JPH06100980A - High tensile strength cold rolled steel sheet excellent in chemical conversion treating property and formability and its production - Google Patents

Abstract

PURPOSE:To obtain a high tensile strength cold rolled steel sheet excellent in chemical conversion treating property and press formability by subjecting a slab of a steel containing specific amounts of C, B, Ag, Si, Mn, Ni, Cu, P, Ti, and Nb to a finish rolling, a cold rolling, and a recrystallization annealing in respectively prescribed conditions. CONSTITUTION:A steel having a composition consisting of, by mass, <=0.005% C, 0.001-0.008% B, 0.005-0.1% Ag, 0.2-2.5% Si, 1-3.5% Mn, 0.05-2% Ni, 0.1-2% Cu, 0.04-0.18% P, 0.003-0.1% Ti and/or 0.003-0.1% Nb, and the balance Fe is refined. At this time, the relations, by mass%, in [Si]/1.5+[P]/0.3>=0.5, 100[Mn]+150[Ni]-200[Si]-1000[P]>=-200, and [Cu]<=3[Ni] are maintained. Subsequently, the slab of this is hot-rolled, finish-rolled at 750-1000 deg.C, further cold- rolled at 60-95% draft, and subjected to recrystallization annealing at 700-950 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for use in bending, press forming, drawing, etc., mainly for automobile bodies, and has a high tensile cold-rolled steel sheet having good chemical conversion treatability. It proposes a manufacturing method.

In recent years, there has been an increasing demand for weight reduction of automobiles in order to improve fuel consumption, due to regulations on automobile exhaust gas due to environmental problems. In addition, increasing the number of fatalities due to car accidents has become a problem, and improving the safety of cars has become an important issue. Therefore, as one of the countermeasures against these problems, a cold rolled steel sheet having a tensile strength of 500 to 700 MPa in terms of material and excellent press formability has been required.

However, in general, cold-rolled steel sheet deteriorates in press formability, that is, the average r value and TS-El balance as the tensile strength is increased, and further, surface properties such as chemical conversion treatment property and plating property are also increased as the tensile strength is increased. It tends to deteriorate. Therefore, in order to use it for automobiles, it is important to improve the press formability and chemical conversion treatability as well as to increase the tensile strength.

[0004]

2. Description of the Related Art Up to now, various methods have been proposed in order to improve press formability associated with higher tension. For example, the high-strength cold-rolled steel sheet having excellent formability described in JP-A-56-139654 and its manufacturing method, and the high-strength cold-rolled steel sheet for deep drawing with a low yield ratio disclosed in JP-B-59-42742, etc. Based on an ultra-low carbon steel with reduced C, carbon and nitride forming components such as Ti and Nb are added to improve workability and aging, and P is used to increase tensile strength, which does not impair workability. Means for measuring are disclosed. However, the tensile strength of these materials was up to about 400 MPa.

In order to further enhance the strength of these, for example, Japanese Patent Laid-Open No. 63-100158 discloses a steel plate containing a large amount of Si, such as a high strength cold rolled steel having excellent formability. However, when a large amount of Si is added, the surface characteristics are unavoidably deteriorated, and there is a problem that the chemical conversion processability is significantly deteriorated. Further, when a large amount of P and Si are added at the same time, there is a problem that an abnormal structure often occurs in the hot-rolled sheet and workability may be significantly deteriorated.

[0006]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and is excellent in workability such as press molding suitable for automobiles and excellent in chemical conversion treatment. It is an object to propose a high-strength cold-rolled steel sheet and a manufacturing method thereof.

[0007]

As a result of repeated research and study, the present invention provides chemical conversion treatability and press molding by adding Ni and Cu in addition to Si, Mn and P in a combined manner and by limiting the production conditions thereof. This is because it has been found that a high-strength cold-rolled steel sheet having a tensile strength of 500 to 700 MPa can be obtained while maintaining the high level of properties.

That is, the gist of the present invention includes C: 0.0050 mass% or less, B: 0.0010 mass% or more, 0.0080 mass% or less and Al: 0.005 mass% or more, 0.10 mass% or less, and Si: 0.2 mass% or less. Or more, 2.5mass% or less, Mn: 1.0mass% or more, 3.5mass% or less, Ni: 0.05mass% or more, 2.0mass% or less, Cu: 0.1mass% or more, 2.0mass% or less and P: 0.040mass% or more, The content of 0.18 mass% or less expressed by mass% is [% Si], [% M
n), [% Ni], [% Cu] and [% P] represented by the following formulas (1), (2) and (3), and Ti: 0.003 mass% or more, 0.10mass% or less and Nb: 0.003mass% or more, 0.10mass% or less, containing one or two selected from the rest, the balance consisting of iron and inevitable impurities composition and press treatment A high-tensile cold-rolled steel sheet having excellent formability (first invention),

[Formula 5] Note [% Si] /1.5 + [% P] /0.3≧0.5 (1) 100 [% Mn] +150 [% Ni] −200 [% Si] −1000 [% P] ≧ −200 ... (2) [% Cu] ≤ 3 [% Ni] (3) Substituting a part of iron in the balance of the first invention for containing Mo: 1.0 mass% or less (second invention),

A steel slab having the composition of the first or second invention is used as a raw material and hot-rolled to 750 ° C. or higher, 10
Finishing rolling is completed in the temperature range of 00 ° C or less, and further cold rolling is performed after pickling with a reduction rate of 60% or more and 95% or less, and then recrystallization in the temperature range of 700 ° C or more and 950 ° C or less A method for producing a high-strength cold-rolled steel sheet excellent in chemical conversion treatment property and press formability, which is characterized by performing annealing (third invention, fourth invention).

[0010]

First, the experimental results which are the basis of the present invention will be described. C: 0.003 mass%, B: 0.0012 mass%, P:
0.07mass%, Al: 0.04mass%, Ti: 0.04mass% and Nb:
Si, Mn, Ni, and Cu of cold-rolled steel sheet with a thickness of 0.8 mm added with varying the Si, Mn, Ni, and Cu contents in the composition of 0.03 mass%
The relationship between the content and the chemical conversion treatability was investigated.

These steel sheets were subjected to hot rolling of a sheet bar having the above composition at a finishing temperature of 820 to 910 ° C., followed by pickling, reduction, and then cold rolling of 75 to 82%. It was manufactured by continuous annealing at an annealing temperature of 790 to 890 ° C.

Here, the chemical conversion treatability was evaluated by the pinhole area ratio and the number of crystal precipitations when a steel plate was degreased, washed with water and treated with a phosphate, and the pinhole test described below was conducted. In addition, the phosphoric acid treatment liquid was used by Nippon Parkerizing Co., Ltd.
Using BT3112 manufactured by BT3112, spraying was performed for 120 seconds. In the pinhole test, a filter paper in which a reagent (ferrooxyl solution) that reacts with iron ions to develop a color is soaked is closely attached to the test surface,
The phosphoric acid crystal non-adhered portion remaining on the surface of the steel sheet was detected, and image analysis was performed to quantify it as the pinhole area ratio.
The number of crystals deposited was determined by SEM observation. And the evaluation standard of these chemical conversion treatability was defined as follows. First, the pinhole area ratio is less than 2% as ○, 2-9% as △, more than 9% as ×, and the number of crystal precipitations (× 10 ⁴ / mm ² ) is 5 or more as ○ and less than 5 as 3. Δ, and if less than 3, evaluated as x.

Table 1 shows the results of investigation of the contents of Si, Mn, Ni and Cu in the steel sheet and the chemical conversion treatability.

[Table 1]

In this table, the A steel having a low Si and Cu content has good chemical conversion treatability, but the B and C steels having both increased Si and Cu have poor chemical conversion treatability. This chemical conversion treatability is equivalent to that of C steel containing Mn of 1.0 mass% or more and
Even if Mn and Ni are added together, the chemical conversion treatability is not improved with D steel having an Mn content of less than 1 mass%. However,
It has been revealed that the chemical conversion treatability is improved to that of the A steel by the combined addition of Ni to 1 mass% or more of Mn as in the E and F steels. Regarding the relationship between Ni and Cu, it was also found that the chemical conversion treatability was inferior when the Cu content was more than 3 times the Ni content as in the G steel, but was good when it was 3 times or less.

Although the details are not clear, the content of 1 mass% or more
The reason why the chemical conversion treatability was improved by adding Ni to Mn together is considered as follows. That is, it is considered that due to the increase in the Si content, the Si concentration on the surface of the steel sheet after annealing became remarkable, and this caused the chemical conversion treatability to deteriorate. However, coexistence of a small amount of Ni and a large amount of Mn suppresses the surface concentration state of Si and increases the Mn
It is considered that the chemical conversion treatability was improved because the concentrated layer was formed. Further, Cu is an element that is more precious than iron and suppresses the reaction between zinc phosphate and the steel sheet, thus deteriorating the chemical conversion treatment property, but it is presumed that the adverse effect thereof was alleviated by the combined addition of Ni.

Further, the improvement of the abnormal structure of the hot rolled sheet, which occurs when the Si and P contents are high, was also examined. Content of Mn: 0.01-3.1mass% and Ni: 0-1.8mass
C: 0.002 mass varied within each range of s%
%, Si: 1.0 mass%, B: 0.0014 mass%, Cu: 0.30 mass
%, 0.70mass%, 2 levels, P: 0.10mass%, Al: 0.04ma
A cold rolled steel sheet having a composition of ss%, Ti: 0.05 mass% and Nb: 0.03 mass% and a thickness of 0.8 mm was investigated for the relationship between the Mn and Ni contents and the press formability, especially the average r value. In addition, these steel sheets were manufactured by the same method as the above experiment.

The average r value was measured by a three-point method after using JIS No. 5 tensile test piece and applying 15% tensile prestrain.
Average r value = (r _L + 2r _D + r _C ) / as an average value in the L direction (rolling direction), the D direction (direction of 45 ° to the rolling direction) and the C direction (direction of 90 ° to the rolling direction) I got from 4.

From the above survey results, the relationship between the average r value and the values of the mass% contents of Si, Mn, Ni and P expressed by [% Si], [% Mn], [% Ni] and [% P] Is shown in FIG. Figure 1
As is clearer, the average r value is 100 [% Mn] +150
[% Ni] -200 [% Si] -1000 [% P] can be arranged, and when the value calculated by this formula is -200 or more, that is, it is significantly improved by increasing the content of Mn and Ni. I understand that As is clear from FIG. 1, the press formability of Cu content (average r
It has little effect on the value), and thus Cu is a preferable component for enhancing the strength while maintaining the workability.

Although the details are not clear, the reason why an excellent average r value is obtained by increasing the Mn and Ni contents is considered as follows. That is, it is considered that when a large amount of Si and P was added, segregation at the time of casting increased, and this segregation was further promoted at the time of hot rolling, so that an abnormal structure appeared in the hot rolled sheet. However, by adding a certain amount or more of Mn and Ni, since the diffusion coefficient and the transformation point were changed, the promotion of segregation during hot rolling was suppressed,
It is considered that the hot-rolled sheet was homogenized by this and the average r value was improved. Further, it has been clarified that even if Mo is added in an amount of 1% or less in the present invention, the characteristics of the present invention are not impaired.

Next, the reasons for limiting the composition range of each component in the present invention will be described. C: 0.0050 mass% or less C is an important component in the present invention, and in order to obtain a cold-rolled steel sheet having good workability, particularly good TS-El balance, an extremely low carbon steel of 0.0050 mass% or less. Must. Desirably 0.0035 mass% or less is preferable.

Si: 0.2 to 2.5 mass% Si has the function of reducing deterioration of workability and strengthening steel.
The content is required to be 0.2 mass% or more and the necessary amount is added according to the desired strength, but the chemical conversion treatability is significantly deteriorated. However, the chemical conversion treatability can be improved by the combined addition of Ni and high Mn, which is a feature of the present invention, but if the content exceeds 2.5 mass%, it cannot be improved by the present invention either.
% Is the upper limit.

Mn: 1.0 to 3.5 mass% Mn is an important component in the present invention, and it has the effect of remarkably improving the chemical conversion treatability by the combined addition with Ni. However, 1.0 mass% is necessary. Mn also has the effect of strengthening steel, and the necessary amount is added according to the desired strength, but its content is 3.5 m.
If it exceeds ass%, the workability deteriorates, so the upper limit is 3.5 m.
Assass%

Ni: 0.05 to 2.0 mass% Ni is also an important component in the present invention, and it has the effect of remarkably improving the chemical conversion treatability by the combined addition of 1.0 mass% or more in total content with Mn. The effect appears when the percentage is over. Therefore, the lower limit of the content is set to 0.05 mass%. Further, Ni has a function of strengthening steel, and is added in a required amount according to desired strength. In addition, Ni has an effect of improving abnormal structure that is larger than Mn, so it is desirable to add it positively, but increasing the amount of Ni causes a large cost increase, and if the content exceeds 2.0 mass%, the workability deteriorates. mass%

B: 0.0010 to 0.0080 mass% B is added as necessary in order to secure the precipitation of N in steel and to secure the secondary work embrittlement resistance, but if it is less than 0.0010 mass%, the effect cannot be obtained. Therefore, the lower limit of the content is 0.00
Set to 10 mass%. Further, if the content is too large, the recrystallization temperature is extremely increased and the workability is deteriorated. Therefore, the upper limit of the content is regulated to 0.0080 mass% or less.

Cu: 0.1 to 2.0 mass% Cu is a component effective in increasing the strength of the steel by forming a solid solution or precipitation in the steel, and the content thereof is 0.
Requires 1 mass% or more. The strength increased almost linearly with the increase of Cu content, and the content was 1.0 mass%.
The strength increase of about 100 MPa can be expected. However, if the content exceeds 2.0 mass%, the steel becomes brittle and the secondary workability and spot weldability deteriorate. Therefore, its content is
0.1 mass% or more and 2.0 mass% or less. Further, if the Cu content exceeds 3 times the Ni content, the chemical conversion treatability deteriorates, so the upper limit is defined within the above range from the relationship with the Ni content. P: 0.040 to 0.18 mass% Although the detailed mechanism is unknown, P has the effect of strengthening the steel and improving the workability, especially the average r value, and is positively added according to the desired strength. The effect becomes remarkable when the content is 0.040 mass% or more. However, if the content exceeds 0.18 mass%, solidification segregation during casting is remarkable and internal cracking is likely to occur, resulting in deterioration of workability. In addition, it is often segregated at the grain boundaries to cause brittleness. Therefore, its content is 0.040 mass% or more, 0.18
It should be less than mass%. Al: 0.005 to 0.10 mass% Al is added as necessary for deoxidation and precipitation fixing of N in steel, but if the content is less than 0.005 mass%, inclusions increase and good workability is obtained. I can't get it. Therefore, the lower limit of the content is set to 0.005 mass%. Further, if the amount of Al is too large, not only the workability is deteriorated but also the surface properties are deteriorated, so the upper limit of the content is regulated to 0.10 mass% or less.

Ti, Nb: 0.003 to 0.10 mass% Ti, Nb is added in one or more kinds to reduce the solute C and solute N in the steel sheet, and improves the workability, but the content is both
If it is less than 0.003 mass%, the effect is small, and if it exceeds 0.10 mass%, the workability is deteriorated. Therefore, their contents are both 0.003 mass% or more and 0.10 mass% or less.

In addition to what has been described above, in the present invention, it is necessary to effectively use Si and P in order to strengthen the steel without significantly deteriorating the workability. TS: 500-700MPa)
i] /1.5 + [% P] /0.3 is 0.5
Limited to the above.

Further, Si and P are made to satisfy the above values.
In some cases, when the alloy contains Al, an abnormal structure may occur in the hot-rolled sheet. In order to prevent the occurrence of this abnormal structure, in the present invention, the content of Mn, Ni, Si and P, that is, 100% Mn] +1
The value calculated from the formula of 50% Ni] -200% Si] -1000 [% P] is limited to -200 or more, and preferably -150 or more and 100 or less. Mo: 1.0 mass% or less In addition to the above components, up to 1.0 mass% Mo can be selectively contained. Mo suppresses deterioration of workability as much as possible,
Further, it is an effective component for increasing the strength without deteriorating the chemical conversion treatability. However, excessive addition causes an increase in cost, so the upper limit of the content is made 1.0 mass%.

Next, the reasons for limiting the process conditions will be described. Steelmaking and casting conditions may be carried out according to ordinary methods.

The hot rolling finishing temperature needs to be at least 750 ° C. in order to improve the workability after cold rolling and annealing. If it is less than this, the rolling structure in the hot-rolled sheet remarkably remains, which is disadvantageous in forming a texture having a good average r value. Meanwhile 1000 ℃
When the rolling is finished beyond the range, the structure of the hot-rolled sheet becomes coarse, and the texture advantageous for the average r value cannot be obtained. Therefore, the temperature should be 750 ℃ or more and 1000 ℃ or less.

In cold rolling, sufficient workability cannot be obtained unless the cold rolling reduction ratio is 60% or more, so it is set to 60% or more. It is advantageous to set the cold rolling reduction to 70% or more. On the other hand, if the cold rolling reduction ratio is set to 95% or more, the workability deteriorates. Therefore, the upper limit is set to 95%. The recrystallization annealing temperature after cold rolling may be 750 ° C. or higher and 950 ° C. or lower, preferably 800 ° C. or higher.

In the present invention, a continuous annealing line or a continuous hot dip galvanizing line may be used in the annealing step,
The hot dip galvanizing method is suitable for both non-alloyed hot dip galvanizing and alloy hot dip galvanizing. Also,
The cold-rolled steel sheet obtained by the present invention may be subjected to surface treatment such as electroplating after annealing, and may be subjected to a special treatment on the surface to further improve chemical conversion treatability, weldability, press formability, and corrosion resistance. You may go. Further, these cold-rolled steel sheets may be temper-rolled for the purpose of straightening the sheet shape and the like within the range of common sense.

[0033]

EXAMPLE A steel slab having the composition shown in Table 2 melted in a converter was used as a raw material, hot-rolled, then pickled and cold-rolled to a thickness of 0.8 mm, and then a continuous annealing line. so
Recrystallization annealing was performed for 20 seconds, and the tensile properties and chemical conversion treatability of the obtained cold rolled sheet were investigated.

[0034]

[Table 2]

As the above manufacturing conditions, hot rolling finish temperature
(FDT), cold rolling reduction, annealing temperature, and investigation results are summarized in Table 3.

[0036]

[Table 3]

Here, the tensile properties were measured using a JIS No. 5 test piece, and the average r value and the chemical conversion treatability were evaluated by the same method as in the case of the above experiment and evaluated by the same method.

From Table 3, all conforming examples of the present invention are TS
It can be seen that the TS-El balance represented by xEl is excellent, the average r value is high, and the chemical conversion treatability is excellent. On the other hand, the comparative examples are inferior in average r value and TS-El balance, and the chemical conversion treatability is also inferior except for 2 cases.

[0039]

The present invention is applicable to ultra-low C steels containing Si, Mn
By adding Ni and Cu in addition to P and P, it is possible to obtain a high-strength cold-rolled sheet that has excellent surface properties, particularly chemical conversion treatment properties, and is also suitable for press forming. It can greatly contribute to the improvement of safety.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the average r value and the contents of Si, Mn, Ni and P.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location C22C 38/16 (72) Inventor Saiji Matsuoka 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Inside the Technology Research Division (72) Inventor Toshiyuki Kato 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Kawasaki Steel Corporation Inside the Technology Research Division (72) Inventor Junsuke Takasaki 1 Kawasaki-cho, Chuo-ku, Chiba Prefecture Kawasaki Chiba Steel Works, Ltd.

Claims (4)

[Claims] 1. C: 0.0050 mass% or less, B: 0.0010 mass% or more, 0.0080 mass% or less and Al: 0.005 mass% or more, 0.10 mass% or less, and Si: 0.2 mass% or more, 2.5 mass% or less. , Mn: 1.0mass% or more, 3.5mass% or less, Ni: 0.05mass% or more, 2.0mass% or less, Cu: 0.1mass% or more, 2.0mass% or less and P: 0.040mass% or more, 0.18mass% or less mass Percentage [% Si], [% M]
n), [% Ni], [% Cu] and [% P] represented by the following formulas (1), (2) and (3), and Ti: 0.003 mass% or more, 0.10mass% or less and Nb: 0.003mass% or more, 0.10mass% or less, containing one or two selected from the rest, the balance consisting of iron and inevitable impurities composition and press treatment High strength cold rolled steel sheet with excellent formability. [Formula 1] Note [% Si] /1.5 + [% P] /0.3≧0.5 (1) 100 [% Mn] +150 [% Ni] −200 [% Si] −1000 [% P] ≧ −200 ... (2) [% Cu] ≦ 3 [% Ni]… (3) 2. C: 0.0050 mass% or less, Mo: 1.0 mass% or less, B: 0.0010 mass% or more, 0.0080 mass% or less and Al: 0.005 mass% or more, 0.10 mass% or less, and Si: 0.2 masss. % Or more, 2.5 mass% or less, Mn: 1.0 mass% or more, 3.5 mass% or less, Ni: 0.05 mass% or more, 2.0 mass% or less, Cu: 0.1 mass% or more, 2.0 mass% or less and P: 0.040 mass% or more , 0.18 mass% or less in terms of mass%, [% Si], [% M
n), [% Ni], [% Cu] and [% P] represented by the following formulas (1), (2) and (3), and Ti: 0.003 mass% or more, 0.10mass% or less and Nb: 0.003mass% or more, 0.10mass% or less, containing one or two selected from the rest, the balance consisting of iron and inevitable impurities composition and press treatment High strength cold rolled steel sheet with excellent formability. [Formula 2] Note [% Si] /1.5 + [% P] /0.3≧0.5 (1) 100 [% Mn] +150 [% Ni] −200 [% Si] −1000 [% P] ≧ −200 ... (2) [% Cu] ≦ 3 [% Ni]… (3) 3. C: 0.0050 mass% or less, B: 0.0010 mass% or more, 0.0080 mass% or less and Al: 0.005 mass% or more, 0.10 mass% or less, and Si: 0.2 mass% or more, 2.5 mass% or less. , Mn: 1.0mass% or more, 3.5mass% or less, Ni: 0.05mass% or more, 2.0mass% or less, Cu: 0.1mass% or more, 2.0mass% or less and P: 0.040mass% or more, 0.18mass% or less mass Percentage [% Si], [% M]
n), [% Ni], [% Cu] and [% P] represented by the following formulas (1), (2) and (3), and Ti: 0.003 mass% or more, 0.10mass% or less and Nb: 0.003mass% or more, 0.10mass% or less 1 type or 2 types selected from, and the balance is steel slab consisting of iron and unavoidable impurities. Finish rolling in the temperature range of 750 ℃ or more and 1000 ℃ or less, and then carry out cold rolling with a reduction rate of 60% or more and 95% or less after pickling, and then a temperature of 700 ℃ or more and 950 ℃ or less. A method for producing a high-strength cold-rolled steel sheet excellent in chemical conversion treatment property and press formability, which comprises performing recrystallization annealing in a range. [Formula 3] Note [% Si] /1.5 + [% P] /0.3≧0.5 (1) 100 [% Mn] +150 [% Ni] −200 [% Si] −1000 [% P] ≧ −200 ... (2) [% Cu] ≦ 3 [% Ni]… (3) 4. C: 0.0050 mass% or less, Mo: 1.0 mass% or less, B: 0.0010 mass% or more, 0.0080 mass% or less and Al: 0.005 mass% or more, 0.10 mass% or less, and Si: 0.2 masss. % Or more, 2.5 mass% or less, Mn: 1.0 mass% or more, 3.5 mass% or less, Ni: 0.05 mass% or more, 2.0 mass% or less, Cu: 0.1 mass% or more, 2.0 mass% or less and P: 0.040 mass% or more , 0.18 mass% or less in terms of mass%, [% Si], [% M
n), [% Ni], [% Cu] and [% P] represented by the following formulas (1), (2) and (3), and Ti: 0.003 mass% or more, 0.10mass% or less and Nb: 0.003mass% or more, 0.10mass% or less 1 type or 2 types selected from, and the balance is steel slab consisting of iron and unavoidable impurities. Finish rolling in the temperature range of 750 ℃ or more and 1000 ℃ or less, and then carry out cold rolling with a reduction rate of 60% or more and 95% or less after pickling, and then a temperature of 700 ℃ or more and 950 ℃ or less. A method for producing a high-strength cold-rolled steel sheet excellent in chemical conversion treatment property and press formability, which comprises performing recrystallization annealing in a range. [Formula 4] Note [% Si] /1.5 + [% P] /0.3≧0.5 (1) 100 [% Mn] +150 [% Ni] −200 [% Si] −1000 [% P] ≧ −200 ... (2) [% Cu] ≦ 3 [% Ni]… (3)