CN102011059A - Smelting technological process of low-silicon low-manganese ultrapure rotor steel - Google Patents
Smelting technological process of low-silicon low-manganese ultrapure rotor steel Download PDFInfo
- Publication number
- CN102011059A CN102011059A CN 201010611912 CN201010611912A CN102011059A CN 102011059 A CN102011059 A CN 102011059A CN 201010611912 CN201010611912 CN 201010611912 CN 201010611912 A CN201010611912 A CN 201010611912A CN 102011059 A CN102011059 A CN 102011059A
- Authority
- CN
- China
- Prior art keywords
- smelting
- steel
- molten steel
- low
- slag
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention discloses a smelting technological process of low-silicon low-manganese ultrapure rotor steel, which comprises the following procedures: (1) selecting raw materials and controlling the content of impurity elements in the raw materials; (2) smelting with a basic electric arc furnace, dephosphorizing with efficient dephosphorization slags, degassing and removing inclusions, and strictly controlling components of tapping molten steel within a target range; (3) refining with a ladle furnace (LF), taking efficient desulfurization slags as reducing and refining slags, deoxidizing, desulfurizing, alloying, modifying inclusions and removing the inclusions in the LF, and adjusting the temperature and the components of the molten steel within a target range; (4) refining with a VD (vacuum degassing) furnace, and carrying out deep desulfurization, degassing (dehydrogenizing) and removing the inclusions in high vacuum; and (5) casting by a vacuum protection mode. By adopting the smelting technological process, the phenomena of silicon increase, manganese increase and rephosphorization of the molten steel are effectively avoided during the smelting process, and the tapping quality of the molten steel is improved; and the obtained rotor steel has high purity, low content of harmful elements and excellent quality.
Description
Technical field
The invention belongs to the process for making technical field, especially belong to a kind of smelting technology method of ultrapure rotor steel.
?
Background technology
Along with development of electric power industry, the steam turbine power generation unit is constantly to high-parameters, large vol development, design, manufacturing and reliability of operation to the atomic power station generating set are had higher requirement, and therefore utilize advanced smelting equipment and production technique to obtain the good high-quality rotor steel of metallurgical performance and are very important.
The steel grade of ultrapure low pressure rotor representative is 30Cr2Ni4MoV, and this steel grade belongs to the medium alloy constructional steel of hypoeutectoid steel class, is the modified High Strength Structural Steel of fine.Data shows that when this steel hydrogen content was higher, the phase transformation meeting caused more serious internal stress (mainly being structural stress) in the process of cooling, the as easy as rolling off a log generation white point of rich hydrogen partial in forging, cause more serious lobe tendency, therefore, need [H] in the steel is controlled at below the 1.5ppm.In addition, in the ultrapure steel of 30Cr2Ni4MoV, impurity elements such as P, As, Sn, Sb will cause the temper embrittlement of steel, and S can cause toughness to reduce, and alloying elements such as Si, Mn can encourage embrittlement, therefore these constituent contents must be dropped to utmost point low value as much as possible.Like this, can guarantee that the low pressure rotor material that at high temperature uses does not produce embrittlement, thereby satisfy the needs in the power industry.In the prior art, the smelting process of ultrapure low pressure rotor steel can not satisfy the needs of the high-quality rotor steel of steam turbine power generation unit.
?
Summary of the invention
The present invention is directed to the smelting process of the ultrapure low pressure rotor steel of prior art, can not satisfy the deficiency of the high-quality rotor steel needs of steam turbine power generation unit, a kind of smelting technology of ultrapure low pressure rotor steel method that provides is provided, the rotor steel high purity that utilizes this technology to smelt, harmful element content is low, and the rotor steel that obtains is superior in quality.
For reaching above-mentioned purpose, the present invention adopts following smelting technology technical scheme: (1) selects raw material, and the content of impurity element makes it satisfy performance requriements in the control raw material; (2) basic electric arc furnace is smelted, and adopts high efficiency dephosphorating slag dephosphorization, and outgasing simultaneously and going is mingled with, and strict each composition of control tapping molten steel is within the target zone; (3) LF stove refining adopts the high-efficiency desulfurization slag as the reduction refining slag, carries out deoxidation, desulfurization, alloying, inclusion modification and removal and be mingled with in ladle furnace, and adjust liquid steel temperature, composition within the target zone; LF stove (LADLE FURNACE), promptly ladle refining furnace is an external refining equipment main in the Iron and Steel Production, its main task is: 1. desulfurization, 2. temperature regulation, 4. 3. accurate trimming improves the molten steel purity, 5. slag making.(4) VD stove refining utilizes high vacuum to carry out dark desulfurization, the degassing (dehydrogenation) and goes to be mingled with processing; (5) the vacuum protection cast is adopted in cast.
Electric furnace steel making raw material selection high-quality steel scrap, and Cu≤0.15% in the control raw material, As≤0.02%, Sn≤0.0015%, Sb≤0.0015%.
During electrosmelting, adopt high efficiency dephosphorating refining slag dephosphorization, its chemical chemical composition and weight content are: FeO:17～20 wt%, CaO:50～59 wt%, SiO
2: 19～20 wt%, CaF2:0.5～1.5 wt%, Al2O3:3～7 wt%, MgO:6～8 wt%, R(CaO/SiO2 dual alkalinity): 2.5～3.5.Slag under the strict control electric furnace adopts and stays the steel operation, tapping molten steel [P]＜0.002% during tapping.
Electric furnace is slightly made steel water requirement Tuo Tan Liang ⊿ C 〉=0.50%, guarantee in smelting process, to have a large amount of CO gas to generate, can and be mingled with the carrier of eliminating as obnoxious flavour in the steel (hydrogen, nitrogen), can cause the boiling of molten steel in the molten bath again, make the molten bath obtain enough dynamic conditionss, promote the carrying out of slag interface reaction (dephosphorization), reach the smelting requirements of deep dephosphorization, the degassing.
During the refining of LF stove, adopt high-efficiency desulfurization reduction refining slag, its chemical chemical composition and weight content are: CaO:60～70 wt%, CaF
2: 12～20 wt%, SiO
2＜6 wt%, Al
2O
3: 2～4 wt%, MgO:6～10 wt%, (MnO+FeO)＜1. 0 wt% guarantees molten steel tapping [S]≤0.003%.
The reduction refining reductive agent adopts carbon dust, aluminum shot and calcium carbide powder composite deoxidant, and its add-on is 2.5～3.5kg/t, and the mixed weight ratio of carbon dust, aluminum shot and calcium carbide powder is 6 ~ 9:0.8 ~ 1.4:0.8 ~ 1.4, and preferred proportion is 8:1:1.
Vacuum tightness is 1 ~ 5 Torr (holder) during the refining of VD stove, treatment time 10 ~ 30min, and 20min is more suitable, and argon blowing rate 100～300 Nl.min-1,200 Nl.min-1 are best.The VD stove, molten steel vacuum outgas system, it is a kind of molten steel treatment system of progressively growing up of China in recent years, its effect is to make molten steel denitrogenation (N), dehydrogenation (H), deoxidation (O), and molten steel stirred, improve the purity of molten steel, satisfy the strict demand of continuous casting and later process, thereby improve the quality of products steel quality.The molten steel purity is controlled at [Si]＜0.05% the most at last, [Mn]＜0.05%, [P]＜0.005%, [S]＜0.002%, Al＜0.01%, [H]＜1.5ppm, T[O]＜30ppm, [N]＜70PPm, As＜0.02%, Sn＜0.0015%, Sb＜0.0015%, Cu＜0.15%.
The content of its harmful element of the strict control of target slag making materials requires H
2O＜0.5%, P＜0.015%, S＜0.018%, wherein, desulfurization slag requires SiO
2＜6 %.
The present invention selects for use the high-quality steel scrap as main raw material when batching, and the content of Cu, As, harmful elements such as Sn, Sb has improved the molten steel purity greatly in strict simultaneously each batching of control; Electric furnace pushing off the slag tapping has effectively prevented the later process rephosphorization; The content of strict control Si, Mn, impurity elements such as P, S in the slag making raw material has prevented that effectively molten steel from increasing silicon, increase manganese in smelting process, rephosphorization, has improved molten steel and has gone out steel quality.
?
Embodiment
The present invention hangs down silicon, the low ultrapure rotor steel smelting technology of manganese method, comprises following operation:
(1) select raw material, for improving the molten steel purity, control the content of impurity element in the raw material, the content of harmful element in the major control raw material includes but not limited to Cu, As, Sn, Sb etc., Cu≤0.15%, As≤0.02%, Sn≤0.0015%, Sb≤0.0015%;
(2) qualified raw material is dropped in the basic electric arc furnace, carry out basic electric arc furnace and smelt, control Tuo Tan Liang ⊿ C 〉=0.5% guarantees sufficient deep dephosphorization, degassing smelting efficient, adopts the high efficiency dephosphorating slag to carry out dephosphorization simultaneously;
The chemical composition of high efficiency dephosphorating slag of the present invention and weight content are: FeO:17～20 wt%, CaO:50～59 wt%, SiO
2: 19～20 wt%, CaF2:0.5 ~ 1.5 wt%, Al2O3:3～7 wt%, MgO:6～8 wt%, R(CaO/SiO2 dual alkalinity): 2.5～3.5, tapping molten steel [P]=0.001%.
(3) the LF stove is smelted, and makes reductive agent with carbon dust, aluminum shot and calcium carbide powder composite deoxidant, and add-on is 2.5～3.5kg/t, and the blending ratio of its carbon dust, aluminum shot and calcium carbide powder is 8:1:1; Adopt the high-efficiency desulfurization slag to carry out desulfurization, the chemical ingredients of high-efficiency desulfurization slag is CaO:60～70 wt%, CaF
2: 12～20 wt%, SiO
2＜6 wt%(are promptly greater than 0 to 6% weight percent), Al
2O
3: 2～4 wt%, MgO:6～10 wt%, (MnO+FeO)＜1. 0 wt% realizes molten steel [S]=0.002% of coming out of the stove.
(4) VD stove smelting vacuum tightness is 2 Torr (holders), under vacuum, utilize the argon bottom-blowing agitation molten pool of the big flow of 200 Nl.min-1, increase molten bath slag interface reaction area, the molten steel purity is controlled at [Si]＜0.05% the most at last, [Mn]＜0.05%, [P]＜0.005%, [S]＜0.002%, Al＜0.01%, [H]＜1.5ppm, T[O]＜30ppm, [N]＜70PPm target.Treatment time is 20min.
(5) protection cast: big bag to middle Baogang stream adopts the long nozzle argon for protecting pouring; Adopt slag blocking wall, dam flow control device in the type tundish of ellipse garden, the molten steel face adopts alkaline covering agent; Molten steel enters ingot mold in the tundish, adopts the mode of vacuum pouring.
The content of its harmful element of the strict control of slag making materials requires H
2O＜0.5%, P＜0.015%, S＜0.018%, wherein, desulfurization slag requires SiO
2＜6 %.
Adopt smelting technology of the present invention, smelting end back molten steel composition is shown in the table 1.
Table 1 hangs down silicon, the low ultrapure rotor steel composition/wt% of manganese
| C | Mn | Si | P | S | Al | Cu |
| ≤0.35% | <0.05% | <0.05% | <0.005% | <0.002% | ≤0.01% | ≤0.15% |
| As | Sn | Sb | [H] | [O] | [N] | ? |
| ≤0.02% | ≤0.0015% | ≤0.0015% | ≤1.5ppm | ≤30ppm | ≤80ppm | ? |
Therefore, the present invention can realize the smelting of low silicon, the low ultrapure rotor steel of manganese, obtains the high ultralow-sulfur steel of purity, satisfies the technical requirements of ultrapure low pressure rotor steel.Patent of the present invention obtains great special subsidize (2009ZX04014-061) of Ministry of Science and Technology's Eleventh Five-Year Plan science and technology.
Claims (2)
1. a low silicon hangs down the ultrapure rotor steel smelting technology of manganese method, it is characterized in that comprising following operation:
(1) selects raw material, the content of impurity element in the control raw material, Cu≤0.15% in the control raw material, As≤0.02%, Sn≤0.0015%, Sb≤0.0015%;
(2) will smelt in the qualified raw material input basic electric arc furnace, control Tuo Tan Liang ⊿ C 〉=0.50% is smelted efficient to guarantee deep dephosphorization, the degassing; Adopt the high efficiency dephosphorating slag to carry out dephosphorization, the chemical composition of described high efficiency dephosphorating slag and weight content are: FeO:17～20 wt%, CaO:50～59 wt%, SiO2:19～20 wt%, CaF2:0.5～1.5 wt%, Al2O3:3～7 wt%, MgO:6～8 wt%, R:2.5～3.5, tapping molten steel [P]＜0.002%;
(3) molten metal after step (2) smelting is entered smelting in the LF stove, make reductive agent with carbon dust, aluminum shot and calcium carbide powder composite deoxidant, add-on is 2.5～3.5kg/t, and the blending ratio of its carbon dust, aluminum shot and calcium carbide powder is 6 ~ 9:0.8 ~ 1.4:0.8 ~ 1.4;
Adopt the high-efficiency desulfurization slag to carry out desulfurization then, the chemical composition of described high-efficiency desulfurization slag and weight content are CaO:60～70 wt%, CaF
2: 12～20 wt%, SiO
2＜6 wt%, Al
2O
3: 2～4 wt%, MgO:6～10 wt%, (MnO+FeO)＜1. 0 wt% realizes molten steel [S]≤0.003% of coming out of the stove;
(4) molten metal after step (3) smelting is entered smelting in the VD stove, the vacuum tightness of VD stove is 1～5Torr, utilize the argon bottom-blowing agitation molten pool of the big flow of 100～300 Nl.min-1 under vacuum, increase molten bath slag interface reaction area, the treatment time is 10 ~ 30min;
(5) protection cast: big bag to middle Baogang stream adopts the long nozzle argon for protecting pouring; Adopt slag blocking wall, dam flow control device in the type tundish of ellipse garden, the molten steel face adopts alkaline covering agent; Molten steel enters ingot mold in the tundish, adopts the mode of vacuum pouring.
2. according to the low ultrapure rotor steel smelting technology of the manganese method of the described low silicon of claim 1, it is characterized in that: the mixed weight ratio of carbon dust, aluminum shot and calcium carbide powder is 8:1:1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010106119124A CN102011059B (en) | 2010-12-29 | 2010-12-29 | Smelting technological process of low-silicon low-manganese ultrapure rotor steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010106119124A CN102011059B (en) | 2010-12-29 | 2010-12-29 | Smelting technological process of low-silicon low-manganese ultrapure rotor steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102011059A true CN102011059A (en) | 2011-04-13 |
| CN102011059B CN102011059B (en) | 2012-04-18 |
Family
ID=43841385
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010106119124A Expired - Fee Related CN102011059B (en) | 2010-12-29 | 2010-12-29 | Smelting technological process of low-silicon low-manganese ultrapure rotor steel |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102011059B (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102965470A (en) * | 2012-12-24 | 2013-03-13 | 中国第一重型机械股份公司 | Smelting and pouring method of low-silicon and aluminum-controlled steel |
| CN102978336A (en) * | 2012-12-14 | 2013-03-20 | 烟台台海玛努尔核电设备股份有限公司 | Smelting technique for removing Sb under arc furnace conditions |
| CN103667603A (en) * | 2013-12-24 | 2014-03-26 | 攀钢集团江油长城特殊钢有限公司 | Coarse vacuum dehydrogenation method |
| TWI507531B (en) * | 2012-01-06 | 2015-11-11 | Univ Nat Chunghsing | Method for removing sulfur from molten steel |
| CN106191634A (en) * | 2016-08-31 | 2016-12-07 | 四川六合锻造股份有限公司 | A kind of method significantly improving 30Cr2Ni4MoV impact property |
| CN106929635A (en) * | 2017-04-26 | 2017-07-07 | 攀钢集团江油长城特殊钢有限公司 | Steel ingot and its manufacture method |
| CN110512048A (en) * | 2019-10-10 | 2019-11-29 | 上海电气上重铸锻有限公司 | A kind of manufacturing method of low aluminium control silicon steel large steel ingot |
| CN113774286A (en) * | 2020-06-10 | 2021-12-10 | 宝武特种冶金有限公司 | High-purity raw steel and preparation method thereof |
| CN114908299A (en) * | 2022-04-22 | 2022-08-16 | 中钢集团邢台机械轧辊有限公司 | Preparation method of gas turbine rotor body forging |
| CN115612910A (en) * | 2021-07-16 | 2023-01-17 | 天津重型装备工程研究有限公司 | Nitrogen-controlled stainless steel smelting and ingot casting method for ultra-supercritical steam turbine rotor |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1858267A (en) * | 2006-06-02 | 2006-11-08 | 重庆大学 | Molten steel composite refining agent |
| JP2007107102A (en) * | 2000-06-14 | 2007-04-26 | Jfe Steel Kk | Method for transportation of reproduced desulfurization agent |
| CN101104876A (en) * | 2006-12-07 | 2008-01-16 | 首钢总公司 | Method for producing ultra-low phosphoretic steel by molten steel dephosphorising outside furnace |
| CN101476013A (en) * | 2009-01-20 | 2009-07-08 | 中国钢研科技集团公司 | Converter smelting process using dephosphorization agent |
-
2010
- 2010-12-29 CN CN2010106119124A patent/CN102011059B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007107102A (en) * | 2000-06-14 | 2007-04-26 | Jfe Steel Kk | Method for transportation of reproduced desulfurization agent |
| CN1858267A (en) * | 2006-06-02 | 2006-11-08 | 重庆大学 | Molten steel composite refining agent |
| CN101104876A (en) * | 2006-12-07 | 2008-01-16 | 首钢总公司 | Method for producing ultra-low phosphoretic steel by molten steel dephosphorising outside furnace |
| CN101476013A (en) * | 2009-01-20 | 2009-07-08 | 中国钢研科技集团公司 | Converter smelting process using dephosphorization agent |
Non-Patent Citations (2)
| Title |
|---|
| 《一重技术》 20080415 张春雨等 超纯转子钢30Cr2Ni4MoV的冶炼 40-41 1-2 , 第02期 2 * |
| 《中小企业管理与科技(上旬刊)》 20080805 徐清泉等 对于提高30Cr1Mo1V钢持久强度的研发 251-252 1-2 , 第08期 2 * |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI507531B (en) * | 2012-01-06 | 2015-11-11 | Univ Nat Chunghsing | Method for removing sulfur from molten steel |
| CN102978336A (en) * | 2012-12-14 | 2013-03-20 | 烟台台海玛努尔核电设备股份有限公司 | Smelting technique for removing Sb under arc furnace conditions |
| CN102978336B (en) * | 2012-12-14 | 2014-03-19 | 烟台台海玛努尔核电设备股份有限公司 | Smelting technique for removing Sb under arc furnace conditions |
| CN102965470A (en) * | 2012-12-24 | 2013-03-13 | 中国第一重型机械股份公司 | Smelting and pouring method of low-silicon and aluminum-controlled steel |
| CN102965470B (en) * | 2012-12-24 | 2014-01-22 | 中国第一重型机械股份公司 | Smelting and pouring method of low-silicon and aluminum-controlled steel |
| CN103667603A (en) * | 2013-12-24 | 2014-03-26 | 攀钢集团江油长城特殊钢有限公司 | Coarse vacuum dehydrogenation method |
| CN106191634A (en) * | 2016-08-31 | 2016-12-07 | 四川六合锻造股份有限公司 | A kind of method significantly improving 30Cr2Ni4MoV impact property |
| CN106929635A (en) * | 2017-04-26 | 2017-07-07 | 攀钢集团江油长城特殊钢有限公司 | Steel ingot and its manufacture method |
| CN110512048A (en) * | 2019-10-10 | 2019-11-29 | 上海电气上重铸锻有限公司 | A kind of manufacturing method of low aluminium control silicon steel large steel ingot |
| CN113774286A (en) * | 2020-06-10 | 2021-12-10 | 宝武特种冶金有限公司 | High-purity raw steel and preparation method thereof |
| CN115612910A (en) * | 2021-07-16 | 2023-01-17 | 天津重型装备工程研究有限公司 | Nitrogen-controlled stainless steel smelting and ingot casting method for ultra-supercritical steam turbine rotor |
| CN115612910B (en) * | 2021-07-16 | 2023-11-14 | 天津重型装备工程研究有限公司 | Nitrogen-controlled stainless steel smelting ingot casting method for ultra-supercritical steam turbine rotor |
| CN114908299A (en) * | 2022-04-22 | 2022-08-16 | 中钢集团邢台机械轧辊有限公司 | Preparation method of gas turbine rotor body forging |
Also Published As
| Publication number | Publication date |
|---|---|
| CN102011059B (en) | 2012-04-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102011059B (en) | Smelting technological process of low-silicon low-manganese ultrapure rotor steel | |
| CN106148844B (en) | A kind of preparation method of sulfur-bearing ultralow titanium high standard bearing steel | |
| CN102071287B (en) | Method for melting high-temperature-resistance and high-pressure-resistance alloy steel | |
| CN103451349B (en) | Control method for preventing nozzle clogging in casting process of ultra-low carbon-aluminium deoxidized molten steel | |
| WO2020093710A1 (en) | High-purity acid-resistant pipeline steel smelting process | |
| CN108330245B (en) | High-purity smelting method for stainless steel | |
| CN102199684B (en) | Production method of ultralow-oxygen titanium-containing ferrite stainless steel | |
| CN103882303B (en) | Smelting method of steel for gas shielded welding wire | |
| CN106086594B (en) | A kind of preparation method of Ti IF steel | |
| CN103741006B (en) | A kind of preparation method containing the low nitrogen stainless steel of Ti | |
| CN107312906B (en) | A kind of smelting process of the ultrapure low titanium bearing steel of low cost | |
| CN102134628A (en) | Smelting method of low-carbon aluminium killed steel with low silicon content | |
| CN103436657A (en) | Welding wire steel smelting process capable of preventing welding spatter | |
| CN104087711B (en) | The method and the carbon that improve molten steel purity close knot steel ingot | |
| CN102021490A (en) | X12CrMoWVNbN10-1-1 high-temperature structural steel and production method thereof | |
| JP7507895B2 (en) | Low-cost smelting method for ultra-high phosphorus hot metal for arctic steel | |
| CN105537549B (en) | The production method of 100 DEG C of low temperature seamless steel pipe steel continuous cast round billets | |
| CN107201422A (en) | A kind of production method of mild steel | |
| CN108588541A (en) | Low-nitrogen boron-containing steel smelting method for improving boron element yield | |
| CN102787206B (en) | Smelting method for controlling nitrogen content in steel ingot of medium carbon chromous mold steel and steel ingot | |
| CN108330240A (en) | Method of the aluminium without calcification processing drops in continuous casting Q235 steel grades | |
| CN109868415A (en) | A kind of smelting process of the low boron pipe line steel of low-sulfur | |
| CN110819761A (en) | Bottom pouring steel ingot or electrode blank and preparation method thereof | |
| CN107287490B (en) | Boron-containing steel smelting process method for improving boron yield | |
| CN111945062B (en) | Smelting method of low-carbon steel for mechanical structure pipe |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20120418 Termination date: 20131229 |