US4361448A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for producing dual-phase and zinc-aluminum coated steels from plain low carbon steels
Assignee: RA-SHIPPING Ltd KESKUSTORNI 4 KRS 02100 ESPOO 10 FINLAND A CORP OF FINLAND Oy
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Filing: 1981-05-27
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Granted: 1982-11-30
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Expires: 2001-05-27
Abstract
Abstract The invention relates to a method for producing coated high strength low alloy steel. A strip of steel is cleaned from rolling oil, is heated to the temperature range A 1 to A 3 in a protective atmosphere, is soaked and subsequently quenched in a zinc-aluminum bath for a short time sufficient to adhere a zinc coating to the steel surface, whereafter the steel strip is rapidly cooled to a temperature below 300° C., to obtain a dual-phase steel structure.
Inventors
- 👤 Pertti J. Sippola
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 17:48
CPC Classifications
C; C21; C21D; C21D9/00; C21D9/52; C23; C23C; C23C2/00; C23C2/003; C23C2/0034; C23C2/00342; C23C2/00344; C23C2/0038; C23C2/004; C23C2/04; C23C2/06; C23C2/34; C23C2/36; C23C2/40
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
118 words
A method for producing coated high strength low alloy steel, comprising the consecutive continuous steps of cleaning a strip of steel from rolling oil, heating the strip in a furnace to the temperature range A 1 to A 3 in a protective atmosphere, annealing the strip in a soaking furnace at a temperature in the range of A 1 to A 2 , quenching the strip in a zinc-aluminum molten metal bath for rapid cooling of the strip to a temperature in the range of 420° C. to 490° C. and for coating the steel with a zinc-aluminum alloy, and rapidly cooling the steel strip to a temperature below 300° C. in order to obtain a dual-phase structure.
Claim 2
Independent Claim
118 words
A method for producing coated high strength low alloy steel, comprising the consecutive continuous steps of cleaning a strip of steel from rolling oil, heating the strip in a furnace to the temperature range A 1 to A 3 in a protective atmosphere, annealing the strip in a soaking furnace at a temperature in the range of A 1 to A 2 , quenching the strip in a zinc-aluminum molten metal bath for rapid cooling of the strip to a temperature in the range of 420° C. to 490° C. and for coating the steel with a zinc-aluminum alloy, and rapidly cooling the steel strip to a temperature below 300° C. in order to obtain a dual-phase structure.
Claim 3
Dependent Claim
23 words
The method according to claim 1, wherein the steel strip is quenched in a zinc-aluminum molten metal bath containing 4 to 6% aluminum.
Claim 4
Dependent Claim
30 words
The method according to claim 1, wherein the rapid cooling of the steel strip to a temperature below 300° C. is performed using gas jets and water jets in combination.
Claim 5
Dependent Claim
51 words
The method according to claim 1, wherein in the zinc-aluminum molten metal bath the melt is directed to flow evenly towards both surfaces of the steel strip to regulate the quenching effect and the zinc-aluminum molten metal bath is cooled to compensate for the heat brought therein by the steel strip.
Claim 6
Dependent Claim
26 words
The method according to claim 4, wherein the temperature of the zinc-aluminum molten metal bath is maintained within the range of 400° C. to 460° C.
Claim 7
Dependent Claim
82 words
The method according to claim 1, wherein the length of the path along which the steel strip travels in the zinc-aluminum molten metal bath is regulated by means of adjustable guide rolls in order to maintain a constant cooling time in the zinc-aluminum molten metal bath for different speeds of the steel strip and to maintain a constant complete quenching time for reaching the temperature below 300° C., whereby an even quality of the dual-phase structure and of the coating is obtained.
Claim 8
Independent Claim
26 words
The method according to any of the preceding claims, wherein the complete quenching time for reaching the temperature below 300° C. is 5 to 10 seconds.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-11-29 | 1986-05-31 | 1986-11-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-11-29 | 1990-05-31 | 1990-11-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-11-29 | 1994-05-31 | 1994-11-30 | $7700.00 | Window Closed / Lapsed |