EP0163784B1 - Procédé de désoxydation d'acier en deux étapes - Google Patents
Procédé de désoxydation d'acier en deux étapes Download PDFInfo
- Publication number
- EP0163784B1 EP0163784B1 EP84303555A EP84303555A EP0163784B1 EP 0163784 B1 EP0163784 B1 EP 0163784B1 EP 84303555 A EP84303555 A EP 84303555A EP 84303555 A EP84303555 A EP 84303555A EP 0163784 B1 EP0163784 B1 EP 0163784B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- molten steel
- steel
- deoxidizing
- silicon
- added
- 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.)
- Expired
Links
- 238000000034 method Methods 0.000 title claims abstract description 58
- 238000009628 steelmaking Methods 0.000 title claims description 7
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 66
- 239000010959 steel Substances 0.000 claims abstract description 66
- 229910001021 Ferroalloy Inorganic materials 0.000 claims abstract description 19
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 14
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 14
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 23
- 239000001301 oxygen Substances 0.000 claims description 23
- 229910052760 oxygen Inorganic materials 0.000 claims description 23
- 229910052710 silicon Inorganic materials 0.000 claims description 16
- 239000010703 silicon Substances 0.000 claims description 13
- 239000010936 titanium Substances 0.000 claims description 11
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 10
- 229910052751 metal Inorganic materials 0.000 claims description 8
- 239000002184 metal Substances 0.000 claims description 8
- 229910052719 titanium Inorganic materials 0.000 claims description 8
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 6
- 239000000155 melt Substances 0.000 claims description 6
- 230000014759 maintenance of location Effects 0.000 claims description 5
- 229910052748 manganese Inorganic materials 0.000 claims description 5
- 239000011572 manganese Substances 0.000 claims description 5
- 239000000377 silicon dioxide Substances 0.000 claims description 4
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 3
- 235000012239 silicon dioxide Nutrition 0.000 claims description 3
- 238000005266 casting Methods 0.000 claims description 2
- 238000010891 electric arc Methods 0.000 claims description 2
- 229910001208 Crucible steel Inorganic materials 0.000 claims 2
- 229910000655 Killed steel Inorganic materials 0.000 abstract description 13
- 238000004519 manufacturing process Methods 0.000 abstract description 8
- 238000010079 rubber tapping Methods 0.000 abstract description 4
- 239000004411 aluminium Substances 0.000 abstract 1
- 238000009848 ladle injection Methods 0.000 abstract 1
- 239000007788 liquid Substances 0.000 description 10
- 238000011084 recovery Methods 0.000 description 9
- 230000015572 biosynthetic process Effects 0.000 description 6
- 238000005755 formation reaction Methods 0.000 description 6
- 238000009749 continuous casting Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 238000005482 strain hardening Methods 0.000 description 5
- 229910001327 Rimmed steel Inorganic materials 0.000 description 4
- 230000003749 cleanliness Effects 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 230000000717 retained effect Effects 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910000616 Ferromanganese Inorganic materials 0.000 description 1
- GDJWXDKMRWCHJH-UHFFFAOYSA-N [Si+4].[O-2].[Mn+2].[O-2].[O-2] Chemical class [Si+4].[O-2].[Mn+2].[O-2].[O-2] GDJWXDKMRWCHJH-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000009844 basic oxygen steelmaking Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000003750 conditioning effect Effects 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009845 electric arc furnace steelmaking Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
Images
Classifications
-
- 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
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
-
- 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
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
Definitions
- This invention relates to deoxidation practice in steelmaking.
- An object of the present invention is to provide an improved deoxidation process whereby steel products of improved cold heading formability may be obtained.
- the use of very minor amounts of deoxidizer results in a high free oxygen content in the molten rimmed steel, which results in a solid skin layer around the ingot surface of good surface quality and soft characteristics but the inner portion of the rimmed steel ingot is not suitable for high grade applications because of contamination by impurities.
- rimmed steel with a high free oxygen content cannot be cast in a continuous casting process.
- An object of the invention is to overcome or alleviate the defects stated above to provide lower cost and higher quality steel products.
- AI and/or Ti are the major deoxidizers used in the continuous casting process.
- Killed steel for cold working or forming applications could be classified into AI-killed and Ti-killed steel according to the deoxidizer adopted.
- Si-containing ferroalloy cannot be added to molten steel during the steelmaking process-only Al is used as the deoxidizer.
- alumina clusters AI 2 0 31 form in the molten steel and remain in the solid steel as inclusions. These inclusions cannot be elongated during deformation, and thus interfere with the cold heading or working formability.
- An object of the invention is to overcome the above shortcoming of deoxidation practice, that is to reduce the work hardening effect.
- US 2,705,196 discloses a method for the deoxidation of molten steel produced in a furnace by a steelmaking process, comprising a predeoxidizing step in which a silicon-containing ferroalloy is added to the molten steel, and a subsequent deoxidizing step in which a deoxidizing metal is added to the pre-deoxidized molten steel.
- the method of the invention starting from this known method provides that said silicon-containing ferroalloy is added in a controlled amount sufficient to reduce the free oxygen content of the melt to a level below 340 ppm but insufficient to result in substantial retention of elemental silicon in the melt; after the pre-deoxidizing step the molten steel is stirred, by gas-bubbling to separate silicon dioxide from the molten steel, and said deoxidizing metal is added in finely divided form by a continuous feeder arrangement so as substantially to prevent retention of silicon in the steel.
- the process of the invention increases the recovery rate of deoxidizing metal, decreases the amount of deoxidizer and ferroalloy consumption and saves on production cost. Because of the reduced deoxidizing metal and alloy addition, deoxidized formations can be reduced, resulting in a remarkable improvement in the internal cleanliness of the steel products.
- Optional features of the invention are set out in Claims 2 to 8 below. After treating by AI and/or Ti with the above process, good shrouding systems should be adopted during continuous casting or ingot teeming processes to protect the molten steel from reoxidizing by the atmosphere. Consequently, cleaner steel could be acquired by this new predeoxidation process, which is referred to below as a WPD (weak predeoxidation) process.
- WPD weak predeoxidation
- Figure 2 indicates that with appropriate amount of Si containing ferroalloy addition the free oxygen content in the liquid steel before AI deoxidation can evidently be lowered.
- the recovery of deoxidizer can be improved and the oxides retained in the liquid steel after deoxidation can be reduced as well, thus the quality of bloom, slab and ingot can be improved.
- Figure 3(a) and 3(b) compare the Si content in the liquid steel between WPD Process and non-WPD Process.
- Figure 3(a) shows the distribution of Si contents in the final molten steel treated by weak pre-deoxidizing with Si contained ferroalloy.
- Figure 3(b) shows the distribution of Si contents in the final molten steel without WPD treatment.
- Figure 3(a) and 3(b) indicates the percent of the number of melts which contain Si less than 0.02% in the liquid steel by using WPD Process is 96.8%, while that of non-WPD Process is 95.8%.
- the data obviously shows that the proportion of Si content below 0.02% in the liquid steel of WPD Process is even a little bit higher than that of non-WPD Process.
- the Si content analyzed by spectro-scope is total Si content (including silica), thus confirms that Si contained ferroalloy will not cause Si to be retained in the liquid steel. (It can also be confirmed by microscope). While Si contained ferroalloy is added into liquid steel, Si will react with free oxygen first and forms silicon dioxide (Si0 2 ) particles, which distribute in the whole liquid steel.
- Figure 4 shows the comparison of the rate of A) recovery between AI-killed steel produced by Weak Pre-Deoxidation Process and conventional deoxidation process.
- the rate of AI recovery was evidently increased by this invention as indicated in Figure 4, that is due to the content of free oxygen in molten steel as remarkably decreased. Because of higher recovery rate of Al, caused less AI addition, deoxidation formations could be effectively reduced. Consequently, the internal cleanliness and surface quality of the steel product was remarkably improved by this new process.
- Table 1 shows the comparison of free oxygen content between WPD Process and conventional deoxidation process before aluminum and/or titanium addition, when the content of free oxygen according to the invention is 1.
- a feature of this invention is to reduce the free oxygen content of molten steel as much as possible before the addition of deoxidizers (aluminum and/or titanium) but without retention of Si in the melt.
- deoxidizers aluminum and/or titanium
- the data listed in the table obviously show that after WPD Process treatment the free oxygen content can be greatly decreased before the addition of deoxidizers.
- the amount of free oxygen content lowered can be controlled directly by adjusting the amount of Si-containing ferroalloy addition. Owing to the decrease of free oxygen content, recovery of aluminum can be improved, cost can be lowered, and the quality of steel products can be improved remarkably.
- Table 2 shows the comparison of typical chemical compositions between the general cold working AI-killed steel grade and the steel designed according to this invention for the same end use.
- typical chemical composition designed according to this invention has lower aluminum content than that of conventional AI-killed steel grade.
- the reason for this composition design is to decrease the inclusion formation of deoxidation to get cleaner molten steel. Because of more deoxidizers are added, more chances to form consistins would result and the cost is also higher. Therefore, the principle of chemical composition design by this invention is to lower the addition of deoxidizers such as aluminum and/or titanium under the condition of no poor deoxidation and good formabilty. And with the aid of WPD Process, the amount of deoxidizers added can be decreased, cleaner steel and lower production cost will be resulted.
- This deoxidation method is also suitable for af other kind of AI-killed steel grade.
- Table 3 shows the comparison of estimated index of inclusions between different deoxidation processes.
- the main purpose of WPD Process is to improve the internal cleanliness, and improve the quality of casted steel.
- the table obviously shows that under this new process, the estimated index of inclusions is much better than that of conventional process. It can also be sured that the WPD Process has much improvement on internal quality of casted steel.
- Table 4 (page 4) shows the comparison of grinding speed of billets between different deoxidation processes. In respect of quality, the WPD process improves not only the internal cleanliness of the casted steel, but also its surface quality. Data listed in the table represent pieces of billets to be ground within unit time (per hour).
- the WPD Process can make much improvement on surfacial quality of casted steel, and save much surface conditioning cost.
- the invention is applicable both to Basic Oxygen and Electric Arc Furnace Steel making processes.
- Si-containing ferroalloy is added to the molten steel as weak predeoxidation agent.
- the free oxygen content of molten steel can be lowered efficiently whilst ensuring that silcon will not remain in molten steel.
- This method not only increases the recovery of aluminum and/or titanium, saves much production cost, improves surfacial and internal quality of steel which is good for formability, but also keeps steelmaking operation in good stability.
- the weak pre-deoxidation step is suitably executed after blowing end and before the addition of aluminum and/or titanium deoxidizer.
- Remark Estimated index value 0-4, 0 is the best.
- Depth of defects to be ground are more than 1.2 mm
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Claims (8)
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP84303555A EP0163784B1 (fr) | 1984-05-25 | 1984-05-25 | Procédé de désoxydation d'acier en deux étapes |
DE8484303555T DE3480350D1 (en) | 1984-05-25 | 1984-05-25 | Two stage deoxidation process in steel-making |
AT84303555T ATE47727T1 (de) | 1984-05-25 | 1984-05-25 | Zweistufiges desoxidationsverfahren bei der stahlherstellung. |
ZA852015A ZA852015B (en) | 1984-05-25 | 1985-03-18 | Si contained ferro-alloy addition as a weak pre-deoxidation process in steelmaking |
AU40220/85A AU567212B2 (en) | 1984-05-25 | 1985-03-21 | Pre-deoxidation process in steelmaking |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP84303555A EP0163784B1 (fr) | 1984-05-25 | 1984-05-25 | Procédé de désoxydation d'acier en deux étapes |
AU40220/85A AU567212B2 (en) | 1984-05-25 | 1985-03-21 | Pre-deoxidation process in steelmaking |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0163784A1 EP0163784A1 (fr) | 1985-12-11 |
EP0163784B1 true EP0163784B1 (fr) | 1989-11-02 |
Family
ID=36838654
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP84303555A Expired EP0163784B1 (fr) | 1984-05-25 | 1984-05-25 | Procédé de désoxydation d'acier en deux étapes |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0163784B1 (fr) |
AT (1) | ATE47727T1 (fr) |
AU (1) | AU567212B2 (fr) |
DE (1) | DE3480350D1 (fr) |
ZA (1) | ZA852015B (fr) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2406580B (en) * | 2000-06-05 | 2005-09-07 | Sanyo Special Steel Co Ltd | High-cleanliness steel and process for producing the same |
GB2410252B (en) * | 2000-06-05 | 2005-09-07 | Sanyo Special Steel Co Ltd | High-cleanliness steel and process for producing the same |
DE10196303B3 (de) * | 2000-06-05 | 2014-11-13 | Sanyo Special Steel Co., Ltd. | Verfahren zur Herstellung eines hochreinen Stahls |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE957665C (de) * | 1957-01-17 | Max-Planck-Institut iur Eisenforschung e V, Dussel dorf | Verfahren und Einrichtung zum Behandeln von Eisen- und Stahlbadern | |
US2705196A (en) * | 1952-02-20 | 1955-03-29 | Manufacturers Chemical Corp | Process for de-oxidizing a molten metal |
DE969295C (de) * | 1954-01-27 | 1958-05-22 | Hoesch Westfalenhuette Ag | Verwendung von Stahl- oder Spiegeleisen zur Vordesoxydation von Stahl |
FR2387292A1 (fr) * | 1977-04-14 | 1978-11-10 | Siderurgie Fse Inst Rech | Nouveau procede de desoxydation d'un bain d'acier |
US4170468A (en) * | 1977-12-22 | 1979-10-09 | United States Steel Corporation | Deoxidation of steel |
-
1984
- 1984-05-25 DE DE8484303555T patent/DE3480350D1/de not_active Expired
- 1984-05-25 AT AT84303555T patent/ATE47727T1/de not_active IP Right Cessation
- 1984-05-25 EP EP84303555A patent/EP0163784B1/fr not_active Expired
-
1985
- 1985-03-18 ZA ZA852015A patent/ZA852015B/xx unknown
- 1985-03-21 AU AU40220/85A patent/AU567212B2/en not_active Ceased
Non-Patent Citations (1)
Title |
---|
"Die physikalische Chemie der Eisen- und Stahlerzeugung", 1964, p. 221 * |
Also Published As
Publication number | Publication date |
---|---|
DE3480350D1 (en) | 1989-12-07 |
ATE47727T1 (de) | 1989-11-15 |
ZA852015B (en) | 1985-09-19 |
EP0163784A1 (fr) | 1985-12-11 |
AU567212B2 (en) | 1987-11-12 |
AU4022085A (en) | 1986-09-25 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CN114085953B (zh) | 一种含铝冷镦钢酸溶铝控制方法 | |
US3459537A (en) | Continuously cast steel slabs and method of making same | |
CN111041352A (zh) | 一种切割金刚线用盘条炉外精炼生产方法 | |
EP0163784B1 (fr) | Procédé de désoxydation d'acier en deux étapes | |
CN108642239B (zh) | 利用含金属钙硅铁合金进行钢液硅合金化和钙处理的方法 | |
CN103225009A (zh) | 高洁净度钢的熔炼方法 | |
JPH10130714A (ja) | 伸線性及び清浄度に優れた線材用鋼の製造方法 | |
US3990887A (en) | Cold working steel bar and wire rod produced by continuous casting | |
US4741772A (en) | Si contained ferroalloy addition as a weak pre-deoxidation process in steelmaking | |
JPH08260030A (ja) | 極低炭素ステンレス鋼の真空精錬方法 | |
JP3870627B2 (ja) | 高燐極低炭素鋼の製造方法 | |
CN113930584B (zh) | 一种提高高硅铝镇静钢的生产稳定性的方法 | |
JPH07103416B2 (ja) | 高炭素鋼線材の製造方法 | |
CN115612912B (zh) | 一种含铝轴用结构钢控硫的精炼方法 | |
KR100370572B1 (ko) | 미니밀연속주조용알루미늄탈산강의제조방법 | |
JP3404115B2 (ja) | 熱間加工性に優れたオーステナイト系ステンレス鋼の精錬方法 | |
CA1249724A (fr) | Addition d'alliage ferro-metallique contenant du silicium, employe pour la desoxydation, et servant a la fabrication de l'acier | |
CN116497175A (zh) | 一种高效精准控制齿轮钢中b含量的冶炼工艺 | |
JPH068481B2 (ja) | 機械切削用軟鋼と、その製造方法 | |
JPH0581642B2 (fr) | ||
JPS6318645B2 (fr) | ||
KR950010171B1 (ko) | 고 청정강의 제조방법 | |
US20040079199A1 (en) | Method for making killed steel | |
CN116397073A (zh) | 钢及细化氮化钛夹杂的控制方法和在铁路车轮钢中的应用 | |
KR800000006B1 (ko) | 연속 주조에 의한 냉간 압조용 붕강 또는 선재의 제조방법 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Designated state(s): AT BE CH DE FR GB IT LI LU NL SE |
|
17P | Request for examination filed |
Effective date: 19860609 |
|
17Q | First examination report despatched |
Effective date: 19870430 |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): AT BE CH DE FR GB IT LI LU NL SE |
|
REF | Corresponds to: |
Ref document number: 47727 Country of ref document: AT Date of ref document: 19891115 Kind code of ref document: T |
|
ITF | It: translation for a ep patent filed | ||
REF | Corresponds to: |
Ref document number: 3480350 Country of ref document: DE Date of ref document: 19891207 |
|
ET | Fr: translation filed | ||
ITTA | It: last paid annual fee | ||
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
26N | No opposition filed | ||
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: GB Payment date: 19940506 Year of fee payment: 11 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: SE Payment date: 19940510 Year of fee payment: 11 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 19940517 Year of fee payment: 11 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: CH Payment date: 19940526 Year of fee payment: 11 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: BE Payment date: 19940527 Year of fee payment: 11 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: NL Payment date: 19940531 Year of fee payment: 11 Ref country code: LU Payment date: 19940531 Year of fee payment: 11 |
|
EPTA | Lu: last paid annual fee | ||
EAL | Se: european patent in force in sweden |
Ref document number: 84303555.1 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 19950505 Year of fee payment: 12 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: LU Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 19950525 Ref country code: GB Effective date: 19950525 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SE Effective date: 19950526 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: AT Payment date: 19950529 Year of fee payment: 12 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: LI Effective date: 19950531 Ref country code: CH Effective date: 19950531 Ref country code: BE Effective date: 19950531 |
|
BERE | Be: lapsed |
Owner name: CHINA STEEL CORP. Effective date: 19950531 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: NL Effective date: 19951201 |
|
GBPC | Gb: european patent ceased through non-payment of renewal fee |
Effective date: 19950525 |
|
REG | Reference to a national code |
Ref country code: CH Ref legal event code: PL |
|
NLV4 | Nl: lapsed or anulled due to non-payment of the annual fee |
Effective date: 19951201 |
|
EUG | Se: european patent has lapsed |
Ref document number: 84303555.1 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FR Effective date: 19960229 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: ST |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: ST |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: AT Effective date: 19960525 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DE Effective date: 19970201 |