CN101608286A - A kind of duplex stainless steel with special magnetic property - Google Patents
A kind of duplex stainless steel with special magnetic property Download PDFInfo
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- CN101608286A CN101608286A CNA2008100393378A CN200810039337A CN101608286A CN 101608286 A CN101608286 A CN 101608286A CN A2008100393378 A CNA2008100393378 A CN A2008100393378A CN 200810039337 A CN200810039337 A CN 200810039337A CN 101608286 A CN101608286 A CN 101608286A
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Abstract
The invention provides a kind of duplex stainless steel with special magnetic property, its chemical ingredients comprises: C+N≤0.12wt%, Si≤1.0wt%, Mn:2.0～6.0wt%, P≤0.04wt%, S≤0.01wt%, Ni:3.0～7.0wt%, Cr:22.0～27.0wt%, Cu≤2.0wt%, Mo≤2.0wt%, W≤2.0wt%, less than the Ce of 0.1wt% or less than the B of 0.006wt%, all the other are Fe and unavoidable impurities, and the ratio (Creq/Nieq) of Cr equivalent and Ni equivalent is 3.1～3.8.Control by above-mentioned chemical ingredients is so that material is 68～85% at cold rolled annealed attitude ferrite volumn concentration, and saturation induction density is 0.72～1.0T.This duplex stainless steel hot-forming property is good, hardness is low, plasticity good, and has antifalsification, is applicable to coinage.
Description
Technical field
The present invention relates to the stainless material class, specifically, the present invention relates to a kind of duplex stainless steel with special magnetic property.
Background technology
Along with the raising of people's standard of living and aesthetic standards, industries such as amusement, commerce are day by day flourishing, and the performance requriements of facilities such as amusement, commerce with coin improved constantly, and the stainless steel coin arises at the historic moment.Stainless steel is with its lower cost, anticorrosion antiwear ability, good processing properties and surface luster, more and more admitted by market and likes.Adopt the material of stainless steel as coins such as manufacturing game machines already in many countries and regions, often the stainless steel that uses has 430 ferritic stainless steels and 304 austenitic stainless steels.
Yet there are a problem in amusement, commercial facility with coin, and as the game machine coin, the game machine storekeeper wishes that the coin stainless material of its use is different from other metallic substance, has special physicals, are difficult for forging and copying.
Stainless kind is a lot, and mostly surface luster, color are bright in vain, very difficult difference mutually, but bigger difference is being arranged aspect other physical propertys, wherein the feature of magnetic property is comparatively obvious, and detects easily, discerns.Duplex stainless steel is made up of ferrite and austenite two-phase structure, and along with the change of ferrite content, the magnetic property of material also changes thereupon, and it is fairly obvious, so just can distinguish with the stainless steel of other kinds, anti-counterfeiting is strong, and safety anti-fake is also strong on coin-in-the-slot machine.And present coinage is not strong with the stainless steel anti-counterfeit capability, so the strong coinage of the antifalsification of development of new become a kind of trend with duplex stainless steel, will obtain the extensive approval in people and market and likes.
By retrieval, find that duplex stainless steel mostly was to form different steel grades by the kind of alloying element and the variation of content in the past, seldom spell out the ratio of control Cr equivalent and Ni equivalent, even have also mostly is that the ratio of Cr equivalent with the Ni equivalent is controlled at less than 3.0, as publication number is that China of CN1155908 applies for a patent and discloses a kind of duplex stainless steel, it points out to control the ratio of Cr equivalent and Ni equivalent between 2.2～3.0, its ferrite content is 50～65%, push away magnetic induction density between 0.5～0.7T, its hardness is about 260.And for example publication number is that China of CN1571862 applies for a patent and points out ferrite content is controlled between 40～65%, push away magnetic induction density between 0.4～0.7, its hardness is about 285.Like this, can sum up the saturation induction density of duplex stainless steel in the past by ferritic content, its scope is between 0.4～0.7T.Because its hardness of material requirements that is used for coinage is low, plasticity good, generally should satisfy hardness HV≤220, unit elongation 〉=20%, and alloying constituent height, especially C, the N content in the duplex stainless steel was higher in the past, caused stainless steel hardness higher, its hardness＞220 are unsuitable for coinage.
Consider the mechanical property that coinage should have with material and can be different from other kind stainless steel that the present inventor regulates ferrite content in the control steel by chemical ingredients, has designed a kind of duplex stainless steel with special magnetic property, thereby has finished the present invention.
The object of the present invention is to provide a kind of duplex stainless steel with special magnetic property.
Summary of the invention
The invention provides a kind of duplex stainless steel with special magnetic property, the chemical ingredients of described duplex stainless steel comprises: C+N≤0.12wt%, Si≤1.0wt%, Mn:2.0～6.0wt%, P≤0.04wt%, S≤0.01wt%, Ni:3.0～7.0wt%, Cr:22.0～27.0wt%, less than the Ce of 0.1wt% or a kind of less than among the B of 0.006wt%, all the other are Fe and unavoidable impurities, and to satisfy Creq/Nieq be 3.1～3.8.
In a preferred implementation: also comprise in the chemical ingredients of described duplex stainless steel: Cu≤2.0wt%, Mo≤2.0wt% and W≤2.0wt%.
In a preferred implementation: C+N≤0.03wt%.
In a preferred implementation: the chromium equivalent Creq of described duplex stainless steel and nickel equivalent Nieq press following formula respectively and determine: Creq=%Cr+%Mo+1.5 * %Si+0.73 * %W, and Nieq=%Ni+30 * (%C+%N)+0.5 * %Mn+0.3 * %Cu.
Below, the chemical ingredients of the duplex stainless steel that originally has special magnetic property is done as being described in detail.
Carbon, nitrogen: be strong austenite former, but content is difficult for too much can making the intensity of steel too high more for a long time, the abrasion loss that adds the large coins press tool increases the coinage cost, controls C+N≤0.12wt% in the duplex stainless steel of the present invention, further, may command C+N≤0.03wt%.
Silicon: play the solution strengthening effect in steel, consider that the coinage steel needs lower hardness, the too high meeting of silicone content increases the hardness of steel, therefore preferably silicone content is controlled at below the 1.0wt%.
Manganese: in steel, play stable austenite and the thermoplastic effect that improves steel, also can save high price nickel to reduce cost, should suitably add more, generally its content is controlled at and is not less than 2.0wt%, but it is if excessive, can promote harmful formation mutually such as σ, also can reduce solidity to corrosion, so its addition preferably be no more than 6.0wt%.
Phosphorus, sulphur: consider that for the reason that duplex stainless steel thermoplasticity is relatively poor these two constituent contents will hang down as far as possible, control P≤0.04wt%, S≤0.01wt% in the steel of the present invention.
Chromium: improving the corrosion proof important element of steel, preferably control its content and be not less than 22wt%, consider the corrosion proof service requirements of coinage steel on the one hand, is the total amount that guarantees alloying element, so that austenite has certain room temperature deformation stability mutually on the other hand.But during the chromium too high levels, the intermetallic compound speed of separating out is accelerated, preferably be controlled its content and be no more than 27wt%.
Nickel: as the element that forms and enlarge the austenitic area consumingly, select suitable addition, reach the purpose of austenitic content in the control coinage steel according to what and forming technology and the thermal treatment process of other elements.The austenitic content of the very few difficult assurance of nickel content, but the price of nickel is higher, generally controls its scope between 3.0～7.0wt%.
Copper: solidity to corrosion, wear resistance and the cold machine-shaping of steel can be improved, also nickel can be saved, but the too high thermoplasticity that can reduce steel of addition, so copper content should be controlled at below the 2.0wt% in the stainless steel of the present invention.
Molybdenum, tungsten: add an amount of molybdenum and tungsten and can improve alloy corrosion resistance, when the formation that molybdenum or tungsten too much can strengthen intermetallic compound, also can gain in strength and cost, preferably controlled contents is no more than 2.0wt% respectively.
In addition,, can improve the thermoplasticity of duplex stainless steel, but these elements can not be too much if add a kind of in Ce or the B element, should control Ce less than 0.1wt%, B less than 0.006wt%, otherwise can damage the plasticity and the use properties of alloy.
It is 3.1～3.8 that alloy of the present invention satisfies Creq/Nieq, be in order to guarantee that the ferrite volumn concentration is at 68～85% o'clock, can obtain this alloy cold-reduced sheet annealed state room temperature saturation induction density is 0.72～1.0T, so just can be different from other stainless material, have obviously and effectively antifalsification.In addition, satisfy the ferrite volumn concentration, can also make alloy have cold working plasticity preferably, guarantee the plumpness of coin pattern after embossing less than 85% o'clock.And alloy of the present invention austenite phase content at high temperature seldom, has good hot workability, guaranteed the hot rolling lumber recovery, thereby further reduced the manufacturing cost of coin.
The present invention selects for use vacuum induction furnace, electric furnace-AOD duplex to smelt or electric furnace-AOD-VOD smelting stainless steel, die casting or continuous casting steel billet, in 1000～1100 ℃ of solution treatment, pickling descales, cold rolling after the hot rolling, 1000～1100 ℃ of annealing, pickling, glazed surface.
Beneficial effect of the present invention is: the saturation induction density of ferritic stainless steel and carbon steel is generally all greater than 1.2T, austenitic stainless steel magnetic a little less than, generally below 0.4T, the saturation induction density of duplex stainless steel of the present invention is 0.72～1.0T, and then make this material have special magnetic property, to be different from the stainless steel of other kinds, has antifalsification, and this duplex stainless steel hot-forming property is good, hardness is low, plasticity is good, corrosion resistance is better than existing coinage stainless steel, can be applied to the souvenir coin, fields such as coin can also provide mother metal for other need the metal articles for use of security feature.
Description of drawings
Fig. 1 (a) is the metallographic structure photo after the comparative example 1 stainless-steel cold-rolling annealing of the present invention, and wherein dark color is a ferritic phase, and light color is the austenite phase.
Fig. 1 (b) is the magnetzation curve after the comparative example 1 stainless-steel cold-rolling annealing of the present invention.
Fig. 2 (a) is the metallographic structure photo after the annealing of the embodiment of the invention 1 stainless-steel cold-rolling, and wherein dark color is a ferritic phase, and light color is the austenite phase.
Fig. 2 (b) is the magnetzation curve after the annealing of the embodiment of the invention 1 stainless-steel cold-rolling.
Embodiment
Below for a more detailed description to the present invention in conjunction with the accompanying drawings with embodiment.These embodiment only are the descriptions to best mode for carrying out the invention, scope of the present invention are not had any restriction.
Embodiment 1-5
Smelt or electric furnace-AOD-VOD smelting stainless steel with vacuum induction furnace, electric furnace-AOD, the casting steel billet, through being hot-rolled down to 4mm, about 1050 ℃ of solid solution+pickling are cold-rolled to 1.5mm, about 1050 ℃ of annealing+pickling, glazed surface.
The chemical ingredients of the duplex stainless steel of the embodiment of the invention sees Table 1.
Comparative example 1-4
Press the chemical ingredients smelting stainless steel shown in the table 1, all the other implementation steps are with embodiment 1-5.
Table 1 embodiment of the invention 1-5 and the stainless chemical ingredients of comparative example 1-4 (wt%)
Test example 1
Embodiment of the invention 1-5 and the stainless saturation induction density of comparative example 1-4 and mechanical property are tested, and test result sees Table 2.
Table 2 embodiment of the invention 1-5 and comparative example 1-4 are stainless
Ferrite volumn concentration, full magnetic induction density and mechanical property
| Sequence number | Ferrite content, % | Saturation induction density, T | ??HV | |
| Embodiment | ||||
| 1 | ??68 | ??0.72 | ??200 | ??31％ |
| |
??70 | ??0.77 | ??198 | ??30％ |
| Embodiment 3 | ??76 | ??0.88 | ??205 | ??24％ |
| |
??80 | ??0.95 | ??197 | ??22％ |
| Embodiment 5 | ??82 | ??0.98 | ??202 | ??21％ |
| Comparative example 1 | ??86 | ??1.03 | ??215 | ??19％ |
| Comparative example 2 | ??66 | ??0.71 | ??226 | ??30％ |
| Comparative example 3 | ??45～65 | ??0.45～0.70 | ??245 | ??30％ |
| Comparative example 4 | ??45～60 | ??0.45～0.65 | ??265 | ??30％ |
Test example 2
After embodiment 1-5 and comparative example 1-2 stainless steel carried out the hot rolling experiment, the limit portion that finds comparative example 1 and comparative example 2 hot-rolled sheets has crackle to occur, and the position that has cracking is more serious, and the embodiment 1-5 hot-rolled sheet that adopts same hot rolling technology is not found crackle, after elements such as having added boron and rare earth was described, stainless thermoplasticity was improved.
Test example 3
(national standard: GB/T17897-1999) duplex stainless steel and the industrial 430L stainless steel (dime material) to embodiment of the invention 1-5 carries out the corrosion resistance nature test, and detected result sees Table 3 according to stainless steel iron trichloride pitting corrosion test method.
The stainless anti-pitting attack performance of the duplex stainless steel of table 3 embodiment of the invention 1-5 and 430L
| Sequence number | ??6％FeCl 3, 35 ℃, 4h, corrosion rate (g/m 2·h) |
| |
??1.10 |
| |
??0.45 |
| Embodiment 3 | ??0.68 |
| |
??0.53 |
| Embodiment 5 | ??0.73 |
| Industry 430L | ??5.84 |
Detected result shows that the stainless solidity to corrosion of duplex stainless steel of the present invention all is better than the 430L stainless steel, has reached the coinage corrosion proof service requirements of stainless steel.
Claims (4)
1, a kind of duplex stainless steel with special magnetic property, it is characterized in that, the chemical ingredients of described duplex stainless steel comprises: C+N≤0.12wt%, Si≤1.0wt%, Mn:2.0～6.0wt%, P≤0.04wt%, S≤0.01wt%, Ni:3.0～7.0wt%, Cr:22.0～27.0wt%, less than the Ce of 0.1wt% or a kind of less than among the B of 0.006wt%, all the other are Fe and unavoidable impurities, and to satisfy Creq/Nieq be 3.1～3.8.
2, the duplex stainless steel with special magnetic property according to claim 1, its feature also is, comprises in the chemical ingredients of described duplex stainless steel: Cu≤2.0wt%, Mo≤2.0wt% and≤2.0wt%.
3, the duplex stainless steel with special magnetic property according to claim 1 and 2, its feature also is, C+N≤0.03wt%.
4, the duplex stainless steel with special magnetic property according to claim 1, wherein Creq and Nieq press following formula respectively and determine: Creq=%Cr+%Mo+1.5 * %Si+0.73 * %W, and Nieq=%Ni+30 * (%C+%N)+0.5 * %Mn+0.3 * %Cu.
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| CNA2008100393378A CN101608286A (en) | 2008-06-20 | 2008-06-20 | A kind of duplex stainless steel with special magnetic property |
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| CNA2008100393378A CN101608286A (en) | 2008-06-20 | 2008-06-20 | A kind of duplex stainless steel with special magnetic property |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014164722A1 (en) * | 2013-03-11 | 2014-10-09 | Crs Holdings, Inc. | A ferrous alloy for coining and mehtod for producing the same |
| CN105886956A (en) * | 2016-07-01 | 2016-08-24 | 东北大学 | Economical duplex stainless steel sheet and preparation method thereof |
| US10472703B2 (en) * | 2017-10-06 | 2019-11-12 | The United States Mint | Metal alloy for coin production |
| CN111500946A (en) * | 2020-05-25 | 2020-08-07 | 徐州优尚精密机械制造有限公司 | Stainless steel casting for ship hardware fitting and preparation process thereof |
| CN115725902A (en) * | 2022-12-02 | 2023-03-03 | 福州大学 | Saving type duplex stainless steel containing rare earth metal Ce and preparation method thereof |
-
2008
- 2008-06-20 CN CNA2008100393378A patent/CN101608286A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014164722A1 (en) * | 2013-03-11 | 2014-10-09 | Crs Holdings, Inc. | A ferrous alloy for coining and mehtod for producing the same |
| US9351547B2 (en) | 2013-03-11 | 2016-05-31 | Crs Holdings Inc. | Ferrous alloy for coining and method for producing the same |
| CN105886956A (en) * | 2016-07-01 | 2016-08-24 | 东北大学 | Economical duplex stainless steel sheet and preparation method thereof |
| CN105886956B (en) * | 2016-07-01 | 2017-10-31 | 东北大学 | A kind of economizing type two-phase stainless steel sheet and preparation method thereof |
| US10472703B2 (en) * | 2017-10-06 | 2019-11-12 | The United States Mint | Metal alloy for coin production |
| CN111500946A (en) * | 2020-05-25 | 2020-08-07 | 徐州优尚精密机械制造有限公司 | Stainless steel casting for ship hardware fitting and preparation process thereof |
| CN115725902A (en) * | 2022-12-02 | 2023-03-03 | 福州大学 | Saving type duplex stainless steel containing rare earth metal Ce and preparation method thereof |
| CN115725902B (en) * | 2022-12-02 | 2024-04-30 | 福州大学 | Rare earth metal Ce-containing saving type duplex stainless steel and preparation method thereof |
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Open date: 20091223 |