JP2012041610A - Steel sheet for hot pressing, manufacturing method therefor and method for manufacturing hot press member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel sheet for hot pressing, manufacturing method therefor and method for manufacturing hot press member, which can stably obtain the hot press member having excellent adhesiveness and corrosion resistance after coating even when temperature raising speed is increased or holding time is shortened during heating before hot pressing.SOLUTION: There is provided the steel sheet for hot pressing containing: Al-Fe alloy plated layer containing, by mass, Fe, 25-90% and Si, less than 3%, the balance Al with inevitable impurities, a total content of Fe and Al of 97% or more, on a surface of the steel sheet, and deposition amount per one side of the steel sheet of 10-200g/m; and an Al layer having the deposition amount per one side of the steel sheet of 5g/mor less on the Al-Fe alloy plated layer.

Description

  The present invention relates to a steel sheet for hot pressing suitable for manufacturing an automobile underbody member, a vehicle body structural member, and the like by hot pressing, a manufacturing method thereof, and a manufacturing method of a hot pressing member using the same.

  2. Description of the Related Art Conventionally, many undercarriage members and body structure members of automobiles are manufactured by pressing a steel plate having a predetermined strength. In recent years, from the viewpoint of the preservation of the global environment, there has been a strong desire to reduce the weight of automobile bodies, and efforts have been made to increase the strength of steel sheets to be used and to reduce their thickness. However, as the strength of the steel plate increases, the press workability decreases, and it is often difficult to process the steel plate into a desired member shape.

  Therefore, Patent Document 1 describes a process called a hot press that enables both easy processing and high strength by simultaneously processing a heated steel sheet using a die and punch die and simultaneously cooling it. Technology has been proposed. However, in this hot press, the steel plate is heated to a high temperature of around 950 ° C before hot pressing, so scale (iron oxide) is generated on the surface of the steel plate and the scale peels off during hot pressing. There is a problem that the mold is damaged or the surface of the member after hot pressing is damaged. In addition, the scale remaining on the surface of the member may cause poor appearance, poor paint adhesion, and poor corrosion resistance after painting. For this reason, the scale on the surface of the member is usually removed by processing such as pickling or shot blasting, but this complicates the manufacturing process and causes a decrease in productivity.

  Therefore, there is a demand for hot press technology that can suppress the generation of scale during heating before hot pressing, and can improve the coating adhesion and post-coating corrosion resistance of members after hot pressing, A steel sheet having a coating such as a plating layer on the surface and a hot pressing method using the steel sheet have been proposed. For example, Patent Document 2 discloses a steel sheet for hot pressing (hot-rolled steel sheet and cold-rolled steel sheet) coated with Al or an Al alloy that provides high strength and excellent corrosion resistance after hot pressing. Further, in Patent Document 3, when heating a plated steel sheet of metal mainly composed of Al before hot pressing, the temperature ranges from (Tm-200) to Tm ° C (where Tm is the melting point of the plated metal). A method of heating a steel sheet for hot pressing (heat forming) is disclosed in which a beautiful appearance and excellent corrosion resistance are obtained after heating for 2 seconds or more.

  On the other hand, in recent methods for producing a hot press member, there is an increasing demand for improvement in productivity, in particular, an increase in temperature rise rate and a reduction in holding time during heating before hot pressing.

GB 1490535 Japanese Patent No. 3931251 Japanese Patent Laid-Open No. 2003-27203

  However, when using a hot-press steel sheet coated with Al or Al alloy described in Patent Document 2 and increasing the heating rate and shortening the holding time, it is possible to achieve hot coating with excellent coating adhesion and corrosion resistance after coating. It becomes difficult to obtain a press member. Also, in the heating method of the steel sheet for hot press described in Patent Document 3, when the temperature increase rate is increased, the temperature increase rate control in the temperature range from the melting point to 200 ° C. below the melting point cannot be performed accurately, and excellent coating is achieved. It becomes difficult to stably obtain a hot press member having adhesion and post-coating corrosion resistance.

  The present invention is a hot press capable of stably obtaining a hot press member having excellent coating adhesion and post-coating corrosion resistance even if the temperature rising rate is increased or the holding time is shortened during heating before hot pressing. It aims at providing the manufacturing method of the hot-pressing member using the steel plate for steel, its manufacturing method, and it.

As a result of intensive studies on the steel sheet for hot pressing for the above-mentioned purpose, the present inventors have previously made mass%, Fe: 25 to 90% and Si: 3% or less, or further Cr: 3% Hereinafter, Al: Fe containing at least one selected from Mg: 3% or less and Zn: 3% or less, the balance being Al and inevitable impurities, and the total content of Fe and Al being 97% or more By using a steel sheet for hot pressing with an alloy plating layer and an Al layer of 5 g / m ² or less, excellent coating adhesion is achieved even when the heating rate is increased and the holding time is shortened during heating before hot pressing. It was found that a hot-pressed member having good properties and corrosion resistance after coating can be obtained stably.

The present invention has been made on the basis of such knowledge, and the steel sheet surface contains, in mass%, Fe: 25 to 90% and Si: 3% or less, the balance is made of Al and inevitable impurities, and Fe. Al-Fe alloy plating layer with a total content of 97% or more of Al and Al, and the adhesion amount per one side of the steel sheet of 10 to 200 g / m ² , and the adhesion amount per one side of the steel sheet on the Al-Fe alloy plating layer The present invention provides a steel sheet for hot pressing characterized by having an Al layer of 5 g / m ² or less. The Al—Fe alloy plating layer preferably further contains at least one selected from Cr: 3% or less, Mg: 3% or less, and Zn: 3% or less by mass%.

  As the base steel sheet of the plating layer in the hot-press steel sheet of the present invention, in mass%, C: 0.15-0.5%, Si: 0.05-2.0%, Mn: 0.5-3%, P: 0.1% or less, S: A steel plate containing 0.05% or less, Al: 0.1% or less, and N: 0.01% or less, with the balance being composed of Fe and inevitable impurities can be used. In this base steel sheet, in addition, by mass%, Cr: 0.01 to 1%, Ti: 0.2% or less, B: 0.0005 to 0.08% or Sb: 0.003 to 0.03% individually Or it is preferable to contain simultaneously.

The steel sheet for hot pressing of the present invention is a steel sheet immersed in an Al-based plating bath containing, by mass%, Al: 80% or more and Si: 3% or less, then gas wiping, and the adhesion amount per one side of the steel sheet There can be produced the Al-Fe alloy plating layer 10 to 200 g / m ^2, by the method the amount of deposition per steel sheet one surface to the Al-Fe alloy plating layer to form a 5 g / m ² or less of Al layer. This Al-based plating bath preferably further contains at least one selected from Cr: 3% or less, Mg: 3% or less, and Zn: 3% or less in mass%. At this time, a steel plate having the above component composition can be used as the steel plate.

The present invention also provides a method for producing a hot press member, characterized in that the hot press steel plate as described above is hot pressed after being heated to a temperature range of Ac ₃ transformation point to 1000 ° C. .

  According to the present invention, a hot press capable of stably obtaining a hot press member having excellent coating adhesion and post-coating corrosion resistance even when the temperature rising rate is increased or the holding time is shortened during heating before hot pressing. Steel plate can be provided. The hot press member manufactured by the method for manufacturing a hot press member of the present invention using the hot press steel plate of the present invention is suitable for an automobile undercarriage member or a vehicle body structure member.

  In the present invention, “%” representing the component content means “% by mass” unless otherwise specified.

1) Hot press steel sheet
1-1) Al-Fe alloy plating layer As described in Patent Document 3, a hot-pressed member with a beautiful appearance and excellent corrosion resistance is produced using a plated steel sheet made mainly of Al. It is effective to make the plating layer an Al—Fe alloy having a high melting point up to the surface before hot pressing. However, as mentioned above, when the plating layer is made into an Al-Fe alloy during heating before hot pressing, if the temperature rise rate is increased or the holding time is shortened for the purpose of improving productivity, the plating layer As a result, it is difficult to obtain a hot press member having excellent coating adhesion and post-coating corrosion resistance.

  Therefore, in the present invention, in the hot-press steel plate that is the material, a plating layer that is alloyed to Al-Fe is formed up to the surface, and it does not depend on the temperature rising rate or holding time during heating before hot pressing. Hot pressing can be performed with the Al-Fe alloy plating layer formed. Therefore, even if the heating rate is increased or the holding time is shortened during heating, a hot press member having excellent coating adhesion and corrosion resistance after coating can be obtained stably.

In the Al-Fe alloy plating layer in the present invention, the composition of the Al-Fe alloy plating layer includes Fe: 25 to 90% and Si: 3% or less, the balance is made of Al and inevitable impurities, and Fe and Al The total content of is not less than 97%, and the amount of adhesion per one surface of the steel sheet needs to be 10 to 200 g / m ² . When the Fe content of the Al-Fe alloy plating layer is less than 25%, there is no Fe on the surface of the Al-Fe alloy plating layer, and the surface is smoothed. If it is not formed sufficiently, the corrosion resistance after coating deteriorates. If it exceeds 90%, the effect of improving the corrosion resistance by Al is remarkably reduced, so that the corrosion resistance after coating becomes poor. Therefore, the Fe content of the Al—Fe alloy plating layer is 25 to 90%. In addition, when the Si content of the Al-Fe alloy plating layer exceeds 3%, the Al-Fe alloy plating layer with an adhesion amount of 10 g / m ² or more is formed by suppressing the alloying reaction between Al and Fe. Therefore, the corrosion resistance after coating becomes poor, so the Si content of the Al-Fe alloy plating layer is 3% or less. Furthermore, if the total content of Fe and Al is less than 97%, a hot press member having excellent coating adhesion and corrosion resistance after coating cannot be stably obtained, so the total content of Fe and Al is 97% or more. And Moreover, if the adhesion amount per one side of the steel sheet of the Al—Fe alloy plating layer is less than 10 g / m ² , the corrosion resistance after coating deteriorates, and if it exceeds 200 g / m ² , the effect is saturated and the cost increases. Therefore, the adhesion amount of the plating layer is 10 to 200 g / m ² .

  Moreover, it is preferable that the Al—Fe alloy plating layer in the present invention further contains at least one selected from Cr: 3% or less, Mg: 3% or less, and Zn: 3% or less. The reason for this is that the Al-Fe alloy plating layer contains at least one selected from Cr: 3% or less, Mg: 3% or less, Zn: 3% or less, thereby further improving post-coating corrosion resistance. Because.

1-2) Al layer In the present invention, an Al layer having an adhesion amount per one surface of a steel sheet of 5 g / m ² or less is formed on the above-described Al—Fe alloy plating layer. If the adhesion amount of the Al layer exceeds 5 g / m ² , a hot press member having excellent coating adhesion and post-coating corrosion resistance cannot be stably obtained. Therefore, the adhesion amount of the Al layer should be 5 g / m ² or less. . Components other than Al of the Al—Fe alloy plating layer described above may be dissolved in the Al layer.

1-3) Base steel plate
In order to obtain a hot pressed member having a strength of 980 MPa or more, for example, C: 0.15-0.5%, Si: 0.05-2.0%, Mn: 0.5-3%, P: 0.1% or less as the base steel plate of the plating layer , S: 0.05% or less, Al: 0.1% or less, N: 0.01% or less, and the steel sheet having a composition composed of Fe and inevitable impurities as the balance can be used. The reason for limitation of each component element is demonstrated below.

C: 0.15-0.5%
C is an element that improves the strength of steel. In order to increase the TS of a hot-pressed member to 980 MPa or more, the amount needs to be 0.15% or more. On the other hand, if the amount of C exceeds 0.5%, the blanking workability of the steel plate as the material will be significantly reduced. Therefore, the C content is 0.15 to 0.5%.

Si: 0.05-2.0%
Si, like C, is an element that improves the strength of steel. In order to increase the TS of a hot-pressed member to 980 MPa or more, the amount needs to be 0.05% or more. On the other hand, when the Si content exceeds 2.0%, the occurrence of surface defects called red scale during hot rolling is remarkably increased, the rolling load is increased, and the ductility of the hot-rolled steel sheet is deteriorated. Furthermore, if the Si content exceeds 2.0%, the plating processability may be adversely affected when a plating process for forming a plating layer mainly composed of Al on the steel sheet surface is performed. Therefore, the Si content is 0.05 to 2.0%.

Mn: 0.5-3%
Mn is an effective element for improving the hardenability by suppressing the ferrite transformation, and also an element effective for lowering the heating temperature before hot pressing because it lowers the Ac ₃ transformation point. is there. In order to exhibit such an effect, the amount needs to be 0.5% or more. On the other hand, when the amount of Mn exceeds 3%, segregation occurs and the uniformity of the characteristics of the raw steel plate and the hot press member decreases. Therefore, the amount of Mn is 0.5 to 3%.

P: 0.1% or less
When the amount of P exceeds 0.1%, segregation occurs and the uniformity of the characteristics of the raw steel plate and hot-pressed member decreases, and the toughness also decreases significantly. Therefore, the P content is 0.1% or less.

S: 0.05% or less
When the amount of S exceeds 0.05%, the toughness of the hot pressed member decreases. Therefore, the S content is 0.05% or less.

Al: 0.1% or less
If the Al content exceeds 0.1%, blanking workability and hardenability of the steel sheet will be reduced. Therefore, the Al content is 0.1% or less.

N: 0.01% or less
If the N content exceeds 0.01%, an AlN nitride is formed during hot rolling or heating before hot pressing, and the blanking workability and hardenability of the raw steel sheet are reduced. Therefore, the N content is 0.01% or less.

  The balance is Fe and inevitable impurities, but for the following reasons, at least one selected from Cr: 0.01 to 1%, Ti: 0.2% or less, B: 0.0005 to 0.08%, Sb: 0.003 to 0.03 % Are preferably contained individually or simultaneously.

Cr: 0.01-1%
Cr is an element effective for strengthening steel and improving hardenability. In order to exhibit such an effect, the Cr content is preferably 0.01% or more. On the other hand, if the Cr content exceeds 1%, the cost is significantly increased, so the upper limit is preferably 1%.

Ti: 0.2% or less
Ti is an element effective for strengthening steel and improving toughness by refining. It is also an element effective for forming a nitride in preference to B, which will be described next, and exhibiting the effect of improving hardenability by solid solution B. However, if the amount of Ti exceeds 0.2%, the rolling load during hot rolling is extremely increased, and the toughness of the hot pressed member is lowered, so the upper limit is preferably 0.2% or less.

B: 0.0005-0.08%
B is an element effective for improving the hardenability during hot pressing and toughness after hot pressing. In order to exhibit such an effect, the B content is preferably 0.0005% or more. On the other hand, if the amount of B exceeds 0.08%, the rolling load during hot rolling is extremely increased, and the martensite phase and bainite phase occur after hot rolling, resulting in cracks in the steel sheet, so the upper limit is It is preferable to set it to 0.08%.

Sb: 0.003-0.03%
Sb has an effect of suppressing a decarburized layer generated in the steel sheet surface layer portion between the time when the steel plate is heated before hot pressing and the time when the steel plate is cooled by a series of processes of hot pressing. In order to exhibit such an effect, the amount needs to be 0.003% or more. On the other hand, if the Sb content exceeds 0.03%, the rolling load increases and the productivity decreases. Therefore, the Sb amount is set to 0.003 to 0.03%.

2) Method for producing hot-pressed steel sheet The hot-pressed steel sheet of the present invention is a base steel sheet having the above component composition, an Al plating bath having an Al concentration of 80% or more and an Si concentration of 3% or less. After immersing in the gas-wiping, the amount of adhesion per side of the steel sheet is 10 to 200 g / m ² and the amount of adhesion per side of the steel sheet on the Al-Fe alloy plating layer is 5 g / m. ^It can be produced by a method of forming an Al layer of ² or less. According to this method, the Al—Fe alloy plating layer is formed on the surface of the steel sheet while the steel sheet is immersed in the Al-based plating bath and immediately after it is pulled up from the plating bath. Immediately after the steel plate is lifted from the plating bath, before the gas wiping, Al-Fe alloy plating layer and molten Al are present in the upper layer. The molten Al present on the surface is gas-wiped to form an Al—Fe alloy plating layer and an Al layer having an adhesion amount of 5 g / m ² or less per one surface of the steel sheet on the Al—Fe alloy plating layer.

Al-based plating baths must have an Al concentration of 80% or more and an Si concentration of 3% or less, which contains 25 to 90% Fe and 3% or less of Si, with the balance being Al and inevitable impurities This is because an Al—Fe alloy plating layer having a total content of Fe and Al of 97% or more is formed. In particular, since Si suppresses the alloying reaction between Al in the plating bath and Fe in the steel sheet, the Si concentration in the Al plating bath is 3% or less in order to form an Al-Fe alloy plating layer of 10 g / m ² or more. It is necessary to. In addition, this plating bath usually unavoidably contains 5% or less of Fe eluted from the steel sheet, but this is allowed in the present invention. Furthermore, it is preferable that this Al-based plating bath contains at least one selected from Cr: 3% or less, Mg: 3% or less, and Zn: 3% or less. By containing at least one selected from Cr: 3% or less, Mg: 3% or less, Zn: 3% or less in the Al-based plating bath, the above Cr: 3% or less, Mg: 3% This is because an Al—Fe alloy plating layer containing at least one selected from Zn: 3% or less is formed.

In order to set the Fe content of the Al-Fe alloy plating layer to 25 to 90% and the adhesion per one side of the steel sheet to 10 to 200 g / m ² , the temperature of the Al-based plating bath should be increased, and the Al-based plating bath for the steel sheet. It is preferable to increase the immersion time. The temperature of the Al plating bath is preferably 670 ° C. or higher. More preferably, it is 680 ° C. or higher, and further preferably 690 ° C. or higher. The immersion time of the steel sheet in the Al plating bath is preferably 0.1 seconds or longer. More preferably, it is 0.2 second or more, and further preferably 0.3 second or more. Examples of intermetallic compounds constituting the Al—Fe alloy plating layer include FeAl ₃ , Fe ₂ Al ₅ , FeAl ₂ , FeAl, and Fe ₃ Al.

In order to make the adhesion amount of the Al layer per one side of the steel sheet 5 g / m ² or less, it is preferable to increase the flow rate of the wiping gas. Preferably, it is 300 L (liter) / min or more, more preferably 400 L / min or more, further preferably 500 L / min or more, and further 1000 L / min or more. As the gas used for wiping, it is preferable to use an inert gas such as N ₂ gas. Also, the amount of Al layer deposited can be adjusted by other conditions such as gas wiping gas pressure, nozzle shape, distance between nozzle and steel plate, distance between plating bath surface and wiping device, line speed, etc. It is preferable to appropriately determine the conditions so that the adhesion amount is as follows.

3) Manufacturing method of hot-pressed member The above-described hot-pressed steel sheet of the present invention is heated to a temperature range of Ac ₃ transformation point to 1000 ° C and then hot-pressed to become a hot-pressed member. The reason for heating above the Ac ₃ transformation point before hot pressing is to make the steel structure austenitic, to form a hard phase such as martensite phase by rapid cooling during hot pressing, and to increase the strength of the member. is there. The upper limit of the heating temperature is set to 1000 ° C. because when the temperature exceeds 1000 ° C., the austenite structure becomes coarse and the toughness of the hot pressed member deteriorates. In addition, the heating temperature here means the highest temperature reached of the steel sheet.

  Since the steel sheet for hot pressing of the present invention has an Al-Fe alloy plating layer formed in advance, the heating rate is increased and the holding time is within the range in which the base steel sheet can be austenitized during heating before hot pressing. Can be shortened. The minimum heating rate and holding time required for the austenitization of the base steel sheet depend on the composition and structure of the steel sheet, but for steel sheets with the above composition, the heating rate is 150 ° C / second and the holding time. Even at 0 seconds, austenite can be formed, and productivity can be remarkably improved.

  Examples of the heating method before hot pressing include heating by an electric furnace or a gas furnace, flame heating, energization heating, high frequency heating, induction heating, and the like. In particular, energization heating, high frequency heating, induction heating, and the like are suitable for increasing the rate of temperature increase.

As a base steel sheet, in mass%, C: 0.23%, Si: 0.25%, Mn: 1.2%, P: 0.01%, S: 0.01%, Al: 0.03%, N: 0.005%, Cr: 0.2%, Ti: A cold-rolled steel sheet containing 0.02%, B: 0.0022%, Sb: 0.008%, the balance being composed of Fe and inevitable impurities, an Ac ₃ transformation point of 820 ° C, and a thickness of 1.6 mm is used. It was. The surface of this cold-rolled steel sheet is immersed for 0.5 to 30 seconds in a molten Al-based plating bath at a temperature of 680 to 720 ° C containing 1% Fe, the concentrations of Al and Si shown in Table 1, and Cr, Mg or Zn. Then, immediately after pulling up from the plating bath, N ₂ gas wiping was performed at a flow rate of 1600 L (liter) / min to produce hot-press steel plates No. 1-16. In addition, as conventional examples, steel plates No. 17 to 19 for hot pressing in which N ₂ gas wiping was performed at a flow rate of 200 L / min immediately after pulling up from the plating bath were produced.

The steel sheet for hot pressing produced in this way was heated to the maximum temperature shown in Table 1 at the average heating rate shown in Table 1 by the direct current method, and held for the holding time shown in Table 1. It was sandwiched between molds and cooled at a cooling rate of 50 ° C./second, and the following coating adhesion and post-coating corrosion resistance were evaluated.
Paint adhesion: A sample was taken from the steel sheet for hot press produced, and after chemical conversion treatment was performed under standard conditions using PB-L3020 made by Nihon Parkerizing Co., Ltd., electrodeposition paint GT-10 made by Kansai Paint Co., Ltd. The electrodeposition was applied and baked to prepare a coating specimen having an electrodeposition coating film with a thickness of 20 μm. Then, a cut that reaches the cross section (10 x 10 pieces, 1 mm interval) of the steel substrate with a cutter knife is applied to the coating film of this test piece, and a cross section tape peeling test is performed in which the adhesive tape is used to attach and peel. It was. Evaluation was made according to the following criteria, and if it was ○, the object of the present invention was satisfied.
○: No peeling of coating film ×: No peeling of coating film Corrosion resistance after painting: After applying a cross cut to the coating film with a cutter knife on a coating test piece prepared in the same manner as in the case of the above coating adhesion, JIS Z 2371 -2000 salt water spray test, tape peel test to stick and peel with adhesive tape after 480 hours, measure the maximum peel width on one side of cut wound, and evaluate according to the following criteria, ○, △ If so, the object of the present invention was satisfied.
○: Maximum peel width ≤ 3mm
Δ: 3 mm <maximum peeling width ≦ 5 mm
×: 5 mm <maximum peel width The results are shown in Table 1. In the steel plate for hot pressing No. 1 to 16 of the present invention, the average temperature rising rate is changed in the range of 10 to 150 ° C./second, and heating is performed with a holding time of 0 seconds, or the average temperature rising rate is 10 ° C. Even when heated at a holding time of 300 seconds, excellent coating adhesion and post-coating corrosion resistance are obtained, and it is possible to increase the heating rate and shorten the holding time during heating before hot pressing. It can be seen that it is. On the other hand, in the steel sheet No.17-19 for hot pressing, which is a comparative example in which the Fe content and adhesion amount of the Al-Fe alloy plating layer are out of the scope of the present invention, the average heating rate is 50 ° C./second, It can be seen that heating at 0 seconds is inferior to either coating adhesion or post-coating corrosion resistance, making it difficult to increase the heating rate and shorten the holding time. In addition, Al-10% Si plated steel sheets (No. 20-24) in which an Al layer exceeding 5 g / m ² is present in the upper layer of the Al-Fe alloy layer that has been used as a steel sheet for hot pressing in the past When the average heating rate is 10 ° C / second and the holding time is 300 seconds, excellent coating adhesion and post-coating corrosion resistance can be obtained, but even with a holding time of 0 seconds or a holding time of 300 seconds When the average heating rate is 50 ° C./second or more, it is found that it is difficult to increase the heating rate or shorten the holding time because it is inferior to coating adhesion or post-coating corrosion resistance.

  In this example, processing by hot pressing is not actually performed. However, as described above, coating adhesion and corrosion resistance after coating depend on the state of the plating layer before hot pressing. As a result, it is possible to evaluate the coating adhesion and the post-coating corrosion resistance of the hot press member.

Claims (9)

On the surface of the steel sheet, by mass%, Fe: 25 to 90% and Si: 3% or less, the balance is made of Al and inevitable impurities, and the total content of Fe and Al is 97% or more, and Al-Fe alloy plating layer adhesion amount of 10 to 200 g / m ² per a feature that the amount deposited per steel sheet one surface to the Al-Fe alloy plated layer has a 5 g / m ² or less of Al layer Steel sheet for hot pressing.   The Al-Fe alloy plating layer further includes at least one selected from Cr: 3% or less, Mg: 3% or less, or Zn: 3% or less by mass%. The steel plate for hot press as described.   The base steel plate of the Al-Fe alloy plating layer is in mass%, C: 0.15-0.5%, Si: 0.05-2.0%, Mn: 0.5-3%, P: 0.1% or less, S: 0.05% or less, Al: 3. The hot-press steel sheet according to claim 1, wherein the hot-press steel sheet contains 0.1% or less and N: 0.01% or less, and the balance has a composition composed of Fe and inevitable impurities.   The base steel plate of the Al-Fe alloy plating layer further contains at least one selected from Cr: 0.01 to 1%, Ti: 0.2% or less, B: 0.0005 to 0.08% by mass%. 4. A steel sheet for hot pressing according to claim 3.   5. The hot-press steel sheet according to claim 3, wherein the base steel sheet of the Al—Fe alloy plating layer further contains Sb: 0.003 to 0.03% by mass%. After immersing the steel sheet in an Al-based plating bath containing Al: 80% or more and Si: 3% or less in mass%, gas wiping is performed, and the amount of adhesion per one side of the steel sheet is 10 to 200 g / m ² . A method for producing a steel sheet for hot pressing, comprising forming an Fe alloy plating layer and an Al layer having an adhesion amount per one surface of the steel sheet of 5 g / m ² or less on the Al-Fe alloy plating layer.   The Al-based plating bath further comprises at least one selected from Cr: 3% or less, Mg: 3% or less, Zn: 3% or less by mass%. The manufacturing method of the steel plate for hot press of description.   8. The method for producing a steel sheet for hot pressing according to claim 6 or 7, wherein a steel sheet having the component composition according to any one of claims 3 to 5 is used as the steel sheet. A method for producing a hot press member, comprising: hot pressing the steel sheet for hot pressing according to any one of claims 1 to 5 to a temperature range of Ac ₃ transformation point to 1000 ° C. .