GB1598570A - Method of treating ferrous strand by hot dip coating procedure - Google Patents
Method of treating ferrous strand by hot dip coating procedure Download PDFInfo
- Publication number
- GB1598570A GB1598570A GB53684/77A GB5368477A GB1598570A GB 1598570 A GB1598570 A GB 1598570A GB 53684/77 A GB53684/77 A GB 53684/77A GB 5368477 A GB5368477 A GB 5368477A GB 1598570 A GB1598570 A GB 1598570A
- Authority
- GB
- United Kingdom
- Prior art keywords
- strand
- ferrous
- coating
- bath
- protective
- 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
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 title claims description 25
- 238000000034 method Methods 0.000 title claims description 20
- 238000003618 dip coating Methods 0.000 title claims description 9
- 230000001681 protective effect Effects 0.000 claims description 26
- 239000011248 coating agent Substances 0.000 claims description 20
- 238000000576 coating method Methods 0.000 claims description 20
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 16
- 239000001257 hydrogen Substances 0.000 claims description 16
- 229910052739 hydrogen Inorganic materials 0.000 claims description 16
- 239000007789 gas Substances 0.000 claims description 14
- 229910052751 metal Inorganic materials 0.000 claims description 12
- 239000002184 metal Substances 0.000 claims description 12
- FJMNNXLGOUYVHO-UHFFFAOYSA-N aluminum zinc Chemical compound [Al].[Zn] FJMNNXLGOUYVHO-UHFFFAOYSA-N 0.000 claims description 10
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 8
- 150000002431 hydrogen Chemical class 0.000 claims description 8
- 229910052757 nitrogen Inorganic materials 0.000 claims description 8
- 229910052782 aluminium Inorganic materials 0.000 claims description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 6
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 4
- 229910045601 alloy Inorganic materials 0.000 claims description 4
- 239000000956 alloy Substances 0.000 claims description 4
- 230000004048 modification Effects 0.000 claims description 4
- 238000012986 modification Methods 0.000 claims description 4
- 229910052725 zinc Inorganic materials 0.000 claims description 4
- 239000011701 zinc Substances 0.000 claims description 4
- 229910000831 Steel Inorganic materials 0.000 claims description 2
- 229910000611 Zinc aluminium Inorganic materials 0.000 claims description 2
- 229910001297 Zn alloy Inorganic materials 0.000 claims description 2
- HXFVOUUOTHJFPX-UHFFFAOYSA-N alumane;zinc Chemical compound [AlH3].[Zn] HXFVOUUOTHJFPX-UHFFFAOYSA-N 0.000 claims description 2
- 230000002596 correlated effect Effects 0.000 claims description 2
- 230000007547 defect Effects 0.000 claims description 2
- 238000002347 injection Methods 0.000 claims description 2
- 239000007924 injection Substances 0.000 claims description 2
- 229910001092 metal group alloy Inorganic materials 0.000 claims description 2
- 239000010959 steel Substances 0.000 claims description 2
- 238000010301 surface-oxidation reaction Methods 0.000 claims description 2
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/26—After-treatment
- C23C2/261—After-treatment in a gas atmosphere, e.g. inert or reducing atmosphere
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Coating With Molten Metal (AREA)
Description
(54) IMPROVEMENT IN THE METHOD OF TREATING
FERROUS STRAND BY HOT DIP COATING PROCEDURE
(71) We, BETHLEHEM STEEL CORPORA
TION, a corporation organised under the laws of the State of Delaware, United States of
America, of 701 East Third Street, Bethlehem,
State of Pennsylvania 18016, United States of
America do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be per.
formed, to be particularly described in and by the following statement:
This invention relates to a process for coating the surface of a ferrous metal or strip with a metallic alloy comprised of between 25% and 70% by weight aluminum, balance substantially zinc, and comprises an improvement in or modification of the invention disclosed in
Specification No. 1436213.
According to the prior invention there is disclosed a process for applying an aluminumzinc alloy coating to a ferrous metal strand by the steps of moving the strand through a protective hood and into a molten metal coating bath comprised of said aluminum-zinc alloy without exposing the strand to the atmosphere, maintaining a reducing environment within the hood by the injection of a hot protective gas which when introduced into said protective hood has a temperature not lower than 750"F, comprsing at least 20% by a volume hydrogen, balance essentially nitrogen, and a dewpoint no greater than 0 F, while moving said strand through said protective hood and molten coating metal.
As will hereinafter be explained, subsequent tests performed on a commercial hot dip coating line have shed additional light on the correlation of the hydrogen content and dewpoint of the reducing, protective atmosphere. Thus, according to the present invention there is provided a process whereby a ferrous metal strand is coated with an aluminum-zinc coating alloy, by a hot dip coating method, wherein the reducing protective atmosphere utilized in said process is correlated in such a manner as to eliminate bath surface oxidation within the protective hood through which the ferrous metal strand passes into the coated bath.Specifically, the reducing, protective atmosphere comprises a gas heated to a temperature of at least 750"F, containing a minimum of from 6% to 15% by volume hydrogen, balance essentially nitrogen and a dewpoint no greater than -1000F, when introduced into said protective hood. A substantial portion, at least, of fresh protective gas is arranged to contact or sweep across the portion of the molten coating bath within the hood prior to passing countercurrently to the movement of the strand along the strand.
It has now been discovered that the correlation of the hydrogen content and dewpoint of the hot reducing atmosphere may be expanded beyond the limits of the prior invention to as low as 6 to 15% hydrogen, with dewpoints not greater than -100 F. Such discovery was particularly surprising as heretofore it was believed that high hydrogen contents for the reducing atmosphere were needed in the presence of a high aluminum containing molten coating bath.
such as the aluminum-zinc coating bath of this invention. Specifically, for example, on a hot dip coating line operating at speeds up to 500 fpm., using gas flow rates of 300m3 /hr, aluminum-zinc coated strip, free of pinhole and ferrous spot defects, was produced using a reducing atmosphere (1) preheated to at least 750"F, (2) comprising an average hydrogen content of 10%, balance nitrogen, and (3) comprising a dewpoint of -112 F.
WHAT WE CLAIM IS:
1. Improvement in or modification of the method of forming a zinc-aluminum coating on a ferrous strand according to Specification
No. 1 436 213 which comprises passing the ferrous strand through a protective hood and into a molten bath consisting essentially of from 25% to 70% by weight aluminum, balance substantially zinc, continuously subjecting the ferrous strand and the portion of the surface of said molten bath within said protective hood to a hot gas which when introduced into said protective hood has a temperature not lower than 750"F, the gas comprising from 6% to 15% by volume of hydrogen, balance essentially nitrogen, and having a dewpoint no greater than -1000F, and wherein a portion at least of said hot gas is first caused to sweep across the surface of the bath adjacent the region of entry of the ferrous strand and then to flow countercurrent to the direction of movement of said ferrous strand.
2. A method of coating a ferrous strand
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (2)
1. Improvement in or modification of the method of forming a zinc-aluminum coating on a ferrous strand according to Specification
No. 1 436 213 which comprises passing the ferrous strand through a protective hood and into a molten bath consisting essentially of from 25% to 70% by weight aluminum, balance substantially zinc, continuously subjecting the ferrous strand and the portion of the surface of said molten bath within said protective hood to a hot gas which when introduced into said protective hood has a temperature not lower than 750"F, the gas comprising from 6% to 15% by volume of hydrogen, balance essentially nitrogen, and having a dewpoint no greater than -1000F, and wherein a portion at least of said hot gas is first caused to sweep across the surface of the bath adjacent the region of entry of the ferrous strand and then to flow countercurrent to the direction of movement of said ferrous strand.
2. A method of coating a ferrous strand according to Claim 1 and substantially as hereinbefore described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB53684/77A GB1598570A (en) | 1977-12-23 | 1977-12-23 | Method of treating ferrous strand by hot dip coating procedure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB53684/77A GB1598570A (en) | 1977-12-23 | 1977-12-23 | Method of treating ferrous strand by hot dip coating procedure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1598570A true GB1598570A (en) | 1981-09-23 |
Family
ID=10468644
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB53684/77A Expired GB1598570A (en) | 1977-12-23 | 1977-12-23 | Method of treating ferrous strand by hot dip coating procedure |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB1598570A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2125437A (en) * | 1982-08-17 | 1984-03-07 | Standard Telephones Cables Ltd | Soldering process |
| EP0172681A1 (en) * | 1984-07-30 | 1986-02-26 | Armco Inc. | Process for controlling snout zinc vapor in a hot dip zinc based coating on a ferrous base metal strip |
-
1977
- 1977-12-23 GB GB53684/77A patent/GB1598570A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2125437A (en) * | 1982-08-17 | 1984-03-07 | Standard Telephones Cables Ltd | Soldering process |
| EP0172681A1 (en) * | 1984-07-30 | 1986-02-26 | Armco Inc. | Process for controlling snout zinc vapor in a hot dip zinc based coating on a ferrous base metal strip |
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