CN1068385C - ultra hypoeutectoid, diphasic stainless steel, and prodn. method thereof - Google Patents
ultra hypoeutectoid, diphasic stainless steel, and prodn. method thereof Download PDFInfo
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- CN1068385C CN1068385C CN96120046A CN96120046A CN1068385C CN 1068385 C CN1068385 C CN 1068385C CN 96120046 A CN96120046 A CN 96120046A CN 96120046 A CN96120046 A CN 96120046A CN 1068385 C CN1068385 C CN 1068385C
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Abstract
The present invention belongs to the alloy steel field and comprises chemical compositions (by weight percentage): at most 0.03% of C, at most 1.00 % of Si, at most 1.00 % of Mn, at most 0.03 % of S, at most 0.035 % of P, 23.0 to 27.0% of Cr, 4.0 to 7.0 % of Ni, 1.0 to 3.0 % of Mo and 0.10 to 0.20 % of No. All the chemical compositions have to satisfy the requirements of 7.9 to 9.9% of nickel equivalent. The steel smelting technologies adopt an electric furnace or an induction furnace for smelting, VOD refining and electroslag remelting, forging roll heat processing and solid solution heat treatment. The alloy steel has the advantages of good corrosion resistance, good corrosion resistance and fatigue resistance, and is mainly used for apparatus in urea production, such as ammonium carbamate pumps, valves, etc.
Description
The invention belongs to field of alloy steel.Mainly be applicable to component anticorrosive, particularly corrosion fatigue resistant and the equipment of requiring of making.
In the chemical fertilizer production process flow process, specific pump, valve are still to fail one of key issue that satisfactorily resolves with material all the time.Pump, valve are dynamic devices, and be fragile, and normal the replacing requires to have excellent corrosion resistance nature and have good resistance to corrosion fatigue performance to material therefor, to the heart equipment of urea production--and first ammonium pump just requires to have excellent corrosion fatigue resistant performance.
Urea production key equipment such as first ammonium pump is in operation, owing to be subjected to the combined action of repeated stress and the deep-etching of first ammonium liquid, be easy to generate erosion fatigue cracking at inner chamber of cylinder block, its work-ing life is short, not only the cylinder body consumption is big, and seriously shadow is to the continuous production of urea, and financial loss is big.The factor relevant with cylinder body cracking is a lot, and as the cylinder block material performance, manufacture and design, use and maintenance etc., but wherein the corrosion fatigue resistant performance of material itself is topmost factor.The corrosion fatigue resistant performance of material depends primarily on the factors such as solidity to corrosion, fatigue strength and material quality of material.
In the prior art, ultra hypoeutectoid, diphasic stainless steel is one of different metallic substance of corrosion fatigue resistant best performance.So-called two-phase is that the metallographic structure of steel is a two-phase: i.e. austenite structure (γ phase) and ferritic structure (α mutually).The Corrosion Fatigue Properties of the anti-urea first ammonium liquid of dual phase steel excellence depends primarily on the purity and the homogeneity of structure of suitable two-phase proportion steel, to avoid separating out of fragility phase simultaneously, think through research for many years, when α mutually and γ mutually between the biphase ratio respectively account for about 50% the time, its corrosion fatigue resistant performance and over-all properties optimum.
Nippon Standard JISG4303 (1974) has announced a kind of duplex stainless steel SUS329J1.The SUS329J1 steel be on the basis of U.S. AISI329 steel with carbon content by C≤0.1%C reduce to≤0.08%, further improve the duplex stainless steel of solidity to corrosion, weldability and other over-all properties.This steel is except that having anti-preferably pitting performance, solidity to corrosion in phosphoric acid and other particular surroundings also is better than containing the 18-8 type austenitic steel of Mo, and this steel is applicable to that mainly the heat exchanger of seawater and other industrial medium is with in heat-transfer pipe and chloride ion-containing brine medium and the phosphoric acid medium.The α phase amount is higher in the microstructure of this steel, reaches 60～70%, so whole corrosion resisting property is poor slightly, especially the corrosion fatigue resistant performance in first ammonium liquid medium is poorer, and this steel application in equipment such as urea production is restricted.
The object of the present invention is to provide the ultra hypoeutectoid, diphasic stainless steel and the manufacture method thereof of a kind of corrosion fatigue resistant performance and excellent combination property.
At above-mentioned purpose, the major technique measure that the present invention adopts is: on chemical ingredients, reduce carbon content, add N, improve Cr, Mo content, especially require control nickel equivalent (Nieq); On manufacture method, adopt refining thing suitable hot-work and heat treating regime.By above-mentioned measure obtain to have best α mutually and γ mutually the material of ratio and clarity height and good uniformity so that obtain the performance of excellence.
Concrete chemical ingredients of the present invention (weight %) is:
C≤0.03%, Si≤1.00%, Mn≤1.00%, S≤0.03%, P≤0.035%, Cr23.0～27.0%, Ni4.0～7.0%, Mo1.0～3.0%, NO.10～0.152%, surplus is Fe;
Simultaneously, the necessary following requirement of satisfying of nickel equivalent (Nieq):
Nieq=7.9～9.9
Nieq=1×Ni％+15×N％+30×C％+0.5×Mn％。
Ferrite in weave construction (α phase) must satisfy following requirement:
α phase (%)=144-10Nieq
Manufacture method of the present invention is as follows:
(1) smelting technology
[1] electric furnace or induction furnace melting+electroslag remelting process;
[2] electrosmelting+VOD refining+electroslag remelting process;
Be cast into steel ingot after the smelting.
(2) heat processing technique
The hot-work of steel ingot can be adopted and forge or rolling, and wherein Heating temperature is 1150～1200 ℃, opens and forges or start rolling temperature 〉=1050 ℃, finish-forging or finishing temperature 〉=950 ℃, air cooling behind the forging rolling.
(3) thermal treatment process
Steel ingot is through forging or the rolling laggard capable thermal treatment of becoming a useful person, and thermal treatment process adopts solution treatment, 1020～1070 ℃ of solid solubility temperatures, and soaking time 20 minutes～2 hours is quickly cooled to room temperature then.
Ultra hypoeutectoid, diphasic stainless steel goods of the present invention are applicable to the key equipment in the urea production--equipment such as first ammonium pump, valve.
On the chemical ingredients of steel, reduce C content, be in order to prevent that fragility from easily losing separating out of phase carbide, to improve the anti intercrystalline corrosion performance and the over-all properties of steel.Higher Cr, Mo content in the steel can not only form densification and passive film uniformly, and the ability of reviewing one's lessons by oneself of passive film is also very strong, makes it to improve solidity to corrosion.Ni and N all can improve the corrosion fatigue resistant performance of steel.Control suitable Ni, N content and nickel equivalent and mainly be regulate α mutually with γ biphase ratio mutually, steel is obtained by the suitable particular tissues structure that two-phase proportion constituted, the α phase amount in the steel can reach satisfied 45～65%.This is to obtain the excellent corrosion fatigue resistant performance and the key of over-all properties.
On the manufacture method of steel, smelting technology adopts electric furnace (or induction furnace) melting+esr, or electric furnace smelting furnace+VOD refining+esr, its objective is and reduce and the refinement inclusion, make it when improving the whole corrosion resistance of steel, further prevent with the inclusion to be the generation of the corrosion fatigue crack that causes of origin, improve the plasticity and toughness of steel simultaneously.In heat processing technique, the control Heating temperature, especially finish-forging or finishing temperature are controlled at more than 950 ℃, mainly be separating out for fear of fragility phase (σ phase), to guarantee enough forgings (rolling) pressure ratio (〉=2.5) simultaneously, make the homogeneous microstructure of steel and densification, prevent that tissue defects from being the generation of the caused corrosion fatigue crack of origin.
Aspect thermal treatment process, research by phase transformation law, verify α mutually with γ mutually the Changing Pattern of two-phase proportion and precipitated phase separate out rule, after determining in the solid solubility temperature scope, to carry out abundant solution treatment, be cooled fast to room temperature, obtain suitable two-phase proportion tissue and the optimal heat processing specification that prevents that fragility from separating out mutually.
According to chemical ingredients, nickel equivalent and the manufacture method of above-mentioned steel, the present invention can reach following index:
α can be controlled in 45～65% mutually
Corrosion Fatigue Properties under pulsating stress σ-1=275MPa, circulation cycle N＞107
Adopt the Huey method to carry out corrosion test, the gained corrosive nature is: the average etching extent in 5 cycles＜1.0 μ m/48h.
Mechanical property: σ b 〉=670MPa, σ s 〉=520MPa, δ 5＞25%, φ 〉=70%, Ak 〉=250J.
Compared with prior art, the present invention's advantage specific as follows:
(1) because chemical ingredients and nickel equivalent are suitable, can obtain 45～65% α phase, so have excellent corrosion fatigue resistant performance and over-all properties.
(2) because corrosion fatigue resistant performance and mechanical property excellence in first ammonium liquid medium, the present invention is applicable to the structural part or the structural device of each generic request corrosion resistance nature and resistance to corrosion fatigue better performances in the urea production equipment, is specially adapted to first ammonium pump, valve in the urea production equipment etc.
(3) nickel content of the present invention lower (comparing with austenitic stainless steel) can be saved a large amount of nickel, reduces cost.
Embodiment
Chemical ingredients designed according to this invention, nickel equivalent and manufacture method have been smelted 4 stove steel, and the chemical ingredients and the nickel equivalent of 4 stove steel are as shown in table 1; Smelting process is as shown in table 2; 4 stove steel are cast into steel ingot respectively after the melting, forge or be rolled into bar then, and it is as shown in table 3 that it forges rolling technological parameter; To forge material after the forging and divide heat (batch) number to carry out solution treatment, its processing parameter is as shown in table 4; Take a sample the forging material after thermal treatment then, carried out mechanical property test, inclusion and the test of α phase content, Huey method corrosion test and Corrosion Fatigue Properties test respectively, test and test result have been listed table 5, table 6, table 7 and table 8 respectively in.
In order to contrast, when carrying out Huey method corrosion test, also with having carried out corrosion test under the condition, its result also lists table 7 in the 316L stainless steel; In addition, also get the sample of 329J1 (00Cr25Ni6Mo2), 3RE60 (00Cr18Ni5Mo3Si2) and three duplex stainless steels of 316L (00Cr18Ni14Mo2), under similarity condition, carried out the corrosion fatigue resistant performance test simultaneously, its result also lists in the table 8.
Find out that by above-mentioned test-results compared with prior art, the nitrogenous ultra hypoeutectoid, diphasic stainless steel of the present invention not only has good mechanical performance and corrosion resistance, but also have excellent corrosion fatigue resistant performance.
Adopt the ultra hypoeutectoid, diphasic stainless steel of embodiment of the invention heat (batch) number 1, replace former import West Germany ALL184H material (urea 316L steel), make the cylinder body of the G2301 first ammonium pump of urea plant.The working medium of this first ammonium pump is a first ammonium liquid, and 75 ℃ of working temperatures use the result to show that the work-ing life of steel of the present invention, urea 316L material than import improved 8 times.
In addition, adopt the ultra hypoeutectoid, diphasic stainless steel of embodiment of the invention heat (batch) number 2, make the first ammonium pump cylinder block on the more harsh trimeric cyanamide device of working conditions, the working medium of this pump is a first ammonium liquid, and work is 105 ℃, and its work-ing life is higher 2 times than 329 steel of former usefulness.
The chemical ingredients and the nickel equivalent of table 1 embodiment grade of steel
| Heat (batch) number | Chemical ingredients (weight %) | Nickel equivalent % | |||||||||
| C | Si | Mn | S | P | Cr | Ni | Mo | N | Fe | ||
| 1 | 0.01 | 0.22 | 0.40 | 0.006 | 0.010 | 25.10 | 6.05 | 1.83 | 0.152 | Surplus | 8.8 |
| 2 | 0.01 | 0.18 | 0.63 | 0.005 | 0.010 | 25.27 | 6.05 | 1.88 | 0.136 | Surplus | 8.7 |
| 3 | 0.014 | 0.45 | 0.65 | 0.024 | 0.030 | 25.25 | 6.06 | 1.92 | 0.13 | Surplus | 8.8 |
| 4 | 0.018 | 0.41 | 0.66 | 0.016 | 0.034 | 24.68 | 6.12 | 1.92 | 0.135 | Surplus | 9.0 |
The smelting technology of table 2 embodiment grade of steel
| Heat (batch) number | Melting | Refining | Esr |
| 1 | Induction furnace melting | / | The consumable esr |
| 2 | Induction furnace melting | / | The consumable esr |
| 3 | Electrosmelting | The VOD refining | The consumable esr |
| 4 | Electrosmelting | The VOD refining | The consumable esr |
The thermal process parameter of table 3 embodiment grade of steel
| Heat (batch) number | Thermal processing method | Heating temperature ℃ | Open forging (rolling) temperature ℃ | Finish-forging (rolling) temperature ℃ | The type of cooling |
| 1 | Forge | 1150 | 1050 | ＞950 | Air cooling |
| 2 | Forge | 1150 | 1060 | ＞950 | Air cooling |
| 3 | Forge | 1150 | 1060 | ＞950 | Air cooling |
| 4 | Rolling | 1150 | 1070 | ＞950 | Air cooling |
The solid solution treatment process parameter of table 4 embodiment grade of steel
| Heat (batch) number | Solution treatment | ||
| Solid solubility temperature ℃ | Soaking time minute | The air cooling mode | |
| 1 | 1050 | 30 | Water-cooled |
| 2 | 1050 | 30 | Water-cooled |
| 3 | 1050 | 30 | Water-cooled |
| 4 | 1050 | 30 | Water-cooled |
The mechanical property of table 5 embodiment grade of steel
| Heat (batch) number | σb MPa | σs MPa | δ5 ％ | φ ％ | Ak J |
| 1 | 715 | 590 | 37 | 79 | 277 |
| 2 | 675 | 567 | 35 | 65 | 253 |
| 3 | 761 | 575 | 39 | 77 | 288 |
| 4 | 761 | 575 | 39 | 77 | 264 |
The inclusion grade of table 6 embodiment grade of steel and α phase content
| Heat (batch) number | The oxide compound rank | Sulphide grade | Ferrite (α phase content) |
| 1 | 0.5 | 0.5 | 58％ |
| 2 | 0.5 | 0.5 | 55％ |
| 3 | 1.0 | 1.0 | 57％ |
| 4 | 0.5 | 0.5 | 54％ |
The corrosive nature of table 7 embodiment and Comparative Examples (check of Huey method)
| The average corrosion rate μ in 5 cycles m/48 hour | Nickel equivalent Nieq | α phase % | ||
| The present invention | 1 | 0.94 | 8.8 | 58 |
| 2 | 0.62 | 8.7 | 55 | |
| 3 | 0.96 | 8.8 | 57 | |
| 4 | 0.91 | 9.0 | 54 | |
| 316L | 2.69 | |||
The corrosion fatigue resistant performance of table 8 embodiment and Comparative Examples
| Pulsating stress σ-1, MPa | Circulation cycle N | α phase % | Test conditions | ||
| The present invention | 1 | 2.75 | ＞107 | 58 | Communicate in the first ammonium liquid medium in the pipeline that links to each other with first ammonium pump |
| 2 | 2.86 | ＞107 | 55 | ||
| 3 | 2.79 | ＞107 | 57 | ||
| 4 | 2.73 | ＞107 | 54 | ||
| 329J1 | 226 | ＞107 | 70 | ||
| 3RE60 | 137 | ＞107 | 65 | ||
| 316L | 127 | ＞107 | |||
Claims (3)
1, a kind of ultra hypoeutectoid, diphasic stainless steel is characterized in that:
(1) chemical ingredients (weight %) is: C≤0.03%, and Si≤1.00%, Mn≤1.00%, S≤0.03%, P≤0.035%, Cr 23.0～27.0%, and Ni 4.0～7.0%, and Mo 1.0～3.0%, and N 0.10～0.152%, and surplus is Fe;
(2) chemical ingredients also must satisfy following nickel equivalent (Nieq) value:
Nieq=7.9～9.9
Nieq=Ni％+15×N％+30×C％+0.5×Mn％。
(3) the shared per-cent of ferrite (α phase) should be in the weave construction of steel:
α phase (%)=144-10Nieq
2, the production method of the described ultra hypoeutectoid, diphasic stainless steel of a kind of claim 1 comprises smelting, hot-work, thermal treatment process, it is characterized in that:
(1) smelting technology
A. electric furnace or induction furnace melting+esr;
B. electrosmelting+VOD refining+esr; Cast steel ingot after the smelting;
(2) steel ingot hot-work can be adopted and forge or rolling, and wherein Heating temperature is 1150～1200 ℃, opens and forges or start rolling temperature 〉=1050 ℃, finish-forging or finishing temperature 〉=950 ℃, air cooling behind the forging rolling;
(3) thermal treatment process
Solution treatment is adopted in thermal treatment, 1020～1070 ℃ of solid solubility temperatures, and soaking time 20 minutes～2 hours is quickly cooled to room temperature then.
3, the purposes of the described ultra hypoeutectoid, diphasic stainless steel of a kind of claim 1 is characterized in that this steel is applicable to the urea production key equipment--on first ammonium pump, the valve device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN96120046A CN1068385C (en) | 1996-10-14 | 1996-10-14 | ultra hypoeutectoid, diphasic stainless steel, and prodn. method thereof |
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| CN96120046A CN1068385C (en) | 1996-10-14 | 1996-10-14 | ultra hypoeutectoid, diphasic stainless steel, and prodn. method thereof |
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| CN1154419A CN1154419A (en) | 1997-07-16 |
| CN1068385C true CN1068385C (en) | 2001-07-11 |
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| CN109594025B (en) * | 2019-01-25 | 2019-08-16 | 无锡市法兰锻造有限公司 | A kind of two-phase steel forgings with anti intercrystalline corrosion performance |
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1117087A (en) * | 1994-05-21 | 1996-02-21 | 朴庸秀 | Duplex stainless steel with high corrosion resistance |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1117087A (en) * | 1994-05-21 | 1996-02-21 | 朴庸秀 | Duplex stainless steel with high corrosion resistance |
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