CA1069806A - Cold-rolled high strength steel sheet - Google Patents
Cold-rolled high strength steel sheetInfo
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- CA1069806A CA1069806A CA242,767A CA242767A CA1069806A CA 1069806 A CA1069806 A CA 1069806A CA 242767 A CA242767 A CA 242767A CA 1069806 A CA1069806 A CA 1069806A
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Abstract
ABSTRACT OF THE DISCLOSURE
Disclosed are a cold-rolled high strength steel sheet having excellent cold workability under the as-annealed condition which consists essentially of, by weight, 0.03 - 0.2% C, 0.6 - 1.5% Si, 1.3 - 3.0% Mn, 0.01 - 0.25% Nb or 0.01 - 0.2% Ti or 0.01 - 0.3% Nb plus Ti, and the remainder of Fe with inevitable amounts of impurities, and the method of making the same. The steel sheet can be as thin as 3 mm or less while possessing a high tensile strength of 50 to 100 kg/mm2, and is extremely suitable for use as a constructional material of car bodies.
Disclosed are a cold-rolled high strength steel sheet having excellent cold workability under the as-annealed condition which consists essentially of, by weight, 0.03 - 0.2% C, 0.6 - 1.5% Si, 1.3 - 3.0% Mn, 0.01 - 0.25% Nb or 0.01 - 0.2% Ti or 0.01 - 0.3% Nb plus Ti, and the remainder of Fe with inevitable amounts of impurities, and the method of making the same. The steel sheet can be as thin as 3 mm or less while possessing a high tensile strength of 50 to 100 kg/mm2, and is extremely suitable for use as a constructional material of car bodies.
Description
6~8~6 This invention relates to a process ~or manufacturing a cold-rolled high strength steel sheet having excellent cold workability, and to the cold-rolled high strength steel sheet manufactured by said process, and further to a car body compris-.ing said cold-rolled hiyh strength steel sheet. Such cold rolled steel sheet for car body has preferably a thickness of 3.0 mm or less.
Recently constant efEorts have been made in the fabrication of cars to reduce the weight of car bod~ not only from the view points of meeting safety requirements and reducing pollution by exhaust gases, but also as a means for reducing the amount of fuel consumed~ For accomplishing -these aims, cold-rolled high strength steel sheets have come into wide use in place of conventional mild steel sheets. `
U.S. Patent No. 3,~330,699, issued to T. Matsuoka et .
al, discloses a process for manufacturing such steel sheet:
The subject matter of the invention of this U.S. Patent resides in making a steel comprising 0.03 - 0.2% C, 1.6 - 3.0% Mn, 0.03 - 0.6% Si, 0.01 - 0. 250/o Nb and/or 0.01 - 0.2% Ti, and the ::
remainder of Fe and inevitable impurities, hot rolling and cold rolling into a steel sheet of thickness of 3 mm or less, and annealing the steel sheet at a temperature of 620C~ to A3 transformation point. In the invention of the U.S. patent, the amount of Si and Mn contained are specified as claimed because silicon contained in excess of 0.6% increases the brittleness and deteriorates the weldability of the steel and manganese contained at less than 1.6% does not impart to the steel a tensile strength of 50 kg/mm2 or more.
The present inventor has found through further study of the steels of the type as disclosed in said U.S. patent that an increase in silicon content even exceeding 0.6% does not deteriorate the weldability for spot-welding and rather .;
.
~(365~ 6 m~y enhance the col~ workability of -the steel wh:ich may be expressed, ~or example, in terms of elongation under tension.
Accordingly, it is an ob ject of the present invention to manufacture a cold-rolled steel sheet having i,mproved cold-wor~ability while ~ceeping high tensile strength.
It is another object of the present invention to provide a car body made of such cold-rolled steel sheet. ~ '' These and other objects, features and advantages ~ of the present invention will appear more fully from the following description. ' ;
Since the steel sheet o~ the present inventio~ is ~ -mainly directed toward usage as a constructional material for car bodies, it is not ordinarily used as sheet but in almost ; all cases is subjected to cold working or forming. Thus not only the strength but the cold workability of the steel sheet is of great importance.
For mild steel plate, Lankford's ~ value is related to the cold forming properties of the steel, and thus must be increased for improvement thereof.
It is, however, known that, for a high strength steel plate such as that of the present invention, elongation due to tension is a better criterion for forming properties than the ~ value. It is, therefore, advantageous in cold forming a steel having a certain desired strength that it be endowed with higher elongation.
As stated above, the present invention is based on the discovery that increase in silicon content rather enhances ' elongation due to tension and does not cause serious deterioration in spot-weldability. As is suggested in the above-mentioned U.S.
patent, higher silicon content is not preferred from the view~
point of brittleness, which may be determined by such a method as the charpy test. However, it can be stated that such
Recently constant efEorts have been made in the fabrication of cars to reduce the weight of car bod~ not only from the view points of meeting safety requirements and reducing pollution by exhaust gases, but also as a means for reducing the amount of fuel consumed~ For accomplishing -these aims, cold-rolled high strength steel sheets have come into wide use in place of conventional mild steel sheets. `
U.S. Patent No. 3,~330,699, issued to T. Matsuoka et .
al, discloses a process for manufacturing such steel sheet:
The subject matter of the invention of this U.S. Patent resides in making a steel comprising 0.03 - 0.2% C, 1.6 - 3.0% Mn, 0.03 - 0.6% Si, 0.01 - 0. 250/o Nb and/or 0.01 - 0.2% Ti, and the ::
remainder of Fe and inevitable impurities, hot rolling and cold rolling into a steel sheet of thickness of 3 mm or less, and annealing the steel sheet at a temperature of 620C~ to A3 transformation point. In the invention of the U.S. patent, the amount of Si and Mn contained are specified as claimed because silicon contained in excess of 0.6% increases the brittleness and deteriorates the weldability of the steel and manganese contained at less than 1.6% does not impart to the steel a tensile strength of 50 kg/mm2 or more.
The present inventor has found through further study of the steels of the type as disclosed in said U.S. patent that an increase in silicon content even exceeding 0.6% does not deteriorate the weldability for spot-welding and rather .;
.
~(365~ 6 m~y enhance the col~ workability of -the steel wh:ich may be expressed, ~or example, in terms of elongation under tension.
Accordingly, it is an ob ject of the present invention to manufacture a cold-rolled steel sheet having i,mproved cold-wor~ability while ~ceeping high tensile strength.
It is another object of the present invention to provide a car body made of such cold-rolled steel sheet. ~ '' These and other objects, features and advantages ~ of the present invention will appear more fully from the following description. ' ;
Since the steel sheet o~ the present inventio~ is ~ -mainly directed toward usage as a constructional material for car bodies, it is not ordinarily used as sheet but in almost ; all cases is subjected to cold working or forming. Thus not only the strength but the cold workability of the steel sheet is of great importance.
For mild steel plate, Lankford's ~ value is related to the cold forming properties of the steel, and thus must be increased for improvement thereof.
It is, however, known that, for a high strength steel plate such as that of the present invention, elongation due to tension is a better criterion for forming properties than the ~ value. It is, therefore, advantageous in cold forming a steel having a certain desired strength that it be endowed with higher elongation.
As stated above, the present invention is based on the discovery that increase in silicon content rather enhances ' elongation due to tension and does not cause serious deterioration in spot-weldability. As is suggested in the above-mentioned U.S.
patent, higher silicon content is not preferred from the view~
point of brittleness, which may be determined by such a method as the charpy test. However, it can be stated that such
- 2 -1~:36913at6 deterioration in brittlenes~ does not become a serious problem in the prac~ical use of fil~ steel sheet such as that of the present invention.
Therefore according to the preser.t invention there is firstly provided a process for manufacturing a cold-rolled high strength steel sheet having excellent cold workability which comprises: making a steel consisting essentially of, by weight, 0.03 - 0.2% C, 0.6 - 1.5% Si, 1.3 - 3.0% Mn, 0.01 - 0.25% Nb or O.01 - O.2% Ti or 0.01 0.3% Nb plus Ti, and the remainder of Fe with inevitable amounts of impurities, hot rolling and cold rolling the steel into a steel sheet, and then annealing the steel sheet at a temperature of 620C. to A3 transformation point.
Secondly, the present invention relates tO a cold rolled steel sheet manufactured by said method.
, The steel sheet of the present invention can be as thin as 3 mm or less while possessing a high tensile strength of 50 to 100 kg/mm . j The steel sheet of the present invention is thus extremely suitable for use as a constructional material of car bodies and results in remarkably reducing the weight of the car body for which it is used while maintaining high strength.
Accordingly, the invention further relates to a car body made of the cold-rolled steel sheet manufactured by said process.
The reasons for specifying the steel composition of the present invention are given below.
A carbon content of less than 0.03% does not provide a tensile strPngth of 50 kg/mm2, while the content must be limited to not more than 0~20% in order to obtain good weldabilityO
AnNb content of less than 0.01% is not ef~ective to improve the strength, while a content exceeding 0.25% fails to improve .
~, stren~th any fu~ther. The Ti con-tent should be limi-tecl from 0.01 to 0. 20% for the sarne reason as that rnen-tioned for Nb.
Further, a Ti content exceeding 0.20% renders ingot-making diffi-cult. The upper limit of ~b plus Ti in combination is specified to be 0.3% since a content exceeding this value does not p~oduce any particular effects.
A ~anganese content of less than 1.3% does not impart to the steel a tensile strength of 50 kg/mm2 or more, whereas a manganese content exceeding 3.0% makes the process OL
steel making difficult. As mentioned previously, a silicon content of 0.6% or more rather enhances the elongation property under tension and at the same time the tensile strength to some de~ree. On the other hand, the upper limit o~ the silicon content should be 1.5%.
With a silicon content of 0.6 to 1.5% and a manganese content of 1.3 to 3.0%, the steel sheet of khe present invention exhibits excellent cold workability as indicated by higher elongation, while it keeps its high tensile strength.
It can be added that the results of tests conducted on the steel sheet of the present invention show that within the defined ranges of Si and Mn, higher silicon content (1.0 - 1.5%, particularly 1.2 ~ 1.5) and lower mang~nese content (1.3 ~ 2.0%) ~ .
enhance elongation to-a further extent. Such increase in the silicon content will slightly lower the weldability of the steel sheet. However, this is not a serious problem, insofar as the spot-welding, which is commonly employed in the manufacture of car bodies, is concerned. Constructional materials for use in car bodies should be excellent in deep drawing property and - ductility, which properties may be expressed in terms o~
elongation under tension, while strength i5 maintained as high as possible. The steel sheet of the present invention is thus suitable for use as a constructional material for car bodies.
~6~l~06 The steel of the present inven-tion is subjected to hot-rolling and cold-rolling into sheet as in the case o~ the manufacture of an ordinary cold-rolled steel. The steel sheet should be annealed thereafter at a temperature of 620C. to A3 transformation point. Annealing below 620C. does not cause satisfactory recrystallization and results in poor recovery of ductility of the product. On the other hand, annealing at a temperature over A3 transformation point should be avoided since such procedure will result in undesirable sintering and deformation of product steel sheet and, fur-ther, is uneconomical.
The present invention will be understood more clearly with reference to the following examples showing some results of tests on the physical properties of the steel sheet of the present invention.
It should be noted however tha-t these examples are intended to illustrate the invention and are not to be construed to limit the scope thereof.
Example 1 Steel ingots prepared with a high frequency furnace and having the compositions indicated in Table 1 were separately hot-rolled at a finishing temperature of 850C. into strips of a thickness of 2.5 mm. Each of the steel strips were pickled and then cold-rolled into a steel sheet of a thickness of 0~8 mm.
The sheets were annealed at a predetermined temperature and samples of each were subject to the tests according to the methods specified by the Japanese Industrial Standards. The results are summarized in Table 2. -~
1~6~ )6 Table I
Composition, % by weight No. Si Mn P S Nb Ti C30.07 0.31 2.08 0.003 0.005 0.06 Steels for C4 " 0.33 2.27 0.004 0.006 0.06 compari son C5 " 0.38 2.47 0.004 0.006 0.05 C6 " 0.34 2.71 0.004 0.006 0.06 C8 " 0O55 1.86 0.004 00006 0.05 _ C140.09 0.70 1.88 0.006 0.007 0.05 Steels of this C15 0.07 0.97 2.090.0060O008 0.05 invention C16 " 0.94 2O24 0.006 0.007 0.05 C17 " 0O93 2.41 0.006 0~006 0.06 -C18 " 0.92 2.61 0.006 0.00~ 0.05 Cl90.11 1.31 1.80 0.006 0.006 0.05 C200.111 r 20 2.63 0.007 0.006 - 0.10 C21O.Og 1035 2071 0.006 00006 OOO5 0~08 069~06 Table 2 Sample Annea~ T.S. 2 Elong No. temp. C. kg/mm %
C3 690 53.2 29.0 720 53.6 29.0 Steels for 750 51.9 30.0 Compari-son C4 690 53.5 28.5 720 55.0 28.0 750 54.1 29.0 C5 690 57.2 28.0 720 60.1 26.5 750 59.7 26.5 C6 690 62.0 25.5 720 64.4 25.0 750 66.0 23.5 C8 690 51.6 28.5 720 51.3 30.0 750 49.5 30.0 .. . . .. _ . . . . .. . .. . . . . . . . ..... . . . .. .... .. . . .
C14 720 53.1 32.3 690 56.7 31.0 C15 720 56.8 30.0 Steels of 750 55-7 30 5 this - -Invention C16 690 58.8 29.0 720 58.9 2809 750 58.1 29.5 ,, C17 790 6104 28.0 720 61.5 2800 750 61.1 28.0 C18 690 64.0 28.0 720 64.5 26.5 750 64.3 27.0 Cl9 690 61.6 28.3 720 61.8 28.0 750 61.5 28.2 C20 750 68.7 24.1 C21 750 71.2 22 n 9 .
" :.. . '' .
~6~ 6 Example 2 This example is to show that hiyher silicon content will increase elongation (%). The samples tested were all prepared in the same manner as in Example 1. The results are summarized in Table 3.
~ o ~
~1 ~ ~ ~ CO ~9 1`
. ~ r~) ~1 ~ r~ ~ a u~ ~; u~ ~n ,i ~i E~ ~ ~ ~ ~ . ~ ~D
~ ~ ~ co ~ ~
~1 ~ E~ ~ ~ ~g Q .
E~ ~ ~ ~ ,~ o ~
o o o o o o a~ ~ o~ ~ ~ ~
o o o o ~ o ~ V~ o o o o o o ~ o o o o o o o O ~1 O O ~1 0 P~ o o o o o o . ~ o o o o o 'o ~ r~ ~ ~1 '~ ~D
.~ ~ ~ ~ r~ I` ~ O
. o ~ ~ ~ ~ ~ ~ .
~ ~ ~ In ~J L~
u~ ~ ~ ~D ~ 'lD
o ,i o ~J ~ ,i o o o o ~ o ~I
. .. o o oo o o . ,:
~o' ~ ~ ~ ~ ~ ~ U~ ~
~1l ~ ~ ~ ~ ~
.
J
~069~306 On comparing E4 wi-th E2 ~ E3 wi th E~, a~d E5 wi th E6 respectively, it can be seen that the steels with higher silicon content exhlbit higher elong~tion at almost the same tensile strength.
-- 10 -- .
Therefore according to the preser.t invention there is firstly provided a process for manufacturing a cold-rolled high strength steel sheet having excellent cold workability which comprises: making a steel consisting essentially of, by weight, 0.03 - 0.2% C, 0.6 - 1.5% Si, 1.3 - 3.0% Mn, 0.01 - 0.25% Nb or O.01 - O.2% Ti or 0.01 0.3% Nb plus Ti, and the remainder of Fe with inevitable amounts of impurities, hot rolling and cold rolling the steel into a steel sheet, and then annealing the steel sheet at a temperature of 620C. to A3 transformation point.
Secondly, the present invention relates tO a cold rolled steel sheet manufactured by said method.
, The steel sheet of the present invention can be as thin as 3 mm or less while possessing a high tensile strength of 50 to 100 kg/mm . j The steel sheet of the present invention is thus extremely suitable for use as a constructional material of car bodies and results in remarkably reducing the weight of the car body for which it is used while maintaining high strength.
Accordingly, the invention further relates to a car body made of the cold-rolled steel sheet manufactured by said process.
The reasons for specifying the steel composition of the present invention are given below.
A carbon content of less than 0.03% does not provide a tensile strPngth of 50 kg/mm2, while the content must be limited to not more than 0~20% in order to obtain good weldabilityO
AnNb content of less than 0.01% is not ef~ective to improve the strength, while a content exceeding 0.25% fails to improve .
~, stren~th any fu~ther. The Ti con-tent should be limi-tecl from 0.01 to 0. 20% for the sarne reason as that rnen-tioned for Nb.
Further, a Ti content exceeding 0.20% renders ingot-making diffi-cult. The upper limit of ~b plus Ti in combination is specified to be 0.3% since a content exceeding this value does not p~oduce any particular effects.
A ~anganese content of less than 1.3% does not impart to the steel a tensile strength of 50 kg/mm2 or more, whereas a manganese content exceeding 3.0% makes the process OL
steel making difficult. As mentioned previously, a silicon content of 0.6% or more rather enhances the elongation property under tension and at the same time the tensile strength to some de~ree. On the other hand, the upper limit o~ the silicon content should be 1.5%.
With a silicon content of 0.6 to 1.5% and a manganese content of 1.3 to 3.0%, the steel sheet of khe present invention exhibits excellent cold workability as indicated by higher elongation, while it keeps its high tensile strength.
It can be added that the results of tests conducted on the steel sheet of the present invention show that within the defined ranges of Si and Mn, higher silicon content (1.0 - 1.5%, particularly 1.2 ~ 1.5) and lower mang~nese content (1.3 ~ 2.0%) ~ .
enhance elongation to-a further extent. Such increase in the silicon content will slightly lower the weldability of the steel sheet. However, this is not a serious problem, insofar as the spot-welding, which is commonly employed in the manufacture of car bodies, is concerned. Constructional materials for use in car bodies should be excellent in deep drawing property and - ductility, which properties may be expressed in terms o~
elongation under tension, while strength i5 maintained as high as possible. The steel sheet of the present invention is thus suitable for use as a constructional material for car bodies.
~6~l~06 The steel of the present inven-tion is subjected to hot-rolling and cold-rolling into sheet as in the case o~ the manufacture of an ordinary cold-rolled steel. The steel sheet should be annealed thereafter at a temperature of 620C. to A3 transformation point. Annealing below 620C. does not cause satisfactory recrystallization and results in poor recovery of ductility of the product. On the other hand, annealing at a temperature over A3 transformation point should be avoided since such procedure will result in undesirable sintering and deformation of product steel sheet and, fur-ther, is uneconomical.
The present invention will be understood more clearly with reference to the following examples showing some results of tests on the physical properties of the steel sheet of the present invention.
It should be noted however tha-t these examples are intended to illustrate the invention and are not to be construed to limit the scope thereof.
Example 1 Steel ingots prepared with a high frequency furnace and having the compositions indicated in Table 1 were separately hot-rolled at a finishing temperature of 850C. into strips of a thickness of 2.5 mm. Each of the steel strips were pickled and then cold-rolled into a steel sheet of a thickness of 0~8 mm.
The sheets were annealed at a predetermined temperature and samples of each were subject to the tests according to the methods specified by the Japanese Industrial Standards. The results are summarized in Table 2. -~
1~6~ )6 Table I
Composition, % by weight No. Si Mn P S Nb Ti C30.07 0.31 2.08 0.003 0.005 0.06 Steels for C4 " 0.33 2.27 0.004 0.006 0.06 compari son C5 " 0.38 2.47 0.004 0.006 0.05 C6 " 0.34 2.71 0.004 0.006 0.06 C8 " 0O55 1.86 0.004 00006 0.05 _ C140.09 0.70 1.88 0.006 0.007 0.05 Steels of this C15 0.07 0.97 2.090.0060O008 0.05 invention C16 " 0.94 2O24 0.006 0.007 0.05 C17 " 0O93 2.41 0.006 0~006 0.06 -C18 " 0.92 2.61 0.006 0.00~ 0.05 Cl90.11 1.31 1.80 0.006 0.006 0.05 C200.111 r 20 2.63 0.007 0.006 - 0.10 C21O.Og 1035 2071 0.006 00006 OOO5 0~08 069~06 Table 2 Sample Annea~ T.S. 2 Elong No. temp. C. kg/mm %
C3 690 53.2 29.0 720 53.6 29.0 Steels for 750 51.9 30.0 Compari-son C4 690 53.5 28.5 720 55.0 28.0 750 54.1 29.0 C5 690 57.2 28.0 720 60.1 26.5 750 59.7 26.5 C6 690 62.0 25.5 720 64.4 25.0 750 66.0 23.5 C8 690 51.6 28.5 720 51.3 30.0 750 49.5 30.0 .. . . .. _ . . . . .. . .. . . . . . . . ..... . . . .. .... .. . . .
C14 720 53.1 32.3 690 56.7 31.0 C15 720 56.8 30.0 Steels of 750 55-7 30 5 this - -Invention C16 690 58.8 29.0 720 58.9 2809 750 58.1 29.5 ,, C17 790 6104 28.0 720 61.5 2800 750 61.1 28.0 C18 690 64.0 28.0 720 64.5 26.5 750 64.3 27.0 Cl9 690 61.6 28.3 720 61.8 28.0 750 61.5 28.2 C20 750 68.7 24.1 C21 750 71.2 22 n 9 .
" :.. . '' .
~6~ 6 Example 2 This example is to show that hiyher silicon content will increase elongation (%). The samples tested were all prepared in the same manner as in Example 1. The results are summarized in Table 3.
~ o ~
~1 ~ ~ ~ CO ~9 1`
. ~ r~) ~1 ~ r~ ~ a u~ ~; u~ ~n ,i ~i E~ ~ ~ ~ ~ . ~ ~D
~ ~ ~ co ~ ~
~1 ~ E~ ~ ~ ~g Q .
E~ ~ ~ ~ ,~ o ~
o o o o o o a~ ~ o~ ~ ~ ~
o o o o ~ o ~ V~ o o o o o o ~ o o o o o o o O ~1 O O ~1 0 P~ o o o o o o . ~ o o o o o 'o ~ r~ ~ ~1 '~ ~D
.~ ~ ~ ~ r~ I` ~ O
. o ~ ~ ~ ~ ~ ~ .
~ ~ ~ In ~J L~
u~ ~ ~ ~D ~ 'lD
o ,i o ~J ~ ,i o o o o ~ o ~I
. .. o o oo o o . ,:
~o' ~ ~ ~ ~ ~ ~ U~ ~
~1l ~ ~ ~ ~ ~
.
J
~069~306 On comparing E4 wi-th E2 ~ E3 wi th E~, a~d E5 wi th E6 respectively, it can be seen that the steels with higher silicon content exhlbit higher elong~tion at almost the same tensile strength.
-- 10 -- .
Claims (6)
1. A process for manufacturing a cold-rolled high strength steel sheet having excellent cold workability which comprises making a steel consisting essentially of, by weight, 0.03-0.2% C, 0.6 - 1.5% Si, 1.3 - 3.0% Mn, 0.01 -0.25% Nb or 0.01 - 0.2% Ti or 0.01 - 0.3% Nb plus Ti, and the remainder of Fe with inevitable amounts of impurities, hot rolling and cold rolling the steel into a steel sheet, and then annealing the steel sheet at a temperature of 620°C.
to A3 transformation point.
to A3 transformation point.
2. The process according to claim 1, wherein the Mn content is 1.3 - 2.0% by weight.
3. The process according to claim 1, wherein the Si content is 1.0 - 1.5% by weight.
4. The process according to claim 1 wherein the Si content of the steel is 1.0 - 1.5% by weight and the Mn content is 1.3 - 2.0% by weight.
5. A cold-rolled high strength steel sheet having excellent cold workability under the as-annealed condition which consists essentially of, by weight, 0.03 - 0.2% C, 0.6 - 1.5% Si, 1.3 - 3.0% Mn, 0.01 - 0.25% Nb or 0.01 - 0.2%
Ti or 0.01 - 0.3% Nb plus Ti, and the remainder of Fe with inevitable amounts of impurities.
Ti or 0.01 - 0.3% Nb plus Ti, and the remainder of Fe with inevitable amounts of impurities.
6. The cold-rolled high strength steel sheet having excellent cold workability according to claim 5 wherein the Si content of the steel is 1.0 - 1.5% by weight and the Mn content of the steel is 1.3 - 2.0% by weight.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA242,767A CA1069806A (en) | 1975-12-30 | 1975-12-30 | Cold-rolled high strength steel sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA242,767A CA1069806A (en) | 1975-12-30 | 1975-12-30 | Cold-rolled high strength steel sheet |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1069806A true CA1069806A (en) | 1980-01-15 |
Family
ID=4104866
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA242,767A Expired CA1069806A (en) | 1975-12-30 | 1975-12-30 | Cold-rolled high strength steel sheet |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1069806A (en) |
-
1975
- 1975-12-30 CA CA242,767A patent/CA1069806A/en not_active Expired
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