JP2015063729A - 440 MPa CLASS HIGH STRENGTH ALLOYED HOT-DIP GALVANIZED STEEL SHEET EXCELLENT IN DEEP DRAWABILITY AND PRODUCTION METHOD THEREOF - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a 440 MPa class high strength hot-dip galvanized steel sheet excellent in deep drawability, and a production method thereof.SOLUTION: A steel sheet having a hot-dip galvanized layer containing Fe of 7 to 15% on a surface of the steel sheet is produced by subjecting a cast slab to hot rolling, pickling, cold rolling and annealing, then Ni pre-plating and hot-dip galvanizing followed by alloying, where the cast slab contains C, Si, Mn, P, S, Al, N, Ti, Nb, B and the balance Fe with inevitable impurities. In the production of the steel sheet, a finishing temperature of hot rolling is set to be 800 to 860°C, cooling of the hot-rolled steel sheet is started within 0.5 sec. from finish rolling, the hot-rolled steel sheet is cooled to a temperature of 700°C to 760°C at a rate of 200°C/sec. or more and the cooled steel sheet is wound at a winding temperature of 650 to 760°C, and thus a 440 MPa class high strength alloyed hot-dip galvanized steel sheet excellent in deep drawability can be obtained which satisfies P(222)/P(200)≥17 and has an average r value≥1.7, and a Δr value satisfying -0.3≤Δr value≤0.3.

Description

  The present invention relates to a 440 MPa class high-strength galvannealed steel sheet excellent in deep drawability used for automobile parts and the like, and a method for producing the same.

In recent years, in order to cope with environmental problems, it is desired to reduce the weight of automobiles for the purpose of reducing carbon dioxide emissions and reducing fuel consumption. In addition, there is an increasing demand for improved collision safety. Increasing the strength of steel is an effective means for reducing the weight of automobiles and improving collision safety. Among automotive parts, panel parts that require severe press formability have been used soft steel sheets with good workability, but in recent years they have excellent deep drawability as described in Patent Documents 1-3. The average r value r _m [r _m = (r _L + 2 × r ₄₅ + r _C ) / 4 (Expression 1)] (where r _L , r ₄₅ and r _C are parallel to the rolling direction, A high-strength cold-rolled steel sheet having a high value of 45 °, which is the r value of the steel sheet in the vertical direction (hereinafter, the same applies to Formula 2). Among the panel parts, a part having a shape such as an outer side frame has a high average r value and an in-plane anisotropy (Δr value) [Δr value = (r _L + r _C ) / 2−r. ₄₅ (Equation 2)] is also required to be small. This is because the r value in the 45 ° direction is required to be high at the four corners of the part where the door fits in each part of the outer side frame, and the r value in the rolling direction is required to be high at the hinge mounting portion of the door. It is. As a steel sheet applicable to such a component, Patent Document 4 describes a high-strength cold-rolled steel sheet for deep drawing excellent in average r value and in-plane anisotropy of r value, and a method for producing the same.

  Further, high strength steel sheets for automobiles require corrosion resistance depending on the applied parts, and in such cases, hot dip galvanized steel sheets are applied. In addition, a hot-dip galvanized steel sheet that has been subjected to alloying treatment after being hot-dip galvanized (alloyed) is also applied.

  Hot-dip galvanized steel sheets are usually manufactured by the Sendzimer method, but annealing equipment and plating equipment are continuous. In high-stretchability high-strength steel sheets, Si is added to ensure strength. If the content is high, Si concentrates on the surface of the steel sheet and oxidizes, so that there is a problem that non-plating is likely to occur during hot dip galvanization.

  On the other hand, in Patent Documents 5 and 6, for Si-added high-strength steel sheet, after Ni pre-plating, it is rapidly heated to 430 to 500 ° C., and after galvanization, it is heated to 470 to 550 ° C. for alloying and melting. A method for producing a galvanized high strength steel sheet is described. If the holding time during the alloying process is short, it can be applied even when the maximum temperature is about 620 ° C. In the case of this method, it is possible to use a cold-rolled steel plate manufactured by a cold-rolling-annealing process in which the material has already been made as the original plate, and the maximum reachable temperature is about 620 ° C. It is considered that an alloyed hot-dip galvanized steel sheet can be produced without much damage. In addition, non-plating is less likely to occur even when the Si content is high due to treatment such as Ni pre-plating.

  However, when an alloyed hot-dip galvanized steel sheet is produced by the method described in Patent Documents 5 and 6 on the deep drawing high-strength cold-rolled steel sheet described in Patent Document 4, the hard plating layer subjected to the alloying treatment is restrained. Since deformation in the plate width direction is suppressed, there is a problem that the in-plane anisotropy of the average r value and the r value is deteriorated as compared with the cold-rolled steel plate before plating.

  Therefore, it is difficult to obtain a high-strength galvannealed steel sheet for deep drawing excellent in average r value and in-plane anisotropy of r value using these techniques.

Japanese Patent Publication No.8-30217 Japanese Patent Publication No. 8-26412 JP 2001-131695 A Japanese Patent No. 4094498 Japanese Patent No. 2526320 Japanese Patent No. 2526322

  The present invention is intended to solve the above-described problems, and provides a 440 MPa class high-strength galvannealed steel sheet excellent in deep drawability used for automobile parts and the like, and a method for producing the same. It is.

  The inventors of the present invention have disclosed a technique of a high-strength cold-rolled steel sheet for deep drawing excellent in average r value and in-plane anisotropy of the r value described in Patent Document 4 and Ni pre-process described in Patent Documents 5 and 6. Based on the technology of manufacturing hot-dip galvanized steel sheet by plating method, melting, hot rolling, cold rolling, annealing, Ni pre-plating, hot-dip galvanizing and alloying treatment are performed in the laboratory, and the required strength, ductility, average r Various methods for obtaining the value, Δr value, and plating property were studied. As a result, after specifying the components, the hot rolling finish temperature is set to 800 to 860 ° C., cooling is started within 0.1 seconds after the finish rolling, and the temperature is from 800 ° C. to 860 ° C. to 700 ° C. to 760 ° C. Cooling at a rate of 200 ° C / second or more to a temperature of ℃ or less, and performing hot rolling at a coiling temperature of 650 to 760 ° C, controlling the texture of the hot rolled sheet, cold rolling, annealing, melting In the steel sheet after galvanizing and alloying treatment, the average r value and the in-plane anisotropy of the r value can be greatly improved, and a 440 MPa class high-strength galvannealed steel sheet excellent in deep drawability is manufactured. I found that I can do it. The gist of the present invention is as follows.

(1) In mass%,
C: less than 0.0040%,
Si: 0.7% or less,
Mn: 1.0 to 2.5%
P: 0.05 to 0.15%,
S: 0.025% or less,
Al: 0.005 to 0.20%,
N: 0.010% or less,
Ti: 0.005-0.020%,
Nb: 0.005 to 0.030%,
B: 0.0002 to 0.0030%,
And the balance of the steel sheet consisting of Fe and inevitable impurities on the surface of the steel sheet, and a hot-dip galvanized layer containing 7 to 15% by mass of Fe. X-ray random intensity ratio of (222) plane and (200) plane (ratio of diffraction intensity of random sample) P (222) and P (200) satisfy P (222) / P (200) ≧ 17, An average r value ≧ 1.7 and −0.3 ≦ Δr value ≦ 0.3, a 440 MPa class high-strength galvannealed steel sheet excellent in deep drawability.
(2) In mass%,
C: less than 0.0040%,
Si: 0.7% or less,
Mn: 1.0 to 2.5%
P: 0.05 to 0.15%,
S: 0.025% or less,
Al: 0.005 to 0.20%,
N: 0.010% or less,
Ti: 0.005-0.020%,
Nb: 0.005 to 0.030%,
B: 0.0002 to 0.0030%,
A hot-rolled slab containing Fe and the inevitable impurities, and after pickling, cold rolling and annealing, Ni pre-plating, and then hot dip galvanizing, alloy When the alloyed hot-dip galvanized steel sheet having a hot-dip galvanized layer containing 7 to 15% by mass of Fe is formed on the surface of the steel sheet, the hot rolling finish temperature is set to 800 to 860 ° C. Cooling is started within 0.5 seconds after rolling, and cooling is performed at a speed of 200 ° C./second or more from a temperature of 800 ° C. or more to 860 ° C. or less to a temperature of 700 ° C. or more to 760 ° C. The X-ray random intensity ratio between the (222) plane and the (200) plane parallel to the rolled surface at a quarter of the plate thickness of the steel sheet (ratio with the diffraction intensity of the random sample) P (222 ) And P (200) (222) / P (200) ≧ 17, average r value ≧ 1.7, −0.3 ≦ Δr value ≦ 0.3, excellent deep drawability 440 MPa class high strength alloying and melting Manufacturing method of galvanized steel sheet.

  According to the present invention, a 440 MPa class high-strength galvannealed steel sheet excellent in deep drawability can be obtained, and the industrial contribution is extremely remarkable.

  First, the reasons for limiting the components of the 440 MPa class high-strength galvannealed steel sheet excellent in deep drawability in the present invention will be described. Hereinafter, mass% in the composition is simply referred to as%.

  C: C is an element that reduces the deep drawability, and is desirably reduced. If it is 0.0040% or more, a large amount of precipitates such as TiC and NbC are precipitated, not only the Δr value is deteriorated, but also the grain growth property during annealing is inhibited, and the average r value is also lowered. Was less than 0.0040%.

  Si: Si is an element useful for increasing the strength of a steel sheet by solid solution strengthening. The excessive addition exceeding 0.7% deteriorates the peelability and chemical conversion property of the scale generated by hot rolling, and also deteriorates the flash butt weldability. Therefore, the Si content is set to 0.7% or less.

Mn: Mn is an element useful for increasing the strength of a steel sheet by solid solution strengthening. Also, it is an element that lowers the Ar ₃ transformation point, and its effect is utilized to reduce the hot rolling finishing temperature (FT), thereby making the hot rolled sheet grain size fine and fine ferrite grains. Is an indispensable element. If it is less than 1.0%, those effects are not exhibited, and an excessive addition exceeding 2.5% deteriorates toughness. Therefore, the Mn content is set to 1.0 to 2.5%.

  P: P is an element useful for increasing the strength of a steel sheet by solid solution strengthening. If it is less than 0.05%, it is difficult to obtain a strength of 440 MPa class, and if it exceeds 0.15%, it segregates at the grain boundary, lowers the grain boundary strength, and deteriorates toughness. Therefore, the P content is set to 0.05 to 0.15%.

  S: S is an impurity element that degrades hot workability and toughness, and is desirably reduced. The upper limit of the S content is limited to 0.025% in consideration of the current refining technology and manufacturing costs.

  Al: Al is effective as a deoxidizer and suppresses grain coarsening by forming AlN. Moreover, it is a ferrite stabilizing element like Si, and can be used as a substitute for Si. If it is less than 0.005%, those effects are not exhibited, and if it is added over 0.20%, the toughness deteriorates, so the Al content was made 0.005 to 0.20%.

  N: N has the effect of forming nitrides and suppressing crystal grain coarsening, but if added over 0.010%, the toughness deteriorates, so the upper limit of the N content was 0.010%.

  Ti: Ti is an element that forms fine carbonitrides and is effective in suppressing the coarsening of crystal grains. Also, TiN and TiC are precipitated to reduce solid solution N and solid solution C, thereby reducing r It is effective to improve the value. If it is less than 0.005%, those effects are not manifested, and if it is added in excess of 0.020%, TiP may be precipitated and the r value may be lowered, or TiN may be coarsened to deteriorate toughness. Therefore, the content of Ti is set to 0.005 to 0.020%.

  Nb: Nb is an element that forms fine carbonitrides, and is effective in suppressing the coarsening of crystal grains. In addition, solid solution C that remains without being fixed by Ti is precipitated as NbC. It is effective for reducing C and improving the r value. If it is less than 0.005%, those effects are not expressed, and if it exceeds 0.030% and added excessively, the precipitates may become coarse and the toughness may deteriorate. Therefore, the Nb content is set to 0.005 to 0.030%.

  B: B is an element that segregates at the grain boundary and suppresses the grain boundary segregation of P and S, and is an element effective for improving secondary work brittleness. If the content is less than 0.0002%, the effect is not exhibited. If the content exceeds 0.0030%, a coarse precipitate is formed at the grain boundary, which may impair hot workability and toughness. Therefore, the content of B is set to 0.0002 to 0.0030%.

Next, the texture of the steel sheet of the present invention will be described.
The alloyed hot-dip galvanized steel sheet of the present invention has an X-ray random strength ratio P (222) of (222) plane parallel to the rolling surface at 1/4 part of the steel sheet thickness and 1/4 of the steel sheet thickness. The ratio [P (222) / P (200)] with the X-ray random intensity ratio P (200) of the (200) plane parallel to the rolling surface in the part satisfies P (222) / P (200) ≧ 17 It is necessary. Here, the X-ray random intensity ratio is a ratio with the diffraction intensity of a random sample. By satisfying P (222) / P (200) ≧ 17, an average r value of 1.7 or more and −0.3 ≦ Δr value ≦ 0.3 can be obtained in the galvannealed steel sheet.

  The X-ray random intensity ratio is determined by measuring the X-ray diffraction intensity of the (222) plane and (200) plane parallel to the rolling surface using a diffractometer method using an appropriate X-ray tube, etc. It shall be measured by comparison with the diffraction intensity. When measurement by X-ray diffraction is difficult, use an EBSD (Electron Back Scattering Diffraction Pattern) method to measure in an area where the measurement interval of pixels is 1/5 or less of the average grain size and 5000 or more crystal grains can be measured. In addition, the random intensity ratio may be measured from a pole figure or an ODF (Orientation Distribution Function) distribution.

Next, the characteristics of the steel plate of the present invention will be described.
The average r value needs to be 1.7 or more in consideration of the characteristics required for an automobile steel plate. If it is less than 1.7, it is difficult to apply to automobile parts such as outer side frames. The average r value is obtained by the above equation 1.

  Regarding the Δr value, it is necessary to satisfy −0.3 ≦ Δr value ≦ 0.3 in consideration of characteristics necessary for an automobile steel plate. If Δr <−0.3 or Δr> 0.3, it is difficult to apply to automobile parts such as outer side frames. The Δr value is obtained by the above equation 2.

Next, the reasons for limiting the manufacturing conditions will be described.
In the present invention, the steel composed of the above components is melted and cast by a conventional method. The obtained slab is hot-rolled. Further, after pickling, cold rolling and annealing, Ni pre-plating is performed, and then hot dip galvanizing and alloying treatment are performed.

  In hot rolling, the finishing temperature is set to 800 to 860 ° C., cooling is started within 0.5 seconds after finishing rolling, and the temperature is increased from 800 ° C. to 860 ° C. to 700 ° C. to 760 ° C. to 200 ° C. / Cool at a rate of at least 2 seconds and set the winding temperature to 650-760 ° C.

  The X-ray random intensity ratio between the (222) plane parallel to the rolling surface and the (200) plane (ratio with the diffraction intensity of the random sample) P (222) and P (1) 200) satisfies P (222) / P (200) ≧ 17, has an average r value ≧ 1.7, and −0.3 ≦ Δr value ≦ 0.3, and has a high 440 MPa class excellent in deep drawability It is indispensable to satisfy the above conditions when manufacturing a high strength hot dip galvanized steel sheet.

  By setting the finishing temperature to 800 to 860 ° C., the structure of the hot-rolled sheet becomes fine and fine ferrite grains, and it is possible to achieve both improvement of the average r value and reduction of the in-plane anisotropy of the r value. Considering the allowance for deterioration after hot dip galvanizing and alloying treatment is not sufficient. If the finishing temperature is less than 800 ° C. or more than 860 ° C., the structure of the hot-rolled sheet becomes coarse or distortion increases, and a fine and fine ferrite structure cannot be obtained.

  Cooling is started within 0.5 seconds after finish rolling, and the structure of the hot-rolled sheet is cooled by cooling at a rate of 200 ° C./second or higher from a temperature of 800 ° C. to 860 ° C. to a temperature of 700 ° C. to 760 ° C. Further, the {112} <110> and {332} <113> orientations effective for improving the average r value of the steel sheet after cold rolling and annealing and reducing the anisotropy of the r value can be obtained. It can be set as a hot-rolled sheet texture having a main orientation. Thereby, the texture of the cold-rolled steel sheet after cold rolling and annealing satisfies P (222) / P (200) ≧ 17, the average r value is high, and the in-plane anisotropy of the r value is small. An excellent texture can be obtained. The texture of this cold-rolled steel sheet does not change even when galvanizing and alloying treatment is performed, and even if the average r value after alloying treatment and the in-plane anisotropy deterioration allowance are taken into account The texture of the hot-dip galvanized steel sheet satisfies P (222) / P (200) ≧ 17, satisfies the average r value ≧ 1.7, satisfies −0.30 ≦ Δr value ≦ 0.30, and has an average r An excellent texture can be obtained in which the value is high and the in-plane anisotropy of the r value is small.

  When the time until the start of cooling after finish rolling exceeds 0.5 seconds, the temperature after the start of cooling and after cooling deviates from the above range, or the cooling rate is less than 200 ° C./second, the above effect is I can't get it.

  By setting the coiling temperature to 650 to 760 ° C., the precipitation of Ti and Nb carbonitrides is promoted, and the r value can be improved by reducing the solid solution C and the solid solution N. If the winding temperature is less than 650 ° C. or more than 760 ° C., this effect cannot be obtained.

  In addition, since the heating temperature of the slab at the time of hot rolling is the range which can ensure said finishing temperature, it is desirable from the lower temperature to obtain a better average r value.

  The rolling ratio of cold rolling is preferably 75 to 83% because the average r value and Δr value can be made more excellent, but the steel sheet of the present invention can be obtained under the normally used cold rolling conditions. Therefore, there is no particular limitation.

  The annealing condition is not particularly limited as long as the recrystallization is completed. In order to obtain a steel sheet having an excellent average r value, it is desirable that the annealing temperature is 800 ° C. or higher. Further, in order to prevent the trouble of “plate drawing” at the time of passing through the furnace in continuous annealing, it is desirable to set the annealing temperature to 830 ° C. or less.

  In order to remove the scale generated during annealing, pickling may be performed after annealing. Further, after annealing, temper rolling may be performed for shape correction and loss of yield point elongation.

  If the elongation is less than 0.6%, the effect is not sufficient, and if the elongation exceeds 2%, the elongation deteriorates. Therefore, when performing temper rolling, it is desirable that the elongation is 0.6 to 2%.

After annealing, Ni needs to be pre-plated. The Ni pre-plating method may be any of electroplating, immersion plating and spray plating, and the plating amount is preferably about 0.2 to ² g / m ² .

  After pre-plating Ni, after heating to 430-480 degreeC with the heating rate of 20 degrees C / second or more, galvanization is performed in a zinc plating bath, and the alloying process for 10-40 seconds is performed at 470-620 degreeC. When the heating rate is less than 20 ° C./second, the effect of promoting alloying cannot be obtained. If the heating temperature is less than 430 ° C., non-plating is likely to occur during plating, and if it exceeds 480 ° C., plating adhesion deteriorates. If the alloying treatment is less than 470 ° C, alloying is insufficient, and if it exceeds 620 ° C, the ductility deteriorates. The alloying time is determined by the balance with the alloying temperature, but a range of 10 to 40 seconds is appropriate. If it is less than 10 seconds, alloying is difficult to proceed, and if it exceeds 40 seconds, ductility deteriorates. In addition, said zinc plating conditions and alloying conditions are examples, What is necessary is just the conditions which can obtain the zinc plating layer in which 7-15% of Fe is contained in a plating layer.

  After galvanizing and alloying treatment, temper rolling may be performed for final shape correction and loss of yield point elongation. If the elongation is less than 0.6%, the effect is not sufficient, and if the elongation exceeds 1%, the elongation deteriorates. Therefore, when performing temper rolling, it is desirable that the elongation is 0.6 to 1%.

Next, the plating layer will be described.
In order to improve spot weldability and paintability, in the present invention, alloying is performed after hot dip galvanizing. Specifically, after immersion in a hot dip galvanizing bath, an alloying treatment is performed so that Fe is taken into the plating layer and a high strength hot dip galvanized steel sheet excellent in paintability and spot weldability can be obtained. . If the Fe content in the plated layer after the alloying treatment is less than 7% by mass, the spot weldability is insufficient. On the other hand, if the amount of Fe exceeds 15% by mass, the adhesion of the plating layer itself is impaired, and the plating layer is broken and dropped during processing and adheres to the mold, thereby causing defects during molding. Therefore, the range of Fe content in the plated layer after alloying is 7% or more and 15% or less. In addition to the Fe, the hot dip galvanized layer contains Ni derived from Ni pre-plating, Zn, Al, and unavoidable impurities contained in the hot dip galvanizing bath.

The plating adhesion amount is not particularly limited, but is preferably 5 g / m ² or more in terms of one-side adhesion amount from the viewpoint of corrosion resistance. For the purpose of improving the paintability and weldability on the hot dip galvanized steel sheet of the present invention, various treatments such as chromate treatment, phosphate treatment, lubricity improvement treatment, weldability improvement treatment, etc. However, the present invention does not depart from the present invention.

Hereinafter, the effects of the present invention will be described more specifically with reference to examples.
After casting steel having the composition shown in Table 1 and performing hot rolling, cold rolling and annealing under the conditions shown in Table 2, Ni pre-plating with a plating amount of 0.5 g / m ² was performed, and 20 ° C./second. After heating to 460 ° C. at the heating rate, galvanizing was performed in a galvanizing bath, alloying heat treatment was performed under the conditions shown in Table 2, and temper rolling was performed at an elongation rate of 1.0%. The cold rolling rate was 80% and the plate thickness was 0.65 mm.

  The mechanical properties, average r value, Δr value, plating appearance, degree of alloying, and plating adhesion of the obtained galvannealed steel sheet were evaluated. The mechanical properties were evaluated by conducting a tensile test according to JIS Z 2241. Yield stress (YP), tensile strength (TS), and total elongation (EL) were determined from the stress-strain curve of the tensile test. The average r value and Δr were evaluated by conducting a plastic strain ratio test according to JIS Z 2254. The average r value and Δr value were also measured for cold-rolled steel sheets after cold rolling and annealing. The appearance of plating was determined by visual observation for the presence or absence of non-plating. The alloying Fe% indicates the mass% of Fe in the plating layer. In the alloyed hot-dip galvanized steel sheet subjected to the alloying treatment, 7 to 15% indicate that the alloying has proceeded well. For plating adhesion, a 25 mm cup squeeze test was conducted, the degree of blackening by a tape test was measured, and a degree of blackening of less than 30% was accepted. In Table 3, the acceptable product was marked with ◯, and the rejected product was marked with ×.

  The texture of the obtained alloyed hot-dip galvanized steel sheet was determined by using a diffractometer method to obtain an X-ray random intensity ratio (random sample) between the (222) plane and the (200) plane parallel to the rolled surface at 1/4 part of the plate thickness. Of the diffraction intensity) P (222) and P (200) were measured, and the value of P (222) / P (200) was calculated and evaluated. The texture of the cold rolled steel sheet after cold rolling and annealing was also evaluated in the same manner.

  Table 3 shows the evaluation results of P (222) / P (200), yield stress, tensile strength, total elongation, average r value, Δr value, plating appearance (non-plating presence / absence), alloyed Fe%, and plating adhesion. . Evaluation items are underlined if they are rejected. No. 1-7 is an example of this invention, and all the characteristics pass and the steel plate of the target characteristic is obtained. On the other hand, the components or production methods are outside the scope of the present invention. As for 8-15, either characteristic has failed.

  Invention Example No. 1, no. 7 and Comparative Example No. 14, no. 15 is an example in which the components, the annealing conditions, and the galvanizing conditions are the same, but only the hot rolling conditions are different. No. 14, no. No. 15, the average r value and Δr value of the cold-rolled steel sheet have good characteristics, but the average r value and Δr value of the alloyed hot-dip galvanized steel sheet are deteriorated by hot dip galvanizing and alloying treatment. It is much lower and the target characteristics have not been achieved. On the other hand, no. 1, no. In No. 7, the average r value and Δr value of the cold-rolled steel sheet are much better. The average r value and Δr value of the galvannealed steel sheet are lower than those of the cold-rolled steel sheet. It can be seen that

Claims (2)

% By mass
C: less than 0.0040%,
Si: 0.7% or less,
Mn: 1.0 to 2.5%
P: 0.05 to 0.15%,
S: 0.025% or less,
Al: 0.005 to 0.20%,
N: 0.010% or less,
Ti: 0.005-0.020%,
Nb: 0.005 to 0.030%,
B: 0.0002 to 0.0030%,
And the balance of the steel sheet consisting of Fe and inevitable impurities on the surface of the steel sheet, and a hot-dip galvanized layer containing 7 to 15% by mass of Fe. X-ray random intensity ratio of (222) plane and (200) plane (ratio of diffraction intensity of random sample) P (222) and P (200) satisfy P (222) / P (200) ≧ 17, An average r value ≧ 1.7 and −0.3 ≦ Δr value ≦ 0.3, a 440 MPa class high-strength galvannealed steel sheet excellent in deep drawability. % By mass
C: less than 0.0040%,
Si: 0.7% or less,
Mn: 1.0 to 2.5%
P: 0.05 to 0.15%,
S: 0.025% or less,
Al: 0.005 to 0.20%,
N: 0.010% or less,
Ti: 0.005-0.020%,
Nb: 0.005 to 0.030%,
B: 0.0002 to 0.0030%,
A hot-rolled slab containing Fe and the inevitable impurities, and after pickling, cold rolling and annealing, Ni pre-plating, and then hot dip galvanizing, alloy When the alloyed hot-dip galvanized steel sheet having a hot-dip galvanized layer containing 7 to 15% by mass of Fe is formed on the surface of the steel sheet, the hot rolling finish temperature is set to 800 to 860 ° C. Cooling is started within 0.5 seconds after rolling, and cooling is performed at a speed of 200 ° C./second or higher from a temperature of 800 ° C. or higher to 860 ° C. or lower to a temperature of 700 ° C. or higher to 760 ° C. or lower. The X-ray random intensity ratio between the (222) plane and the (200) plane parallel to the rolled surface at a quarter of the plate thickness of the steel sheet (ratio with the diffraction intensity of the random sample) P (222 ) And P (200) (222) / P (200) ≧ 17, average r value ≧ 1.7, −0.3 ≦ Δr value ≦ 0.3, excellent deep drawability 440 MPa class high strength alloying and melting Manufacturing method of galvanized steel sheet.