OA17675A - Steel plate provided with a zinc coating. - Google Patents
Steel plate provided with a zinc coating. Download PDFInfo
- Publication number
- OA17675A OA17675A OA1201600049 OA17675A OA 17675 A OA17675 A OA 17675A OA 1201600049 OA1201600049 OA 1201600049 OA 17675 A OA17675 A OA 17675A
- Authority
- OA
- OAPI
- Prior art keywords
- chamber
- coated
- zinc
- déposition
- pressure
- Prior art date
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 39
- 239000010959 steel Substances 0.000 title claims abstract description 39
- HCHKCACWOHOZIP-UHFFFAOYSA-N zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 title claims abstract description 19
- 239000011701 zinc Substances 0.000 title claims abstract description 19
- 229910052725 zinc Inorganic materials 0.000 title claims abstract description 19
- 238000000576 coating method Methods 0.000 title claims abstract description 17
- 239000011248 coating agent Substances 0.000 title claims abstract description 15
- 238000004519 manufacturing process Methods 0.000 claims abstract description 7
- 238000005260 corrosion Methods 0.000 claims description 8
- 229910000922 High-strength low-alloy steel Inorganic materials 0.000 claims description 2
- 238000001771 vacuum deposition Methods 0.000 abstract 1
- 239000003921 oil Substances 0.000 description 10
- 241000282485 Vulpes vulpes Species 0.000 description 5
- 239000000758 substrate Substances 0.000 description 5
- 238000003860 storage Methods 0.000 description 4
- 230000032683 aging Effects 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 239000011651 chromium Substances 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 230000001681 protective Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000006011 modification reaction Methods 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- 230000001131 transforming Effects 0.000 description 2
- 210000003800 Pharynx Anatomy 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- REDXJYDRNCIFBQ-UHFFFAOYSA-N aluminium(3+) Chemical class [Al+3] REDXJYDRNCIFBQ-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000005755 formation reaction Methods 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- 238000001912 gas jet deposition Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
Abstract
The invention relates to a steel plate provided with a coating comprising at least one layer of zinc produced by a vacuum deposition coating method using a sonic steam jet wherein the ratio between the pressure inside the zinc ejection chamber Pchlore, and the pressure inside the deposition chamber Pchlore is between 2.10-3 and 5,5.10-2. The invention also relates to the associated production method.
Description
This invention relates to a steel sheet provided with a coating comprising a layer of 5 zinc optionally covered by paint, which is intended in particular for the fabrication of automobile parts, although it is not limited to that application.
Galvanized coatings comprising essentially zinc are conventionally used for the effective protection they provide against corrosion, whether in the automotive sector or in the construction industry, for example.
In the following text, a zinc coating means a coating of pure zinc, potentially including the unavoidable impurities acquired during production and présent in trace quantifies.
Coils of steel coated in this manner can sometimes remain in storage warehouses for several months, and their surface must not be altered by the appearance of surface corrosion before they are shaped by the final user. In particular, no incipient corrosion may appear, 15 whatever the storage environment, even if the steel is exposed to the sun and/or to a moist, humid or even saline environment. A layer of protective oil can also be applied to the surface of the steel coil to provide temporary protection in the event of storage in a moist or humid environment
The methods most frequently used to deposit a zinc coating on the surface of a steel 20 sheet are galvanizing and electrogalvanizing. However, these conventional methods do not make it possible to coat grades of steel that contain high levels of oxidizable éléments such as Si, Mn, Al, P, Cr or B, which has led to the development of new coating methods, and in particular vacuum déposition technologies such as jet vapor déposition (JVD).
Nevertheless, these vacuum coatings do not provide the same level of temporary 25 protection as conventional coatings, even after application of a layer of protective oil.
The purpose of this invention is therefore to eliminate the disadvantages of steels coated using methods of the prior art by making available a steel sheet coated with zinc by vacuum déposition that offers good temporary protection against corrosion.
For this purpose, a first object of the invention is a steel sheet as recited in Claim 1.
' 30 The sheet can also hâve the characteristics of Claims 2 to 5, considered individually or in combination.
An additional object of the invention is a method as recited in Claim 6.
The method can also hâve the characteristics of Claims 7 to 8, considered individually or in combination.
Additional characteristics and advantages of the invention are described in greater detail below.
To illustrate the invention, tests hâve been conducted and will be described by way of non-restricting examples, in particular with reference to the accompanying figures, in which:
Figure 1 illustrâtes a jet vapor déposition installation that can be used to carry out the method claimed by the invention
- Figure 2 is a full-scale photograph of a sheet coated according to the prior art.
- Figure 3 is a full-scale photograph of a sheet coated according to the invention.
The sheet coated according to the invention first comprises a steel substrate, preferably hot-rolled then cold-rolled so that it can be used for the fabrication of automobile body parts. The invention is not limited to this field, however, and can be used for any steel part regardless of its intended final use.
The steel substrate can in particular be one of the following grades of a VHS (Very High Strength steel, generally between 450 and 900 MPa) or UHS (Ultra High Strength, generally greater than 900 MPa) steel, which contain high levels of oxidizable éléments:
- steels without interstitial éléments (IF, Interstitial Free), which can contain up to 0.1% by weight Ti;
- dual-phase steels such as DP 500 steels, up to DP 1200 steels, which can contain up to 3% by weight Mn in association with up to 1% by weight Si, Cr and/or Al,
- TRIP (TRansformation Induced Plasticity) steels such as TRIP 780 steel, which contains, for example, approximately 1.6% by weight Mn and 1.5% by weight Si;
- TRIP steels or dual phase steels containing phosphorus;
- TWIP (TWinning Induced Plasticity) steels having a high content of Mn (generally 17 - 25% by weight),
- low-density steels such as Fe-Al steels, which can contain up to 10% by weight Al, for example;
- stainless steels, which have a high concentration of chromium (generally 13-35% by weight), in association with other alloy éléments (Si, Mn, AI etc.).
The steel sheet can optionally be coated with one or more additional layers in addition to the zinc layer in a manner appropriate to the desired properties of the final product. The zinc layer will preferably be the top layer of the coating.
A method for the fabrication of the steel sheet according to the invention is illustrated more particularly in Figure 1, which shows an installation 1 that comprises a vacuum déposition chamber 2. This chamber comprises an entry iock and an exit lock (not shown), between which the steel sheet 3 to be coated circulâtes. The sheet 3 can be moved by any appropriate means, for example a rotating support roller on which the strip can be supported.
Located facing the surface of the strip to be coated is an injection chamber 7 equipped with a slot 8, the upper part of the slot 8 being located at a distance d from the surface of the strip to be coated of for example, between 20 and 60 mm. This chamber 7 is mounted on an évaporation crucible 4 that contains the liquid zinc 9 to be deposited on the surface of the steel strip 3. The évaporation crucible 4 is advantageously equipped with an induction-heating device 5 that makes possible the formation of the vapor. The vapor then escapes from the crucible via a conduit 10 that conducts it to the injection chamber 7 and the slot 8, which is preferably calibrated to form a jet directed toward the surface of the substrate to be coated. The presence of the slot 8 allows for the régulation of the mass flow of vapor, at a constant sonie speed along the slot (sonie throat) that has the advantage of achieving a uniform deposit. Reference to this technology is made below, using the acronym “JVD” (for Jet Vapor Déposition). Additional information on this technology is presented in patent EP07447056.
In another embodiment not illustrated, the crucible and the éjection chamber are one and the same part, comprising a slot directed toward the surface of the substrate to be coated. In this embodiment, the vapor created by heating the zinc rises directly toward the slot and forms a jet directed toward the surface of the substrate to be coated.
The pressure Pchambcr in the déposition chamber 2 and the pressure Pcjcct in the éjection chamber 7 are maintained so that the ratio Plomber to Pq«t is between 2· l0‘3 and 5.5· 10’.
The pressure in the déposition chamber 2 is optionally maintained at a pressure between 6· 10mbar and2 -10' mbarto improve thesurfaceappearanceofthecoating.
A layer of oil is then applied to the surface of the sheet thus coated to provide temporary protection when the sheet is stored in a moist, humid and/or saline environment before delivery or the transformation into the final product.
The sheet 1, which may or may not hâve been subjected to a skin-pass step, can then be eut and shaped, for example by stamping, bending or shaping, to form a part that can then be painted to form a paint film on the coating.
The invention will now be explained below on the basis of tests performed by way of non-restricting examples.
Tests
Surface corrosion
The test performed is also called a “humidotherm test” and is conducted in a controlled-climate chamber as specified by DIN EN ISO 6270-2
The temporary protection against corrosion can be assessed on fiat panels simulating a sheet during storage or transport, or on deformed panels representing a métal part (e.g. a vehicle door) stamped at one site and transported to another.
Each panel to be tested is de-greased, and then coated on both faces with an appropriate oil by means of an oil-spray device as specified by ISO 6270-2. The panels are oiled using Fuchs Anticorit RP 4107s, Fuchs 3802/395 or Zeller PL6l at 1.2 g/m2 when the test is performed for a German automaker, or using Quaker Ferrocoat N 6130 at 1.2 g/m2 ± 0.3g/m2 when the test is performed for a French automaker. The panels are left unassembled and unpainted.
A sériés of 24-hour aging cycles is then applied to the panels, each cycle including:
- 8 hours at 40°C ± 3°C and approximately 100% relative humidity (climate-controlled chamber closed, including during the heating), then hours between 18°C and 28°C and at ambient humidity (climate-controlled chamber open or ventilated, including during cooling).
At the end of the sériés of cycles, the modification of the surface appearance of the panels is assessed in tenus of percentage of the surface that has been altered.
The proportion of modification of the surface appearance must be less than 10% after 10 cycles for the specimens treated with the Quaker oil or after 15 cycles for the samples treated with one of the Fuchs oils or the Zeller oil.
Tests
Four sériés of cold-rolled IF steel sheet specimens, type DC06, of the type marketed by ArcelorMittal were produced, which comprise a zinc coating 7.5 pm thick. This coating was depositéd using a jet vapor-deposition method.
For each of the specimens, the coating was applied with a different pressure ratio between the pressure in the déposition chamber Pfhambcr and the pressure in the éjection chamber PCjCC(. The distance d between the upper part of the slot 8 of the éjection chamber and the surface of the strip to be coated is identical and equal to approximately 35 mm, and the pressure inside the éjection chamber 7 is approximately 3.4 mbar. The specimens coated as described above are then covered with protective oil and then subjected to a certain number of cycles.
The tests are carried out for 10 or 15 cycles, depending on the type of oil applied, but 5 are interrupted before the end of the 10 or 15 cycles if the entire surface has been degraded.
Table 1
| Specimen | Type of oil |
| 1 | Quaker 6130-1.5 g/m2 |
| 2 | Fuchs 4107-1.2 g/m2 |
| 3 | Fuchs 3802/39-1.2 g/m2 |
| 4 | Zeller Gmelin -1.2 g/m2 |
They are then subjected to the surface conosion tests, the results are presented in table
2, with the ratio between the pressure Pchamber in the déposition chamber and the pressure Pcjccl in the éjection chamber being:
Table 2
| Specimen | Ratio Pchambci/Pcjcct | |||
| 2.9-10'5 | 1.73-10’2 | 3.23-10'2 | 8.8-10'2 | |
| 1 | 100% after 6 cycles | < 10% after 10 cycles | <10% after 10 cycles | 100% after 3 cycles |
| 2 | 20% after 15 cycles | < 10% after 15 cycles | < 10% after 15 cycles | 100% after 15 cycles |
| 3 | / | <10% after 15 cycles | < 10% after 15 cycles | / |
| 4 | / | < 10% after 15 cycles | < 10% after 15 cycles | / |
* According to the invention
It has been found that the sheets coated according to the invention exhibit better surface corrosion résistance than a sheet that has not been coated according to the invention.
Figure 2 is a ftill-scale photograph of specimen No. 1 coated with a pressure ratio of 2.9· 10'5, after six aging cycles as described above. The figure shows that the entire surface of 10 the sheet has altered 11 after six cycles.
Figure 3 is a full-scale photograph of specimen No. 1 as above but coated with a pressure ratio of 3.23· 10 , after ten aging cycles as described above. The figure shows that the entire surface of the sheet is practically unaltered.
Claims (8)
- Claims1) Steel sheet offering a good temporary protection against corrosion provided with a coating comprising at least one layer of zinc, obtained by a sonie jet vapor déposition method in which the ratio between the pressure inside the déposition chamber Pchambcr and the pressure inside the zinc éjection chamber Ρη-κι is between 2· 103 and 5.5-10*2.
- 2) Steel sheet according to Claim 1 obtained by a method wherein the déposition chamber is maintained at a pressure Pchambcr between 6-10‘2 mbarand 2· 10'1 mbar.
- 3) Steel sheet according to Claim I or 2 obtained by a method wherein the distance d between the upper portion of the slot 8 of the éjection chamber 7 and the steel sheet to be coated is between 20 and 60 mm.
- 4) Steel sheet according to anyone of Claims 1 to 3, wherein the zinc layer is the top layer of the coating.
- 5) Steel sheet according to anyone of the above claims wherein the coated steel is a Very High Strength steel.
- 6) Method for the fabrication of a coated sheet that comprises the coating of the sheet by a sonie vapor jet of zinc via an éjection chamber 7 maintained at a pressure PejCCt and contained inside a déposition chamber maintained at a pressure Pchambcr, the ratio of the pressures Pchambcrto Pcjcctbeing between 2· 10'3 and 5.5-10’2.
- 7) Method for the fabrication of a coated sheet that comprises the coating of the sheet by a sonie vapor jet of zinc inside a déposition chamber maintained at a pressure Pchambcr between 6· 10‘2 mbar and 2· 10’1 mbar.
- 8) Method according to Claim 7, wherein the distance d between the upper portion of the slot 8 of the éjection chamber 7 and the steel sheet to be coated is between 20 and 60 mm.
Publications (1)
| Publication Number | Publication Date |
|---|---|
| OA17675A true OA17675A (en) | 2017-07-04 |
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