JP2012012671A - Galvannealed steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a galvannealed steel sheet excellent in alloying characteristics.SOLUTION: In surfaces of both sides of the steel sheet, X-ray intensity of a {100} plane of a direction parallel to the sheet side is 2.5 or more in a random intensity ratio, and a half value width of an X-ray diffraction peak of the {100} plane in the surface is 0.15 degrees or more. By specifying in this manner, many {100} planes of unrecrystallized grains exist in the steel sheet surface, a diffusion rate of metal atoms in a plating introduced into the steel or the surface becomes large, and an alloying reaction of iron and zinc is promoted after galvanizing, Further, since difference of reaction rates in the grain boundaries can be reduced, outbursts are hard to occur. Solid solution of Ti contributes to making such texture distribution, and Ti of 0.01 to 0.1% is contained in a range satisfying that Ti* is more than 0.007 in an equation Ti*=(Ti%)-3.4×(N%)-1.5×(S%)-4×(C%).

Description

  The present invention relates to a hot-dip galvanized steel sheet that is soft and excellent in alloying characteristics, and is used for an exterior plate of an automobile.

Conventionally, a cold-rolled steel sheet having a tensile strength of less than 350 MPa and being excellent in workability has been used as an automobile exterior board.
As a cold-rolled steel sheet that is soft and excellent in workability, an ultra-low carbon steel containing carbonitride-forming elements is hot-rolled to produce carbonitride at the stage of hot-rolled steel sheet. In addition, a cold-rolled steel sheet, so-called IF (Interstitial Free) steel sheet, which is manufactured through cold rolling and recrystallization annealing after reducing solute N is known.

  Such an IF steel sheet is often used after being subjected to a galvannealing treatment from the viewpoint of extending the life of the vehicle body. However, with IF steel sheets, there is almost no solid solution element such as C at the grain boundaries, so the iron-zinc alloying reaction rate is significantly increased using the grain boundaries as a diffusion path, so the alloying is uniformly controlled by the so-called outburst reaction. There was a problem that it was difficult to do. In addition, the Ti-added IF steel sheet, which is particularly excellent in deep drawing workability, has a problem that unevenness in appearance is likely to occur due to non-uniform alloying reaction.

As a technique for solving these problems, for example, Patent Document 1 discloses that one or more selected from a carbon compound, a nitrogen compound, and a boron compound are provided on the surface of a steel sheet when performing hot dip galvanizing treatment. C, N, B amount 0.1 to 1000 mg / m ² adhered to as, and sulfur, or after the sulfur compound to 0.1 to 1000 mg / m ² is deposited as a S content, a temperature above 680 ° C. in a non-oxidizing atmosphere containing hydrogen A method of annealing in is disclosed.

  In addition, in Patent Document 2, in order to solve the uneven surface appearance called “straight unevenness”, the slab immediately after continuous casting is held at a surface temperature of 1000 ° C. or higher and led to the finishing rolling process, and the Ar3 point or higher A method of finishing at the following temperature is disclosed.

  Furthermore, in Patent Document 3, in order to solve the similar surface appearance non-uniformity, steel is continuously cast into a slab and then heated, and an oxidizing gas containing oxygen is blown into a slab having a surface temperature of 1000 ° C. or higher. A method of performing hot rolling, pickling, cold rolling, and annealing after application is disclosed.

Japanese Patent Laid-Open No. 11-50221 JP-A-9-29622 Japanese Patent Laid-Open No. 10-330846

  However, the above technique has the following problems.

In the method described in Patent Document 1, a step of attaching 0.1 to 1000 mg / m ^{2 of} sulfur or a sulfur compound as the amount of S is required, and there is a problem that the productivity is lowered and the cost is increased.

  In the method described in Patent Document 2, it is impossible to perform so-called slab maintenance that prevents surface defects by, for example, cutting the surface of the slab, and it is used for automotive exterior board applications that require a particularly beautiful surface appearance. Inappropriate for

  In the method described in Patent Document 3, in order to prevent non-uniform appearance on both surfaces of the steel sheet, it is necessary to invert a high-temperature slab of 1000 ° C. or higher and spray an oxidizing gas, which is not practical.

  This invention is made | formed in view of this situation, and it aims at providing the galvannealed steel plate excellent in the alloying characteristic which can obtain a uniform external appearance, without giving a special process.

In order to solve the above-mentioned problems, the present inventors have conducted extensive research.
As a result, by forming non-recrystallized grains with a specific crystal orientation in the surface layer portion and controlling the surface layer structure, the alloying characteristics after hot dip galvanization are improved, and the formation of this non-recrystallized grains It was found that the strengthening of precipitates was greatly involved, and the control of the component composition centered on Ti was important.

The present invention has been made based on the above findings, and the gist thereof is as follows.
In mass%, C: 0.0005 to 0.01%, Si: 0.2% or less, Mn: 0.1 to 1.5%, P: 0.10% or less, S: 0.003 to 0.03%, Ti: 0.01 to 0.1%, Al: 0.01 to 0.10 %, N: Including 0.005% or less and satisfying Ti *> 0.007 when Ti * = (Ti%) − 3.4 × (N%) − 1.5 × (S%) − 4 × (C%) In the range, the balance has a component composition consisting of Fe and inevitable impurities, the surface of both surfaces of the steel plate, the {100} plane X-ray intensity in the direction parallel to the plate surface is 2.5 or more in random intensity ratio, An alloyed hot-dip galvanized steel sheet characterized by having a half width of a {100} plane X-ray diffraction peak of 0.15 ° or more.
However, (Ti%), (N%), (S%), and (C%) indicate the contents (mass%) of Ti, N, S, and C, respectively.

  In the present specification, “%” indicating the component of steel is “% by mass”.

  According to the present invention, an IF hot-dip galvanized steel sheet with excellent alloying characteristics that can obtain a uniform appearance without performing special treatment in an IF steel sheet with a reduced amount of C for improving deep drawability Is obtained.

  In addition, since the galvannealed steel sheet of the present invention is excellent in alloying characteristics, for example, it is excellent also for a plated steel sheet in which P and Mn are added to strengthen the steel and the alloying speed tends to be slow. Can exert the effect.

  The alloyed hot-dip galvanized steel sheet of the present invention has a {100} plane X-ray intensity in a direction parallel to the plate surface on the surfaces of both surfaces of the steel sheet, and a random intensity ratio of 2.5 or more, and the {100} plane on the surface The half width of the X-ray diffraction peak is 0.15 ° or more. This is the most important requirement in the present invention. Moreover, the component composition at that time is mass%, C: 0.0005-0.01%, Si: 0.2% or less, Mn: 0.1-1.5%, P: 0.10% or less, S: 0.003-0.03%, Ti: 0.01-0.1% , Al: 0.01 to 0.10%, N: 0.005% or less and Ti * = (Ti%) − 3.4 × (N%) − 1.5 × (S%) − 4 × (C%) It is contained in a range satisfying Ti *> 0.007, and the balance is Fe and inevitable impurities. However, (Ti%), (N%), (S%), and (C%) indicate the contents (mass%) of Ti, N, S, and C, respectively. Thus, the steel plate excellent in the alloying characteristic after hot dip galvanization can be obtained by prescribing | regulating the state of the steel plate surface.

  In the present invention, the {100} plane X-ray intensity in the direction parallel to the plate surface has a random intensity ratio of 2.5 or more, and the half width of the {100} plane X-ray diffraction peak on the surface is 0.15 ° or more. After cold rolling, the α → γ transformation and recrystallization did not occur, and only the recovery phenomenon passed. Compared with the recrystallized grains, unrecrystallized grains in the form of dislocation density and extended in the rolling direction were formed on the plate surface. It shows a state of being accumulated on {100} planes in parallel directions. Therefore, it is different from a structure in which recrystallized grains generated through α → γ → α transformation obtained by annealing performed at a temperature equal to or higher than the transformation point are accumulated.

  Thus, in the present invention, in the accumulation of {100} planes in the direction parallel to the plate surface, there is a feature in the morphology and dislocation density of the crystal grains accumulated in the {100} plane orientation, and the recrystallized grains that are usually obtained The composition is different from that of a structure composed of {100} plane orientations formed through the γ → α transformation. Therefore, in the present invention, in order to clarify the difference between unrecrystallized grains and recrystallized grains, in addition to the random intensity ratio, the half-value width of the {100} plane X-ray diffraction peak at the surface is measured, and the random intensity ratio is measured. The structure of the alloyed hot-dip galvanized steel sheet is shown using the half width.

  If the {100} plane X-ray intensity in the direction parallel to the plate surface is 2.5 or more in terms of the random intensity ratio, the area ratio of the {100} plane in the direction parallel to the plate surface on the surface is sufficiently high. Furthermore, if the half width of the {100} plane X-ray diffraction peak on the surface is 0.15 ° or more, the dislocation density is sufficiently high, so that the diffusion rate increases during the alloying treatment after hot dip galvanizing, and the alloy It is possible to improve the conversion characteristics.

  Hereinafter, the present invention will be described in detail.

  Conventionally, it is known that the texture of a steel plate for an exterior plate of an automobile is formed with many {111} surfaces in a direction parallel to the plate surface. As a result of repeated experiments under various production conditions, the present inventors have found that a steel sheet having many {111} faces in the steel sheet but having many {100} faces in the outermost layer is obtained. I found. When the {100} plane accumulation is not the {100} plane obtained by annealing at or above the transformation point, but the {100} plane of unrecrystallized grains having a high dislocation density, the alloying characteristics are markedly It was also found to be excellent.

  The {100} plane of unrecrystallized grains has a higher dislocation density in the crystal, so the diffusion rate of metal atoms in the steel or plating introduced to the surface is higher than that of the {111} plane that is recrystallized grains. growing. Therefore, a steel sheet with a texture distribution in which many {100} faces of unrecrystallized grains are present on the surface layer, compared to the conventional IF steel sheet with many {111} faces formed on the surface, Since the zinc alloying reaction is promoted and the difference in reaction rate at the grain boundary can be made extremely small, so-called outburst is unlikely to occur.

  Moreover, since the alloying reaction rate is higher than that of the conventional steel plate surface, the alloying reaction time can be shortened, and the productivity can be improved. Furthermore, even if P or Mn, which is a strengthening element that conventionally had to be added in a small amount for the reason of delaying the alloying reaction, is added in the present invention, a sufficient alloying reaction occurs in the conventional process. There is also an advantage that can be made.

  Based on the above examination results, in the present invention, in order to improve alloying characteristics and achieve both uniform appearance and productivity improvement, {100} plane X-rays in a direction parallel to the plate surface on both surfaces of the steel plate The intensity is 2.5 or more in random intensity ratio, and the half width of {100} plane X-ray diffraction peak on the surface is 0.15 ° or more.

  The {100} plane X-ray intensity in the direction parallel to the plate surface can be measured by the inverse pole figure method. The half-value width of the {100} plane X-ray diffraction peak on the surface can be determined by measuring the {100} plane X-ray diffraction peak on the surface using Mo as the X-ray source and the θ-2θ method. it can. Detailed conditions of the measurement method will be described in the examples described later.

  Moreover, the thickness from the outermost layer to the plate thickness center direction in the region where many non-recrystallized grains exist can be measured by observing a cross section in the rolling direction of the steel plate with an optical microscope. The form of the cross section in the rolling direction of the non-recrystallized grains can be easily distinguished because it has a smaller thickness than the recrystallized grains and extends in the rolling direction. In general, in order to obtain the effect of improving the alloying characteristics, it is preferable that there are many {100} planes of non-recrystallized grains at least from the outermost layer to the region in the thickness direction of 5 μm. More preferably, it is from the outermost layer to the region of 20 μm in the plate thickness center direction.

  In addition, the {100} plane X-ray intensity in the direction parallel to the plate surface on the steel sheet surface as described above has a random intensity ratio of 2.5 or more and the half width of the {100} plane X-ray diffraction peak on the surface is 0.15 ° or more. A certain steel plate is obtained by controlling the manufacturing conditions in the hot rolling and annealing processes. Specifically, for example, the coiling temperature in hot rolling is set to 630 ° C. or less, the hydrogen concentration in the atmosphere in the annealing heating process, particularly the atmosphere (mixed gas of nitrogen and hydrogen) is 5 vol% or more, and the dew point is − By setting the temperature to 40 ° C or less, the {100} plane X-ray intensity in the direction parallel to the plate surface is 2.5 or more in random intensity ratio, and the half width of the {100} plane X-ray diffraction peak on the surface is 0.15 ° or more. It becomes.

Furthermore, as a result of further investigation, in the annealing process of the steel sheet, as Ti, Ti, C, N, S and Ti compounds are not contributed to precipitation, that is, there is a solid solution Ti in the steel It has also been found that the composition of the steel component is important for accumulating many {100} plane orientations of unrecrystallized grains in the surface layer as described above.
Although the exact mechanism by which the presence of solute Ti accumulates many {100} orientations of unrecrystallized grains on the surface layer is not clear, during the annealing after cold rolling, Ti reacts with N present in the atmosphere. It is assumed that the nitride formed in the vicinity of the surface layer inhibits the formation of {111} planes that are originally formed by preventing the movement of crystal grain boundaries and suppressing recrystallization.

  From the above, as the component composition for making solute Ti present in this way, when Ti * = (Ti%) − 3.4 × (N%) − 1.5 × (S%) − 4 × (C%), It should be contained within the range satisfying Ti *> 0.007. However, (Ti%), (N%), (S%), and (C%) indicate the contents (mass%) of Ti, N, S, and C, respectively. Detailed description will be given later.

  Next, the reasons for limiting the component elements will be described.

C: 0.0005-0.01%
C is a solid solution strengthening element, contributes to an increase in yield strength, and is advantageous for improving the in-plane rigidity. However, in order to obtain excellent deep drawability, it is preferable to reduce as much as possible. In addition, if C is contained in a large amount, the amount of Ti carbide in the steel increases, the amount of solute Ti in the steel decreases, and the formation of the {100} plane parallel to the plate surface in the surface layer is obstructed. Is done. Based on the above, the upper limit is 0.01%. On the other hand, if it is less than 0.0005%, the crystal grain size becomes extremely coarse and the yield strength is greatly reduced, so that the in-plane rigidity is lowered and defects such as hip breakage are likely to occur. Moreover, the decarburization cost increases. Therefore, the content is 0.0005% or more and 0.01% or less.

Si: 0.2% or less
Si is a useful element for strengthening steel by solid solution strengthening without relatively degrading workability. On the other hand, it concentrates on the surface during annealing and significantly impairs hot dip galvanizing properties. Therefore, it is 0.2% or less.

Mn: 0.1-1.5%
Mn must be added in an amount of 0.1% or more in order to increase the steel strength as a solid solution strengthening element and to secure the rigidity of the steel plate. On the other hand, excessive addition inhibits processability, so it is made 1.5% or less.

P: 0.10% or less
P is a solid solution strengthening element, which is effective for strengthening steel. However, in order to inhibit the alloying reaction, the upper limit of the additive amount is limited to about 0.05% in the alloyed hot-dip galvanized steel sheet. However, in the present invention, since the alloying characteristics are improved, a larger amount can be added. However, excessive addition exceeding 0.10% not only causes hot and cold cracks, but also tends to cause poor welding. Therefore, the upper limit is set to 0.10%.

S: 0.003-0.03%
S is present in the steel as an unavoidable impurity, but if it exceeds 0.03%, hot cracking is likely to occur during the production of the steel sheet, and inclusions are formed in the steel, thereby significantly reducing workability. Excessive addition also promotes the formation of Ti sulfide and leads to a decrease in solid solution Ti. Therefore, the upper limit is 0.03%. On the other hand, it is preferable that the amount of S is small. However, if it is less than 0.003%, the desulfurization cost increases, so 0.003% is set as the lower limit.

Al: 0.01-0.10%
Al is an element to be added as a deoxidizer and needs to be 0.01% or more. However, even if added in a large amount, a further deoxidizing effect cannot be obtained. Therefore, the upper limit is 0.10%.

N: 0.005% or less
The smaller N, the better the workability, so the smaller N is desirable. Moreover, when it exceeds 0.005% and it adds excessively, it will lead to the remarkable fall of a moldability and the fall of solid solution Ti amount. Therefore, the upper limit is made 0.005%.

Ti: 0.01-0.1%
Ti is one of the most important elements in the present invention. Ti has an effect of improving workability by fixing C, N, and S in steel as precipitates. Further, in the present invention, by adding Ti in excess of the amount necessary to form precipitates, N and nitride in the atmosphere are formed at the time of manufacturing to form {100 } Indispensable for increasing the plane orientation. If it is less than 0.01%, such an effect cannot be obtained. On the other hand, adding more than 0.1% of Ti not only can not expect further effects, but also promotes the formation of abnormal structure inside the plate and lowers workability. From the above, it is set to 0.01% or more and 0.1% or less.

Further, as described above, Ti in steel forms precipitates with C, N, and S in steel. Therefore, Ti is added to the C, N, and S components in excess of the equivalent amount to form a solid solution. It is important in the present invention to accumulate {100} planes of non-recrystallized grains on the surface layer by making Ti excessive. Therefore, in addition to the above specification of 0.01% to 0.1%, the following relational expression should be satisfied.
When Ti * = (Ti%) − 3.4 × (N%) − 1.5 × (S%) − 4 × (C%), Ti *> 0.007
However, (Ti%), (N%), (S%), and (C%) indicate the contents (mass%) of Ti, N, S, and C, respectively.
When Ti * exceeds 0.007, nitrogen in the atmosphere that penetrates into the steel during annealing and solute Ti form very fine nitrides, preventing the movement of grain boundaries and suppressing recrystallization. As a result, non-recrystallized grains having a high dislocation density are likely to remain, and on the surfaces of both surfaces of the steel plate, the {100} plane X-ray intensity in the direction parallel to the plate surface is 2.5 or more in a random intensity ratio, and The half width of the {100} plane X-ray diffraction peak is 0.15 ° or more. Therefore, it is limited to Ti *> 0.007.

  The remainder other than the above consists of Fe and inevitable impurities. As an unavoidable impurity, for example, O forms non-metallic inclusions and adversely affects quality, so it is desirable to reduce it to 0.003% or less. In the present invention, Cu, Cr, Ni, W, V, Zr, Sn, and Sb may be contained in a range of 0.1% or less as trace elements that do not impair the effects of the present invention.

Next, the manufacturing method of the galvannealed steel plate of this invention is demonstrated.
The alloyed hot-dip galvanized steel sheet of the present invention is obtained by roughly rolling a steel adjusted to the above chemical composition range, finish rolling at a desired finishing temperature, then cooling under desired cooling conditions, winding, pickling Thereafter, it is obtained by cold rolling, annealing, hot dip galvanizing, and alloying treatment. Above all, on the steel sheet surface, which is a feature of the present invention, the {100} plane X-ray intensity in the direction parallel to the plate surface is 2.5 or more in random intensity ratio, and the half width of the {100} plane X-ray diffraction peak on the surface is In order to make it 0.15 ° or more, the winding temperature is preferably 630 ° C. or less. By setting the temperature to 630 ° C or less, the precipitate containing Ti becomes finer, and re-dissolves during subsequent annealing to increase the solid solution Ti. On both surfaces of the steel sheet, unrecrystallized in the direction parallel to the plate surface The {100} faces of the grains can be accumulated.

  In addition, the atmosphere in the heating process during annealing is a mixed gas of hydrogen and nitrogen containing 5 vol% or more of hydrogen, and the dew point is −40 ° C. or less. {100} planes of non-recrystallized grains in a direction parallel to a high plate surface can be accumulated. The reason for this is not always clear, but the higher the hydrogen concentration and the lower the dew point, the more nitrogen can penetrate into the steel and form more fine nitrides with Ti in the steel. This is presumed to be because the recrystallization suppression effect is enhanced. More preferably, the hydrogen concentration is 8 vol% or more and the dew point is −45 ° C. or less.

Molten steel consisting of the components shown in Table 1 is vacuum degassed, then slabd by continuous casting, reheated to 1180 ° C, hot rolled to a thickness of 3.5mm at a finishing temperature of 900 ° C, and wound up as shown in Table 2. The coil was wound up at temperature.
Next, the wound steel sheet was pickled, cold-rolled to a thickness of 0.65 mm, degreased as a pretreatment, and immediately annealed and hot-dip galvanized using a hot-dip galvanizing simulator. In order to evaluate the properties of the original sheet before plating, some of the test materials were not subjected to hot dip galvanization but were subjected to annealing only. In addition, annealing was performed at an annealing temperature shown in Table 2, and the atmosphere was a non-oxidizing gas containing hydrogen (mixed gas of 10 vol% hydrogen and 90 vol% nitrogen) at a dew point of −50 ° C. The hot dip galvanizing treatment was performed using a 460 ° C. galvanizing bath containing 0.12% Al at an immersion plate temperature of 460 ° C. and an immersion time of 3 seconds.

Subsequently, after the hot dip galvanizing treatment, the N ₂ gas wiper was used to adjust the zinc adhesion amount to 60 g / m ² per side. Furthermore, the alloying temperature was adjusted with respect to the steel sheet after the plating treatment so that the iron content in the film was 9.5 to 10.5% by an induction heating device, and the alloying treatment was performed for 20 seconds.

With respect to the annealed steel sheet obtained as described above, the {100} plane X-ray random intensity ratio and the half width were measured and evaluated by the following method. Further, after annealing, the steel sheet subjected to hot dip galvanizing treatment and alloying treatment and temper rolled was measured and evaluated for mechanical properties, alloying speed, and appearance by the following methods.
The obtained results are shown in Table 2 together with the production conditions.

The {100} plane X-ray random intensity ratio and the {100} plane X-ray intensity in the direction parallel to the half width plate surface were measured by the inverse pole figure method. The {100} plane X-ray intensity at the surface is measured after the specimen is cleaned and dried, while the {100} plane X-ray intensity in the direction parallel to the plane at the center of the thickness is One surface was chemically polished with oxalic acid to expose the central portion of the plate thickness on the surface, and then each measurement was performed. White X-rays were used as the X-ray source, and a Ge semiconductor detector was used to detect {100} plane X-rays. At the same time, the {100} plane X-ray intensity (random intensity) of a random sample with no selective orientation and an irregular distribution of crystal orientation was measured. The random intensity ratio was calculated by the ratio of the {100} plane X-ray intensity of the actual test piece to the {100} plane X-ray intensity of the random sample.
The {100} plane X-ray peak half-width in the direction parallel to the plate surface at the surface is the θ-2θ method, and Mo is used as the X-ray source, and the {100} plane X-ray diffraction peak at the surface is measured. I asked.

Mechanical properties Formability was evaluated by tensile properties and r-value mechanical properties. Tensile properties were measured according to the test method described in JISZ 2241 after being processed into a No. 5 test piece described in JISZ 2201. The average r value was measured by a three-point method after giving a tensile pre-strain of 15%, and the average r value in the 90 °, 45 °, and 0 ° directions relative to one direction of the steel sheet. = (r (0 °) + 2 × r (45 °) + r (90 °)) / 4.

The steel plate after the alloying rate plating treatment is subjected to alloying treatment for 20 seconds by changing the temperature to 450 ° C, 475 ° C, 500 ° C, 525 ° C, 550 ° C, 575 ° C, 600 ° C with an induction heating device. Thus, the alloying speed was compared according to the temperature at which alloying was possible up to the surface layer. The alloying temperature was adjusted so that the iron content in the film was 9.5 to 10.5%. When alloying treatment is performed for a fixed time of 20 seconds, the lower the temperature at which alloying is possible up to the surface layer, the higher the alloying speed, and if it is 525 ° C or less, the alloying characteristics are better compared to general steel plates. is there. When the temperature exceeds 525 ° C., the alloying speed is equal to or lower than that of a general conventional steel sheet, which is not preferable.

The appearance of the surface after the external alloying treatment was visually observed, and the presence or absence of local non-plating and color unevenness (so-called unevenness) that occurred because the degree of alloying was locally different was evaluated. Those having a uniform color tone without any unplating or streaking were regarded as “good”, and the appearance defect materials in which unplating or streaking occurred were listed in Table 2 together with the types of appearance defects.

From Table 2, the {100} plane X-ray intensity in the direction parallel to the plate surface is 2.5 or more in random intensity ratio, and the half-value width of the {100} plane X-ray diffraction peak on the surface is 0.15 ° or more. In the present invention example, the average r value which is an index of deep drawability is excellent as 1.5 or more, the alloying speed is higher than that of the comparative example, so that the productivity can be improved, and the appearance is uniform and the automobile exterior plate It had the performance suitable for the application. Further, as a result of observing the cross section in the rolling direction of the steel sheet with an optical microscope, it was confirmed that the thickness of the region where many non-recrystallized grains existed from the outermost layer to the thickness center direction was 5 μm or more.
On the other hand, in the comparative example, any one of the average r value, the alloying speed, and the appearance was inferior, and the performance suitable for the automobile exterior plate application could not be satisfied.

  The alloyed hot-dip galvanized steel sheet of the present invention is excellent in deep drawability and alloying characteristics and has a uniform appearance, so that it can be used in various applications, mainly for automobile exterior panels.

Claims (1)

In mass%, C: 0.0005 to 0.01%, Si: 0.2% or less, Mn: 0.1 to 1.5%, P: 0.10% or less, S: 0.003 to 0.03%, Ti: 0.01 to 0.1%, Al: 0.01 to 0.10 %, N: Including 0.005% or less and satisfying Ti *> 0.007 when Ti * = (Ti%) − 3.4 × (N%) − 1.5 × (S%) − 4 × (C%) In a range, the remainder has a component composition consisting of Fe and inevitable impurities,
On the surfaces of both sides of the steel plate, the {100} plane X-ray intensity in the direction parallel to the plate surface is 2.5 or more in random intensity ratio, and the half width of the {100} plane X-ray diffraction peak is 0.15 ° or more. An alloyed hot-dip galvanized steel sheet.
However, (Ti%), (N%), (S%), and (C%) indicate the contents (mass%) of Ti, N, S, and C, respectively.