Further, a layer having a high concentration of Fe and Cr is formed in a thickness of about 10 to 60 μm below the layer. This is a chromium-densified layer in which chromium diffuses and penetrates into the base material. The surface of FIG. 2(A) indicates the positions where Cr and N rise.
In comparative example 1, Cr is present2Nitrogen was not detected in the high Cr concentration layer below the N layer, and nitrogen was substantially absent.
In example 1, Cr is added2Below the N layer, there is a layer of a gradient composition in which the Cr concentration and the N concentration gradually decrease. The layer of the inclined composition is the precipitate layer of the present invention.
Fig. 3(a) is a sectional photomicrograph of the surface layer portion of comparative example 1.
Fig. 3(B) is a sectional photomicrograph of the surface layer portion of example 1.
Comparative example 1 Cr on the surface was clearly observed2The interface of the N layer, the high Cr diffusion layer and the base material.
In example 1, Cr2The interface between the N layer and the underlying precipitate layer and the base material was not clearly observed as compared with comparative example 1.
Fig. 4 is a result of measuring the sectional hardness of comparative example 1 and example 1.
In comparative example 1, the hardness was as high as MHv1500 or more at about 10 μm from the surface, but the hardness was drastically reduced to about MHv500 or less at a depth of 20 μm and beyond from the surface. This part is substantially free of nitrogen and substantially free of Cr2And (4) precipitating N.
In example 1, there was a layer having a high hardness of about 20 μm from the surface, and a hardness gradient layer in which the hardness gradually decreased from about MHv1400 to about MHv500 or less toward the base material side was formed. In other words, a chromium compound layer having a hardness of a chromium compound layer is formed at about 20 μm from the surface, a portion having a depth of about 50 μm or more from the surface is a base material layer having a hardness of a base material, and a hardness gradient layer having a gradually decreasing hardness is formed between the chromium compound layer and the base material layer.
In the hardness-graded layer, the chromium concentration and the nitrogen concentration are gradually decreased. At least 5 atomic% or more of nitrogen atoms are combined with chromium by chromizing treatment at 850 ℃ or higher to form Cr2And N is added. Therefore, in Cr2Under the N layer, a layer in which the chromium concentration and the nitrogen concentration gradually decrease is formed. The layer being Cr2N is dispersed and precipitated, and the amount of N precipitated gradually decreases toward the base material side.
Next, the surfaces of comparative example 1 and example 1 were subjected to shot blasting (glass frit: 0.4MPa), thereby performing an impact force test.
Fig. 5(a) is an appearance observation photograph of comparative example 1 after shot blasting for 10 seconds.
FIG. 5(B) is an appearance observation photograph of example 1 after shot blasting was performed for 30 seconds.
In the surface of comparative example 1, a large number of peelings occurred due to the impact of the shot peening in the portions indicated by several arrows as an example.
Such peeling, cracking, and the like did not occur on the surface of example 1.
Further, a test was performed in which heating and cooling from 1000 ℃ to room temperature were repeated 100 times.
Fig. 6(a) is an appearance observation photograph of comparative example 1.
Fig. 6(B) is an appearance observation photograph of example 1.
In addition to a large amount of separation, cracks were generated in the portion surrounded by the circular shape in the surface of comparative example 1 in the portions indicated by several arrows as an example.
Such peeling, cracking, and the like did not occur on the surface of example 1.
[ example 2 ]
As example 2, a duplex stainless steel SUS329J4L was used as a base material, and fluorination treatment, nitriding treatment, and chromizing treatment were performed under the following conditions.
Very good fluorination treatment
Atmosphere: fluorine-based gas (NF)3：10vol％+N2：90vol％)
Temperature: 400 deg.C
Time: 60 minutes
Nitriding treatment-
Atmosphere: NH (NH)3:H2:N2＝30:20:50
Temperature: 590 deg.C
Time: 20 hours
Chromizing very good
Treating agent: metal Cr particles or Fe-Cr alloy particles + Al for preventing sintering2O3+ small amount of NH for promoting the reaction4Cl
Airflow: hydrogen or argon
Temperature: 1050 deg.C
Time: 5 hours
FIG. 7 is a photomicrograph of a cross-section of the surface layer portion of example 2.
Example 2 also the N concentration is at Cr2The inner side of the N layer rises and the austenite is stableAfter the quantification, no σ layer was observed.
FIG. 8 is a diagram showing the element distribution of the surface-modified layer of example 2.
Example 2 also clearly confirmed that Cr was added2The N layer is formed with a sloped composition region on the inner side.
In the case of a duplex stainless steel such as SUS329J4L, the conventional treatment technique involves Cr in the surface layer2The sigma layer is precipitated in the high Cr alloy layer inside the N layer. Therefore, in Cr2When the N layer is peeled off, there is a risk that the corrosion resistance may be deteriorated.
In example 2, it is found that the duplex stainless steel of SUS329J4L has a structure in which the σ phase is suppressed from being precipitated and the separation is hardly caused.
FIG. 9 is a photograph showing the appearance of the steel sheet obtained in example 2 after the shot peening test (glass frit: 0.4 MPa. times.30 seconds) was performed.
Fig. 10 is a photograph showing the appearance of example 2 after the test in which heating and cooling from 1000 ℃ to room temperature were repeated 100 times.
In this case, peeling, cracking, and the like do not occur.
The treatment conditions, the thicknesses of the respective treatment layers, and the presence or absence of peeling or cracking of the examples 1 to 8 and comparative examples 1 to 4 are shown in the following table 1. The atmosphere for the fluorination treatment is a fluorine-based gas (NF)3：10vol％+N2: 90 vol%) of NH as regards the atmosphere of the nitriding treatment3:H2:N2Comparative example is NH at 30:20:503:N2＝50:50。
[ Table 1]
Not the precipitated layer of the present invention, but the thickness of MHv 500-1400 is specified based on the cross-sectional hardness measurement
With respect to the thickness of the precipitated layer shown in Table 1, Cr is present in the invention2The interface between the N layer and the underlying precipitate layer and the base material is unclear, but Cr2The hardness of the N layer is MHv1400 so as toIn addition, Cr is dispersed and precipitated in a region of MHv1400 or less and MHv500 or more2N increases the hardness to form a hardness gradient layer, and therefore the thickness of MHv500 to 1400 is specified from the results of the cross-sectional hardness measurement and expressed as the deposition layer thickness. In the comparative examples, the deposition layer of the present invention was not present, but the thickness of MHv 500-1400 was specified and expressed from the results of the sectional hardness measurement.
In examples 1 to 8, as shown in Table 1, the thickness of the nitrided layer (compound layer + diffused layer) formed by the nitriding treatment was the chromium compound layer (Cr) included in the surface-modified layer to be finally formed2N layer) of at least 1.5 times the thickness of the substrate. On the other hand, in comparative examples 1 to 4, the nitrided layer formed by the nitriding treatment was the chromium compound layer (Cr) finally formed2N layer) of 1.5 times or less.
Summarize
By mixing Cr2The inclined composition of N is set in Cr2Between the N layer and the base material, as shown in FIG. 1, Cr is absorbed2The difference in thermal expansion coefficient between the interface of the N layer and the base material reduces the thermal stress generated.
As described above, the treatment according to the present application significantly improves the resistance to peeling and cracking due to thermal stress and impact force.
Modification example
While the above description has been made of a particularly preferred embodiment of the present invention, the present invention is not limited to the embodiment shown, but can be implemented in various modified forms, and the gist of the present invention includes various modified examples.
The claims (modification according to treaty clause 19)
A metal product comprising a base material of an iron-based metal or a nickel-based metal and a surface-modified layer formed on the surface of the base material,
the surface modification layer is composed of:
cr existing on the surface side2N layers; and
is present in said Cr2N layer and the base materialCr is precipitated in the base metal constituting the base material2A precipitation layer of N, and a solvent,
the precipitation layer has an inclined concentration gradient of N and Cr, and the thickness of a portion having a nitrogen concentration of 5 atomic% or more is formed to be about 5 to 100 μm.
2. The metal product according to claim 1, wherein the precipitation layer has a larger precipitation amount of the chromium compound as it is closer to the chromium compound layer on the surface side.
(modification) the metal product according to claim 1 or 2, wherein the base material is any one of stainless steel, heat-resistant steel, and nickel-based alloy having a carbon concentration of 0.6 wt% or less.
(modification) A manufacturing method of a metal product, characterized in that,
for the base material of iron-based metal or nickel-based metal,
performing a nitriding treatment for heating and holding the base material in an atmosphere containing a nitrogen source gas,
performing a chromizing treatment in which the base metal subjected to the nitriding treatment is present in a powder containing a chromium metal powder and is held by heating,
thereby forming a surface modified layer on the surface of the base material,
the surface modification layer is composed of:
cr existing on the surface side2N layers; and
is present in said Cr2Cr is precipitated between the N layer and the base metal2A precipitation layer of N, and a solvent,
the precipitation layer has an inclined concentration gradient of N and Cr, and the thickness of a portion having a nitrogen concentration of 5 atomic% or more is formed to be about 5 to 100 μm.
(modification) the method for manufacturing a metal product according to claim 4, wherein the nitriding treatment produces the Cr included in the surface-modified layer to be finally formed2A nitrided layer having a thickness at least 1.5 times or more the thickness of the N layer.
6. The method of manufacturing a metal product according to claim 5, wherein the chromizing treatment is performed for a time for the nitrided layer generated in the nitriding treatment to reach a prescribed thickness.
Statement or declaration (modification according to treaty clause 19)
1. Features of the present application
The following features (a) and (B) are specified in claims 1 and 4.
(A) The chromium compound constituting the chromium compound layer in the surface-modified layer is Cr2N。[0038]
(B) The precipitation layer in the surface modification layer has an inclined concentration gradient of N and Cr, and the thickness of a portion having a nitrogen concentration of 5 atomic% or more is formed to be about 5 to 100 μm. [0067][0045]
2. Comparison with literature
(A) Documents 1 and 2 are salt bath treatment at 500 to 700 ℃ and chromium nitride, CrN, formed is stable and not converted into Cr2And N layers.
Paragraph 0025 of document 1 describes CrN.
In FIG. 4 of document 2, the atomic weight ratio of Cr to N is about 3.7:1, and CrN is mainly.
In document 3, the surface nitrogen concentration after nitriding treatment is extremely low, ranging from 0.30% to 35%, from Table 3, and it is considered that Cr is not formed2N。
(B) None of documents 1 to 3 disclose that the deposited layer has an inclined concentration gradient of N and Cr, and the thickness of the portion having a nitrogen concentration of 5 atomic% or more is about 5 to 100 μm.
Claims (6)
1. A metal product comprising a base material of an iron-based metal or a nickel-based metal and a surface-modified layer formed on the surface of the base material,
the surface modification layer is composed of:
a chromium compound layer present on the surface side; and
a precipitation layer which is present between the chromium compound layer and the base material and in which a chromium compound is precipitated in the base material metal constituting the base material.
2. The metal product according to claim 1, wherein the precipitation layer is more precipitated as closer to the chromium compound layer on the surface side.
3. The metal product according to claim 1 or 2, wherein the base material is any one of stainless steel, heat-resistant steel, and nickel-based alloy having a carbon concentration of 0.6 wt% or less, and the chromium compound is chromium nitride.
4. A method for manufacturing a metal product, characterized in that,
as the base material of iron-based metal or nickel-based metal,
performing a nitriding treatment for heating and holding the base material in an atmosphere containing a nitrogen source gas,
performing a chromizing treatment in which the base metal subjected to the nitriding treatment is present in a powder containing a chromium metal powder and is held by heating,
thereby forming a surface modified layer on the surface of the base material,
the surface modification layer is composed of:
a chromium compound layer present on the surface side; and
a precipitation layer which is present between the chromium compound layer and the base material and in which a chromium compound is precipitated in the base material metal constituting the base material.
5. The method of manufacturing a metal product according to claim 4, wherein the nitriding treatment produces a nitrided layer having a thickness of at least 1.5 times or more the thickness of the chromium compound layer included in the surface modified layer to be finally formed.
6. The method of manufacturing a metal product according to claim 5, wherein the chromizing treatment is performed for a time for the nitrided layer generated in the nitriding treatment to reach a prescribed thickness.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
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| JP2019-212791 | 2019-11-26 | ||
| JP2019212791 | 2019-11-26 | ||
| JP2020013197A JP7370263B2 (en) | 2019-11-26 | 2020-01-30 | Metal products and their manufacturing methods |
| JP2020-013197 | 2020-01-30 | ||
| PCT/JP2020/005455 WO2021106233A1 (en) | 2019-11-26 | 2020-02-13 | Metal component and method for producing same |
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| CN114585768A true CN114585768A (en) | 2022-06-03 |
| CN114585768B CN114585768B (en) | 2024-05-10 |
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