GB2066852A - A process for producing two- phase cold rolled steel sheet - Google Patents
A process for producing two- phase cold rolled steel sheet Download PDFInfo
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- GB2066852A GB2066852A GB8037995A GB8037995A GB2066852A GB 2066852 A GB2066852 A GB 2066852A GB 8037995 A GB8037995 A GB 8037995A GB 8037995 A GB8037995 A GB 8037995A GB 2066852 A GB2066852 A GB 2066852A
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- steel sheet
- cold rolled
- sheet
- rolled steel
- steel
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- 238000000034 method Methods 0.000 title claims abstract description 25
- 230000008569 process Effects 0.000 title claims abstract description 23
- 239000010960 cold rolled steel Substances 0.000 title claims abstract description 15
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 51
- 239000010959 steel Substances 0.000 claims abstract description 51
- 238000001816 cooling Methods 0.000 claims abstract description 41
- 238000000137 annealing Methods 0.000 claims abstract description 12
- 238000002791 soaking Methods 0.000 claims abstract description 11
- 229910052748 manganese Inorganic materials 0.000 claims description 9
- 229910052710 silicon Inorganic materials 0.000 claims description 9
- 229910052799 carbon Inorganic materials 0.000 claims description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- 239000010703 silicon Substances 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 4
- 239000000654 additive Substances 0.000 claims description 4
- 239000007858 starting material Substances 0.000 claims description 4
- 238000009628 steelmaking Methods 0.000 claims description 4
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 3
- 150000002910 rare earth metals Chemical class 0.000 claims description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 2
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 2
- 229910052791 calcium Inorganic materials 0.000 claims description 2
- 239000011575 calcium Substances 0.000 claims description 2
- 239000011651 chromium Substances 0.000 claims description 2
- 229910052804 chromium Inorganic materials 0.000 claims description 2
- 238000005097 cold rolling Methods 0.000 claims description 2
- 229910052802 copper Inorganic materials 0.000 claims description 2
- 239000010949 copper Substances 0.000 claims description 2
- 238000005098 hot rolling Methods 0.000 claims description 2
- 239000012535 impurity Substances 0.000 claims description 2
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- 229910052726 zirconium Inorganic materials 0.000 claims description 2
- 230000000996 additive effect Effects 0.000 claims 1
- 230000003245 working effect Effects 0.000 abstract description 2
- 239000011572 manganese Substances 0.000 description 10
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 229910001566 austenite Inorganic materials 0.000 description 5
- 239000007788 liquid Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 230000009466 transformation Effects 0.000 description 4
- 238000005275 alloying Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 229910000734 martensite Inorganic materials 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 101100001670 Emericella variicolor andE gene Proteins 0.000 description 1
- 241000283986 Lepus Species 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000013585 weight reducing agent 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
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
- C21D8/0473—Final recrystallisation annealing
-
- 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
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/185—Hardening; Quenching with or without subsequent tempering from an intercritical temperature
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
- C21D1/60—Aqueous agents
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Sheet Steel (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
A process for producing a high tensile steel sheet having excellent working properties, in which the cold rolled steel sheet is subjected to continuous annealing comprising soaking the sheet at a temperature between 730 and 800 DEG C for not less than 20 seconds, and then cooling the sheet to 250 DEG C or below with a cooling rate ranging from 30 to 300 DEG C/sec. The steel sheet obtained by the present invention is especially suitable for automobile car bodies. The steel contains in wt% <IMAGE>
Description
SPECIFICATION
A process for producing nnro-phase cold rolled steel sheet
This invention relates to a process for producing a two-phase, cold rolled steel sheet. Steel strip as well as cut steel sheets are collectively referred to herein as "sheet".
Recently, in the automobile industry, much effort has been made to reduce the weight of car bodies, mainly for the purpose of lowering the car fuel consumption. Since weight reduction necessitates a thickness reduction of the body steel sheet, it is essential then to use high strength steel sheets, both for the above purpose as well as to enhance safety. Now the use of high tensile steel sheets is more common in the automobile industry.
To meet the demands of the automobile industry, it is necessary for the steel industry to provide steel sheets having improved properties as compared with conventional high strength cold rolled steel sheets, but at lower prices.
A conventional two-phase high tensile cold rolled steel sheet and a production process thereof is disclosed, for example, in Japanese Laid-Open Patent Application Sho 50-98419, according to which a steel containing carbon and manganese, and if necessary 0.1 to 0.7% of silicon, is heated to the twophase (ce + y) co-existing zone as determined from the phase equilibrium diagrams, and then relatively rapidly cooled to 5000C with an average cooling rate of from 0.5 to 300C/sec. to obtain a steel structure mainly composed of ferrite and the transformation product produced by the rapid cooling and partially containing the residual austenite.
One object of the present invention is to provide a process for producing at a relatively low cost a two-phase high tensile cold rolled steel sheet having excellent workability, by the combination of defined cooling conditions following a soaking step such as a continuous annealing step, the chemical composition of the starting material being selected appropriately.
Accordingly, this invention provides a process for producing a two-phase high tensile cold rolled steel sheet which comprises hot rolling a steel containing by weight from 0.01 to 0. 12% C, not more than 1.2% Si, from 1.0 to 1.8% Mn, from 0.01 to 0.10% sol. Al, with the balance being Fe, normal steelmaking additives and unavoidable impurities, cold rolling the hot rolled steel sheet, subjecting the cold rolled steel sheet to continuous annealing comprising soaking the sheet within a temperature range of from 730 to 8000C for a period of not less than 20 seconds, and then cooling the continuously annealed sheet to a temperature of 2500C or less with a cooling rate ranging from 30 to 3000C/sec.
Steel sheet obtained by the process according to the present invention may show a low yield point and yet have a tensile strength ranging from 40 to 80 kg/mm2 and high elongation properties.
Therefore, the steel sheet obtained by the process of the present invention may display the following advantages.
The yield point is related to the "spring-back" phenomenon of steel sheet when subjected to the press forming. Therefore, a low yield point (low yield ratio) assures a better fit of the press-formed steel to the press-forming dies and hence a better formed shape, so that loads on the press forming machine can be substantially reduced. Thus the steel sheet of this invention can contribute to meeting the demands of the automobile industry for high tensile steel sheets at lower prices, because a two-phase high strength steel sheet can be produced with relatively low production costs, with lower amounts of alloying elements.
The relatively high ductility of steel sheet obtained by the process of the present invention can naturally assure success even if the sheet is subjected to a high degree of working. On this point, the sheet can display significant advantages.
Steel sheets conventionally used for the outer skins of automobile car bodies have a thickness of about 0.8 mm. However, as mentioned hereinbefore, many efforts have been made to reduce the weight of car bodies, and one way of achieving this is to reduce the thickness of the steel sheets used.
However, before the steel sheet thickness can much be reduced the problem of dent resistance has to be overcome -- that is, the resistance to the local denting of the sheet. The dent resistance depends on the thickness and strength of the steel sheet. One reason for using a high strength thin gauge steel sheet for the outer skin of an automobile car body is to obtain an improvement of the dent resistance. Therefore, the present invention hase particular industrial utility in that a steel sheet having an improved dent resistance with a high tensile strength while maintaining satisfactory working characteristics with a low yield point and high elongation properties can be obtained.As a consequence sheet produced by the method of this invention may have great commercial significance in that the steel sheet may well serve to meet the demands of the automobile industry, as a substitute for the conventional soft steel sheets used as the outer skins of automobile car bodies.
One of the principal features of the present invention is, as described in detail hereinafter, to apply to a very high cooling rate ranging from 30 to 300 C/sec. to cool the annealed sheet to a temperature not higher than 2500C. In order to achieve a sheet satisfying the required objects of the present invention by using such a rapid cooling, the starting steel material must satisfy the following conditions concerning the chemical composition.
When the carbon content is less than 0.01%, the structure which can be produced by the rapid cooling is not satisfactory, but on the other hand when the carbon content is greater than 0.12%, the amount of the transformation product resulting from the rapid cooling is excessive so that it is difficult to obtain a two-phase structure having a high ductility, as required by the present invention. In this case, the transformation product is composed of martensite and non-transformed austenite.
Manganese is effective at increasing the hardenability of the y phase, to promote the rapid cooling transformation product during the cooling step, and to strength the ferrite matrix, hence increasing the ductility. However, manganese contents of less than 1.0% are insufficient to yield the desired hardenability. On the other hand, manganese contents exceeding 1.8% are not desirable because the weldability then deteriorates and certain economical disadvantages are brought about.
Aluminium (sol. Al) is essential for deoxidation of the steel, but less than 0.01% Al is not enough for this purpose, though a content of not larger than 0.10% is.
Silicon is not essential, but when present, a silicon content of not greater than 0.1% is adequate for improving the ductility of the two-phase structure. Silicon may however be added in an amount of not larger than 1.2%, but a silicon content of more than 1.2% will produce an adverse effect on the paintability and corrosion resistance of the resultant steel sheets. Therefore, the upper limit of the silicon content is set at 1.2%.
For further improvement in the strength of the final steel sheet, one or more of chromium, copper and nickel, each in amount not more than 1%, may be added, and for improving the bending working properties, one or more of calcium, rare earth metals (REM) and zirconium, each in an amount of not more than 0.1%, may be added.
The starting material with a chemical composition adjusted as above is processed into slabs by a conventional continuous casting process or ingot-breaking process, then the slabs are hot rolled and cold rolled into cold rolled sheets. The thus-obtained cold rolled sheets are subjected to a continuous annealing process, which is one of features of the present invention.
The soaking in the continuous annealing process should be performed within the temperature range of from 730 to 8000C for a period of at least 20 seconds but limited preferably to 2 minutes for the following reasons.
Soaking at lower than 7300C and for less than 20 seconds will not produce a sufficient amount of y phase nor a sufficient concentration of carbon, manganese, and so on in the y phase necessary for obtaining the desired residual austenite, and even if rapid cooling is performed, the required two-phase structure cannot be obtained. Thus it would not be possible to obtain a steel the required two-phase structure cannot be obtained. Thus it would not be possible to obtain a steel sheet having a good balance between strength and ductility. On the other hand, soaking at a temperature in excess of 8000C will produce an excessive amount of y phase and the manganese concentration in the y phase is diluted, so that even with rapid cooling only an insufficient amount of residual austenite will be produced, and instead the amount of hard martensite increases.Thus the resultant steel sheet would not be well balanced between strength and ductility. The upper limit for the soaking time is preferably set at 2 minutes: although a longer soaking time may be used, this would require a longer annealing furnace and thus this is not desirable from the point of view of capital cost and economy.
Cooling subsequent to the annealing soaking is performed with a cooling rate ranging from 30 to 3000C/sec. but preferably from 100 to 3000 C/sec., down to 2500C. The reason why the terminal point of the rapid cooling is set at 2500C at the highest is that if the rapid cooling is terminated at a temperature above 2500C, the residual austenite transforms into martensite so that a two-phase structure will not result.
Regarding the cooling rate, it is noted that if the cooling rate is less than 300C/sec., it is impossible to obtain a two-phase structure with the low alloy steel composition defined by the present invention, but should the cooling rate exceed 300"C/sec., the ductility of the resultant steel is low. So far as ductility is concerned, it does not substantially change if the cooling rate is within the range of from 30 to 3000C/sec. A cooling rate controlled to lie within the above range is difficult to obtain with liquid cooling or with cooling by immersion in water, but can easily be obtained by vapour-liquid cooling, in which a mixture of vapour and liquid is blown on to the steel sheet.An additional advantage of such vapour-liquid cooling is that a uniform cooling effect across the width of the steel strip can be achieved, and hence a uniform quality of the material can be achieved.
In a typical production process, the steel sheets produced by the continuous annealing and cooling steps are subjected to straightening, normally with a reduction of about 10%.
This invention extends to steel sheets whenever produced by a process of this invention as described above.
In order that the present invention may better be understood, it will now be described in greater detail by way of certain specific Examples thereof, reference being made to the accompanying drawings in which:
Figures 1(a), (b) and (c) respectively show the tendency of two-phase structure formation relative to various contents of carbon and manganese in combination, at certain cooling rates.
Steel slabs having various steel compositions as shown in Table 1 were prepared and hot rolled
into hot rolled steel strips of 2.5 mm thickness, and further cold rolled into cold rolled steel strips of 0.7 mm in thickness. These cold rolled steel strips were subjected to continuous annealing, in which they were soaked at 7700 for 40 seconds, and cooled to ordinary temperatures with various cooling rates ranging from 1 00C to about 10000 C/sec. (water quenching). The properties of the resultant steel sheets are also shown in Table 1.
According to the conventional continuous annealing processes, the cooling rate subsequent to the soaking is about 10 C/sec. With such a slow cooling rate, it is impossible to obtain a two-phase steel sheet having a low yield point and low yield ratio unless the amount of alloying elements (Mn) is large, as in Steel D. Further, this conventional art has the disadvantage that as the manganese content increases, the weldability deteriorates and the production cost increases.
When the cooling rate is maintained within the range of from 30 to 3000C/sec., as defined in the present invention, a satisfactory two-phase structure can be obtained even with a smaller amount of alloying elements, and the resultant ductility does not substantially change, as illustrated by Steels A to C and E to 1.
On the other hand, when the cooling rate is further increased to 3500C/sec. (water spray) or 10000 C/sec. (immersion in water), the resultant ductility is significantly deteriorated and the sheet does not satisfy the required objects of the present invention.
Figures 1 (a), (b) and (c) show the relation between the cooling rate and the formation of the two
phase structure at various contents of carbon and manganese. The numerical references represent the yield ratio in per cent, and a yield ratio of 50% is set as the border line for the two-phase structure. TABLE 1
Cooling Pate ( C/seo,) Composltion (%) 10 20 30 sol. Y.P. T.S. EI C Mn Si Cr Al (kg/mm) (kg/mm) (%) *1 Y.P. T.S. EI *1 Y.P. T.S. EI *1 less than A 0.051 1.48 0.10 - 0.035 28.4 43.1 37.7 X B 0.031 1.69 " - 0.079 23.9 42.4 38.7 X C 0.033 1.77 " - 0.052 24.6 47.5 35.7 X 23.0 47.8 35.7 O D 0.038 2.10 " - 0.026 26.2 52.9 30.4 O 26.1 53.2 31.0 O E 0.099 1.46 0.60 - 0.028 35.8 58.2 30.8 X 33.8 62.1 30.2 X F 0.062 1.59 1.03 - 0.010 40.3 62.4 29.1 X 41.1 64.1 29.1 X less than 0.015 G 0.078 1.39 0.10 0.33 0.022 31.0 61.7 26.2 X 28.2 63.4 29.2 O H 0.107 1.75 1.07 - 0.041 40.6 64.1 30.0 X 35.9 70.4 28.1 X less than I 0.066 0.10 - 42.1 70.5 23.0 X * Steel D is conventional ; Steels A to C andE to 1 are of this Invention.
TABLE 1 (Continued)
Cooling Rate ( C/sec.) 50 100 250 350 Water Quenching 100 Y.P. T.S. EI *1 Y.P. T.S. EI *1 Y.P. T.S. EI *1 Y.P. T.S. EI *1 Y.P. T.S. EI *1 A 22.4 48.8 35.0 O B 21.2 45.3 35.9 O C 20.5 49.9 35.5 O D 25.4 54.4 29.0 O 26.5 56.5 28.4 O 27.4 58.7 28.0 O 29.8 61.0 23.0 # 31.2 63.1 20.2 # E 31.3 62.8 29.8 O 27.7 66.1 28.4 O 28.2 69.1 27.5 O 32.0 75.0 19.8 # 34.9 61.0 15.2 # F 32.1 65.4 29.1 O 30.1 68.1 27.2 O 32.1 70.1 26.2 O 33.9 71.9 21.0 # 34.9 72.1 16.1 # G 29.2 64.3 27.2 O 28.8 66.1 27.3 O 35.3 74.2 20.2 # 40.1 61.8 16.4 # H 32.9 72.3 28.3 O 32.6 71.6 27.0 O 37.2 75.6 19.6 # 41.6 84.4 17.2 # I 35.5 72.0 24.0 O 38.9 77.6 18.0 # *1 O Satisfactory two-phase structure (yleld ratio : 50% or less).
X Unsatisfactory two-phase structure (yield ratl: 50% or higher).
# In spite of satlsfactory two-phase structure, the ductillty Is very low.
Claims (9)
1. A process for producing a two-phase high tensile cold rolled steel sheet which comprises hot rolling a steel containing (by weight) from 0.01 to 0.12% C, not more than 1.2% Si, from 1.0 to 1.8% Mn, from 0.01 to 0.10% sol.Al, with the balance being Fe, normal steel-making additives and unavoidable impurities, cold rolling the hot rolled steel sheet, subjecting the cold rolled steel sheet to continuous annealing comprising soaking the sheet within a temperature range of from 730 to 8000C for a period of not less than 20 seconds and then cooling the continuously annealed sheet to a temperature of 2500C or less with a cooling rate ranging from 30 to 3000 C/sec.
2. A process according to claim 1, in which the silicon content in the steel is not more than 0.1%.
3. A process according to claim 1 or claim 2, in which the cooling rate lies in the range of from 100 to 3000C/sec.
4. A process according to any of the preceding claims, in which the cooling is performed by means of a vapour-water mixture.
5. A process according to any of the preceding claims, in which the normal steel-making additives contained in the starting material include one or more of chromium, copper and nickel, each (when present) in an amount of not more than 1%.
6. A process according to any of the preceding claims, in which the normal steel-making additive contained in the starting material include one or more of calcium, rare earth metals and zirconium, each (when present) in an amount of not more than 0.1%.
7. A process according to any of the preceding claims, in which the steel sheet is soaked at the annealing temperature for a period of not more than 2 minutes.
8. A process for producing a two-phase high tensile cold rolled steel sheet substantially as hereinbefore described in any one of Examples A to C or E to
9. Two-phase cold rolled steel sheet whenever produced by a method according to any of the preceding claims.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15339179A JPS5677329A (en) | 1979-11-27 | 1979-11-27 | Production of composite structure high tensile cold-rolled steel plate of superior workability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2066852A true GB2066852A (en) | 1981-07-15 |
| GB2066852B GB2066852B (en) | 1983-03-23 |
Family
ID=15561454
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8037995A Expired GB2066852B (en) | 1979-11-27 | 1980-11-27 | Process for producing two-phase cold rolled steel sheet |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS5677329A (en) |
| BE (1) | BE886350A (en) |
| BR (1) | BR8007714A (en) |
| CA (1) | CA1142069A (en) |
| DE (1) | DE3044339A1 (en) |
| FR (1) | FR2470163A1 (en) |
| GB (1) | GB2066852B (en) |
| IT (1) | IT1134491B (en) |
| NL (1) | NL184790C (en) |
| SE (1) | SE441278C (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4961793A (en) * | 1987-06-26 | 1990-10-09 | Nippon Steel Corporation | High-strength cold-rolled steel sheet having high r value and process for manufacturing the same |
| CN104388816A (en) * | 2014-10-29 | 2015-03-04 | 江苏沙钢集团有限公司 | Low-carbon steel plate with ultralow yield-strength ratio and manufacturing method thereof |
| CN111826507A (en) * | 2020-06-19 | 2020-10-27 | 华菱安赛乐米塔尔汽车板有限公司 | Ultrahigh-yield-ratio steel and production process thereof |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0674487B2 (en) * | 1986-11-28 | 1994-09-21 | 新日本製鐵株式会社 | High toughness electric resistance welded steel pipe with excellent saw resistance |
| JP2531591Y2 (en) * | 1991-03-19 | 1997-04-02 | 株式会社ノダ | Fire door |
| CN106480305A (en) * | 2015-08-24 | 2017-03-08 | 鞍钢股份有限公司 | A kind of production method improving cold rolling electric decarburization efficiency |
| CN106480282A (en) * | 2015-08-24 | 2017-03-08 | 鞍钢股份有限公司 | A kind of production method of the efficient electrical sheet of No yield point |
| CN106480281A (en) * | 2015-08-24 | 2017-03-08 | 鞍钢股份有限公司 | A kind of production method of high magentic induction oriented electrical sheet |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5443453B2 (en) * | 1973-07-25 | 1979-12-20 | ||
| JPS5619380B2 (en) * | 1973-08-11 | 1981-05-07 | ||
| JPS5157623A (en) * | 1974-11-18 | 1976-05-20 | Nippon Kokan Kk | Takaitosoyakitsukekokaseitosugureta hijikoseiomotsukochoryokureienkohanno seizohoho |
| US4033789A (en) * | 1976-03-19 | 1977-07-05 | Jones & Laughlin Steel Corporation | Method of producing a high strength steel having uniform elongation |
| BE846024A (en) * | 1976-09-09 | 1977-03-09 | PROCESS FOR THE CONTINUOUS THERMAL TREATMENT OF SHEETS | |
| JPS5827329B2 (en) * | 1978-04-05 | 1983-06-08 | 新日本製鐵株式会社 | Manufacturing method of low yield ratio high tensile strength hot rolled steel sheet with excellent ductility |
-
1979
- 1979-11-27 JP JP15339179A patent/JPS5677329A/en active Pending
-
1980
- 1980-11-24 NL NLAANVRAGE8006404,A patent/NL184790C/en not_active IP Right Cessation
- 1980-11-25 SE SE8008247A patent/SE441278C/en not_active IP Right Cessation
- 1980-11-25 DE DE19803044339 patent/DE3044339A1/en active Granted
- 1980-11-26 BR BR8007714A patent/BR8007714A/en not_active IP Right Cessation
- 1980-11-26 BE BE2/58877A patent/BE886350A/en not_active IP Right Cessation
- 1980-11-26 FR FR8025126A patent/FR2470163A1/en active Granted
- 1980-11-27 IT IT26281/80A patent/IT1134491B/en active
- 1980-11-27 GB GB8037995A patent/GB2066852B/en not_active Expired
- 1980-11-27 CA CA000365677A patent/CA1142069A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4961793A (en) * | 1987-06-26 | 1990-10-09 | Nippon Steel Corporation | High-strength cold-rolled steel sheet having high r value and process for manufacturing the same |
| CN104388816A (en) * | 2014-10-29 | 2015-03-04 | 江苏沙钢集团有限公司 | Low-carbon steel plate with ultralow yield-strength ratio and manufacturing method thereof |
| CN111826507A (en) * | 2020-06-19 | 2020-10-27 | 华菱安赛乐米塔尔汽车板有限公司 | Ultrahigh-yield-ratio steel and production process thereof |
| CN111826507B (en) * | 2020-06-19 | 2021-12-03 | 华菱安赛乐米塔尔汽车板有限公司 | Production process of steel with ultrahigh yield ratio |
Also Published As
| Publication number | Publication date |
|---|---|
| IT1134491B (en) | 1986-08-13 |
| FR2470163B1 (en) | 1985-04-19 |
| JPS5677329A (en) | 1981-06-25 |
| SE8008247L (en) | 1981-05-28 |
| SE441278B (en) | 1985-09-23 |
| NL184790C (en) | 1989-11-01 |
| FR2470163A1 (en) | 1981-05-29 |
| NL184790B (en) | 1989-06-01 |
| DE3044339A1 (en) | 1981-07-02 |
| GB2066852B (en) | 1983-03-23 |
| DE3044339C2 (en) | 1987-01-08 |
| NL8006404A (en) | 1981-07-01 |
| CA1142069A (en) | 1983-03-01 |
| BE886350A (en) | 1981-03-16 |
| BR8007714A (en) | 1981-06-09 |
| SE441278C (en) | 1987-02-18 |
| IT8026281A0 (en) | 1980-11-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19991127 |