GB2069001A - Aluminium-plated steel sheets - Google Patents
Aluminium-plated steel sheets Download PDFInfo
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- GB2069001A GB2069001A GB8101817A GB8101817A GB2069001A GB 2069001 A GB2069001 A GB 2069001A GB 8101817 A GB8101817 A GB 8101817A GB 8101817 A GB8101817 A GB 8101817A GB 2069001 A GB2069001 A GB 2069001A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 64
- 239000010959 steel Substances 0.000 title claims abstract description 64
- 230000003647 oxidation Effects 0.000 claims abstract description 26
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 26
- 238000007747 plating Methods 0.000 claims abstract description 23
- 238000000137 annealing Methods 0.000 claims abstract description 10
- 238000010438 heat treatment Methods 0.000 claims abstract description 7
- 238000004519 manufacturing process Methods 0.000 claims abstract description 7
- 239000000203 mixture Substances 0.000 claims description 15
- 239000004411 aluminium Substances 0.000 claims description 14
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 14
- 229910052782 aluminium Inorganic materials 0.000 claims description 14
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 10
- 238000009849 vacuum degassing Methods 0.000 claims description 7
- 238000005098 hot rolling Methods 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 6
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 239000012535 impurity Substances 0.000 claims description 4
- 238000005554 pickling Methods 0.000 claims description 4
- 238000009749 continuous casting Methods 0.000 claims description 3
- 239000004615 ingredient Substances 0.000 claims description 3
- 238000007670 refining Methods 0.000 claims description 3
- 238000005096 rolling process Methods 0.000 claims description 3
- 238000005266 casting Methods 0.000 claims description 2
- 206010037660 Pyrexia Diseases 0.000 claims 1
- 230000001590 oxidative effect Effects 0.000 abstract description 6
- 238000005097 cold rolling Methods 0.000 abstract description 3
- 239000010936 titanium Substances 0.000 description 32
- 239000000463 material Substances 0.000 description 18
- 239000011651 chromium Substances 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 14
- 208000021017 Weight Gain Diseases 0.000 description 10
- 239000011572 manganese Substances 0.000 description 10
- 229910052719 titanium Inorganic materials 0.000 description 10
- 230000004584 weight gain Effects 0.000 description 10
- 235000019786 weight gain Nutrition 0.000 description 10
- 239000000758 substrate Substances 0.000 description 9
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- 239000010410 layer Substances 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 230000032683 aging Effects 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 6
- 238000010791 quenching Methods 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- 238000009628 steelmaking Methods 0.000 description 4
- 238000005054 agglomeration Methods 0.000 description 3
- 230000002776 aggregation Effects 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 3
- 238000006731 degradation reaction Methods 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 229910018125 Al-Si Inorganic materials 0.000 description 1
- 229910018520 Al—Si Inorganic materials 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910001021 Ferroalloy Inorganic materials 0.000 description 1
- 229910000604 Ferrochrome Inorganic materials 0.000 description 1
- 229910000616 Ferromanganese Inorganic materials 0.000 description 1
- 229910001200 Ferrotitanium Inorganic materials 0.000 description 1
- 229910001327 Rimmed steel Inorganic materials 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000001939 inductive effect Effects 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
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000000979 retarding effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0278—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular surface treatment
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
-
- 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
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
-
- 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
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
- C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
-
- 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
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
- C23C2/024—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by cleaning or etching
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0236—Cold rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0273—Final recrystallisation annealing
Abstract
A process for preparing molten- aluminium-plated steel sheets having good formability and high oxidation resistance at elevated temperatures comprises producing a steel containing 0.001-0.020% of C, 0.05-0.30% of Mn, 0.05-0.50% of Cr, 0.01-0.10% of Al, and 0.10-0.50% and not less than 10 times the C content of Ti, and making the steel into a hot coil with the coiling temperature not lower than 700 DEG C, cold-rolling said hot coil and plating the cold-rolled sheet by heating it to a temperature not lower than 850 DEG C using an in-line annealing type plating apparatus with non- oxidizing furnace.
Description
SPECIFICATION
A process for preparing aluminium-plated steel sheets having low yield strength and high oxidation resistance
This invention reiates to a process for preparing molten aluminium-plated steel sheets which have
low yield strength and exhibit a low oxidation weight again when subjected to oxidation at high temperatures.
BACKGROUND OF THE INVENTION
Heretofore, molten-aluminium-plated steel sheets (hereinafter simply referred to as "aluminium-plated steel sheets") for use where heat resistance and corrosion resistance are required have been mainly made of cold-rolled sheets of low carbon rimmed steels. However, it is well known that aluminium-plated steel sheets made of rimmed steel substrate sheets incur degradation in quality due to quench ageing caused by rapid cooling at the time of plating, which hardens the material.
Included amongst measures that can be employed to prevent the above-mentioned degradation are:
(1) To use substrate sheets made of a steel from which carbon and nitrogen, which cause quench ageing, have been removed as completely as possible;
(2) To add a carbide-forming element such as titanium to fix carbon and nitrogen, which cause quench ageing, in the substrate material; and
(3) To effect over-ageing of the aluminium-plated sheets in which quench ageing has occurred.
However, the measure (1) is not economical in the case when steel sheets are plated by an in-line annealing type hot dip plating apparatus with a non oxidizing furnace, although it can be realized in an ordinary steel-making process by employment of decarburizing annealing.
The measure (2) is economical per se, but when it is applied to low carbon steels which are to be obtained by the ordinary converter process only, a considerable amount of titanium must be used and highly oxidizable titanium produces not a small amount of oxide inclusion which results in degradation of the surface quality of the product. Therefore, this measure is not, in the final analysis, either economically or technically desirable.
The measure (3) is also economical. However, this treatment may increase the Fe-AI alloy layer, which has poor formability, even if the aluminium plating has been carried out under the conditions that control formation of the Fe-AI alloy layer. Therefore, by this treatment, although the property of the substrate material is improved, formability of the aluminium-plated layer is impaired
In Japanese Patent Publication No. 35532/76, we describe a process for preparing aluminiumplated steel sheets comprising:
hot-rolling a steel essentially consisting of C 0.001-0.020%; Si < 0.05%;Mn 0.050.40%; Cr 0.100.30%, effective Ti (Total Ti less Ti in the oxide form) 0;03--0.40% and that not less than 4 times the combined (C + N)%; N < 0.006%; 0 (oxygen) = < 0.020%; and the balance being Fe, apart from impurities and incidental ingredients that are inevitable, at a temperature not lower than 8000 C; coldrolling the hot coil at a reduction rate of 40% or more; annealing the rolled sheet at 800-9500C, and immersing the sheet in an Al-Si Ailoy bath (Si < 10%) maintained at 640-7000C for not more than 10 minutes.
The aluminium-plated steel sheet obtained by this process has a yield point strength of 13-1 7 kg/mm2 and an elongation of 4447% in the state of a cold-rolled sheet of 00.8 mm thickness. Today, however, demand for more easily formable materials is rising.
DISCLOSURE OF THE INVENTION
We have studied ways for meeting this demand and have devised a number of measures which we have combined in a process to obtain improved aluminium-plated steel sheets which have good formability with low yield strength and are very low in the high temperature oxidation weight gain. We feel it is important
(1) To lower the content of C and 0 in the substrate steel sheet by employing vacuum degassing treatment and preliminarily deoxidizing with Al in the stage of steel-making and thus reducing the titanium content which is necessary to fix C and N and controlling formation of oxides.
(2) To reduce the content of manganese which raises yield strength and to add chromium which lowers yield strength.
(3) To promote agglomeration and growth of the precipitated Ti carbide by coiling the finished hot coil at a temperature as high as 7000C and thus to prevent hardening by formation of carbide of the Ti added to the substrate material, and to further promote agglomeration of the Ti carbide by heating the cold-rolled sheet at a temperature of 8500C or more when it is passed through an in-line annealing type hot dip plating apparatus with a non-oxidizing furnace (which is commonly called NOF type plating apparatus in Japan). Additionally, the present invention is characterized in that high temperature oxidation resistance of the material is improved by the combined addition of the Ti and Cr. That is, oxidation weight gain at high temperatures is remarkably reduced by decarburizing the substrate material, and it is further improved by addition of Ti.The resons are believed to be that: (1) by
decarburizing or the addition of Ti, cleanliness of the iron material is improved, and aluminium of the
aluminium layer easily diffuses into the iron substrate and an aluminium diffusion layer, having excellent
high temperature oxidation resistance is formed; and (2) the titanium in the material diffuses toward the
surface and forms a Ti-concentrated layer under the aluminium diffusion layer when the material is
subjected to high temperature. This prevents the further diffusion of aluminium into the interior, thereby
retarding decrease in the aluminium concentration in the surface layer, and also fixes oxygen which has
penetrated into the iron.
Thus according to this invention we provide a process for preparing molten-aluminium-plated steel sheets having low yield strength and high resistance to high-temperature oxidation comprising
producing a steel the chemical composition of which essentially consists of 0.001-0.020%;
Mn 0.05-0.30%; Cr 0.05-0.50%; Al 0.01-0.10%;Ti 0.100.50% and that not less than 10 times the percentage of C, the balance being iron apart from impurities and incidental ingredients that are inevitable, by a converter-refining and vacuum degassing; forming it into a slab by a casting and slabbing or continuous casting; continuously hot-rolling said coiling it at a temperature not lower than 7000 C; cold-rolling the resulting hot coil after a pickling treatment; heating the cold-rolled sheet at a temperature not lower than 8500 C; and plating it with molten aluminium by means of an in-lining annealing type hot dip plating apparatus with a non-oxidizing furnace.
In a preferred embodiment, the C content is 0.001-0.010%. the Mn content is 0.05-0.20%, the cr content is 0.07-0.45%, the Al content is 0.02-0.05%, and the Ti content is 0.15-0.40% and not less than 20 times the C content.
In a more preferred embodiment, the C content is 0.001-0.007%, the Mn content is 0.100.17%, the Cr content is 0.070.42%, the Al content is 0.030.041 %, and the Ti content is 0.1 9-0.23% and not less than 30 times the C content, the hot coil coiling temperature is 720-7300C and the heating temperature at plating is 860-900 C.
It is our belief that the lower the carbon content is, the more the effect of quench ageing is reduced. Therefore, it is desirable to reduce the C content as much as possible. However, it is not easy to reduce the C content to less than 0.001% even by the modern steel-making process in which vacuum degassing is employed. Even if this can be achieved, it not an economical operation. Furthermore, if the
C content is over 0.020% the amount of titanium that has to be added for prevention of the undesirable effect of C inducing quench ageing must be uneconomically increased.
Generally speaking, it is difficult to obtain a steel the manganese content of which is less than 0.05% by the ordinary steel-making process and when the Mn content exceeds 0.30%, the steel becomes hard and, as a consequence, has high yield strength.
It is our belief that in the amount of less than 0.5%, chromium does not give sufficient effect in reducing yield ratio, and on the other hand, more than 0.50% of Cr also reduces said effect.
Aluminium is used for deoxidation of the molten steel and, especially in this invention, it plays an important role as the preliminary doxidation material which prevents wasteful use of Ti. For this reason, the lower limit of the Al content is defined as 0.01%. However, if Al is added in an amount over 0.10%, the surface properties and formability of the resulting steel sheet are impaired.
The titanium content is defined as 0.100.50% and 10 times the C content. If the Ti content is less then 0.10%, the effect of improving high temperature oxidation resistance as represented by oxidation weight gain is not sufficient, although the yield strength is rather low. On the other hand, if the
Ti content is in excess of 0.50%. the material becomes hard and loses its low yield strength characteristic, although the oxidiation weight gain becomes smaller. If the Ti content is less than 10 times the C content, the fixation of C with Ti is not sufficient, resulting in a rise in the yield strength and an increase in the oxidation weight gain, which eliminate the characteristics of this invention.
Included amongst impurities which may be present in steels formed in the process of this invention are Si, P and S to the extent that is ordinary and common in steels of this kind. Nitrogen and oxygen can, without any inconveniences, be present at the levels usually attained by the vacuum degassing process.
The coiling temperature is defined as not lower than 7000C because at temperature lower than this, softening of the material owing to agglomeration and growth of the titanium precipitate, which has been formed by fixation of C with Ti, is not sufficient, and thus one of the features of this invention is lost. Further it is required that in the aluminium plating line the cold-rolled sheet must be heated at not lower than 8500C before entering the plating bath in order to give the cold-rolled sheet an annealing effect so that the Ti precipitate further agglomerates to larger particles and thus softens the material.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
The invention may further be understood with reference to the results oft he following experiments.
Steel samples, the compositions of which are indicated in Table 1, were prepared by converter refining and vacuum degassing. The ingots were subjected to slabbing and continuous hot-rolling and the rolled products were coiled at varied temperatures as indicated therein an hot coils of 2.5mm thickness were obtained. After ordinary pickling, the hot coils were made into cold-rolled sheets of 0.8mm thickness. The thus prepared cold-rolled sheets were heated at varied temperatures and plated with aluminium (60g/m2) by means of an in-line annealing type hot dip plating apparatus with a non oxidizing furnace (practically, a modified Sendzimir apparatus), under the ordinary conditions. The aluminium-plated sheets were subjected to the material test and oxidation test. The results (mechanical properties and oxidation weight gains) are shown in the same table.The material tests were carried out with specimens prepared according to JIS (Japanese Industrial Standards) Z-2201 No. 5 cut in the direction or rolling, and the oxidation test with five repeated runs of a cycle of holding the samples at 8300C in the atmosphere for 48 hours and cooling to room temperature.
In Table 1, samples 1 D, 1 E and 1 F are within the composition range defined in this invention but only 1 F is within the scope of the invention in the temperature requirements of coiling and plating. This table shows that materials excellent both in formability and oxidation resistance are obtained only when all three factors of the composition of the substrate steel, the coiling temperature and the plating temperature satisfy the conditions defined in this invention.
When sample 1 A and 1 B are compared, it is learned that decrease in the Mn content contributes to lowering of the yield strength. Comparison of 1 B and 1 C shows that addition of Ti contributes to lowering of the yield strength, too. Comparison of 1 C and 1 F shows that combined addition of Ti and Cr also contributes to lowering of the yield strength.
Table 2 shows mechanical properties of the aluminium-plated steel sheet samples which were prepared by obtaining the steels with the compositions indicated therein and treating them in the same way as 1 F above. According to this table, it is learved that Cr is effective for lowering the yield strength when contained in the amount of about 0.050.50%.
Table 3 shows mechanical properties and oxidation weight gains of the aluminium-plated steel sheet samples which were prepared by obtaining the steels the compositions of which are indicated therein and treating them in the same way as above. According to this table, it is learned that when the amount of the added Ti is 0.1% or more and that more than 10 times the amount of C, the effects of lowereing the yield strength and oxidation weight gain are achieved. But as seen in sample 3G, when the Ti content exceeds 0.5%, the yield strength again rises.
Table 4-2 shows the results of the same tests as above carried out with respect to the samples prepared in the same way as above from steels with the compositions indicated in Table 4-1.
According to this table, it is learned that when the coiling temperature is lower than 7000 C, the softening of the material is not sufficient, and when the heating temperature before plating is 8500C or higher, the softening is remarkable.
The following Examples illustrate the invention.
EXAMPLE 1
Ingots, the compositions of which are indicated in Table 5 as samples Nos. 5A and 5B were obtained by vacuum-degassing molten steel prepared by an LD converter so as to reduce the contents of C and 0, and thereafter adjusting the composition by addition of ferro alloys such as ferrochromium, ferrotitanium, ferromanganese, etc. The ingots were made into slabs and the slabs were not-rolled into 2.5mm thick hot coils under the conditions indicated in Table 5. After pickling, the hot coils were coldrolled into 0.8mm thick sheets. The cold-rolled sheets were plated with aluminium by means of an inline annealing type hot dip plating apparatus with a non-oxidizing furnace (a modified Sendzimir apparatus) under the conditions indicated in Table 5.The mechanical properties and oxidation weight gain of the thus obtained aluminium plated steel sheets as tested in the same manner as above are shown in
Table 5. Both streets exhibit excellent properties-low yield strength and high oxidation resistance at high temperatures.
EXAMPLE 2
Slabs, the compositions of which are indicated in Table 5 as samples Nos. 5C and 5D were obtained by continuous casting after smelting in the same way as in Example 1. The slabs were made into aluminium-plated steel sheets in the same way as described in Example 1. Mechanical properties and the test results of the thus obtained steel sheets as tested in the same way as in Example 1 are shown in Table 5. These sheets have excellent characteristics comparable to those of the sheets of
Example 1.
The products of this invention are suitable for manufacturing parts with complicated shapes used at high temperatures such as exhaust gas treating apparatuses for internal combustion engines. TABLE 1
Temp.
of cold Chemical Composition (%) Coiling rolled Mechanical Temp. sheets Properties Oxidation in hot at weight rolling plating TS YP E1 gain Samples C Mn Ti Cr Al ( C) ( C) Kg/mm Kg/mm % (g/m) Remarks 1A 0.007 0.27 - - 0.03 570 870 34 22 49 182 Comparative steel 1B 0.006 0.15 - - 0.04 560 880 33 19 49 138 Comparative steel 1C 0.007 0.13 0.21 - 0.04 710 890 31 15 51 78 Comparative steel 1D 0.006 0.13 0.23 0.11 0.04 550 890 32 16 48 48 Comparative steel 1E 0.004 0.11 0.20 0.14 0.03 730 810 31 15 51 47 Comparative steel 1F 0.005 0.12 0.23 0.13 0.04 720 890 31 13 53 43 Invention steel TS : Tensile strength, YP : Yield point strength, E1 :Elongation TABLE 2
Mechanical Properties Chemical Composition (%) TS YP El Samples C Mn Ti Cr Al Kg/mm2 Kg/mm2 % Remarks 2A 0.007 0.14 0.19 - 0.03 32 16 47 Comparative steel 2B 0.006 0.15 0.22 0.03 0.05 31 15 48 Comparative steel 2C 0.004 0.17 0.20 0.07 0.04 31 13 51 Invention steel 2D 0.005 0.15 0.18 0.16 0.04 32 13 52 Invention steel 2E 0.004 0.13 0.19 0.30 0.05 31 14 51 Invention steel 2F 0.007 0.14 0.22 0.42 0.03 32 14 49 Invention steel 2G 0.004 0.11 0.19 0.58 0.05 32 17 46 Comparative steel TS : Tensile strength, YP : Yield point strength, El :Elongation
TABLE 3
Mechnical Properties Chemical Composition (%) Oxidation TS YP El weight gain Samples C Ti Cr Ti/C Kg/mm2 Kg/mm2 % g/m2 Remarks 3A 0.016 0.13 0.11 8 34 19 45 118 Comparative steel 38 0.011 0.12 0.14 11 32 16 49 61 Invention steel 3C 0.007 0.08 0.12 11 33 17 48 92 Comparative steel 3D 0.006 0.18 0.11 30 30 13 52 48 Invention steel 3E 0.007 0.23 0.15 33 32 14 50 39 Invention steel 3F 0.006 0.34 0.12 57 33 17 49 57 Invention steel 3G 0.017 0.56 0.10 33 38 24 41 69 Comparative steel TS : Tensile strength, YP : Yield point strength, El : Elongation
TABLE 4-1
C Si Mn P S Cr Al Ti Ti/C 0.006 0.02 0.12 0.008 0.006 0.10 0.027 0.21 35
TABLE 4-2
Hot rolling conditions Temp. of cold- Mechanical Properties Oxidation Finish Coiling rolled sheets weight temp. temp. at plating TS YP El g/m Remarks C C Kg/mm Kg/mm % 850 680 905 33 18 44 89 Comparative steel 830 650 890 33 17 45 101 Comparative steel 840 730 810 32 15 49 76 Comparative steel 850 720 860 31 13 52 47 Invention steel 860 730 880 30 13 53 39 Invention steel TS : Tensile strength, YP : Yield point strength, El :Elongation
TABLE 5
Chemical Composition (%) Sample C Si Mn P S Cr Al Ti Ti/C 5A 0.007 0.02 0.12 0.009 0.009 0.11 0.028 0.19 27 5B 0.006 0.03 0.11 0.008 0.007 0.10 0.034 0.21 35 5C 0.008 0.04 0.13 0.009 0.006 0.14 0.038 0.20 25 5D 0.007 0.05 0.12 0.008 0.007 0.09 0.041 0.22 31 Hot rolling conditions Temp. of cold- Mechanical Properties Oxidation Finish Coiling rolled sheets weight temp. temp. at plating TS YP E1 gain Sample ( C) ( C) ( C) Kg/mm Kg/mm % g/m 5A 850 730 900 31 13 50 46 5B 830 730 880 30 12 51 48 5C 840 720 890 30 13 52 39 5D 860 730 880 31 13 51 54 TS : Tensile strength, YP : Yield point strength, El : Elongation
Claims (6)
1. A process for preparing molten-aluminium-plated steel sheets having low yield strengthen and high resistance to high-temperature oxidation comprising producing a steel the chemical composition of which essentially consists of C 0.001-0.020%; Mn 0.05-0.30%; Cr 0.05-0.50%; Al 0.01-0.10%;
Ti 0.10-0.50%; and that not less than 10 times the percentage of C, the balance being iron apart from impurities and incidental ingredients that are inevitable, by a converter-refining and vacuum degassing; forming it into a slab by a casting and slabbing or continuous casting; continuously hot-rolling said slab coiling it at a temperature not lower than 700CC; coid-rolling the resulting hot coil after the ordinary pickling treatment; heating the cold-rolled sheet at a temperature not lower than 850CC; and plating it with molten aluminium by means of an in-lining annealing type hot dip plating apparatus with a nonoxidising furnace.
2. A process as claimed in claim 1, wherein the C content is 0.001-0.010%, the Mn content is 0.050.20%, the Cr content is 0.070.45%, the Al content is 0.02-0.05%, and the Ti content is 0.15-0.40% and not less than 20 times the C content.
3. A process as claimed in claim 1 or claim 2, wherein the C content is 0.001-0.007%, the Mn content is 0.10-0.17%, the Cr content is 0.07-0.42%, the Al content is 0.03-0.041%, and the Ti content is 0.19-0.23% and not less than 30 times the C centent, the hot coiling temperature is 720-730 C and the heating temperature at the plating is 860900CC.
4. A process as claimed in claim 1 substantially as hereinbefore described.
5. A process as claimed in claim 1 substantially as hereinbefore described with reference to the
Examples.
6. Molten-aluminium-plated steel sheets having low yield strength and high resistance to hightemperature oxidation whenever produced by a process as claimed in anv of claims 1-5.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP533380A JPS56102523A (en) | 1980-01-22 | 1980-01-22 | Manufacture of aluminum-plated steel sheet having resistance to oxidation at high temperature |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2069001A true GB2069001A (en) | 1981-08-19 |
| GB2069001B GB2069001B (en) | 1983-06-02 |
Family
ID=11608303
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8101817A Expired GB2069001B (en) | 1980-01-22 | 1981-01-21 | Aluminium-plated steel sheets |
Country Status (15)
| Country | Link |
|---|---|
| JP (1) | JPS56102523A (en) |
| AU (1) | AU538073B2 (en) |
| BE (1) | BE887191A (en) |
| BR (1) | BR8100316A (en) |
| CA (1) | CA1178182A (en) |
| DE (1) | DE3101850C2 (en) |
| DK (1) | DK157690C (en) |
| ES (1) | ES498742A0 (en) |
| FR (1) | FR2474060A1 (en) |
| GB (1) | GB2069001B (en) |
| IT (1) | IT1143260B (en) |
| NL (1) | NL182414C (en) |
| NZ (1) | NZ196063A (en) |
| SE (1) | SE449758B (en) |
| ZA (1) | ZA8167B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4584211A (en) * | 1983-08-17 | 1986-04-22 | Nippon Steel Corporation | Continuous hot dip aluminum coating method |
| US20120073351A1 (en) * | 2008-04-22 | 2012-03-29 | Nippon Steel Corporation | Plated steel sheet and method of hot-stamping plated steel sheet |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6013053A (en) * | 1983-07-04 | 1985-01-23 | Nisshin Steel Co Ltd | Aluminized steel sheet with superior strength at high temperature and superior heat resistance |
| JPS61177378A (en) * | 1985-02-01 | 1986-08-09 | Nippon Steel Corp | Chromated cr-containing steel sheet having superior suitability to coating with paint |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1015231A (en) * | 1971-12-07 | 1977-08-09 | David W. Gomersall | Aluminum coated steel |
| US3881880A (en) * | 1971-12-07 | 1975-05-06 | Inland Steel Co | Aluminum coated steel |
| DE2264519A1 (en) * | 1972-11-13 | 1974-05-22 | Toyo Kogyo Co | Aluminising treatment for automobile mufflers - improve high temp. corro-sion resistance as well as giving oxidn. resistance |
| US3881882A (en) * | 1973-04-19 | 1975-05-06 | Inland Steel Co | Aluminum coated steel |
| US3905780A (en) * | 1973-06-25 | 1975-09-16 | Armco Steel Corp | Oxidation-resistant low alloy steel with Al coating |
| JPS5135532A (en) * | 1974-09-20 | 1976-03-26 | Sumitomo Shipbuild Machinery | KAATSUSENKANSHI KISAIDEIHO |
| JPS582248B2 (en) * | 1976-09-16 | 1983-01-14 | 日新製鋼株式会社 | Manufacturing method for hot-dip galvanized steel sheet with excellent workability |
| US4144379A (en) * | 1977-09-02 | 1979-03-13 | Inland Steel Company | Drawing quality hot-dip coated steel strip |
-
1980
- 1980-01-22 JP JP533380A patent/JPS56102523A/en active Granted
-
1981
- 1981-01-06 ZA ZA00810067A patent/ZA8167B/en unknown
- 1981-01-07 NL NLAANVRAGE8100030,A patent/NL182414C/en not_active IP Right Cessation
- 1981-01-09 IT IT67019/81A patent/IT1143260B/en active
- 1981-01-16 AU AU66291/81A patent/AU538073B2/en not_active Ceased
- 1981-01-19 DK DK022381A patent/DK157690C/en active
- 1981-01-20 SE SE8100310A patent/SE449758B/en not_active IP Right Cessation
- 1981-01-20 CA CA000368870A patent/CA1178182A/en not_active Expired
- 1981-01-20 FR FR8100958A patent/FR2474060A1/en active Granted
- 1981-01-21 BR BR8100316A patent/BR8100316A/en unknown
- 1981-01-21 NZ NZ196063A patent/NZ196063A/en unknown
- 1981-01-21 GB GB8101817A patent/GB2069001B/en not_active Expired
- 1981-01-21 DE DE3101850A patent/DE3101850C2/en not_active Expired
- 1981-01-22 ES ES498742A patent/ES498742A0/en active Granted
- 1981-01-22 BE BE0/203568A patent/BE887191A/en not_active IP Right Cessation
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4584211A (en) * | 1983-08-17 | 1986-04-22 | Nippon Steel Corporation | Continuous hot dip aluminum coating method |
| US20120073351A1 (en) * | 2008-04-22 | 2012-03-29 | Nippon Steel Corporation | Plated steel sheet and method of hot-stamping plated steel sheet |
| US9074277B2 (en) * | 2008-04-22 | 2015-07-07 | Nippon Steel & Sumitomo Metal Corporation | Plated steel sheet and method of hot-stamping plated steel sheet |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2069001B (en) | 1983-06-02 |
| BE887191A (en) | 1981-07-22 |
| NL182414B (en) | 1987-10-01 |
| ES8204477A1 (en) | 1982-05-01 |
| JPS56102523A (en) | 1981-08-17 |
| AU538073B2 (en) | 1984-07-26 |
| DK22381A (en) | 1981-07-23 |
| DK157690B (en) | 1990-02-05 |
| AU6629181A (en) | 1981-07-30 |
| CA1178182A (en) | 1984-11-20 |
| JPS633929B2 (en) | 1988-01-26 |
| BR8100316A (en) | 1981-08-11 |
| DK157690C (en) | 1990-07-02 |
| ZA8167B (en) | 1982-03-31 |
| SE8100310L (en) | 1981-07-23 |
| NL182414C (en) | 1988-03-01 |
| NZ196063A (en) | 1984-02-03 |
| DE3101850C2 (en) | 1983-12-22 |
| SE449758B (en) | 1987-05-18 |
| NL8100030A (en) | 1981-08-17 |
| IT1143260B (en) | 1986-10-22 |
| ES498742A0 (en) | 1982-05-01 |
| IT8167019A0 (en) | 1981-01-09 |
| FR2474060A1 (en) | 1981-07-24 |
| FR2474060B1 (en) | 1984-06-01 |
| DE3101850A1 (en) | 1981-11-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19940121 |