JP2002030383A - Hot dip galvanized steel sheet excellent in baking hardenability, powdering resistance and press formability and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot dip galvanized steel sheet or a hot dip galvannealed steel sheet having high baking hardenability and also excellent in plating suitability and press formability. SOLUTION: C, Si, Mn, S, P, Al, Nb, Ti, N and B are incorporated into a steel, and the relation among Ti, Nb or B, C and N are set in a prescribed range. This steel is subjected to hot rolling and annealing under prescribed conditions, so that the hot dip galvanized steel sheet and hot dip galvannealed steel sheet having good baking hardenability (>=300 MPa) and (r) value (>=1.3) can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-dip galvanized steel sheet excellent in bake hardenability, powdering resistance and press formability, and a method for producing the same.

[0002]

2. Description of the Related Art In order to reduce the weight of automobiles originating from global environmental problems, it is necessary to increase the strength of steel sheets used in automobiles as much as possible. There is a method that utilizes an increase in strength when a baking process is performed after forming and painting a steel sheet. This type of steel sheet is generally required to have good press forming, and therefore it is necessary to have both good press formability and high bake hardenability.

Furthermore, not only these mechanical properties,
Although plating is required on the surface from the viewpoint of rust prevention, a hot-dip galvanized steel sheet or alloyed hot-dip galvanizing has recently become common. From such a viewpoint, Japanese Patent Application Laid-Open Nos. 59-31827 and 59-38
No. 337 discloses a method for producing a steel sheet having excellent press formability, bake hardenability and plating properties by adding Ti and Nb to ultra-low carbon steel in appropriate amounts according to the amounts of C and N. However, the amount of bake hardening obtained by this method does not exceed the level of a conventional steel sheet, and if measures are taken to increase the amount of bake hardening, non-aging at room temperature cannot be ensured.

Japanese Patent Application Laid-Open Nos. 61-27,928 and 61-276,931 disclose the aforementioned Ti, N
There is disclosed a manufacturing method in which not only b but also the amount of S is appropriately adjusted, and the manufacturing conditions are also appropriately adjusted. However,
In the technique disclosed in Japanese Patent Application Laid-Open No. 61-276,928, the winding temperature in the hot rolling step is 490 ° C. or less, and in the technology disclosed in Japanese Patent Application Laid-Open No. The current equipment employs a production method that reduces productivity, such as setting the annealing temperature of 850 ° C. or higher.

[0005] From the viewpoint of increasing the strength described above, JP-A-59-31827, JP-A-59-38337 and JP-A-57-70258 disclose techniques for adding Si and P. ing. Also, JP-A-6-108
No. 153 discloses a technique of adding Si, Mn, and P. However, elements such as Si, Mn, and P added in these disclosed technologies are elements that impair the adhesion of the plating. There is a high possibility that problems such as insufficient alloying will occur.

[0006] In addition to the characteristics described above, there is a problem of powdering caused by peeling of the plating layer during press molding.
Japanese Patent Application Laid-Open No. 61-27691 discloses a technique using an extremely high alloying treatment temperature to solve this problem. However, there is a concern that the production under these conditions actually impairs productivity significantly. In Japanese Patent Application Laid-Open No. 4-182250, the winding temperature after hot rolling is set to 600 ° C. or less, and the time from the start of heating to the start of hot-dip galvanizing during annealing is set to 30 ° C.
Although the technology for manufacturing in less than a second is disclosed, it is difficult to realize this condition in the current hot-dip galvanizing process, and there is a concern that equipment modification will be required to be able to adopt this condition. There is.

[0007]

As described above, a steel plate having high bake hardening property and powdering resistance capable of hot-dip galvanizing or alloyed hot-dip galvanizing using the techniques disclosed so far. It is difficult to stably produce a high-strength steel sheet on an actual machine under conditions that are easy to produce. The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a galvanized steel sheet having excellent bake hardenability and excellent press formability, and a method for producing the same.

[0008]

Means for Solving the Problems The present inventors have conducted basic studies to solve the above-mentioned problems. as a result,
It has been found that by appropriately adding Ti, Nb, Si, Mn, and Ni, a hot-dip galvanized steel sheet and an alloyed hot-dip galvanized steel sheet having excellent seizure effect and powdering resistance can be manufactured. The present invention is based on this finding, and its gist is as follows.

(1) In mass% (% means mass%), C: 0.0005 to 0.0040%, Si: 0.1 to 1.5%, Mn: 0.05 to 1.5 %, S ≦ 0.02%, P ≦ 0.1%, Al: 0.01 to 0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1-1.0%, B ≦ 0.0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amount of C, N, S, Nb is Ti / 48-S / 32 ≦ 0 0.2 ≦ {(1 + Si / 5) × (C / 12) + N / 14-Nb / 93-B / 11} × 10000
≦ 1 Nb / 93 + B / 11−N / 14 ≧ 0
The amount of i, Mn, Ni satisfies Mn-Si + 1.2 × Ni ≧ 0, the bake hardening amount is 30 MPa or more, and the r value is 1.3 or more, bake hardenability, powdering resistance, Hot-dip galvanized steel sheet with excellent press formability.

(2) C: 0.0005-0.0040%, Si: 0.1-1.5%, Mn: 0.05-1.5%, S ≦ 0.02%, P ≦ 0. 1%, Al: 0.01 to 0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1 to 1.0%, B ≦ 0. 0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amounts of C, N, S, Nb and Ti are Ti / 48−S / 32> 0 0.2 ≦ ｛(1 + Si / 5) × (C / 12) + N / 14 + S / 32-Ti / 48− Nb / 93-B / 1
1｝ × 10000 ≦ 1 Ti / 48 + Nb / 93 + B / 11-N / 14-S / 3
2 ≧ 0 and the amount of Si, Mn and Ni is Mn-Si
+ 1.2 × Ni ≧ 0 and bake hardening amount is 30MPa
As described above, a hot-dip galvanized steel sheet excellent in bake hardenability, powdering resistance, and press formability, having an r value of 1.3 or more.

(3) C: 0.0005-0.0040%, Si: 0.1-1.5%, Mn: 0.05-1.5%, S ≦ 0.02%, P ≦ 0. 1%, Al: 0.01 to 0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1 to 1.0%, B ≦ 0. 0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amount of C, N, S, Nb is Ti / 48-S / 32 ≦ 0 0.2 ≦ {(1 + Si / 5) × (C / 12) + N / 14-Nb / 93-B / 11} × 10000
≦ 1 Nb / 93 + B / 11−N / 14 ≧ 0
The amount of i, Mn, Ni satisfies Mn-Si + 1.2 × Ni ≧ 0, the bake hardening amount is 30 MPa or more, and the r value is 1.3 or more, bake hardenability, powdering resistance, Alloyed hot-dip galvanized steel sheet with excellent press formability.

(4) C: 0.0005 to 0.0040%, Si: 0.1 to 1.5%, Mn: 0.05 to 1.5%, S ≦ 0.02%, P ≦ 0. 1%, Al: 0.01 to 0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1 to 1.0%, B ≦ 0. 0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amounts of C, N, S, Nb and Ti are Ti / 48−S / 32> 0 0.2 ≦ ｛(1 + Si / 5) × (C / 12) + N / 14 + S / 32-Ti / 48− Nb / 93-B / 1
1｝ × 10000 ≦ 1 Ti / 48 + Nb / 93 + B / 11-N / 14-S / 3
2 ≧ 0 and the amount of Si, Mn and Ni is Mn-Si
+ 1.2 × Ni ≧ 0 and bake hardening amount is 30MPa
As described above, an alloyed hot-dip galvanized steel sheet excellent in bake hardenability, powdering resistance, and press formability, having an r value of 1.3 or more.

(5) C: 0.0005-0.0040%, Si: 0.1-1.5%, Mn: 0.05-1.5%, S ≦ 0.02%, P ≦ 0. 1%, Al: 0.01 to 0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1 to 1.0%, B ≦ 0. 0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amount of C, N, S, Nb is Ti / 48-S / 32 ≦ 0 0.2 ≦ {(1 + Si / 5) × (C / 12) + N / 14-Nb / 93-B / 11} × 10000
≦ 1 Nb / 93 + B / 11−N / 14 ≧ 0
The amount of i, Mn, Ni satisfies Mn-Si + 1.2 × Ni ≧ 0, and contains one or more of Cr, Ni, Cu, Sn, V, and As at 0.3% or less, and the bake hardening amount Is 30
A hot-dip galvanized steel sheet excellent in bake hardenability, powdering resistance, and press formability, having an r value of at least 1.3 and an r value of at least 1.3.

(6) C: 0.0005-0.0040%, Si: 0.1-1.5%, Mn: 0.05-1.5%, S ≦ 0.02%, P ≦ 0. 1%, Al: 0.01 to 0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1 to 1.0%, B ≦ 0. 0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amounts of C, N, S, Nb and Ti are Ti / 48−S / 32> 0 0.2 ≦ ｛(1 + Si / 5) × (C / 12) + N / 14 + S / 32-Ti / 48− Nb / 93-B / 1
1｝ × 10000 ≦ 1 Ti / 48 + Nb / 93 + B / 11-N / 14-S / 3
2 ≧ 0 and the amount of Si, Mn and Ni is Mn-Si
+ 1.2 × Ni ≧ 0, and Cr, Ni, Cu,
Baking hardenability, powdering resistance, wherein one or more of Sn, V and As are contained in an amount of 0.3% or less, and a bake hardening amount is 30 MPa or more and an r value is 1.3 or more;
Hot-dip galvanized steel sheet with excellent press formability.

(7) C: 0.0005-0.0040%, Si: 0.1-1.5%, Mn: 0.05-1.5%, S ≦ 0.02%, P ≦ 0. 1%, Al: 0.01 to 0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1 to 1.0%, B ≦ 0. 0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amount of C, N, S, Nb is Ti / 48-S / 32 ≦ 0 0.2 ≦ {(1 + Si / 5) × (C / 12) + N / 14-Nb / 93-B / 11} × 10000
≦ 1 Nb / 93 + B / 11−N / 14 ≧ 0
The amount of i, Mn, Ni satisfies Mn-Si + 1.2 × Ni ≧ 0, and contains one or more of Cr, Ni, Cu, Sn, V, and As at 0.3% or less, and the bake hardening amount Is 30
An alloyed hot-dip galvanized steel sheet excellent in bake hardenability, powdering resistance, and press formability, having an r value of at least 1.3 and an r value of at least 1.3.

(8) C: 0.0005 to 0.0040%, Si: 0.1 to 1.5%, Mn: 0.05 to 1.5%, S ≦ 0.02%, P ≦ 0. 1%, Al: 0.01 to 0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1 to 1.0%, B ≦ 0. 0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amounts of C, N, S, Nb and Ti are Ti / 48−S / 32> 0 0.2 ≦ ｛(1 + Si / 5) × (C / 12) + N / 14 + S / 32-Ti / 48− Nb / 93-B / 1
1｝ × 10000 ≦ 1 Ti / 48 + Nb / 93 + B / 11-N / 14-S / 3
2 ≧ 0 and the amount of Si, Mn and Ni is Mn-Si
+ 1.2 × Ni ≧ 0, and Cr, Ni, Cu,
Baking hardenability, powdering resistance, wherein one or more of Sn, V and As are contained in an amount of 0.3% or less, and a bake hardening amount is 30 MPa or more and an r value is 1.3 or more;
Alloyed hot-dip galvanized steel sheet with excellent press formability.

(9) Finish rolling of the steel having the component described in any one of the above (1), (2), (5) or (6) at a temperature not lower than the Ar ₃ transformation point, After winding at 600 ° C. or more, pickling and cold rolling, annealing is performed for 10 seconds or more in a range of 750 to 900 ° C., and a baking hardening amount characterized by applying galvanizing is 30 MPa or more, A method for producing a hot-dip galvanized steel sheet having an r value of 1.3 or more and excellent in bake hardenability, powdering resistance, and press formability.

(10) The steel having the composition described in any one of (3), (4), (7) and (8) above is subjected to finish rolling at a temperature not lower than the Ar ₃ transformation point, After winding at 600 ° C. or higher, pickling and cold rolling, annealing for 10 seconds or more in the range of 750 to 900 ° C., and performing galvanizing and then alloying the galvanized layer. A method for producing an alloyed hot-dip galvanized steel sheet excellent in bake hardenability, powdering property, and press formability having a characteristic bake hardening amount of 30 MPa or more and an r value of 1.3 or more.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. First, the reasons for limiting the steel composition will be described. C
When present as a solid solution element, it segregates on mobile dislocations during heat treatment after molding and develops bake hardening properties by fixing the mobile dislocations. In this case, the non-aging property cannot be secured, which is not desirable as a steel sheet for press forming. Therefore, the amount of addition is set to 0.0005% or more and 0.004% or less. In order to further exhibit bake hardenability, the amount of addition is desirably 0.0010% or more.

Si is a solid solution strengthening element, and can increase the strength of a steel sheet relatively inexpensively and, as described later, can obtain a high bake hardening amount by adding Ni and Mn in combination. Therefore, the addition amount is 0.1% or more. 0.2% to make this effect more effective
It is desirable to add above. On the other hand, unnecessarily adding causes deterioration of press formability, deterioration of hot-dip galvanizing property and delay of alloying of a coating layer, so that it is set to 1.5% or less.

Mn has a lower limit of 0.0 for the same reason as Si.
The content is set to 5% or more. However, if the addition amount is excessively increased, the moldability is deteriorated.

S is an element inevitably contained, and it is necessary to reduce it as much as possible because it causes deterioration of workability.
Since the problem with workability is solved by setting the content to 0.02% or less, the range is set to 0.02% or less.

P is a solid solution strengthening element and can be used as an element for adjusting the strength of the steel sheet because it can increase the strength of the steel sheet relatively inexpensively. In order to deteriorate workability, the content is set to 0.1% or less.

Although Al is used as a deoxidizing material, it is necessary to contain 0.01% or more in steel in order to exhibit this effect. On the other hand, if the content exceeds 0.1%, an increase in oxide-based inclusions is caused, and there is a concern that the surface properties are deteriorated. Therefore, the upper limit is set to 0.1%.

Nb and Ti are added in order to control the amount of solid solution C which affects bake hardening characteristics. However, if added excessively, it is possible to secure solid solution C for obtaining bake hardening characteristics. In order to increase the recrystallization temperature and decrease the productivity by increasing the recrystallization temperature, the content of Nb is set to 0.08% or less.
Ti is set to 0.2% or less. In order to exert this effect more, it is desirable that Nb is 0.05% or less and Ti is 0.08% or less.

N is an element exhibiting aging like C, but if added excessively, it becomes difficult to ensure non-aging at room temperature, so the upper limit is made 0.0040%.

Ni is a very important element in the present invention. Even in a steel sheet to which an element such as Si or Mn which deteriorates hot-dipability is added, good hot-dip galvanization can be exhibited and powdering resistance can be prevented. It is an element that improves the properties, and it is necessary to add 0.1% or more to exhibit this effect. On the other hand, Ni is an element having a relatively high cost, and increasing the amount of addition results in unnecessarily increasing the price of the product. Therefore, the upper limit is set to 1.0%. Note that, in order to further exhibit the effects of improving the hot-dipability and the powdering resistance as described above, it is desirable that the addition amount be 0.2% or more.

B is added because it has a strong effect of binding to N at high temperatures and can be used to secure non-aging at room temperature when the amount of N increases. However, if added unnecessarily, the moldability deteriorates. 0040%. Further, since B also exerts an effect of improving the secondary workability, the amount of B added is 0.0%.
001% or more is desirable. Further, since this effect is saturated when it exceeds 0.0007%, it is 0.00%.
It is desirable to set it to 07% or less.

In addition to the above components, C, N,
By appropriately adjusting the amounts of S, Nb, Ti, Si, and B,
Baking hardenability can be sufficiently secured, and non-aging property at room temperature can be secured. In order to exhibit such an effect, the amounts of C, N, Nb, Si, and B are expressed by the following formula for a component system satisfying Ti / 48-S / 32 ≦ 0.
(1), Equation (2) 0.2 ≦ {(1 + Si / 5) × (C / 12) + N / 14−Nb / 93−B / 11} × 10000 ≦ 1 Equation (1) Nb / 93 + B / 11−N / 14 ≧ 0 It is necessary to satisfy Expression (2), and Ti / 48−S / 32>
For the component system satisfying 0, the following equations (1) 'and (2)' 0.2 ≦ {(1 + Si / 5) × (C / 12) + N / 14 + S / 32-Ti / 48-Nb / 93−B / 11｝ × 10000 ≦ 1 Expression (1) ′ Ti / 48 + Nb / 93 + B / 11-N / 14-S / 32 ≧ 0 Expression (2) ′ must be satisfied.

The plating wettability, plating adhesion, alloying speed, and the like during hot-dip galvanizing are, as described above, Si and Ni.
Is known to have an adverse effect, but these can be improved by controlling the amounts of Si, Mn, and Ni in the range of Mn-Si + 1.2 × Ni ≧ 0 (3). The reason for this is not clear at present, but it is presumed that the properties of the steel sheet surface before plating are subtly changed by controlling the components within the above-described range. The reason why this subtle difference has not been clarified is that measurement is difficult with current analysis equipment.

The addition of Cr, Sn, and Cu in combination with Mn and Ni changes the surface properties of the steel sheet, and has the effect of improving the galvanic adhesion and alloying behavior of hot-dip galvanizing. However, since a large amount of addition may cause surface flaws, one or more of these may be added in a total amount of 0.3%.
% Or less. Other components are not particularly limited, but the presence of elements mixed from scrap such as V, W, Zr, Mo, As, etc. has no effect on the properties of the steel of the present invention.

Next, the manufacturing conditions will be described. The steel having the composition described above is cast, and the obtained hot slab is directly or heated, or the cold slab is reheated to perform hot rolling. At that time, almost no change in the characteristics between the direct rolling of the hot slab and the rolling after reheating is observed. The reheating temperature is not particularly limited, but is preferably in the range of 1000 ° C. to 1300 ° C. in consideration of productivity.

The hot rolling is performed in a normal hot rolling process or finishing.
In the continuous hot rolling process of joining and rolling slabs in rolling
Either is possible. The rolling end temperature during hot rolling is
Ar _ThreeAbove the transformation point. This is Ar_ThreeBelow the transformation point
When finish rolling is performed at a temperature, texture develops in the hot-rolled steel sheet.
Crystal orientation, which deteriorates deep drawability after cold rolling and annealing
To develop. The upper limit of the rolling end temperature is not particularly limited.
It should not be higher than 1000 ° C from the viewpoint of productivity.
Is desirable. The finish rolling temperature is set to such a temperature.
Thus, an r value of 1.3 or more can be secured.

Cooling after hot rolling is performed by a usual method.
The winding temperature at that time is set to 600 ° C. or higher. This is because baking hardenability is slightly reduced when winding is performed at a temperature lower than this temperature.

With the above components and hot rolling conditions, a bake hardening amount (BH) of 30 Mpa or more can be secured.
After hot rolling and winding, pickling and cold rolling are performed by a usual method, and thereafter, a hot-dip galvanized steel sheet or an alloyed hot-dip galvanized steel sheet is formed in a hot-dip galvanizing step. On this occasion,
Pickling is not particularly limited since it does not affect the properties of the steel sheet regardless of the method used. The conditions for the cold rolling are not particularly limited, but from the viewpoint of obtaining good press formability, it is desirable to perform the rolling in a range of 50% to 90%.

The hot-dip galvanizing step is also performed by a usual method, but the annealing temperature at that time is set to 750 ° C. or higher in order to recrystallize the steel sheet and secure good press formability. Also,
If the annealing is performed at a temperature exceeding 900 ° C., the press formability deteriorates. If this annealing time is short, good press formability cannot be ensured, so the annealing time is 1
0 seconds or more. The conditions after this annealing are not particularly limited, but in order to secure baking hardenability, press formability, plating properties, productivity, and the like, the temperature is cooled to 500 ° C. or less at a cooling rate of 3 ° C./s or more, and 400 to 600 It is desirable that a steel sheet be penetrated into a hot-dip galvanizing bath at a temperature of 0 ° C. to form a zinc layer on the surface layer. When an alloyed hot-dip galvanized steel sheet is manufactured, it is desirable to perform alloying treatment in the range of 430 to 650 ° C. in addition to these conditions.

[0037]

Embodiments of the present invention will be described below. Steels of various chemical compositions shown in Table 1 were cast,
After reheating to a temperature of 50 ° C., hot rolling, pickling, cold rolling (60
〜90%), annealing, plating (with and without alloying), and then 1% temper rolling. Table 2 shows the conditions related to the present invention among these conditions. JIS Z22 as a material survey of these steel sheets
No. 01 and No. 5 test pieces were processed and subjected to a tensile test according to the test method described in No. 2241. In addition, the bake hardenability was evaluated by the amount of increase in yield point stress before and after heat treatment when holding at 170 ° C. for 20 minutes after applying a 2% prestrain. The aging property was evaluated by the yield point elongation after holding at 100 ° C. for 1 hour.

Regarding the plating property, the degree of non-plating was judged from the appearance by 、, ×, and Δ.
Indicates no plating, × indicates that plating is clearly observed, △
Indicates that slight plating was observed, and only ○ could be used as a product. In addition, the product evaluated as "O" in this external appearance inspection had no problem in plating adhesion at all.

The powdering resistance was evaluated based on the peeling width of the plating layer adhered to the tape after 180 ° bending and after adhesion and peeling of the cellophane tape at the bent portion, and the width was 5 mm or less. Those that passed were judged as rejected.

Steel types 1 to 9 and 13 to 17 are component-based steels within the scope of the present invention, and all produced under the production conditions within the scope of the present invention have high bake hardenability, non-aging property at room temperature, and good powdering resistance. It satisfies the target characteristics such as good plating property. Regarding steel type 1, results of those manufactured with a hot rolling finish temperature of Ar ₃ or less, those manufactured with a winding temperature of less than 600 ° C., those with an annealing temperature of less than 750 ° C., and those manufactured with a short annealing time were used. Are shown, respectively,
Undesirable characteristics such as low r-value indicating press formability, low bake hardening amount and low r-value are obtained. For steel types 10 to 12, 18, and 19, baking hardenability, powdering resistance, or plating property cannot be ensured because the components indicated by underlines in Table 1 or indices obtained from the components are out of the range of the present invention.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

As described above, according to the present invention, a hot-dip galvanized steel sheet or an alloyed hot-dip galvanized steel sheet having high bake hardenability and excellent plating properties and press formability can be manufactured.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K037 EA01 EA02 EA04 EA11 EA13 EA15 EA18 EA19 EA20 EA23 EA25 EA27 EA28 EA31 EB01 EB02 EB06 EB08 EB09 FA02 FA03 FC04 FC07 FE02 FE03 FF05 FJ05 FJ GA

Claims (10)

[Claims] 1. Mass%, C: 0.0005 to 0.0040%, Si: 0.1 to 1.5%, Mn: 0.05 to 1.5%, S ≦ 0.02%, P ≦ 0.1%, Al: 0.01-0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1-1.0%, B ≦ 0.0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amount of C, N, S, Nb is Ti / 48-S / 32 ≦ 0 0.2 ≦ {(1 + Si / 5) × (C / 12) + N / 14-Nb / 93-B / 11} × 10000
≦ 1 Nb / 93 + B / 11−N / 14 ≧ 0
The amount of i, Mn, Ni satisfies Mn-Si + 1.2 × Ni ≧ 0, the bake hardening amount is 30 MPa or more, and the r value is 1.3 or more, bake hardenability, powdering resistance, Hot-dip galvanized steel sheet with excellent press formability. 2. Mass%, C: 0.0005 to 0.0040%, Si: 0.1 to 1.5%, Mn: 0.05 to 1.5%, S ≦ 0.02%, P ≦ 0.1%, Al: 0.01-0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1-1.0%, B ≦ 0.0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amounts of C, N, S, Nb and Ti are Ti / 48−S / 32> 0 0.2 ≦ ｛(1 + Si / 5) × (C / 12) + N / 14 + S / 32-Ti / 48− Nb / 93-B / 1
1｝ × 10000 ≦ 1 Ti / 48 + Nb / 93 + B / 11-N / 14-S / 3
2 ≧ 0 and the amount of Si, Mn and Ni is Mn-Si
+ 1.2 × Ni ≧ 0 and bake hardening amount is 30MPa
As described above, a hot-dip galvanized steel sheet excellent in bake hardenability, powdering resistance, and press formability, having an r value of 1.3 or more. 3. Mass%, C: 0.0005 to 0.0040%, Si: 0.1 to 1.5%, Mn: 0.05 to 1.5%, S ≦ 0.02%, P ≦ 0.1%, Al: 0.01-0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1-1.0%, B ≦ 0.0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amount of C, N, S, Nb is Ti / 48-S / 32 ≦ 0 0.2 ≦ {(1 + Si / 5) × (C / 12) + N / 14-Nb / 93-B / 11} × 10000
≦ 1 Nb / 93 + B / 11−N / 14 ≧ 0
The amount of i, Mn, Ni satisfies Mn-Si + 1.2 × Ni ≧ 0, the bake hardening amount is 30 MPa or more, and the r value is 1.3 or more, bake hardenability, powdering resistance, Alloyed hot-dip galvanized steel sheet with excellent press formability. 4. Mass%, C: 0.0005 to 0.0040%, Si: 0.1 to 1.5%, Mn: 0.05 to 1.5%, S ≦ 0.02%, P ≦ 0.1%, Al: 0.01-0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1-1.0%, B ≦ 0.0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amounts of C, N, S, Nb and Ti are Ti / 48−S / 32> 0 0.2 ≦ ｛(1 + Si / 5) × (C / 12) + N / 14 + S / 32-Ti / 48− Nb / 93-B / 1
1｝ × 10000 ≦ 1 Ti / 48 + Nb / 93 + B / 11-N / 14-S / 3
2 ≧ 0 and the amount of Si, Mn and Ni is Mn-Si
+ 1.2 × Ni ≧ 0 and bake hardening amount is 30MPa
As described above, an alloyed hot-dip galvanized steel sheet excellent in bake hardenability, powdering resistance, and press formability, having an r value of 1.3 or more. 5. Mass%, C: 0.0005 to 0.0040%, Si: 0.1 to 1.5%, Mn: 0.05 to 1.5%, S ≦ 0.02%, P ≦ 0.1%, Al: 0.01-0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1-1.0%, B ≦ 0.0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amount of C, N, S, Nb is Ti / 48-S / 32 ≦ 0 0.2 ≦ {(1 + Si / 5) × (C / 12) + N / 14-Nb / 93-B / 11} × 10000
≦ 1 Nb / 93 + B / 11−N / 14 ≧ 0
The amount of i, Mn, Ni satisfies Mn-Si + 1.2 × Ni ≧ 0, and contains one or more of Cr, Ni, Cu, Sn, V, and As at 0.3% or less, and the bake hardening amount Is 30
A hot-dip galvanized steel sheet excellent in bake hardenability, powdering resistance, and press formability, having an r value of at least 1.3 and an r value of at least 1.3. 6. Mass%, C: 0.0005 to 0.0040%, Si: 0.1 to 1.5%, Mn: 0.05 to 1.5%, S ≦ 0.02%, P ≦ 0.1%, Al: 0.01-0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1-1.0%, B ≦ 0.0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amounts of C, N, S, Nb and Ti are Ti / 48−S / 32> 0 0.2 ≦ ｛(1 + Si / 5) × (C / 12) + N / 14 + S / 32-Ti / 48− Nb / 93-B / 1
1｝ × 10000 ≦ 1 Ti / 48 + Nb / 93 + B / 11-N / 14-S / 3
2 ≧ 0 and the amount of Si, Mn and Ni is Mn-Si
+ 1.2 × Ni ≧ 0, and Cr, Ni, Cu,
Baking hardenability, powdering resistance, wherein one or more of Sn, V and As are contained in an amount of 0.3% or less, and a bake hardening amount is 30 MPa or more and an r value is 1.3 or more;
Hot-dip galvanized steel sheet with excellent press formability. 7. In mass%, C: 0.0005 to 0.0040%, Si: 0.1 to 1.5%, Mn: 0.05 to 1.5%, S ≦ 0.02%, P ≦ 0.1%, Al: 0.01-0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1-1.0%, B ≦ 0.0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amount of C, N, S, Nb is Ti / 48-S / 32 ≦ 0 0.2 ≦ {(1 + Si / 5) × (C / 12) + N / 14-Nb / 93-B / 11} × 10000
≦ 1 Nb / 93 + B / 11−N / 14 ≧ 0
The amount of i, Mn, Ni satisfies Mn-Si + 1.2 × Ni ≧ 0, and contains one or more of Cr, Ni, Cu, Sn, V, and As at 0.3% or less, and the bake hardening amount Is 30
An alloyed hot-dip galvanized steel sheet excellent in bake hardenability, powdering resistance, and press formability, having an r value of at least 1.3 and an r value of at least 1.3. 8. In mass%, C: 0.0005 to 0.0040%, Si: 0.1 to 1.5%, Mn: 0.05 to 1.5%, S ≦ 0.02%, P ≦ 0.1%, Al: 0.01-0.1%, Ti ≦ 0.2%, Nb ≦ 0.08%, N ≦ 0.0040%, Ni: 0.1-1.0%, B ≦ 0.0040%, and one or more of Cr, Sn, and Cu in a total amount of 0.3
% Or less, with the balance being Fe and unavoidable impurities,
And the amounts of C, N, S, Nb and Ti are Ti / 48−S / 32> 0 0.2 ≦ ｛(1 + Si / 5) × (C / 12) + N / 14 + S / 32-Ti / 48− Nb / 93-B / 1
1｝ × 10000 ≦ 1 Ti / 48 + Nb / 93 + B / 11-N / 14-S / 3
2 ≧ 0 and the amount of Si, Mn and Ni is Mn-Si
+ 1.2 × Ni ≧ 0, and Cr, Ni, Cu,
Baking hardenability, powdering resistance, wherein one or more of Sn, V and As are contained in an amount of 0.3% or less, and a bake hardening amount is 30 MPa or more and an r value is 1.3 or more;
Alloyed hot-dip galvanized steel sheet with excellent press formability. 9. The finish rolling of a steel having the composition described in any one of claims 1, 2, 5, and 6 is completed at a temperature equal to or higher than the Ar ₃ transformation point, and the steel is wound at 600 ° C. or higher. After washing and cold rolling, 1
Melting with baking hardening amount of 30 MPa or more and r value of 1.3 or more, excellent in baking hardenability, powdering resistance, and press formability, characterized by performing annealing for 0 second or more and applying galvanizing. Manufacturing method of galvanized steel sheet. 10. The steel having the composition according to any one of claims 3, 4, 7, and 8 is finish-rolled at a temperature not lower than the Ar ₃ transformation point, wound up at 600 ° C. or more, and then acidified. After washing and cold rolling, 1
Baking hardening amount of 30 MPa or more and r value of 1.3 or more, characterized by performing annealing for 0 second or more and alloying the galvanized layer after applying hot-dip galvanizing;
A method for producing an alloyed hot-dip galvanized steel sheet having excellent powdering properties and press formability.