JP2007314858A - Hot dip galvannealed steel sheet and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot dip galvannealed steel sheet having improved interface adhesive strength while having formability, and to provide a method for producing a hot dip galvannealed steel sheet providing improved productivity. <P>SOLUTION: The hot dip galvannealed steel sheet is obtained by providing the surface of a steel sheet base material with a hot dip galvannealing layer. The steel sheet base material has a chemical composition comprising, by mass, ≤0.25% C, 0.030 to 0.15% Si, 0.030 to 3.0% Mn, ≤0.050% P, ≤0.010% S, ≤0.0060% N and 0.10 to 0.80% sol.Al, and the balance Fe with inevitable impurities. The hot dip galvannealing layer comprises 8.0 to 15% Fe and 0.080 to 0.50% Al, and is further free from a η phase, and, in the interfacial debonding part between the hot dip galvannealing layer and the base material, the ratio of area interfacial debonding in the grain unit on the base material side in the steel sheet is ≥5.0%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an alloyed hot-dip galvanized steel sheet and a method for producing the same. More specifically, the present invention relates to an alloyed hot-dip galvanized steel sheet and a method for producing the same, mainly used in the fields of home appliances, building materials, automobiles, and the like.

  In recent years, hot-dip galvanized steel sheets have been used in large quantities in fields such as home appliances, building materials, and automobiles.In particular, alloyed hot-dip galvanized steel sheets that are excellent in terms of economy, rust prevention function, performance after painting, etc. Widely used.

This alloyed hot-dip galvanized steel sheet is usually produced as follows. The steel sheet is heated in a preheating furnace before hot dipping, annealed in a reducing atmosphere of H ₂ + N ₂ with a dew point adjusted to −20 ° C. or lower, then cooled to around the plating bath temperature, and hot dip galvanized. And the Fe-Zn alloy plating layer is formed by heating the steel plate which gave this hot dip galvanization over 30 seconds on the conditions which a steel plate temperature will be 480-600 degreeC in a heat treatment furnace.

  When pressing an alloyed hot-dip galvanized steel sheet (hereinafter sometimes simply referred to as “steel sheet”), if the plating surface layer is provided with a soft alloy layer (ζ phase) having a relatively low Fe content, Peeling (hereinafter referred to as “flaking”), press cracking of the steel sheet, and the like may occur due to an adhesion phenomenon between the plating surface layer and the mold surface. On the other hand, when the Fe content in the plating layer is high, a hard Γ, Γ1, δ1c phase is formed in the vicinity of the interface between the steel plate and the plating layer. Powdering (hereinafter referred to as “powdering”) tends to occur. When powdering occurs, a peeling piece adheres to the mold and a pushing-in flaw occurs.

  On the other hand, in Non-Patent Document 1, as a problem when applying the galvannealed steel sheet to an automobile body, the galvannealed steel sheet is inferior in chipping resistance compared to other galvanized steel sheets. It has been. This is because the hard Fe-Zn intermetallic compound layer is formed thick at the interface between the plated layer and the base material of the alloyed hot-dip galvanized steel sheet, so compared to other plating types, the plating layer-base material interface This is probably due to the low interfacial adhesion strength.

In order to solve such problems, various proposals have been made so far regarding alloyed hot-dip galvanized steel sheets. For example, Patent Document 1 proposes an galvannealed steel sheet excellent in powdering resistance and flaking resistance having a plating layer having a basis weight of 45 to 90 g / m ² on at least one surface. In the steel sheet disclosed in Patent Document 1, the Fe content in the plating layer is controlled to 8 to 12%, and the Al content is controlled to 0.05 to 0.25%. The Γ phase at the interface between the base material and the plating layer is 1.0 μm or less.

  Moreover, in patent document 2, in the manufacturing method of the alloying hot-dip galvanized steel plate which performs an alloying process so that Fe content in a film | membrane may be 8-12%, the amount of Al in a galvanizing bath is 0.13. In addition to controlling the intrusion temperature of the steel sheet as the base metal and the amount of Al in the bath, plating is performed, and the plate temperature on the high-frequency induction heating furnace exit side is managed within an appropriate range after plating. A method for producing an galvannealed steel sheet excellent in press formability and powdering resistance, which is cooled after holding, is disclosed.

  Further, in Patent Document 3, the chemical composition of the base material is C: 0.01% or less, Si: 0.03-0.3%, Mn: 0.05-2%, P: 0.017-0. 15%, Al: 0.005 to 0.1%, Ti: 0.005 to 0.1%, Nb: 0.1% or less, B: 0.005% or less, and the mother in contact with the plating layer An alloyed hot-dip galvanized steel sheet characterized by having an average crystal grain size of 12 μm or less on the surface of the material and a method for producing the same have been proposed.

  In Patent Document 4, the chemical composition of a steel sheet as a base material is, in mass%, C: 0.05% to 0.20%, Si: 0.02% to 0.70%, Mn: 0.00. 50% or more and 3.0% or less, P: 0.005% or more and 0.10% or less, S: 0.1% or less, sol. Al: 0.10% or more and 2.0% or less, N: 0.01% or less, and satisfying Si (%) + Al (%) ≧ 0.5, and the balance is made of Fe and impurities, and the base material Contains 1% or more of austenite phase by volume%, and the plating film has an Fe concentration of 8% by mass or more and 15% by mass or less, and an average thickness of Γ phase in the plating film: 2 μm or less, maximum in the thickness direction. An galvannealed steel sheet that satisfies the relationship of Γ1 phase length: 1.5 μm or less and satisfies the relationship of maximum Γ1 phase length / Γ phase thickness ≦ 1.0 has been proposed. Furthermore, in Patent Document 4, the steel sheet is subjected to reduction annealing at 750 ° C. or more and 870 ° C. or less, and then retained at a temperature of 350 ° C. or more and 550 ° C. or less for 20 s or more, and then hot dip galvanized, A method for producing an alloyed hot-dip galvanized steel sheet in which alloying treatment is performed at the alloying temperature and residence time is disclosed. In the invention concerning patent document 4, the local ductility and high intensity | strength which were excellent in the said steel plate are provided by leaving the austenite ((gamma)) phase 1 volume% or more in the steel plate used as a base material. The amount of Fe in the film is regulated to 8 to 15% by mass, the average thickness of the Γ phase in the plating layer is 2 μm or less, the maximum Γ1 phase length in the thickness direction is 1.5 μm or less, and the maximum Γ1 phase length By defining the ratio of the Γ phase thickness to 1 or less, the powdering resistance is improved.

  Patent Document 5 includes mass%, C: 0.05% to 0.20%, Si: 0.01% to 1.50%, Mn: 0.5% to 3.0%, P : 0.05% or less, S: 0.01% or less, Al: 0.01% or more and 2.0% or less, N: 0.01% or less, and Si (%) + Al (%) ≧ 0.5 A steel plate that has a chemical composition composed of the remaining impurities and Fe, contains an austenite phase at 1% or more by volume, and satisfies tensile strength Ts (MPa) × elongation El (%) ≧ 20000, After annealing the steel plate at 780 ° C. or higher and 870 ° C. or lower in advance, the temperature range from 700 ° C. to 550 ° C. is further cooled at an average cooling rate of 30 ° C./s or higher, and then 350 ° C. or higher and 550 ° C. or lower. Stay in the temperature range for 20s or more and cool to room temperature. One or two or more of Ni, Fe, Cu and Co are attached to the base material, and again reduced and retained at 780 ° C. or higher and 870 ° C. or lower for 5 seconds or longer and 500 seconds or shorter. Alloying hot dip galvanizing, characterized in that after cooling from temperature to near the plating bath temperature, plating is performed, alloying is performed at 520 ° C. or less, and a film having a Fe concentration of 7% or more and 15% or less is formed. A method for manufacturing a steel sheet is disclosed. In the invention according to Patent Document 5, an austenite (γ) phase is contained in a steel sheet as a base material in an amount of 1% or more by volume, whereby the tensile strength Ts (MPa) × elongation El (%) is given to the steel sheet as a base material. High strength and high ductility satisfying ≧ 20000 are imparted. And, the amount of Al in the film is defined as 0.20% or more and 0.40% or less, the amount of Fe is defined as 8% or more and 15% or less, and the amount of Ni, Cu, Co after the first annealing is increased, By promoting alloying, the powdering resistance and flaking resistance are improved.

  In Patent Document 6, as an alloyed hot-dip galvanized steel sheet excellent in workability and plating adhesion, etc., in mass%, C: 0.0001 to 0.004%, Si: 0.001 to 0.1%, Mn: 0.01 to 0.5%, P: 0.001 to 0.015%, S: 0.015% or less, Al: 0.1 to 0.5%, Ti: 0.002 to 0.1 %, N: 0.0005 to 0.004%, and if necessary, Nb: 0.002 to 0.1%, and B: 0.0002 to 0% by mass. An alloyed hot-dip galvanized steel sheet containing 0.003% is disclosed, and further alloying of Al: 0.05 to 0.5%, Fe: 7 to 15%, the balance being Zn and inevitable impurities It is described that a hot-dip galvanized layer is formed.

Patent Document 7 discloses an alloyed hot-dip galvanized steel sheet provided with an alloyed hot-dip galvanized layer on the surface of the steel sheet, wherein the steel sheet is in mass%, C: 0.05 to 0.25%, Si: 0.02. -0.20%, Mn: 0.5-3.0%, S: 0.01% or less, P: 0.035% or less, and sol. Al: 0.01 to 0.5% is contained, the remainder has a chemical composition composed of Fe and impurities, and the alloyed galvanized layer is in mass%, Fe: 10 to 15% and Al: 0.00. A high-strength alloy containing 20 to 0.45%, the balance having a chemical composition consisting of Zn and impurities, and having an interface adhesion strength between the steel sheet and the galvannealed layer of 20 MPa or more A galvannealed steel sheet is disclosed.
JP-A 64-68456 JP-A-4-276053 JP-A-10-81948 JP 2002-30403 A JP 2002-47535 A JP 2003-96540 A JP 2006-97102 A Journal of Japan Adhesion Association, Vol. 25, no. 8, p. 306 (1989)

  By the way, recently, as a joining technique of steel materials when manufacturing an automobile body, a part to which joining by an adhesive (hereinafter referred to as “adhesion”) is applied instead of welding is increasing. However, when an alloyed hot-dip galvanized steel sheet is applied to an adhesive structure member, the adhesive strength is lower than other plated steel sheets. Specifically, cohesive failure of the adhesive itself occurs in other plated steel sheets, whereas in an alloyed hot dip galvanized steel sheet, peeling at the plating layer-steel base material interface is likely to occur. The reason for this is that, as described above, the interfacial adhesion strength at the plating layer-steel base material interface of the alloyed hot-dip galvanized steel sheet (hereinafter simply referred to as “interfacial adhesion strength” is the adhesion strength at the plating layer-steel base material interface). This means that peeling occurs at the interface. Also in improving chipping resistance and powdering resistance, it is effective to increase the interfacial adhesion strength, and higher interfacial adhesion strength is required when it is suitable as an adhesive structure material.

  Here, the alloyed hot-dip galvanized steel sheet described in Patent Document 1 and the alloyed hot-dip galvanized steel sheet obtained by the method for producing an alloyed hot-dip galvanized steel sheet described in Patent Document 2 are as follows. It defines the alloy phase. However, the alloy phase in the plated layer has little influence on the improvement of the interfacial adhesion strength of the alloyed hot-dip galvanized steel sheet, although it affects the anti-flaking property and the powdering property. Therefore, the technique described in Patent Document 1 or Patent Document 2 has a problem that it is difficult to obtain an alloyed hot-dip galvanized steel sheet having high interface adhesion strength.

  Patent Document 3 describes that 0.03 to 0.3% of Si is added to the steel plate base material as a means for improving the chipping resistance of the galvannealed steel plate. Inclusion of Si in the steel plate base material is effective in improving the interfacial adhesion strength, but if the Si content of the steel plate base material is increased, the alloying speed may be reduced and the productivity may be reduced. Further, Si is an element that generally increases the strength of a steel sheet while decreasing elongation and reducing formability. Therefore, when formability is required for a steel plate, it is not possible to contain a large amount of Si in the steel plate base material in the first place. Even with the technique described in Patent Document 3, alloying and melting having high interfacial adhesion strength. There was a problem that it was difficult to obtain a galvanized steel sheet.

  In addition, the alloyed hot-dip galvanized steel sheet proposed in Patent Document 4 or Patent Document 5 is a steel type that has a relatively high Si content and P content in the steel sheet base metal, and has a complicated reduction due to its production. It is necessary to perform heat treatment with an annealing heat pattern. Furthermore, in order to obtain the galvannealed steel sheet proposed in Patent Document 4 or Patent Document 5, a long alloying time is required. Therefore, the technique described in Patent Document 4 or Patent Document 5 has a problem that the productivity of the galvannealed steel sheet is likely to decrease.

  Further, in Patent Document 6, by increasing the Al content of the steel plate base material, it is possible to slow the alloying speed without substantially increasing the strength of the steel plate and satisfy the workability and plating adhesion of the steel plate. It can be done. However, the adhesion referred to in Patent Document 6 means powdering resistance in view of the description in the prior art column and the evaluation method of the example (V-shaped bending of a steel plate) and the like. However, there is no description about the intended interfacial adhesion strength. Therefore, the technique described in Patent Document 6 has a problem that it is difficult to obtain an galvannealed steel sheet having high interfacial adhesion strength.

  Moreover, in patent document 7, since there was much C content of a steel plate base material, there existed a problem that it was inferior to workability. Moreover, although the upper limit of Si content of the steel plate base material is set to 0.20%, there is a problem that the alloying speed is slow when the Si content of the steel plate base material is high.

  Therefore, the present invention provides an alloyed hot-dip galvanized steel sheet capable of improving interfacial adhesion strength while having formability, and a method for producing an alloyed hot-dip galvanized steel sheet capable of improving productivity. The task is to do.

  As a result of diligent research, the present inventors have found that it is effective to contain a small amount of Si in a steel plate base material and to contain Al in a composite manner in order to improve interfacial adhesion strength while providing formability. I found it. Furthermore, it discovered that the thing with high interface adhesive strength had the characteristic in the peeling form at the time of making it peel at the interface of a plating layer-steel plate base material compulsorily. In addition, it discovered that the steel plate provided with the said peeling form can be manufactured, maintaining productivity, by devising the composition and manufacturing process of a steel plate base material. The present invention has been made based on such new findings.

  The present invention will be described below.

  A first aspect of the present invention is an alloyed hot-dip galvanized steel sheet provided with an alloyed hot-dip galvanized layer on the surface of a steel sheet base material, the steel sheet base material being in mass%, C: 0.25% or less, Si: 0.030% or more and 0.15% or less, Mn: 0.030% or more and 3.0% or less, P: 0.050% or less, S: 0.010% or less, N: 0.0060% or less, And sol. Al: 0.10% or more and 0.80% or less, with the balance being a chemical composition consisting of Fe and inevitable impurities, in the alloyed hot-dip galvanized layer, by mass, Fe: 8.0% or more and 15% or less And Al: 0.080% or more and 0.50% or less, and there is no η phase in the alloyed hot-dip galvanized layer, and the interface between the alloyed hot-dip galvanized layer and the steel plate base material It is an alloyed hot-dip galvanized steel sheet characterized by having a grain size peeled area ratio on the steel sheet base metal side in the peeling part of 5% or more.

  Here, “sol.Al: 0.10% or more and 0.80% or less” means that 0.10% by mass or more and 0.80% by mass or less of Al in a solid solution state is included in the steel plate base material. means. Furthermore, “the alloyed hot-dip galvanized layer contains Fe: 8.0% to 15% and Al: 0.080% to 0.50% by mass%, and the η phase is “Not present” means that the alloyed hot-dip galvanized layer (hereinafter sometimes simply referred to as “plated layer”) contains 8.0% by mass to 15% by mass of Fe and 0.080% by mass to 0.50%. This means that not more than mass% Al is provided, and that the η phase does not exist in the plating layer. In addition, “grain size peeled area ratio” means “the crystal grain size unit provided in the steel plate base material after peeling when these are forcibly separated at the interface between the plating layer and the steel plate base material”. The ratio of the part peeled off with the size of the entire observation field ”. The same applies to the following.

  A second aspect of the present invention is an alloyed hot-dip galvanized steel sheet provided with an alloyed hot-dip galvanized layer on the surface of the steel sheet base material, the steel sheet base material being in mass%, C: 0.010% or less, Si: 0.030% to 0.15%, Mn: 0.030% to 1.5%, P: 0.050% or less, S: 0.010% or less, N: 0.0060% or less, And sol. Al: 0.10% or more and 0.80% or less, with the balance being a chemical composition consisting of Fe and inevitable impurities, in the alloyed hot-dip galvanized layer, by mass, Fe: 8.0% or more and 15% or less And Al: 0.080% or more and 0.50% or less, and the η phase does not exist, and the steel plate base side at the interface peeling portion between the alloyed hot-dip galvanized layer and the steel plate base material This is an alloyed hot-dip galvanized steel sheet characterized by having a particle size peeled area ratio of 5% or more.

  In the first aspect of the present invention or the second aspect of the present invention, instead of a part of Fe contained in the steel plate base material, by mass%, Ti: 0.0040% or more and 0.50% or less, and It is preferable that the additive elements of Nb: 0.0040% or more and 0.50% or less and B: 0.0050% or less are contained.

  The third aspect of the present invention is, in mass%, C: 0.25% or less, Si: 0.030% to 0.15%, Mn: 0.030% to 3.0%, P: 0 .050% or less, S: 0.010% or less, N: 0.0060% or less, and sol. Al: 0.10% or more and 0.80% or less, a slab having a chemical composition composed of Fe and unavoidable impurities in the balance, hot rolled into a steel sheet, and after the hot rolling process A winding step for winding the steel plate at a temperature of 600 ° C. or less, a pickling step for pickling the steel plate after the winding step, a cold rolling step for cold rolling the steel plate after the pickling step, and the cold After the rolling process, the steel sheet is immersed in a hot dip galvanizing bath containing 0.080% or more and 0.14% or less Al in mass% after the reduction annealing process in which the steel sheet is annealed in a reducing atmosphere. An immersion step, an adhesion amount control step for controlling the zinc adhesion amount on the steel sheet surface after the immersion step, and an alloying treatment step for alloying the steel plate at a temperature of 530 ° C. or less after the adhesion amount control step, In the alloying process, in mass%, Fe An alloyed hot-dip galvanized layer containing 8.0% to 15% and Al: 0.080% to 0.50% and having no remaining η phase is formed. This is a method for producing an alloyed hot-dip galvanized steel sheet.

  The fourth aspect of the present invention is, in mass%, C: 0.010% or less, Si: 0.030% to 0.15%, Mn: 0.030% to 1.5%, P: 0 .050% or less, S: 0.010% or less, N: 0.0060% or less, and sol. Al: 0.10% or more and 0.80% or less, a slab having a chemical composition composed of Fe and unavoidable impurities in the balance, hot rolled into a steel sheet, and after the hot rolling process A winding step for winding the steel plate at a temperature of 600 ° C. or less, a pickling step for pickling the steel plate after the winding step, a cold rolling step for cold rolling the steel plate after the pickling step, and the cold After the rolling process, the steel sheet is immersed in a hot dip galvanizing bath containing 0.080% or more and 0.14% or less Al in mass% after the reduction annealing process in which the steel sheet is annealed in a reducing atmosphere. An immersion step, an adhesion amount control step for controlling the zinc adhesion amount on the steel sheet surface after the immersion step, and an alloying treatment step for alloying the steel plate at a temperature of 530 ° C. or less after the adhesion amount control step, In the alloying process, in mass%, Fe An alloyed hot-dip galvanized layer containing 8.0% to 15% and Al: 0.080% to 0.50% and having no remaining η phase is formed. This is a method for producing an alloyed hot-dip galvanized steel sheet.

  In the third aspect of the present invention or the fourth aspect of the present invention, instead of a part of Fe contained in the slab, by mass%, Ti: 0.0040% or more and 0.50% or less, and / or Nb: 0.0040% or more and 0.50% or less and B: 0.0050% or less are preferably contained.

  According to the first aspect of the present invention or the second aspect of the present invention, alloyed hot dip galvanizing is provided that has formability and can improve the interfacial adhesion strength between the plating layer and the steel plate base material. Steel sheet can be provided. An alloyed hot-dip galvanized steel sheet that exhibits such an effect is suitable for the automobile field and the home appliance field.

  According to the third aspect of the present invention or the fourth aspect of the present invention, production of an alloyed hot-dip galvanized steel sheet that has formability and can improve the interfacial adhesion strength between the plating layer and the steel sheet base material. The manufacturing method of the galvannealed steel plate which can improve property can be provided.

  Embodiments of the present invention will be described below.

1. Alloyed hot-dip galvanized steel sheet The alloyed hot-dip galvanized steel sheet of the present invention will be described in detail. Hereinafter, “%” means “% by mass” unless otherwise specified. Further, the galvannealed steel sheet of the present invention is simply referred to as “steel sheet”, and the steel sheet base material provided with a plating layer on the surface is referred to as “base material”.

1.1. Base material (1) C: 0.25% or less Since the steel sheet of the present invention is intended for applications in which formability is important, C is an impurity in the present invention, and its content is preferably as small as possible. When a large amount of C is contained in the base material, the workability of the steel sheet is lowered. Therefore, the C content is 0.25% or less. Preferably, it is 0.010% or less.

(2) Si: 0.030% to 0.15% Si is an important element that increases the interfacial adhesion strength between the plating layer and the base material in the alloying process. As an increase mechanism of interfacial adhesion strength due to the inclusion of Si in the base material, “Iron and Steel, Vol. 89, No. 1 (2003), pages 46 to 53” includes an alloy containing Si. This promotes the diffusion of Zn in the plating layer to the grain boundary of the base material during the conversion, increases the unevenness of the interface between the base material and the plating layer, and bypasses the separation flow path to absorb energy. It has been proposed that there be.
If the content of Si is small, the effect of improving the interfacial adhesion strength cannot be obtained sufficiently. Therefore, the Si content is 0.030% or more. Preferably, it is 0.040% or more. On the other hand, when there is too much content of Si, it will have a bad influence on the moldability of a steel plate. Further, since the alloying speed is remarkably reduced, the alloying treatment time is prolonged, leading to a decrease in productivity and an increase in equipment length. Therefore, the Si content is 0.15% or less. Preferably, it is 0.10% or less.

(3) Mn: 0.030% or more and 3.0% or less If the content of Mn is too large, the steel plate becomes brittle. Therefore, the Mn content is 3.0% or less. Preferably, it is 2.5% or less. Furthermore, it is more preferably 1.5% or less from the viewpoint of preventing an excessive decrease in elongation or preventing precipitation of TiC and increasing the yield point more than necessary. On the other hand, if the Mn content is too small, the base material may become brittle. Therefore, the Mn content is 0.030% or more.

(4) P: 0.050% or less P is an impurity in the present invention, and the smaller the content, the better. When the content of P is too large, the formability of the steel sheet is adversely affected, such as the elongation becomes small, as in Si. Moreover, since the alloying speed is also lowered, the alloying treatment time is lengthened, leading to a decrease in productivity and an increase in equipment length. Therefore, the P content is 0.050% or less. Preferably, it is 0.030% or less.

(5) S: 0.010% or less S is an impurity in the present invention, and the smaller the content, the better. When there is too much content of S, precipitation of MnS will become remarkable and the ductility of a steel plate will be reduced. Therefore, the content of S is set to 0.010% or less. Preferably, it is 0.0050% or less.

(6) sol. Al: 0.10% or more and 0.80% or less Al, like Si, is an important element that increases the interfacial adhesion strength between the plating layer and the base material. In order to express the effect, Al is contained in a solid solution state at 0.10% or more. Preferably, it is 0.20% or more. On the other hand, even if Al is contained in a large amount in a solid solution state, the effect is saturated, and weldability when steel strips are welded to each other during plating line passing decreases, so the upper limit is 0.80%. To do. sol. A preferable content of Al is 0.20% or more and 0.60% or less.

(7) N: 0.0060% or less N reduces the formability of the steel sheet. Therefore, the smaller the content, the better. In the present invention, the N content is set to 0.0060% or less.

(8) Ti: 0.0040% to 0.50%, Nb: 0.0040% to 0.50%, B: 0.0050% or less These elements are arbitrarily added elements. By adding 0.0040% or more and 0.50% or less of Ti and / or Nb, it becomes possible to fix C and N as carbides and nitrides and improve the formability of the steel sheet. However, a molded product obtained by forming a steel sheet with a small content of C and added with Ti and / or Nb may be easily cracked if an impact stress in a direction different from the work deformation stress is applied at a low temperature. . Therefore, in order to prevent such cracking, it is preferable to add a trace amount (0.0050% or less) of B.

  In the present invention, the chemical composition of the steel plate base material excluding the above elements is Fe and inevitable impurities. However, in addition to the above elements, the steel plate of the present invention may contain a small amount of Mo, Cr, Cu, Ni, Cu, V, and the like. Further, the texture of the steel sheet is not particularly limited. When emphasis is placed on formability rather than strength, it is preferable that the base material has a ferrite structure and recrystallization is sufficiently advanced.

1.2. Plating layer (1) Fe: 8.0% or more and 15% or less, η phase If the η phase remains locally on the surface of the plating layer, seizure with the mold is likely to occur during press molding, and Adhesive strength at the interface between the disposed adhesive and the plating layer is reduced, and peeling tends to occur at the interface. For this reason, it is necessary to sufficiently alloy the plating layer so that the η phase does not remain in the plating layer. As a measure of the degree of alloying, the Fe content in the plating layer is 8.0% or more. Preferably, it is 9.0% or more. On the other hand, when there is too much content of Fe, powdering resistance will fall. Moreover, since it takes time for alloying, it is also disadvantageous in terms of productivity. Therefore, the Fe content is 15% or less. Preferably, it is 14% or less, more preferably less than 10%.

(2) Al: 0.080% or more and 0.50% or less If the content of Al in the plating layer is too small, it becomes difficult to control the amount of plating. Therefore, the Al content is 0.080% or more. On the other hand, when there is too much content of Al, there exists a possibility that the alloying speed | rate may fall and the productivity of a steel plate may fall. Therefore, the Al content is 0.50% or less. Al contained in the plating layer is substantially determined by the Al concentration in the plating bath described later, but slightly varies depending on the plating adhesion amount and Al of the base material. In the present invention, since a base material containing a large amount of Al is used as the plating base material, the Al content tends to be higher than when a base material having a low Al content is used as the base material. In the present invention, the content of Al in the plating layer, when the amount of plating deposition is about ^40g / ^{m 2 ~60g} / m 2 per side, preferably not less than 0.25% 0.50% or less.

1.3. Grain peeling area ratio on base material side When the steel sheet of the present invention is forcibly peeled off at the plating layer-base material interface, the part peeled off in the size of crystal grains is observed on the base material side after peeling. Is done.
FIG. 1 is an SEM image of the base material side release surface when it is forcibly peeled off at the plating layer-base material interface under the conditions described below. The part indicated by the arrow in the photograph is the part peeled off in a size of about a crystal grain unit, and the grain size peeling area ratio in each field of view is (a) 1.0% or less, (b) about 7.0%.

  In FIG. 2, the form of the sample at the time of forcedly peeling at the interface of a plating layer and a base material is shown schematically. In the present invention, using the adhesive 20 having an adhesive shear strength of about 30 MPa or more, the two steel plates 10 and 10 are bonded together, and a shear tensile test as shown in FIG. 2 is performed. There is a correlation between the interfacial adhesion strength and the particle size separation area ratio, and the higher the interface adhesion strength, the larger the value of the particle size separation area ratio. When the interfacial adhesion strength is increased and the particle size peeling area ratio is increased, the chipping resistance and the powdering resistance of the steel sheet can be improved. Therefore, the particle size peeling area ratio on the base material side in the steel sheet of the present invention is 5.0% or more. Preferably, it is 10% or more.

  FIG. 3 is a diagram schematically showing a cross section of the interface between the plating layer and the base material, and shows a part of the crystal grain and a simplified shape of the crystal grain. Hereinafter, the description will be continued with reference to FIGS. 2 and 3. When the above-described shear tensile test is performed on the steel plate 10 of the present invention including the base material 1 and the plating layer 2, delamination in the size of almost crystal grains is observed on the base material 1 side. As will be described later, this is because the steel sheet 10 of the present invention promotes Zn intrusion into the crystal grain boundary of the base material 1 during the alloying treatment, and therefore at the interface between the base material 1 and the plating layer 2. When these are forcedly peeled off, a part of the crystal grains 3, 3,... In the vicinity of the base material surface having a crystal grain boundary in which Zn has not invaded or in which Zn has not sufficiently infiltrated becomes a plating layer 2. This is considered to adhere to the side and peel off.

2. Manufacturing method of steel plate (1) Hot rolling step, winding step In the manufacturing method of the present invention, a slab having the same chemical composition as the base material is heated in a heating furnace, for example, to a roughing mill and a finishing mill. A strip-shaped steel plate (strip) is obtained by a hot rolling process of hot rolling. The steel sheet rolled in the hot rolling process is then wound around a coil by a winder (winding process). The coil winding temperature at the time of winding on the coil is set to 600 ° C. or less from the viewpoint of preventing a decrease in interfacial adhesion strength. Preferably, it is 550 degrees C or less. On the other hand, when the coil winding temperature is less than 480 ° C., the rolling load after the hot rolling becomes high, which may exceed the facility capacity. Therefore, the coil winding temperature is preferably 480 ° C. or higher.
In the manufacturing method of the present invention, in the alloying treatment step described later, penetration of Zn into the crystal grain boundary of the base material is promoted by the effect of the base material Si and Al, and the interfacial adhesion strength between the plating layer and the base material is increased. Improve. Therefore, it is preferable that Si and Al contained in the base material exist in a solid solution state. In the manufacturing method of the present invention, it is considered that the oxidation of Si and Al inside the base material is suppressed by setting the coil winding temperature low.

(2) Pickling process The steel sheet (steel strip) wound in the winding process has a scale formed on the surface. Therefore, the steel sheet is pickled to remove this scale. The acid used in the pickling process is mainly hydrochloric acid and sulfuric acid. Moreover, in order to prevent peracid washing, a very small amount of an inhibitor (for example, an acid corrosion inhibitor (Ibit 710N manufactured by Asahi Chemical Industry Co., Ltd.)) can be added.

(3) Cold rolling process The steel sheet from which the scale has been removed by the pickling process is subsequently subjected to cold rolling in order to obtain a cold rolled base material having a predetermined thickness from the hot rolled steel sheet. From the viewpoint of motor power, speed range of each stand, shape, plate thickness variation, workability, etc., the compression ratio in the cold rolling process is preferably 40% or more and 95% or less.

(4) Reduction annealing process Rolled oil and iron powder are adhering to the cold rolled base metal. Therefore, from the standpoint of improving the plating appearance, the steel sheet after the cold rolling step may be washed by placing it in an alkaline degreasing tank and performing alkaline degreasing. Then, reduction annealing is performed by raising a steel plate to required temperature (for example, 820 degreeC) in the reducing atmosphere containing hydrogen.

(5) Immersion step The steel sheet that has undergone the reduction annealing step is then cooled to near the plating bath temperature (for example, about 470 ° C.) and immersed in the plating bath (immersion step). If the Al concentration in the plating bath is too low, it is difficult to control the amount of plating adhesion. Therefore, the Al concentration in the plating bath is set to 0.080% or more. Preferably, it is 0.090% or more. On the other hand, if the Al concentration in the plating bath is too high, a thick Fe-Al alloy layer is formed at the plating layer-base metal interface, which is necessary for obtaining a predetermined degree of alloying in the alloying process described later. Processing time becomes longer and productivity is lowered. Therefore, the Al concentration in the plating bath is 0.14% or less. Preferably, it is 0.13% or less.
If the immersion time in the plating bath is 1 second or longer, the performance and operability are not impaired. Other plating conditions that are generally employed can be used. The plating bath temperature can be 450 ° C. or higher and 470 ° C. or lower, and the intrusion material temperature (temperature after cooling after the reduction annealing step) can be 450 ° C. or higher and 480 ° C. or lower. As a component other than Al in the plating bath, even if each of Fe, Pb, Cd, Cr, Ni, W, Ti, Mg, and Si, which are inevitable impurities, is contained in an amount of 0.10% or less, the performance of the steel sheet is Almost unchanged.

(6) after adhesion amount control step said soaking step generally such that 25 g / m ² or more 70 g / m ² or less used as a product, to control the coating weight of the plating layer.

(7) Alloying treatment step When the alloying treatment temperature is increased, the diffusion rate of Zn into the crystal grains of the base material increases, and Zn is more easily diffused into the grains than the grain boundaries. As a result, the interfacial adhesion strength between the plating layer and the base material decreases. Therefore, the alloying treatment temperature is set to 530 ° C. or lower. Preferably, it is 520 degrees C or less.
On the other hand, when the alloying treatment temperature is low, the diffusion rate of Zn becomes small and the alloying treatment time becomes long. Even in such a case, if the alloying treatment is performed to such an extent that the η layer does not exist, a steel sheet having interfacial adhesion strength can be obtained. However, from the viewpoint of preventing a decrease in productivity, the alloying treatment temperature is preferably set to 470 ° C. or higher. More preferably, it is 480 degreeC or more.
In the present invention, the rate of temperature rise to the alloying treatment temperature, the holding time at the alloying treatment temperature, the cooling rate after holding, etc. are not particularly limited. The heating means in the alloying treatment may be any means such as radiant heating, high frequency induction heating, and energization heating as long as the texture and degree of alloying of the plating layer are as described above.

(8) Post-treatment process On the surface of the steel sheet manufactured through the above-mentioned processes, if necessary, after rust prevention treatment (for example, chromate treatment or chromium-free treatment), phosphate treatment, resin film application, etc. It can be treated and rust-preventing oil can be applied.

  The alloyed hot-dip galvanized steel sheet of the present invention comprising at least a hot rolling process, a winding process, a pickling process, a cold rolling process, a reduction annealing process, an immersion process, an adhesion amount control process, and an alloying treatment process According to the manufacturing method (hereinafter simply referred to as “manufacturing method”), the chemical composition of the base material (slab) is limited, the Al concentration of the plating bath is specified, and further the alloying treatment temperature is limited. , Preventing a decline in productivity. And the steel plate manufactured by the said manufacturing method has the outstanding interface adhesive strength, and can be used also for the use for which a moldability is requested | required.

Hereinafter, the present invention will be described more specifically with reference to examples.
1. Preparation of test materials Table 1 also shows the chemical composition of the test materials used this time. The test materials included in the technical scope of the present invention were designated as “Examples”, and the test materials not included in the technical scope of the present invention were designated as “Comparative Examples”.

これらの成分を実験室にて溶製、鋳造し、板厚３０ｍｍのスラブを作製した。当該スラブを大気中（１１５０℃）で１時間に亘って保持し、粗圧延及び仕上圧延に供した。仕上圧延は９５０℃で行い、大気中にて巻き取り温度を適宜変更して巻き取った。熱延仕上げ厚みは、４．５ｍｍとした。かかる厚みに調整後の鋼板を酸洗後、板厚が１．６ｍｍとなるまで冷間圧延を行った。縦型溶融亜鉛めっき装置を用い、冷間圧延後の鋼板に対して、以下の条件でめっきを施した。
まず、板厚１．６ｍｍの鋼板を７５℃のＮａＯＨ溶液で脱脂洗浄し、雰囲気ガスがＮ_２＋２０％Ｈ_２（露点−４０℃）、雰囲気温度８２０℃の還元雰囲気中で、１分間に亘って焼鈍した。焼鈍後、めっき浴温近傍（４７０℃）まで鋼板を冷却し、浴中Ａｌ濃度０．０７０％〜０．１６％、浴温４６０℃の溶融亜鉛めっき浴に１．５秒間浸漬した後、ワイピング方式により、めっき付着量を調整した。その後、赤外線加熱装置を用いて合金化処理温度を適宜変更しながら、鋼板に合金化処理を施した。合金化処理後の片面あたりのめっき付着量は、５０ｇ／ｍ^２であった。そして、合金化処理後に、圧延線荷重１．２ＭＮ／ｍで調質圧延を施した。
上記手順により得られた供試材に対し、以下に示す方法で分析・評価を行った。その結果を、巻き取り温度、浴中Ａｌ濃度、及び、合金化温度の値とともに、表２に示す。なお、表２の鋼種欄の数字は、表１の鋼種欄の数字と対応している。すなわち、表２の鋼種欄に「１」と記載されている場合には、表１の鋼種欄に「１」と記載されている供試材を用いて、以下の分析・評価を行ったことを意味している。
上記手順により得られた供試材に対し、以下に示す方法で分析・評価を行った。その結果を表２にあわせて示す。

These components were melted and cast in a laboratory to produce a slab having a thickness of 30 mm. The slab was held in the atmosphere (1150 ° C.) for 1 hour and subjected to rough rolling and finish rolling. Finish rolling was performed at 950 ° C., and winding was performed by appropriately changing the winding temperature in the air. The hot rolled finish thickness was 4.5 mm. After the steel plate adjusted to such thickness was pickled, cold rolling was performed until the plate thickness became 1.6 mm. Using a vertical hot dip galvanizing apparatus, the steel sheet after cold rolling was plated under the following conditions.
First, a steel plate having a plate thickness of 1.6 mm is degreased and washed with a NaOH solution at 75 ° C., and the atmosphere gas is N ₂ + 20% H ₂ (dew point −40 ° C.) and the atmosphere temperature is 820 ° C. for 1 minute. And annealed. After annealing, the steel sheet is cooled to near the plating bath temperature (470 ° C.), immersed in a hot dip galvanizing bath with an Al concentration of 0.070% to 0.16% and a bath temperature of 460 ° C. for 1.5 seconds, and then wiped. The plating adhesion amount was adjusted by the method. Thereafter, the steel sheet was subjected to alloying treatment while appropriately changing the alloying treatment temperature using an infrared heating device. The plating adhesion amount per one side after the alloying treatment was 50 g / m ² . After the alloying treatment, temper rolling was performed with a rolling line load of 1.2 MN / m.
The specimens obtained by the above procedure were analyzed and evaluated by the following methods. The results are shown in Table 2 together with the values of the winding temperature, the Al concentration in the bath, and the alloying temperature. The numbers in the steel type column in Table 2 correspond to the numbers in the steel type column in Table 1. That is, when “1” is described in the steel type column of Table 2, the following analysis / evaluation was performed using the test material described as “1” in the steel type column of Table 1. Means.
The specimens obtained by the above procedure were analyzed and evaluated by the following methods. The results are also shown in Table 2.

2. Analysis and evaluation 2.1. Evaluation of alloying treatment property After alloying treatment (air cooling by air blowing after holding) held for 30 seconds at the alloying treatment temperature shown in Table 2, the η phase remained clearly (surface appearance The specimens judged to have a high metallic luster were evaluated as “alloying delay”. The test material evaluated as alloying delay is indicated by “x” in Table 2, and the test material not evaluated as alloying delay is indicated by “◯” in Table 2. The analysis and evaluation described below were not performed on the specimens that were judged as “.” In Table 2, No. No. 25 is a sample in which the alloying treatment time was shortened and a sample in which the η phase remained was prepared, so the alloying processability was not evaluated and “−” was described.

2.2. Composition analysis of plating layer A sample piece of 25 mmφ was collected from the test material after alloying treatment, and contained 10% HCl containing 0.50% by volume inhibitor (trade name “Ibit 710N”, manufactured by Asahi Chemical Industry Co., Ltd.). The composition of the plating layer was analyzed by dissolving the plating layer with an aqueous solution and analyzing this by an inductively coupled plasma (ICP) method. The analysis results (“Fe concentration (%)” and “Al concentration (%)”) are shown in Table 2.

2.3. Measurement of base material side particle size peeled area ratio The test material after alloying was cut into 20 mm × 100 mm so that the longitudinal direction was the rolling direction, and a one-component heat-curing adhesive (trade name “EW2020”) , Manufactured by Sumitomo 3M Co., Ltd.) as an adhesive, stacking allowance: 12.5 mm, adhesive film thickness: 200 μm, baking conditions: 170 ° C. × 30 minutes, tensile speed: 5.0 mm / min, at room temperature A tensile test was carried out in the longitudinal direction.
In this tensile test, the peeled surface on the steel sheet side was observed with a scanning electron microscope (SEM) at 200 times with respect to the material that had peeled at the interface between the plating layer and the base material. The base material-side grain size peeled area ratio was expressed as an area ratio of the area of the part of the peeled surface where peeling in crystal grain units was observed to the entire visual field. For one specimen, SEM observation was performed at three locations, and the average value of the particle size peeled area ratios at the three locations was used as a representative value. Table 2 shows representative values of the respective test materials.

2.4. Film peeling test The sample after alloying treatment was brushed with rust preventive oil (trade name “550HN”, manufactured by Nihon Parkerizing Co., Ltd.) on a sample cut into 30 mm × 100 mm so that the longitudinal direction is the rolling direction. A hat forming test was performed at room temperature with coating and blank holder pressure free (a space greater than the plate thickness was ensured between the die and the punch). A schematic diagram of the hat forming test is shown in FIG. Here, the “hat forming test” means that a part of the test apparatus is enlarged and shown on a die 41, 41 provided at a predetermined interval as shown in FIG. It means a test in which a specimen 42 is placed and the punch 43 is moved downward from above the specimen 42 to form a molded specimen 44 (see FIG. 4B). After forming into the test material 44 in this way, tape (the cello tape made by Nichiban Co., Ltd. according to JIS Z-1522 is applied to the vertical wall portion 45 of the test material 44. “Cello tape” is a registered trademark of Nichiban Co., Ltd. Then, the tape was peeled off, and the mass of the molded product after the tape peeling was measured. And the peeling amount of the plating layer per sample was computed by comparing the mass of the molded product after tape peeling, and the mass of the test material 41 before shaping | molding. Other conditions were: punch parallel part: 28 mm, die parallel part: 30 mm, punch shoulder R: 3.0 mm, die shoulder R: 5.0 mm, molding speed: 60 mm / min. The results of the amount of peeling of the plating layer are shown in Table 2.

3. Result In the tensile test when measuring the base material side particle size peeling area ratio, No. Except for 25, peeling at the plating layer-base material interface was observed. On the other hand, no. In 25, the plating layer and the adhesive peeled off.

Si content in the base material is less than 0.030%, or sol. When the Al content is less than 0.10%, specimens (No. 1, 10, 11) using slabs (steel types No. 1, 10, 11) not included in the technical scope of the present invention. In either case, the particle size peeled area ratio was about 2%. Furthermore, as shown in Table 2, in these, the plating layer was peeled off by 25 mg or more, and the anti-flaking property was inferior. Further, when the Si content in the base material exceeds 0.15% (steel type No. 6) or the P content exceeds 0.050% (steel type No. 9), the technical scope of the present invention. The specimens (Nos. 6 and 9) using slabs not included in the sample required a long alloying time to obtain a predetermined degree of alloying, and were evaluated as being delayed in alloying. In addition, if there is much Si content or P content, it will be thought that a moldability also falls.
On the other hand, specimens (No. 2-5, 7-8, 12-15) using slabs (steel types No. 2-5, 7-8, 12-15) included in the technical scope of the present invention. ) Had a particle size peeled area ratio of the peeled surface on the base material side of 5.0% or more, and the peeled amount of the plating layer was about 20 mg or 20 mg or less, and a good result was obtained. Note that sol. Although the test material (No. 15) using the slab (steel type No. 15) having an Al content of 0.80% does not show an adverse effect on performance or an adverse effect on the production, There was a tendency to saturate the effect obtained by increasing the Al content (the effect of improving the interfacial adhesion strength).

  No. in Table 2 Nos. 16 to 20 are test materials manufactured by changing the Al concentration in the plating bath using a slab (steel type No. 3) included in the technical scope of the present invention. Since the Al concentration in the bath is less than 0.080%, No. not included in the technical scope of the production method of the present invention. In No. 16, the peeled amount of the plating layer was 41 mg, and the flaking resistance was inferior. Moreover, when the Al concentration in the bath exceeds 0.14%, No. not included in the technical scope of the production method of the present invention. Nos. 19 and 20 were evaluated as being delayed in alloying because a long alloying time was required to obtain a predetermined degree of alloying. On the other hand, the Al concentration in the bath is 0.080% or more and 0.14% or less, and No. 1 included in the technical scope of the production method of the present invention. Nos. 17 and 18 had a particle size peeling area ratio of 5.0% or more and a plating layer peeling amount of 20 mg or less, and good results were obtained.

  No. in Table 2 21-24 are the test materials manufactured by changing the alloying process temperature using the slab (steel type No. 3) included in the technical scope of the present invention. When the alloying temperature exceeds 530 ° C., No. not included in the technical scope of the production method of the present invention. In Nos. 23 and 24, the particle size peeled area ratio was less than 5%. On the other hand, the alloying treatment temperature is 530 ° C. or lower, and No. included in the technical scope of the production method of the present invention. Nos. 21 and 22 had a particle size exfoliation area ratio of 5.0% or more, and a plating layer exfoliation amount of 20 mg or less, and good results were obtained.

  No. in Table 2 25-29 investigates the influence of an alloying degree using the slab (steel type No. 3) included in the technical scope of the present invention. As described above, no. In No. 25, peeling occurred between the plating layer and the adhesive. When the plating layer was analyzed by X-ray diffraction, a spectrum of η phase was observed. In addition, No. which becomes a standard of the degree of alloying. In 25 specimens, the Fe content of the plating layer was 7.0%. On the other hand, when the alloying treatment was performed up to 16% in which the Fe content of the plating layer exceeded 15%, No. 1 was obtained. In the sample material 29, the powdering resistance was lowered, and the amount of peeling of the plating layer was large. On the other hand, the Fe content of the plating layer is 15% or less, and No. included in the technical scope of the production method of the present invention. In Nos. 26 to 28, the particle size peeling area ratio was 5.0% or more, and the peeling amount of the plating layer was 20 mg or less, or a little over 20 mg, and good results were obtained.

  No. in Table 2 30 to 34 are test materials manufactured using the slab (steel type Nos. 16 to 20) included in the technical scope of the present invention under the conditions included in the technical scope of the manufacturing method of the present invention. As shown in Table 2, all of these test materials had a particle size peeling area ratio of 5.0% or more and a plating layer peeling amount of 20 mg or less, and good results were obtained. .

  No. in Table 2 35-37 investigates the influence of coiling temperature using the slab (steel type No. 3) included in the technical scope of the present invention. When the winding temperature is increased, the particle size peeling area ratio is decreased and the amount of peeling of the plating layer tends to increase, and the winding temperature exceeds 600 ° C., so that the technical scope of the production method of the present invention is increased. No. not included in No. 37 had a particle size peeled area ratio of almost zero. On the other hand, the winding temperature is 600 ° C. or lower, and No. included in the technical scope of the production method of the present invention. In 35-36, the particle size peeling area ratio was 5.0% or more, and the peeling amount of the plating layer was 20 mg or less, or a little over 20 mg, and good results were obtained.

It is a SEM image of a base material side peeling surface when it is made to peel forcibly at a plating layer-base material interface. It is a figure which shows the form at the time of making it peel forcibly at the interface of a plating layer and a base material. It is a figure which shows roughly the cross section of the interface of a plating layer and a base material. Fig.4 (a) is a schematic diagram which expands and shows a part of hat formation test apparatus. FIG.4 (b) is a side view which shows the test material after shaping | molding.

Explanation of symbols

1 Base material (steel plate base material)
2 Plating layer (alloyed zinc plating layer)
10 Alloyed hot-dip galvanized steel sheet

Claims (6)

An alloyed hot-dip galvanized steel sheet provided with an alloyed hot-dip galvanized layer on the surface of a steel sheet base material,
The steel plate base material is mass%, C: 0.25% or less, Si: 0.030% or more and 0.15% or less, Mn: 0.030% or more and 3.0% or less, P: 0.050% Hereinafter, S: 0.010% or less, N: 0.0060% or less, and sol. Al: 0.10% or more and 0.80% or less, the balance having a chemical composition consisting of Fe and inevitable impurities,
The alloyed hot dip galvanized layer contains Fe: 8.0% or more and 15% or less and Al: 0.080% or more and 0.50% or less in mass%, and η phase does not exist. Without
An alloyed hot-dip galvanized steel sheet characterized by having a grain size peeled area ratio of 5.0% or more on the steel sheet base metal side in an interface peel portion between the alloyed hot-dip galvanized layer and the steel sheet base material . An alloyed hot-dip galvanized steel sheet provided with an alloyed hot-dip galvanized layer on the surface of a steel sheet base material,
The steel plate base material is mass%, C: 0.010% or less, Si: 0.030% or more and 0.15% or less, Mn: 0.030% or more and 1.5% or less, P: 0.050%. Hereinafter, S: 0.010% or less, N: 0.0060% or less, and sol. Al: 0.10% or more and 0.80% or less, the balance having a chemical composition consisting of Fe and inevitable impurities,
The alloyed hot dip galvanized layer contains Fe: 8.0% or more and 15% or less and Al: 0.080% or more and 0.50% or less in mass%, and η phase does not exist. Without
An alloyed hot-dip galvanized steel sheet characterized by having a grain size peeled area ratio of 5.0% or more on the steel sheet base metal side in an interface peel portion between the alloyed hot-dip galvanized layer and the steel sheet base material . Instead of a part of the Fe contained in the steel plate base material, in mass%, Ti: 0.0040% to 0.50% and / or Nb: 0.0040% to 0.50% The alloyed hot-dip galvanized steel sheet according to claim 1, wherein B: 0.0050% or less of an additive element is contained. In mass%, C: 0.25% or less, Si: 0.030% or more and 0.15% or less, Mn: 0.030% or more and 3.0% or less, P: 0.050% or less, S: 0.00. 010% or less, N: 0.0060% or less, and sol. Al: 0.10% or more and 0.80% or less, a slab having a chemical composition composed of Fe and unavoidable impurities in the balance, hot rolled into a steel plate,
After the hot rolling step, winding the steel sheet at a temperature of 600 ° C. or less, and a winding step,
After the winding step, pickling the steel plate, pickling step,
After the pickling step, cold rolling the steel sheet, a cold rolling step,
After the cold rolling step, annealing the steel sheet in a reducing atmosphere, a reduction annealing step,
After the reduction annealing step, the steel plate is immersed in a hot dip galvanizing bath containing 0.080% or more and 0.14% or less Al in mass%,
After the dipping step, control the zinc adhesion amount on the steel sheet surface,
An alloying treatment step of alloying the steel sheet at a temperature of 530 ° C. or less after the adhesion amount controlling step;
In the alloying treatment step, by mass%, Fe: 8.0% or more and 15% or less and Al: 0.080% or more and 0.50% or less, and alloying and melting without η phase remaining A method for producing an galvannealed steel sheet, wherein a galvanized layer is formed. In mass%, C: 0.010% or less, Si: 0.030% or more and 0.15% or less, Mn: 0.030% or more and 1.5% or less, P: 0.050% or less, S: 0.00. 010% or less, N: 0.0060% or less, and sol. Al: 0.10% or more and 0.80% or less, a slab having a chemical composition composed of Fe and unavoidable impurities in the balance, hot rolled into a steel plate,
After the hot rolling step, winding the steel sheet at a temperature of 600 ° C. or less, and a winding step,
After the winding step, pickling the steel plate, pickling step,
After the pickling step, cold rolling the steel sheet, a cold rolling step,
After the cold rolling step, annealing the steel sheet in a reducing atmosphere, a reduction annealing step,
After the reduction annealing step, the steel plate is immersed in a hot dip galvanizing bath containing 0.080% or more and 0.14% or less Al in mass%,
After the dipping step, control the zinc adhesion amount on the steel sheet surface,
An alloying treatment step of alloying the steel sheet at a temperature of 530 ° C. or less after the adhesion amount controlling step;
In the alloying treatment step, by mass%, Fe: 8.0% or more and 15% or less and Al: 0.080% or more and 0.50% or less, and alloying and melting without η phase remaining A method for producing an galvannealed steel sheet, wherein a galvanized layer is formed. Instead of a part of the Fe contained in the slab, by mass%, Ti: 0.0040% or more and 0.50% or less, and / or Nb: 0.0040% or more and 0.50% or less, and B: The additive element of 0.0050% or less is contained, The manufacturing method of the galvannealed steel plate of Claim 4 or 5 characterized by the above-mentioned.

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