CN116770196A - Ultra-high strength stainless steel bar based on titanium element reinforcement and preparation method thereof - Google Patents
Ultra-high strength stainless steel bar based on titanium element reinforcement and preparation method thereof Download PDFInfo
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- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 121
- 239000010935 stainless steel Substances 0.000 title claims abstract description 118
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 title claims abstract description 33
- 230000002787 reinforcement Effects 0.000 title claims abstract description 17
- 238000002360 preparation method Methods 0.000 title abstract description 8
- 238000010438 heat treatment Methods 0.000 claims abstract description 42
- 239000010936 titanium Substances 0.000 claims abstract description 29
- 238000003723 Smelting Methods 0.000 claims abstract description 19
- 230000006698 induction Effects 0.000 claims abstract description 14
- 239000012535 impurity Substances 0.000 claims abstract description 7
- 238000005242 forging Methods 0.000 claims description 64
- 229910000831 Steel Inorganic materials 0.000 claims description 42
- 239000010959 steel Substances 0.000 claims description 42
- 229910052719 titanium Inorganic materials 0.000 claims description 19
- 238000001816 cooling Methods 0.000 claims description 16
- 229910052799 carbon Inorganic materials 0.000 claims description 14
- 239000000463 material Substances 0.000 claims description 14
- 239000000126 substance Substances 0.000 claims description 14
- 229910052750 molybdenum Inorganic materials 0.000 claims description 13
- 229910052759 nickel Inorganic materials 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 12
- 238000005728 strengthening Methods 0.000 claims description 12
- 238000005096 rolling process Methods 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 10
- 229910052717 sulfur Inorganic materials 0.000 claims description 10
- 229910052748 manganese Inorganic materials 0.000 claims description 9
- 229910052804 chromium Inorganic materials 0.000 claims description 8
- 229910052698 phosphorus Inorganic materials 0.000 claims description 8
- 238000010791 quenching Methods 0.000 claims description 8
- 230000000171 quenching effect Effects 0.000 claims description 8
- 229910052710 silicon Inorganic materials 0.000 claims description 8
- 238000007599 discharging Methods 0.000 claims description 6
- 238000010079 rubber tapping Methods 0.000 claims description 6
- 239000002994 raw material Substances 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- 238000004321 preservation Methods 0.000 claims description 2
- 238000003303 reheating Methods 0.000 claims description 2
- 230000007797 corrosion Effects 0.000 abstract description 26
- 238000005260 corrosion Methods 0.000 abstract description 26
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract description 14
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 10
- 229910000734 martensite Inorganic materials 0.000 abstract description 8
- 230000008018 melting Effects 0.000 abstract description 7
- 238000002844 melting Methods 0.000 abstract description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 4
- 239000011159 matrix material Substances 0.000 abstract description 4
- 229910052760 oxygen Inorganic materials 0.000 abstract description 4
- 239000001301 oxygen Substances 0.000 abstract description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 3
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 3
- 239000001257 hydrogen Substances 0.000 abstract description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 22
- 229910001566 austenite Inorganic materials 0.000 description 14
- 239000011651 chromium Substances 0.000 description 12
- 238000004881 precipitation hardening Methods 0.000 description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- 239000000243 solution Substances 0.000 description 10
- 229910000859 α-Fe Inorganic materials 0.000 description 10
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 8
- 239000011572 manganese Substances 0.000 description 8
- 239000000203 mixture Substances 0.000 description 7
- 239000011733 molybdenum Substances 0.000 description 7
- 230000008569 process Effects 0.000 description 7
- 230000032683 aging Effects 0.000 description 6
- 239000006104 solid solution Substances 0.000 description 6
- 230000000087 stabilizing effect Effects 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 239000011593 sulfur Substances 0.000 description 5
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 230000005496 eutectics Effects 0.000 description 4
- 239000003921 oil Substances 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 239000011574 phosphorus Substances 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000002161 passivation Methods 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 230000035882 stress Effects 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- VNNRSPGTAMTISX-UHFFFAOYSA-N chromium nickel Chemical compound [Cr].[Ni] VNNRSPGTAMTISX-UHFFFAOYSA-N 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000003009 desulfurizing effect Effects 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910001105 martensitic stainless steel Inorganic materials 0.000 description 1
- -1 medical Substances 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 239000003209 petroleum derivative Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/005—Manufacture of stainless steel
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
The invention discloses an ultra-high strength stainless steel bar based on titanium element reinforcement and a preparation method thereof, wherein Ti element reinforcement is adopted, and a finer dispersed reinforcement phase (Ni) can be separated out from a martensitic matrix through solution heat treatment 3 Ti phase) can obtain higher tensile strength on the premise of keeping good plasticity; adding a proper amount of Mo elementThe corrosion resistance of the stainless steel is improved; meanwhile, vacuum Induction Melting (VIM) +vacuum consumable remelting (VAR) is adopted for smelting, so that the content of impurities, particularly nitrogen, hydrogen and oxygen in the ultra-high strength stainless steel bar is less, and the ultra-high strength stainless steel bar can be ensured to have good plasticity, fracture toughness and hot working performance under the condition of ultra-high strength.
Description
Technical Field
The invention relates to the technical field of metal materials, in particular to an ultra-high strength stainless steel bar based on titanium element reinforcement and a preparation method thereof.
Background
With the rapid development of aerospace industry in recent decades, aircraft gradually develop towards the directions of long service life and high reliability, the requirement on the corrosion resistance of materials is also higher and higher, and the adoption of high-strength stainless steel for manufacturing certain important parts has become a main development trend, so that the high-performance stainless steel material becomes an important substance and a technical foundation for aviation products to achieve high performance, long service life and high reliability; it has been shown statistically that these high performance stainless steels are almost exclusively precipitation hardening stainless steels.
Precipitation hardening stainless steel is generally obtained by adding hardening elements to precipitate fine intermetallic compounds and certain small amounts of carbides during aging heat treatment to achieve a hardening effect, thereby achieving high strength, high toughness and high corrosion resistance; martensitic precipitation-hardenable stainless steels are usually in service in the martensitic state, the properties of which can be obtained by the combination of the formation of martensite and one or both of the precipitation-hardening mechanisms, and the mechanical properties of which can also be adjusted over a fairly wide range by varying the ageing temperature; because the martensite phase transformation and precipitation hardening mechanism are adopted, the defects of lower strength of the austenitic steel, reduced corrosion resistance after the martensitic steel is heat-treated to high strength and the like are overcome.
Precipitation hardening type ultra-high strength stainless steel is widely applied to some key load-bearing structural members of an airplane, such as landing gear, girder, large stress joint and high stress fastener, because of high strength and corrosion resistance; in addition to the aerospace field, high-performance stainless steel, such as medical, petroleum and natural gas, energy, automobile, hand tools, consumer products, and the like, has high demand, particularly ultra-high strength stainless steel with strength exceeding 1700 MPa.
Chinese patent nos. CN 105714063B and CN 101538686B respectively propose two methods for preparing precipitation hardening stainless steel rods reinforced with Cu element, and a precipitation hardening stainless steel rod with high strength, high toughness, and high corrosion resistance is manufactured by vacuum melting ingot casting, forging cogging, extrusion deformation, and the like. However, the final product strength of the two precipitation hardening stainless steel bars is only about 1400MPa, and the hardness is HRC40-45.
Application number CN201610591787 proposes a martensitic precipitation-hardening stainless steel reinforced with Al element, and a precipitation-hardening stainless steel profile with high strength and high toughness is manufactured by vacuum induction + electroslag smelting ingot casting, cogging forging, heat treatment, etc.; however, the final product strength is only about 1500MPa, and the hardness HRC is about 43.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to provide an ultra-high strength stainless steel bar material based on titanium element reinforcement and a preparation method thereof, wherein the Ti element reinforcement is adopted, and a more fine dispersed reinforcement phase (Ni 3 Ti phase) can obtain higher tensile strength on the premise of keeping good plasticity; proper amount of Mo element is added, so that the corrosion resistance of the stainless steel is improved; meanwhile, vacuum Induction Melting (VIM) +vacuum consumable remelting (VAR) is adopted for smelting, so that the content of impurities, particularly nitrogen, hydrogen and oxygen in the ultra-high strength stainless steel bar is less, and the ultra-high strength stainless steel bar can be ensured to have good plasticity, fracture toughness and hot working performance under the condition of ultra-high strength.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention provides a titanium-based reinforced ultra-high strength stainless steel bar, which comprises the following chemical components in percentage by weight: less than or equal to 0.01 percent of C, less than or equal to 0.005 percent of S, less than or equal to 0.01 percent of P, less than or equal to 0.01 percent of Si, less than or equal to 0.10 percent of Mn, and Cr:10.0 to 13.0 percent of Ni:10.50 to 12.50 percent of Mo:0.75 to 1.25 percent of Ti:1.40 to 1.70 percent, N is less than or equal to 0.005 percent, and the balance is Fe and unavoidable impurities.
Preferably, the tensile strength of the ultra-high strength stainless steel bar based on titanium element reinforcement is more than or equal to 1700MPa, and the fracture toughness is more than or equal to 78 MPa.m 1/2 The hardness HRC is more than or equal to 47.
Preferably, the yield strength of the ultra-high strength stainless steel bar based on titanium element reinforcement is more than or equal to 1640MPa, the elongation is more than or equal to 10%, and the surface shrinkage is more than or equal to 55%.
The second aspect of the invention provides a preparation method of the ultra-high strength stainless steel bar reinforced by titanium element according to the first aspect of the invention, which comprises the following steps:
s1, vacuum induction smelting, namely adding raw materials into a vacuum induction furnace for smelting, detecting components of molten steel before tapping, and pouring and tapping after the components reach target components of the ultra-high strength stainless steel bar to obtain an electrode rod;
s2, carrying out vacuum consumable remelting, namely carrying out vacuum consumable remelting smelting on the electrode rod to obtain a stainless steel cast ingot with chemical components meeting the requirements of the ultra-high strength stainless steel rod material;
s3, forging, namely heating the stainless steel cast ingot to 1130-1260 ℃, preserving heat for 24-26 hours, and cogging and forging to obtain an intermediate forging stock; then the intermediate forging stock is heated again, and a stainless steel bar is obtained through forging or rolling;
s4, carrying out solution heat treatment and quenching treatment on the stainless steel bar;
s5, cooling the stainless steel bar material processed in the step S4 in an environment with the temperature less than or equal to 73 ℃, naturally recovering the stainless steel bar material to the room temperature, then carrying out heating treatment, and then discharging and air cooling.
Preferably, in the step S1, the target composition of the ultra-high strength stainless steel bar satisfies: less than or equal to 0.01 percent of C, less than or equal to 0.005 percent of S, less than or equal to 0.01 percent of P, less than or equal to 0.01 percent of Si, less than or equal to 0.10 percent of Mn, and Cr:10.0 to 13.0 percent of Ni:10.50 to 12.50 percent of Mo:0.75 to 1.25 percent of Ti:1.40 to 1.70 percent, N is less than or equal to 0.005 percent, and the balance is Fe in percentage by weight.
Preferably, in the step S3:
when the intermediate forging stock adopts a forging mode, heating the intermediate forging stock to 1050-1120 ℃, preserving heat for 3-5 hours, and forging to obtain the stainless steel bar; or (b)
When the intermediate forging stock adopts a rolling mode, the intermediate forging stock is heated to 1050-1120 ℃ and is preserved for 3-5 hours, and then is forged again to obtain a secondary forging stock; and then heating the secondary forging stock to 1030-1100 ℃ and preserving heat for 3-5 hours, and rolling the secondary forging stock into the stainless steel bar.
Preferably, in the step S3:
the reheating temperature is 850-1120 ℃; and/or
The total deformation ratio of the stainless steel cast ingot to the stainless steel bar is more than or equal to 4.
Preferably, in the step S4, in the solution heat treatment process, the solution temperature is 960-1000 ℃ and the solution time is 1-5 h.
Preferably, in the step S4, during the quenching treatment, the stainless steel rod after the solution heat treatment of the mirror is cooled to room temperature by water or oil.
Preferably, in the step S5, the heating treatment temperature is 500-530 ℃, and the heat preservation time is 4-10 hours.
The design principle of the chemical composition of the ultra-high strength stainless steel bar based on titanium element reinforcement is as follows:
carbon (C) is a gap solid solution element, can obviously improve the matrix strength of steel, can stabilize austenite and inhibit delta ferrite from forming; however, due to limited solubility in austenite and ferrite, too high carbon content can reduce the toughness of the steel, and can cause precipitation of M23C6 type carbide in the heat treatment process, so that the intergranular corrosion resistance of the steel is reduced; therefore, the carbon content in the present invention is controlled to be 0.01% or less.
Chromium (Cr) is a ferrite stabilizing element which mainly improves corrosion resistance and oxidation resistance in stainless steel, and studies have shown that a minimum of 10.5% Cr in steel forms a stable passivation film protecting the steel from atmospheric corrosion. The corrosion resistance of stainless steel increases with increasing Cr content. However, too high Cr content promotes the formation of harmful phases, reduces the hot workability of stainless steel, and also easily causes the occurrence of metal segregation during smelting, so that the Cr content of the present invention is controlled to be 10.00-13.00%.
Nickel (Ni) is an austenite stabilizing element that expands the austenite phase region, thereby ensuring that the stainless steel has good plastic deformation characteristics. The increase of the nickel content can effectively reduce the delta ferrite content; nickel can improve the composition, structure and performance of an oxide film of chromium, so that the corrosion resistance and oxidation resistance of stainless steel are improved, and the cold work hardening tendency of the stainless steel can be obviously reduced; however, too high a nickel content will lead to an increase in production costs, and the nickel content of the present invention is controlled to be 10.50 to 12.50% in comprehensive consideration.
Molybdenum (Mo) is advantageous for strength, toughness and corrosion resistance of martensitic stainless steel. The molybdenum-rich precipitate can play a role in strengthening, can also keep the toughness of steel and plays an important role in strengthening the steel when being precipitated in the early aging stage. The existence of molybdenum can also prevent the precipitated phase from precipitating on the prior austenite grain boundary, avoid the along-grain fracture and improve the fracture toughness of the steel. In some reducing media, molybdenum also promotes the passivation of Cr. Therefore, the molybdenum can improve the corrosion resistance of the chromium-nickel stainless steel in some reducing acids such as sulfuric acid, hydrochloric acid, phosphoric acid and some organic acids, can effectively inhibit the pitting corrosion tendency of chloride ions to the steel, and improves the intergranular corrosion resistance. Since molybdenum is also an austenite forming element like nickel, molybdenum element cannot be excessively added to form residual austenite, and thus the tensile strength is affected, and thus the molybdenum content of the present invention is controlled to 0.75 to 1.25%.
Titanium (Ti) is the most effective strengthening alloying element in stainless steel. In general, adding a proper amount of titanium has remarkable aging strengthening effect, and mainly forms a Ni3Ti strengthening phase in the aging process. However, too much titanium element is extremely easy to form sharp quadrilateral Ti (C, N) inclusion with C, N in steel, and also forms hard polygonal (Ti, mo) C inclusion with Mo element, so that the toughness of stainless steel is seriously reduced, and therefore, the titanium content of the invention is controlled to be 1.40-1.70%.
Silicon (Si) is mainly used as a deoxidizer during smelting, and can strengthen a matrix, improve corrosion resistance and high-temperature oxidation resistance of steel; however, too high a silicon content may cause precipitation of harmful phases, reducing the hot workability and toughness of the steel. Therefore, the silicon content of the invention is controlled below 0.10%.
Manganese (Mn), an austenite stabilizing element that enlarges the austenite phase region, is a good deoxidizer and desulfurizing agent, and is generally contained in an amount in industrial steels; in stainless steel, manganese can replace part of nickel to stabilize austenite, so that the production cost is reduced, the nitrogen content in the steel can be improved, and the strength of the steel is ensured; however, too high a manganese content can greatly reduce the corrosion resistance, especially the pitting and intergranular corrosion resistance, of the steel. Therefore, the manganese content of the invention is controlled below 0.10 percent.
Sulfur (S) is present in the steel in the form of FeS and causes hot shortness of the steel. FeS has a melting point of 1193 ℃, and a eutectic of Fe and FeS has a melting point of only 985 ℃; the liquid Fe and FeS can be infinitely mutually dissolved, but the solubility of FeS in solid iron is very small and is only 0.015-0.020%. Therefore, when the sulfur content of the steel exceeds 0.020%, the Fe-FeS is distributed in a network form at the grain boundary in a eutectic of a low melting point due to segregation during cooling solidification of the molten steel. The hot working temperature of the steel is 1150-1200 ℃, at which the eutectic at the grain boundary is melted, and when the steel is pressed, the grain boundary is broken, which is the 'hot brittleness' of the steel; when the oxygen content in the steel is higher, the eutectic melting point formed by FeO and FeS is lower, only 940 ℃, and the phenomenon of thermal embrittlement of the steel is more remarkable. In addition, sulfur significantly reduces the weldability of the steel, causes high Wen Guilie, and creates many voids and porosity in the metal weld, thereby reducing the strength of the weld. When the sulfur content exceeds 0.06%, corrosion resistance of the steel is significantly deteriorated. Therefore, the sulfur content of the invention is controlled below 0.005%.
The phosphorus (P) steel can be completely dissolved in ferrite, and the strength and hardness of the ferrite are improved. However, at room temperature, the plasticity and toughness of steel are drastically reduced, and low-temperature brittleness is generated, which is called cold embrittlement. In general, phosphorus is a harmful element in steel, and mainly precipitates a brittle compound Fe3P to increase brittleness of the steel, and is more remarkable particularly at low temperatures. Therefore, the phosphorus content of the invention is controlled below 0.01 percent.
The nitrogen (N) acts similarly to the carbon (C), and exists in the form of interstitial atoms in the unit cell, which is more favorable for solid solution strengthening of steel due to the larger difference in atomic size. The effect of the austenite stabilizing element N on enlarging and stabilizing the austenite structure is about 25 times that of Ni, and the solid solubility content of the austenite stabilizing element N in austenite is far higher than that of ferrite. Typically, small amounts of ferrite are present in conventional stainless steel, and as the carbon content decreases, the ferrite content will increase, resulting in a decrease in the strength, plasticity, and toughness of the stainless steel. The addition of N can suppress ferrite precipitation and compensate for the decrease in strength and toughness due to the decrease in C content. However, too high a nitrogen content tends to cause precipitation of Cr2N during heat treatment or welding, which affects the mechanical properties of the stainless steel. When a certain Ti element exists in the stainless steel, N is very easy to form hard TiN or Ti (C, N) inclusion with the N, so that the toughness of the stainless steel is seriously reduced, and the nitrogen content is controlled below 0.005%.
The invention has the following beneficial effects:
1. compared with 17-4PH, 15-5PH and PH13-8Mo stainless steel which are widely used in the industrial field, the invention adopts Ti element for strengthening, and through solid solution aging heat treatment, a more fine dispersed strengthening phase (Ni 3Ti phase) can be separated out from a martensitic matrix, and higher tensile strength can be obtained on the premise of keeping good plasticity; proper amount of Mo element is added, so that the corrosion resistance of the stainless steel is improved; meanwhile, vacuum Induction (VIM) +vacuum consumable remelting (VAR) smelting is adopted in the preparation method, so that the content of gas impurities, particularly nitrogen, hydrogen and oxygen, in the ultra-high strength stainless steel bar is less, and the ultra-high strength stainless steel bar has good plasticity, fracture toughness and hot workability under the condition of ensuring the ultra-high strength;
2. the ultra-high strength stainless steel bar based on titanium element reinforcement is easy to process, good in corrosion resistance, high in tensile strength of 1700MPa or more and high in fracture toughness K IC ≥78MPa·m 1/2 The hardness HRC is more than or equal to 47;
3. the ultra-high strength stainless steel bar based on titanium element reinforcement can be applied to the aerospace field with high requirements on strength, toughness, corrosion resistance and the like, and also can be applied to the petroleum, chemical industry, energy and power fields, particularly in the aerospace field, the high-strength high-toughness precipitation hardening stainless steel is adopted to replace the traditional high-strength steel, so that the service life of an airplane is prolonged, the maintenance period is shortened, the manufacturing cost is reduced, and the environmental pollution is reduced.
Detailed Description
In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below with reference to examples.
The invention relates to a titanium-based reinforced ultra-high strength stainless steel bar, which comprises the following chemical components in percentage by weight: less than or equal to 0.01 percent of C, less than or equal to 0.005 percent of S, less than or equal to 0.01 percent of P, less than or equal to 0.01 percent of Si, less than or equal to 0.10 percent of Mn, and Cr:10.0 to 13.0 percent of Ni:10.50 to 12.50 percent of Mo:0.75 to 1.25 percent of Ti:1.40 to 1.70 percent, N is less than or equal to 0.005 percent, and the balance is Fe and unavoidable impurities.
The tensile strength of the ultra-high strength stainless steel bar is more than or equal to 1700MPa, and the fracture toughness is more than or equal to 78 MPa.m 1/2 The hardness HRC is more than or equal to 47; the yield strength is more than or equal to 1640MPa, the elongation is more than or equal to 10%, and the surface shrinkage is more than or equal to 55%.
The preparation method of the ultra-high strength stainless steel bar based on titanium element reinforcement comprises the following steps:
s1, vacuum induction smelting: preparing raw materials of industrial pure iron, metal Cr, metal Mo, metal Ti and the like, adding the raw materials into a vacuum induction furnace for smelting to obtain high-purity molten steel, detecting the components of the molten steel before tapping to obtain target components (namely, C is less than or equal to 0.01 percent, S is less than or equal to 0.005 percent, P is less than or equal to 0.01 percent, si is less than or equal to 0.01 percent, mn is less than or equal to 0.10 percent, cr is 10.0-13.0 percent, ni is 10.50-12.50 percent, mo is 0.75-1.25 percent, ti is 1.40-1.70 percent, N is less than or equal to 0.005 percent and the balance is Fe) of the ultra-high strength stainless steel bar, and pouring the steel bar into a steel ingot mold in a vacuum environment for tapping to obtain the electrode bar.
S2, vacuum consumable remelting: carrying out vacuum consumable remelting smelting on the electrode rod to obtain a stainless steel cast ingot with chemical components meeting the requirements of the ultra-high strength stainless steel rod material;
s3, forging: heating the stainless steel cast ingot to 1130-1260 ℃, preserving heat for 24-26 hours, and cogging and forging to obtain an intermediate forging stock; and then, the intermediate forging stock is heated to 850-1120 ℃ again, and then the stainless steel bar is obtained by forging or rolling. When the intermediate forging stock adopts a forging mode, heating the intermediate forging stock to 1050-1120 ℃ and preserving heat for 3-5 hours, and forging to obtain the stainless steel bar; when the intermediate forging stock adopts a rolling mode, the intermediate forging stock is heated to 1050-1120 ℃ and is preserved for 3-5 hours and then forged again to obtain a secondary forging stock; then heating the secondary forging stock to 1030-1100 ℃ and preserving heat for 3-5 hours, and rolling the secondary forging stock into the stainless steel bar; in the process, the total deformation ratio of the stainless steel cast ingot to the stainless steel bar is more than or equal to 4.
S4, carrying out solution heat treatment and quenching treatment on the stainless steel bar, wherein the solution heat treatment comprises the following steps: heating the stainless steel bar to 960-1000 ℃ and preserving heat for 1-5 h according to the diameter of the stainless steel bar; quenching: the stainless steel bar material after solution heat treatment is cooled to room temperature by water or oil.
And S5, placing the stainless steel bar material treated in the step S4 in an environment with the temperature less than or equal to 73 ℃ for cooling treatment, preserving heat for 1-8 hours, taking out, heating to 500-530 ℃ after the stainless steel bar material naturally returns to the room temperature, preserving heat for 4-10 hours according to the diameter of the bar material, and then discharging and air cooling.
The ultra-high strength stainless steel bar based on titanium element reinforcement according to the present invention and the method for preparing the same are further described below with reference to specific examples.
Example 1
(1) Adopting a Vacuum Induction (VIM) +vacuum consumable remelting (VAR) smelting process to obtain a stainless steel cast ingot with the diameter of 610mm, wherein the chemical compositions are shown in table 1;
(2) Heating the obtained cast ingot to 1240+/-20 ℃, preserving heat for 24 hours, and cogging and forging on a 4000 ton quick forging machine to obtain a 280mm octagonal intermediate forging stock;
(3) Heating the 280mm octagonal middle forging stock to 1100+/-20 ℃, preserving heat for 3 hours, and forging on a 1300 ton diameter forging machine to obtain a large-size bar with phi 150 mm;
(4) Heating the phi 150mm forged bar to 975+/-15 ℃, preserving heat for 3 hours, and cooling the oil to room temperature;
(5) Placing the bar subjected to solid solution and quenching treatment in an environment below-73 ℃ for 1 hour, taking out, and naturally recovering to room temperature;
(6) And heating the bar subjected to cooling treatment to 520-530 ℃, preserving heat for 6 hours, discharging from a furnace, and air-cooling to room temperature.
(7) The mechanical properties of 150mm phi forged bars were tested and the results are shown in table 2.
Example 2
(1) Adopting a Vacuum Induction (VIM) +vacuum consumable remelting (VAR) smelting process to obtain a stainless steel cast ingot with the diameter of 360mm, wherein the chemical compositions are shown in table 1;
(2) Heating the obtained cast ingot to 1150+/-20 ℃, preserving heat for 24 hours, and cogging and forging on a 2000-ton quick forging machine to obtain a 220-mm octagonal intermediate forging stock;
(3) Heating the 220mm octagonal intermediate forging stock to 1100+/-20 ℃, preserving heat for 3 hours, and forging on a 1300-ton diameter forging machine to obtain a 140mm square intermediate forging stock;
(4) Heating the 140mm square intermediate forging stock to 1050+/-20 ℃, preserving heat for 3 hours, and rolling on a rolling mill to obtain a phi 70mm bar;
(5) Heating the phi 70mm bar to 990+/-10 ℃, preserving heat for 3 hours, and cooling to room temperature by water;
(6) Placing the bar subjected to solid solution and quenching treatment in an environment below-73 ℃ for 4 hours, taking out, and naturally recovering to room temperature;
(7) Heating the bar after cooling treatment to 500-510 ℃, preserving heat for 4 hours, discharging from the furnace, and air cooling to room temperature;
(8) The mechanical properties of the bars with the diameter of 70mm are detected, and the results are shown in Table 2.
Example 3
(1) Adopting a Vacuum Induction (VIM) +vacuum consumable remelting (VAR) smelting process to obtain a stainless steel cast ingot with the diameter of 810mm, wherein the chemical compositions are shown in table 1;
(2) Heating the obtained cast ingot to 1240+/-20 ℃, preserving heat for 24 hours, and cogging and forging on a 4000 ton quick forging machine to obtain a 750mm octagonal intermediate forging stock;
(3) Heating the 750mm octagonal intermediate forging stock to 1100+/-20 ℃, preserving heat for 3 hours, and forging on a 4000 ton diameter forging machine to obtain a large-size bar with phi 350 mm;
(4) Heating the phi 350mm forged bar to 980+/-15 ℃, preserving heat for 5 hours, and cooling the oil to room temperature;
(5) Placing the bar subjected to solid solution and quenching treatment in an environment below-73 ℃ for 8 hours, taking out, and naturally recovering to room temperature;
(6) Heating the bar after cooling treatment to 510-520 ℃, preserving heat for 10 hours, discharging from the furnace, and air cooling to room temperature.
(7) The mechanical properties of the phi 350mm forged bars were tested and the results are shown in Table 2.
Table 1 chemical composition (mass%) of stainless steel in examples
Table 2 mechanical properties of ultra high strength stainless steel bars
As is clear from the combination of Table 1 and Table 2, the ultra-high strength stainless steel bar obtained by the titanium-based reinforced ultra-high strength stainless steel bar and the method for producing the same of the present invention in examples 1 to 3 has a tensile strength of 1700 to 1820MPa, a yield strength of 1640 to 1750MPa, an elongation of 10 to 15%, a reduction in area of 50 to 60%, and a fracture toughness of 90 to 130 MPa.m 1/2 The hardness HRC is more than or equal to 47.
In conclusion, the high-strength and high-toughness stainless steel is reinforced by titanium element, has fewer impurities through vacuum induction and consumable smelting, contains extremely small C content and higher Ni and Mo content, and has good corrosion resistance; compared with the traditional 17-4PH, 15-5PH and PH13-8Mo alloys, the 1700 MPa-grade ultra-high strength stainless steel has higher strength and corrosion resistance under the condition of keeping higher toughness indexes. The composite material can be applied to the aerospace field with high requirements on strength, toughness and corrosion resistance, and can also be applied to the fields of petroleum, chemical industry, energy and power. In particular in the aspect of aerospace, the high-strength high-toughness precipitation hardening stainless steel is adopted to replace the traditional high-strength steel, so that the service life of the aircraft is prolonged, the maintenance period is shortened, the manufacturing cost is reduced, and the environmental pollution is reduced.
It will be appreciated by persons skilled in the art that the above embodiments are provided for illustration only and not for limitation of the invention, and that changes and modifications to the above described embodiments are intended to be within the scope of the appended claims.
Claims (10)
1. The ultra-high strength stainless steel bar based on titanium element reinforcement is characterized by comprising the following chemical components in percentage by weight: less than or equal to 0.01 percent of C, less than or equal to 0.005 percent of S, less than or equal to 0.01 percent of P, less than or equal to 0.01 percent of Si, less than or equal to 0.10 percent of Mn, and Cr:10.0 to 13.0 percent of Ni:10.50 to 12.50 percent of Mo:0.75 to 1.25 percent of Ti:1.40 to 1.70 percent, N is less than or equal to 0.005 percent, and the balance is Fe and unavoidable impurities.
2. The ultra-high strength stainless steel bar based on the strengthening of the titanium element according to claim 1, wherein the tensile strength of the ultra-high strength stainless steel bar based on the strengthening of the titanium element is more than or equal to 1700MPa, and the fracture toughness is more than or equal to 78 MPa-m 1/2 The hardness HRC is more than or equal to 47.
3. The ultra-high strength stainless steel bar based on the strengthening of the titanium element according to claim 2, wherein the yield strength of the ultra-high strength stainless steel bar based on the strengthening of the titanium element is more than or equal to 1640MPa, the elongation is more than or equal to 10% and the surface shrinkage is more than or equal to 55%.
4. A method for producing a titanium-based reinforced ultra-high strength stainless steel bar according to any one of claims 1 to 3, comprising the steps of:
s1, vacuum induction smelting, namely adding raw materials into a vacuum induction furnace for smelting, detecting components of molten steel before tapping, and pouring and tapping after the components reach target components of the ultra-high strength stainless steel bar to obtain an electrode rod;
s2, carrying out vacuum consumable remelting, namely carrying out vacuum consumable remelting smelting on the electrode rod to obtain a stainless steel cast ingot with chemical components meeting the requirements of the ultra-high strength stainless steel rod material;
s3, forging, namely heating the stainless steel cast ingot to 1130-1260 ℃, preserving heat for 24-26 hours, and cogging and forging to obtain an intermediate forging stock; then the intermediate forging stock is heated again, and a stainless steel bar is obtained through forging or rolling;
s4, carrying out solution heat treatment and quenching treatment on the stainless steel bar;
s5, cooling the stainless steel bar material processed in the step S4 in an environment with the temperature less than or equal to 73 ℃, naturally recovering the stainless steel bar material to the room temperature, then carrying out heating treatment, and then discharging and air cooling.
5. The method for producing a titanium-based reinforced ultra-high strength stainless steel bar according to claim 4, wherein in the step S1, the target components of the ultra-high strength stainless steel bar satisfy: less than or equal to 0.01 percent of C, less than or equal to 0.005 percent of S, less than or equal to 0.01 percent of P, less than or equal to 0.01 percent of Si, less than or equal to 0.10 percent of Mn, and Cr:10.0 to 13.0 percent of Ni:10.50 to 12.50 percent of Mo:0.75 to 1.25 percent of Ti:1.40 to 1.70 percent, N is less than or equal to 0.005 percent, and the balance is Fe in percentage by weight.
6. The method for preparing a titanium-based reinforced ultra-high strength stainless steel bar according to claim 4, wherein in the step S3:
when the intermediate forging stock adopts a forging mode, heating the intermediate forging stock to 1050-1120 ℃, preserving heat for 3-5 hours, and forging to obtain the stainless steel bar; or (b)
When the intermediate forging stock adopts a rolling mode, the intermediate forging stock is heated to 1050-1120 ℃ and is preserved for 3-5 hours, and then is forged again to obtain a secondary forging stock; and then heating the secondary forging stock to 1030-1100 ℃ and preserving heat for 3-5 hours, and rolling the secondary forging stock into the stainless steel bar.
7. The method for preparing a titanium-based reinforced ultra-high strength stainless steel bar according to claim 4, wherein in the step S3:
the reheating temperature is 850-1120 ℃; and/or
The total deformation ratio of the stainless steel cast ingot to the stainless steel bar is more than or equal to 4.
8. The method for producing a titanium-based reinforced ultra-high strength stainless steel bar according to claim 4, wherein in the step S4, the solution temperature is 960 to 1000 ℃ and the solution time is 1 to 5 hours during the solution heat treatment.
9. The method for producing a titanium-based reinforced ultra-high strength stainless steel bar according to claim 4, wherein in the step S4, the mirror solution heat treated stainless steel bar is cooled to room temperature by water or oil.
10. The method for preparing a titanium-based reinforced ultra-high strength stainless steel bar according to claim 4, wherein the heating treatment temperature is 500-530 ℃ and the heat preservation time is 4-10 h in the step S5.
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