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Hot Stamped Product And Process For Producing Hot Stamped Product

Abstract: Provided are: a hot stamped product which can be obtained by hot stamping an electro-galvanized steel sheet having a low coating weight through use of a rapid heating means such as electrical heating induction heating or the like at a high efficiency without causing the adhesion of the plating to a die and which can ensure high coating adhesion even without conducting post treatment such as shot blasting after the hot stamping; and a process for producing the same. A hot stamped product obtained by hot stamping an electro galvanized steel sheet which has a prescribed composition and which has been plated with electrolytic zinc at a coating weight of 5 to less than 40g/m per side wherein: the plating layer of the hot stamped product contains 0 to 15g/m of a Zn Fe intermetallic compound with the balance consisting of an Fe Zn solid solution phase; and 1×10 to 1×10 particles having a mean diameter of 10nm to 1µm are present in the plating layer of the hot stamped product per millimeter of the length of the plating layer.

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Patent Information

Application #
Filing Date
14 December 2015
Publication Number
23/2016
Publication Type
INA
Invention Field
METALLURGY
Status
Email
Parent Application
Patent Number
Legal Status
Grant Date
2020-08-02
Renewal Date

Applicants

NIPPON STEEL & SUMITOMO METAL CORPORATION
6 1 Marunouchi 2 chome Chiyoda ku Tokyo 1008071

Inventors

1. AKIBA Kojiro
c/o Nippon Steel & Sumitomo Metal Corporation 6 1 Marunouchi 2 chome Chiyoda ku Tokyo 1008071
2. KONDO Yusuke
c/o Nippon Steel & Sumitomo Metal Corporation 6 1 Marunouchi 2 chome Chiyoda ku Tokyo 1008071
3. KIKUCHI Yoshitaka
c/o Nippon Steel & Sumitomo Metal Corporation 6 1 Marunouchi 2 chome Chiyoda ku Tokyo 1008071
4. KATO Satoshi
c/o Nippon Steel & Sumitomo Metal Corporation 6 1 Marunouchi 2 chome Chiyoda ku Tokyo 1008071

Specification

DESCRIPTION HOT STAMP MOLDED BODY, AND METHOD FOR PRODUCING HOT STAMP MOLDED BODY Technical Field [0001] The present invention relates to a hot stamp molded body, which is a component molded and quenched at the same time by hot press molding, and applied mainly to a skeletal component, a reinforcing component, a chassis component, or the like of an automobile body, and a method for producing the same. Background Art |"0002| In recent years, for the sake of weight reduction of an automobile leading to improvement in fuel efficiency, weight reduction of a steel sheet to be used by increasing the strength of a steel sheel has been endeavored. However, when the strength of a slcel sheet lo be used is increased, there occurs a problem of occurrence of scoring or steel sheet fracture during molding, or instability of the shape of a molded item due lo a spring-back phenomenon.[0003J As a technology for producing a high strength component, there is a method by which the strength is increased after press molding, instead of pressing a high strength steel sheet. An example of the same is hot stamp molding. Hot stamp molding is a method by which a slcel sheel to be molded is heated in advance for facilitating molding, and subjected to press molding keeping the high temperature as also described in Patent Literature 1, and 2. As a molding material therefor, a qucnchablc steel grade is selected, and a higher strength is achieved by quenching on the occasion of cooling after pressing. By this procedure, the strength of a steel sheel can be enhanced at the same lime as press molding without conducting a separate heal treatment step for strength increase after press molding. [0004] However, since hot stamp molding is a molding method by which a healed steel sheet is processed, formation of a Fc scale by surface oxidation of the sleel sheet is unavoidable. Even in a case in which a steel sheet is heated in a non-oxidizing atmosphere, when the sheet is taken out from a healing furnace for press molding, a Fc scale is formed on a surface due lo exposure to the air. Further, healing in such a non-oxidi/.ing atmosphere is cosily. 10005J In a case in which a Fc scale is formed on a sleel sheet surface during heating, the Fe scale may be peeled oJVduring pressing to slick lo a mold, so as lo develop such a problem thai the productivity of pressing may be impaired, or the Fc scale remains on a product after pressing lo disfeature the appearance. Further, in a case in which such an oxide film remains, since a Fe scale on a surface of a molded item is poor in adhesiveness, when a conversion 1 treatment and painting are performed on a molded item without removing the scale, a problem in paint adhesiveness will be developed. [0006] Therefore, ordinarily a Fe scale is removed by applying a sandblasting treatment or a shotblasting treatment after hot stamping, and thereafter a conversion treatment or painting is carried out as described in Patent Literature 3. However, such a blasting treatment is troublesome, and impairs remarkably the productivity of hot stamping. Further, a strain may be generated in a molded item. [0007] Meanwhile, a technology, by which hot stamping is conducted on a zinc-based coated steel sheet or an aluminum coated steel sheet, while suppressing Fe scale generation, has been disclosure in Patent Literature 4 to 6. Further, a technology for preforming a hot press on a coated steel sheet is also disclosed in Patent Literature 7 to 9. [0008] Further, a method for producing a zinc-based coated steel sheet is disclosed in Patent Literature 10 and 11. [0009] Patent Literature 1: Japanese Patent Application Laid-Open (JP-A) No. 1107-116900 Patent Literature 2: JP-A No. 2002-102980 Patent 1 ,iteraluie 3: JP-A No. 2003-2058 Patent Literature 4: JP-A No. 20.00r3£64.0 Patent Literature 5: JP-A No. 2001-353548 Patent Literature 6: JP-A No. 2003-126921 Patent Literature 7: JP-A No. 2011-202205 Patent Literature 8: JP-A No. 2012-233249 Patent Literature 9: J J'-A No. 2005-74464 Patent Literature 9: JP-A No. 2003-126921 Patent Literature 10: JP-A No. 1104-191354 Patent Literature II: JP-A No. 2012-17495 SUMMARY OF INVENTION Technical Problem j0010J However, in a case in which an aluminum coated steel sheet, especially a hot-dip aluminum coaled sleel sheet is hot-stamped, counter diffusion of a plated layer and a steel matrix material lakes place during sleel sheet healing and an intcrmelallic compound, such as Fe-AI and Fe-Al-Si, is formed al a plating interface. Further, an oxide film of aluminum is formed on a surface of a plated layer. The aluminum oxide film compromises paint adhesiveness, although not so seriously as an iron oxide film, and cannot necessarily satisfy 2 such severe paint adhesiveness as required for an automobile outer plate, a chassis component, etc. Further, it is difficult to form a conversion coating used broadly as a painting surface treatment. [0011] Meanwhile, in a case in which a zinc-based coated steel sheet, especially a hot-dip zinc coated steel sheet is hot-stamped, a Zn-Fe intermetallic compound or a Fe-Zn solid solution phase is formed by counter diffusion of a plated layer and a steel matrix material during steel sheet heating, and a Zn-based oxide film is formed on the outermost surface. The compound, phase, or oxide film does not impair paint adhesiveness or conversion treatability, unlike the aluminum-based oxide film. [0012] In recent years, as a producing process for a steel sheet for hot stamping, a technique by which a steel sheet can be rapidly heated by Joule heating or induction healing has been acquiring popularity. In this case, the total of the temperature elevation time and the retention time at hot stamping is frequently less than 1 min. When a zinc-based eoatcd steel sheet is hot-stamped under such conditions, a soft plated layer sticks lo a mold, which requires frequent maintenance works of a mold, and therefore there has been a drawback in that the productivity is impaired. fOOl 3J An object of the invention is to overcome the above problems and lo provide a hot stamp molded body that can be.produced highly efficiently without causing slicking of plating to a mold, when an cleelrogalvanizcd steel sheet with a light plating weight is hot-stamped using a rapidly heating method such as Joule healing and induction healing, and can secure favorable paint adhesiveness without a posit realmenl such as sholblasling alter hot stamping, as well as a method for producing the same. Solution to Problem 10014] The essentials of the invention arc as follows. 11] A hot stamp molded body produced by hot-stamping an elcctrogalvanized steel sheet comprising as components of a sled sheet, by mass %: C: Si: Ai: Mn: P: S: N: Ti: Nb: from 0.10 lo 0.35%, from 0.01 to 3.00%, from 0.01 lo3.00%, from 1.0 to 3.5%, from 0.001 to 0.100%, from 0.001 lo 0.010%, from 0.0005 to 0.0100%, from 0.000 lo 0.200%, from 0.000 to 0.200%, Mo: from 0.00 to 1.00%, Cr: from 0.00 to 1.00%, V: from 0.000 to 1.000%, Ni: from 0.00 to 3.00%, B: from 0.0000 to 0.0050%, Ca: from 0.0000 to 0.0050%, and Mg: from 0.0000 to 0.0050%, a balance being Fe and impurities, wherein the steel sheet is electrogalvanized on each face with a plating weight not less than 5 g/m2 and less than 40 g/m2; wherein a galvanized layer of the hot stamp molded body is configured with 0 g/m to 15 g/m2 of a Zn-Fe intermetallic compound and a Fe-Zn solid solution phase as a balance, and wherein in the galvanized layer of the hot stamp molded body, 1x10 pes to IxlO4 pes of particulate matter with an average diameter of from 10 nm to 1 um are present per 1 mm length of the galvanized layer. [0015] [2] The hot stamp jnolded body-according to [1] above, wherein the steel sheet comprises, by mass %, one, or two or more kinds of: Ti: from 0.001 to 0.200%, Nb: from 0.001 to 0.200%, Mo: from 0.01 to 1.00%, Cr: from 0.01 to 1.00%, V: from 0.001 to 1.000%, Ni: from 0.01 to 3.00%, B: from 0.0002 to 0.0050%, Ca: from 0.0002 to 0.0050%, or Mg: from 0.0002 to 0.0050%. [0016] [3] The hot stamp molded body according to [1] or [2] above, wherein the particulate matter is one, or two or more kinds of oxides containing one, or two or more kinds out of Si, Mn, Cr or Al. [0017] [4] The hot stamp molded body according to any one of claims [1] to [3] above, wherein the electrogalvanized steel sheet is an electrolytic zinc alloy-coated steel sheet. 4 [0018] [5] A method for producing a hot stamp molded body, in which a steel comprising as components, by mass %: C: Si: Al: Mn: P: S: N: Ti: Nb: Mo: Or: V: Ni: B: Ca: Mg: from 0.10 to 0.35%, from 0.01 to 3.00%, from 0.01 to 3.00%, from 1.0 to 3.5%, from 0.001 to 0.100%, from 0.001 to 0.010%, from 0.0005 to 0.0100%, from 0.000 lo 0.200%, from 0.000 to 0.200%, from 0.00 lo 1.00%, from 0.00 lo 1.00%, from 0.000 to 1.000%, from 0.00 lo 3.00%, from 0.0000 lo 0.0050%, from 0.0000.to 0.0050%.and from 0.0000 lo 0.0050%, a balance being he and impurities, is subjected to a hot rolling step, a pickling step, a cold rolling step, a continuous annealing step, a temper rolling step, and an eleetrogalvani/.ing step lo yield an eleetrogalvani/.ed steel sheet, and the electrogalvani/ed steel sheet is subjeeled to a hot stamp molding *stcp lo produce a hot slamp molded body; wherein in the continuous annealing step, the steel sheet is subjected lo repealed bending at a bending angle of from 90° to 220° (bur or more times during heating of the steel sheet in an atmosphere gas containing hydrogen al from 0.1 volume % lo 30 volume %, and IlaO corresponding lo a dew point of from -70°C to -20"C as well as nitrogen and impurities as a balance at a sheet temperature within a range of from 350°C to 700°C, wherein in the elcclrogalvanizing step, each face of the steel sheet is eleclrogalvanized with a plating weight of not less than 5 g/m and less than 40 g/m', and wherein in the hoi slump molding step, the electrogalvani/ed steel sheet is healed with an average tcnijieiaturc elevation rate of 50°C/see or more to a temperature range of from 700°C lo 1100°C, hol-slampcd within 1 min from the initiation of the temperature elevation, and thereafter cooled to normal temperature. [0019] 5 [6] The method for producing r a hot stamp molded body according to [5] above, wherein the steel comprises, by mass %, one, or two or more kinds of: Ti: from 0.001 to 0.200%, Nb: from 0.001 to 0.200%, Mo: from 0.01 to 1.00%, Cr: from 0.01 to 1.00%, V: from 0.001 to 1.000%, Ni: from 0.01 to 3.00%, B: from 0.0002 to 0.0050%, Ca: from 0.0002 to 0.0050%, and Mg: from 0.0002 to 0.0050%. Advantageous Effects of Invention [0020J According lo the invention, a hot stamp molded body that can be produced highly efficiently without causing slicking of plating lo a mold, when an zinc coated steel sheet with a light plating weight is hot-stamped using a rapidly healing method such as Joule heating and induction healing, and can secure favorable paint adhesiveness without a posllrealmenl such as shotblasting after hot stamping, as well as a method for producing the same can be provided. BRIEF DESCRIPTION OF DRAWINGS [0021] Fig. I is a diagram showing a heal history during heating for hot stamping, increase in a Fc concentration in a plated layer, and a phase change of a tissue. Fig. 2 is a graph showing a relationship between the remaining amount of a Zn-Fc intennetallic compound after heating for hot stamping and the degree of sticking ofplaling to a mold. Fig. 3A is a schematic diagram showing a relationship between the remaining amount of a Zn-Fc intennetallic compound after heating for hot stamping and the structure of a plated layer in a case in which a residual Zn-Fc inlermetallie compound is not present. big. 313 is a schematic diagram showing a relationship between the remaining amount of a Zn-Fc inlermetallie compound after heating for hot stamping and the structure of a plated layer in a case in which the remaining amount of a Zn-Fc intennetallic compound is 15 g/m' or less. Fig. 3C is a schematic diagram showing a relationship between the remaining amount of a Zn-Fc inlermetallie compound after heating for hot stamping and the structure of a plated layer in a ease in which the remaining amount of a Zn-Fe intennetallic compound is beyond 6 15g/m2. Fig. 4 is a graph showing a relationship between a Zn plating weight before hot stamping and the amount of a Zn-Fe intermetallic compound after plating. Fig. 5 is a graph showing a relationship between the formation amount of an oxide inside a steel sheet and the paint adhesiveness. Fig. 6Ais a graph showing a relationship between the number of 90° bending during heating and the formation amount of an oxide inside a steel sheet, with respect to the number of bending of 0, 1, 2, and 3 times. Fig. 6B is a graph showing a relationship between the number of 90° bending during heating and the formation amount of an oxide inside a steel sheet, with respect to the number of bending of 4, 5, and 7 times. Fig. 6C is a graph showing a relationship between the number of 90° bending during heating and the formation amount of an oxide inside a steel sheet, with respect to the number of bending of 9, and 10 times. Fig. 7 is a graph showing a relationship between the bending angle inflicted on a sample during healing and the formation amount of an oxide inside a steel sheet. DESCRIPTION OF EMBODIMENTS [0022] The invention will be described in detail below. A numerical range expressed herein by "x to y" includes, unless otherwise specified, the values of x and y in the range as the minimum and maximum values respectively. [0023J The inventor conducted hot stamp molding using cleclrogalvanizcd steel sheets with a plurality of plating weights under various heating conditions. As the results, it has been made clear that slicking of plating to a mold can be suppressed with a structure, in which the amount of a Zn-Fe intcrmetallie compound in a plated layer after heating for hot stamping is controlled within 0 g/m to 15 g/m , and a balance is a Fe-Zn solid solution phase, wherein a particulate matter with a predetermined size is present in the plated layer in an appropriate amount. The details will be described below. 10024] Since a Zn-Fe intcrmetallie compound is soft in a high temperature condition in which a hot stamp molding is conducted, the Zn-Fe intermetallic compound may slick to a mold, when the Zn-Fe intcrmetallie compound receives a sliding action during pressing. Therefore, as shown in Fig. 1, the Fe conccnlialion in a plalcd layer is increased by promoting a Zn-Fc alloying reaction by healing. When a structure, in which a Zn-Fe intermetallic compound composed of a 1' phase (FC3Z1110) is not present in a steel sheet surface and only a Fe-Zn solid solution phase composed of an u-Fc phase is present (the solid line arrow in Ihe 7 Figure), is formed by the above means, sticking of plating to a mold can be suppressed. Further, it has been known that, even when a Zn-Fe intermetallic compound remains, insofar as the remaining amount is 15 g/m or less, such severe sticking of plating to a mold as disturbs production does not occur. [0025] Next, a relationship between the remaining amount of a Zn-Fe intermetallic compound after heating for hot stamping and the degree of sticking of plating to a mold is shown in Fig. 2. When an electrogalvanized steel sheet with a plating weig ht of 30 g/m2 was heated to 850°C, then cooled to 680°C, and hot-stamped, the remaining amount of a Zn-Fe intermetallic compound was regulated by adjusting the retention time at 850°C. Then, the relationship between the remaining amount of a Zn-Fe intermetallic compound and the sticking to a mold after heating for hot stamping was determined. Based on the remaining amount of a Zn-Fe intermetallic compound after hot stamping, evaluation of the remaining amount of a Zn-Fc intermetallic compound was graded in; a double circle: (here is no need for mold maintenance work (slicking of plating to a mold is extremely insignificant), a circle: adhered substances can be simply wiped off with rags, or the like (sticking of plating to a mold is insignificant), and a cross mark: polishing of a mold is necessary (slicking of plating lo a mold is significant), wherein a double circle and a circle were deemed as acceptable as on-spccillcation. As obvious from Fig. 2, when the remaining amount of a Zn-Fe intermetallic compound exceeds 15 g/m', the degree of sticking of plating to a mold becomes severer. [0026] The reasons, although based on a presumption, are described referring to Fig. 3A lo Fig. 3G. Fig. 3 lo Fig. 3C are schematic diagrams showing a relationship between the remaining amount of a Zn-Fc intermetallic compound after heating for hot stamping and the structure of a plated layer. When the remaining amount of a Zn-Fc intermetallic compound is 15 g/m' or less, a Zn-Fe intermetallic compound does not cover any surface of a steel sheet, or remains in a stale where the compound is present in small pieces as shown in Fig. 3A and Fig. 313, and therefore sticking of plating to a mold presumably occurs hardly. Meanwhile, when the remaining amount of a Zn-Fc intermetallic compound exceeds 15 g/m , a Zn-Fc inlcrmctallie compound covers the entire surface of a steel sheet as shown in Fig. 3C, and therefore slicking of plating lo a mold presumably occurs easily. [0027J In this regard, after heating for hoi stamping, there is only a slight or almost no change in the amount of a Zn-Fc intermetallic compound before and after hot stamping (pressing). Consequently, the amount of a Zn-Fe intermetallic compound after heating for hot stamping may be examined after cooling before hot stamping (pressing), or may be examined on a formed body after hoi stamping (pressing). In other words, when the amount 8 ofa Zn-Fe intermetallic compound remaining in a plated layer ofa hot-pressed body is from 0 g/m2 to 15 g/m2, sticking of plating to a mold can be suppressed. [0028] Further, in recent years in need of rapid heating for productivity improvement, a technique for heating rapidly a steel sheet, such as Joule heating and induction heating, has been introduced in a producing process for a hot stamp molded body. In this case, the temperature elevation rate can be 50°C/s or more on the occasion of hot stamping, and in most cases the total of temperature elevation time and retention time is 1 min or less. In order to reduce the remaining amount ofa Zn-Fe mtermetallic compound to 15 g/m or less near the outer surface layer of a steel sheet after hot stamping, it is required to adjust the plating weight according to the heating time or the heating temperature. [0029] In order to mitigate sticking of plating to a mold, the amount ofa Zn-Fe intermetallic compound in a plated layer after heating is preferably 0 g/m . However, when the remaining amount ofa Zn-Fe intermetallic compound is 15 g/m or less, a Zn-Fe intermetallic compound is in a formation stale, in which the compound does not cover the entire surface ofa steel sheet, lather remains in small pieces, and sticking of plating to a mold as severe as obstructive to production does not occur. The remaining amount ofa Zn-Fe intermetallic compound is preferably 10 g/m or less. [0030] An amount of a Zn-Fc inicrmctallie compound in a plated layer allcr healing is determined by constant current electrolysis of the sample at 4 mA/cm in a 150 g/L aqueous solution of NH4CI using a saturated calomel electrode as a reference electrode. Namely, a weight ofa Zn-Fe intermetallic compound per unit area can be determined by measuring a time period, when the electric potential is -800 mV vs. SCli or less during execution of the constant current electrolysis, and deriving a quantity of electricity flown per unit area during the time period. Meanwhile, although not quantitatively, existence or nonexistence ofa Zn-Fe intermetallic compound can be roughly estimated by observation ofa backscattered electron image. [0031] In a production process ofa hot stamp molded body, a steel sheet is ordinarily healed to approx. from 700°C to 1100°C. It has come to be known, in a case in which a sheet is heated to the steel sheet temperature by the rapid heating, that the remaining amount ofa Zn-Fe intermetallic compound disadvantageous])' exceeds 15 g/m . This is because the total duration of heating is short to follow the dolled line pattern in Fig. 1 so that a Fe-Zn solid solution phase cannot be secured sufficiently, and rather a Zn-Fe inlermetallic compound lends lo be formed. Additionally, in the ease of conventional radiant heat transfer healing, there appears a temperature gradient for heat transfer from Ihe surface ofa steel sheet to Ihe inside so dial there appears a gradient in Ihe thickness direction ofa plated layer with respect 9 to formation of a Zn-Fe intermetallic compound, however in the case of rapid heating by Joule heating, induction heating, or the like, since a heating current flows along the steel sheet surface, the steel sheet surface, namely the entire plated layer is rapidly and actively heated, so that a Zn-Fe intermetallic compound is presumably formed uniformly in the thickness direction of the plated layer. [0032] Consequently, in order to avoid generation of a Zn-Fe intermetallic compound, subject to conditions, such as a heating temperature and a retention time, a strategy for avoidance of increase in a generation amount of a Zn-Fe intermetallic compound was decided such that the plating weight of an original plated layer was tried to be reduced and its preferable range was narrowed. [00331 Fig. 4 shows a relationship between a plating weight before heating for hot stamping and the amount of a Zn-Fe intermetallic compound after heating for hot skimping. The above is a result with respect to a steel sheet, which was heated in the air at a rate of 50°C/s to a temperature of 950°C, maintained there for 2 s, then cooled at a rale of 20°C/s to 680°C, and pressed. [0034J When a plating weight is 40 g/m' or more, a Zn-Fe intermetallic compound in a plated layer can be hardly decreased to 15 g/m or less. Therefore, in the present process, a plating weight is required to be Jess, than 40 g/m . Since a plating weight is required to be 5 g/m or more from a viewpoint of suppression of scaling during healing for hot stamping, this value is deemed as the lower limit. The plating weight is preferably from 10 g/m to 30 g/m . Meanwhile, in a case in which clectrogalvanizcd coating is electric zinc alloy plating, the amount of Zn in a plated layer is from the same viewpoints from 5 g/m to 40 g/m , and preferably from 10 g/m7' to 30 g/m2. [00351 In this regard, for measuring a plating weight and a Zn amount, a broadly prevailing analytical method for a plating weight and a Zn amount can he applied without a hitch, for example, a measurement of a plating weight and a Zn amount can be performed by dipping a plated steel sheet in a hydrochloric acid solution containing hydrochloric acid at a concentration of 5% and a corrosion inhibitor for pickling at a temperature of 25°C until the plating is dissolved, and analyzing the obtained solution by a TCP emission analyzer. [0036J Although an clectrogalvanizcd coating may be either of electric zinc plating, and electric zinc alloy plating, electric zinc alloy plating is preferable. Namely, a steel sheet for hot slam]) molding is preferably an electrolytic zinc alloy-coaled slecl sheet. [00371 However, in the ease of clectrogalvanizcd coating with a light plating weight, when 10 an electrogalvanized steel sheet with a small plating weight was heated by a rapidly heating method as described above and subjected to hot stamp molding, there arose a new problem that the paint adhesiveness of a formed body after hot stamping became inferior. [0038] The reasons behind the above are presumed as follows. When a heating time is short and the plating weight is small, a Zn-based oxide film to be formed during heating on the outermost surface of a plated layer becomes also thin, and a Zn-Fe alloying reaction advances rapidly before a Zn-based oxide film grows sufficiently so that most part of Zn in the plated layer is consumed in a Fe-Zn solid solution phase. Presumably, a Zn-based oxide film can grow when a plated layer is in a form of Zn-Fe intermetailic compound, in which the Zn activity is relatively high, but when a plated layer comes to take a form of Fe-Zn solid solution phase, the growth is not any more possible due to increase in the Fe activity and decrease in the Zn activity. In (he case of a thin Zn-bascd oxide film, when a steel sheet receives a sliding action during pressing, a Fe-Zn solid solution phase is exposed easily where Fe scales are formed presumably, and the paint adhesiveness becomes inferior. 10039] In order to improve the paint adhesiveness of a formed body, the inventors carried out hot slumping tests using electrogalvanized sleel sheets produced under various conditions. As the result, it was found, through observation of a sleel sheet cross-section tissue of a formed body having favorable, paint adhesiveness, that a Zn-bascd oxide film was not peeled oifand could remain mostly on a steel sheet surface, when there were a certain atnount of fine particulate matters with an average diameter of 1 pm or less. Further, it was confirmed that the paint adhesiveness ol such a hot stamp molded body was superior to a case where a particulate mailer is not present. J 0040] The particulate matters were analyzed lo find that they were mostly an oxide containing an easily oxidi/ablc element contained in steel, such as Si, Mn, Cr, and Al. To study the phenomenon thai the adhesiveness of a Zn-based oxide film is superior, when there are a certain amount of fine particulate matters (mainly an oxide as described below) in a plated layer, the tissue of a steel sheet which was heated at the same condition as for hot stamp molding but not pressed and directly cooled was investigated. As the result, it has been known thai when there are a certain amount of fine particulate matters in a plated layer, moderate ruggedness appears at an interface between a Zn-bascd oxide film and a plated layer. Since it was known that when an interface had a complex morphology, a keying effect at the interface developed generally lo improve the paint adhesiveness, it was presumed that the adhesiveness of a Zn-based oxide film was enhanced similarly by a keying effeel, and exposure of a Fe-Zn solid solution phase was suppressed during pressing and therefore generation of the Fe scale was avoided lo enhance the paint adhesiveness. II [0041] A particulate matter causing formation of moderate ruggedness at the interface is considered as follows. It is presumed from the component and the generation amount that a particulate matter is an oxide of not an impurity element in a plated layer, but mainly an element contained in steel, which has been conceivably present before heating for hot stamping at an interface between a plated layer and a steel matrix, or inside a steel matrix. Further, it is believed that the oxide has been formed in a steel sheet production process during annealing of a steel sheet after cold rolling. It is believed that, when an oxide is present at an interface between a plated layer and a steel matrix, the oxide exhibits generally a barrier effect so as to suppress locally a Zn-Fe alloying reaction during healing for hot stamping. It is, however, further believed that in the case of a line particulate oxide with an average diameter of 1 um or less, the suppression effect on a Zn-Fe alloying reaction is weak, and therefore influence of an oxide at an interface on a Zn-Fe alloying reaction is small. [0042] Meanwhile, when an oxide is formed inside a steel matrix, by pinning a crystal grain boundary near a steel sheet surface during annealing, growth of a crystal grain is suppressed. When a crystal grain near a steel sheet surface is small, and the number of crystal grain boundaries is large, the Zn-Fe.alloying reaction rale becomes high. In olher words, where an inside oxide is present, a Zn-Fe alloying reaction is conceivably becomes high locally. [0043] Examples of the oxide mentioned here include, but are not particularly limited to, oxides containing one, or two or more kinds out of Si, Mn, Cror Al. Specific examples include single oxides, such as MnO, M11O2, Mn?.O.j, M113O4, SiC>2, AI2O3, and O2O3, and single oxides with a non-stoichiomctric composition corresponding to each of these; complex oxides, such as FcSi(>t, I't^SKX), MnSiCh, MnzSiO^ AIM11O3, FcCi^O/i, Fe?.CrO-i, MnCr?.05 O y CM ( 1 U-, en en Example < 0 0 y 00 en O MExample < < 0 y 0 0 0 X CO Example < 0 y 0 y en 0 d W 00 en Example < 0 0 y V3 en 0 d K-J Example < << 0 y 0 en r-i '/1 0 0 S 0 [0104] [Table 5] Test Number 41; 42 43 44' 45' 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 61 Steel grade N 0 P Q R S T A A A A A A A A A A A A A A A A A A A A Plated layer of hot press formed body Amount of Zn:Fe intermetallic compound (g/m2) 3.5 0.0 0.0 0.0 0.0 0.0 6.9 0.0 0.0 1.4 5.1 0.0 3.4 0.0 0.0 0.0 0.0 0.0 0.0 2.3 4.3 0.0 4.7 0.0 0.0 0.0 0.0 Average diameter of particulate matter (nm) 25 27 26 20 16 18 22 18 18 23 22 24 28 22 19 13 26 16 15 21 18 19 22 19 26 11 21 Number of particulate matter log (pcs/mm) 3.2 2.3 3.8 1.7 1.6 2.2 3.1 2 2.2 2.8 2.4 3.2 3.7 3.8 1.7 1.6 3.8 1.5 2.4 2.6 2.4 3.1 3.7 3.6 1.2 1.1 3.4 Evaluation Plating stuck to mold Existent or not No No V- No ;•. NO v: No ;•• No '•- No No No No No No No No No No NO' No No No No No No No No No No Formation of Fe scale Existent or not No No No No No No No No No No No No No No No No No No No No No No No No No No No Paintin adhesiven AA AA A AA AA AA A AA AA AA AA AA A A AA AA A AA AA AA AA AA AA AA AA A AA 32 68 69 70 71 72 73 74 A A A A A A A 17.4 18 1.7 Unevaluable due to formation of Fe scales over the entire surface 0.0 0.0 0.0 0.0 22.0 8 4 12 16 20 0.4 0.2 0.4 0.3 1.8 Yes Fe scale sticking No No No No Yes No Yes Yes Yes Yes Yes No AA C C c c c AA 33 [0105] Although the invention has been described in terms of the preferred Embodiments and Examples according to the invention, such Embodiments and Examples are just an example within the range of the essentials of the invention, and addition, omission, replacement, and other alternations of the constitution without departing from the spirit of the invention are possible. Namely, the foregoing description is not intended to limit the scope of the invention, and various alterations are no doubt possible within the scope of the invention. [0106] The entire contents of the disclosures by Japanese Patent Application No. 2013-122351 are incorporated herein by reference. All the literature, patent application, and technical standards cited herein are also herein incoiporated to the same extent as provided for specifically and severally with respect to an individual literature, patent application, and technical standard to the effect that the same should be so incorporated by reference. CLAIMS [Claim 1] Ahot stamp molded body produced by hot-stamping an electrogalvanized steel sheet comprising as components of a steel sheet, by mass %: C: Si: Al: Mn: P: S: N: '11: Nb: Mo: Cr: V: Ni: B: Ca: Mg: from 0.10 to 0.35%, horn 0.01 to 3.00%, from 0.01 to 3.00%, from 1.0 to 3.5%, horn 0.001 to 0.100%, fiom 0.001 to 0.010%, from 0.0005 to 0.0100%, from 0.000 to 0.200%, from 0.000 to 0.200%, from 0.00 to 1.00%, from 0.00 to 1.00%, from 0.000 to 1.000%, from 0.00 to 3.00%, from 0.0000 to 0.Q050%, from 0.0000 to 0.0050%, and from 0.0000 to 0.0050%, a balance being l;e and impurities, wherein the steel sheet is electrogalvanized on each face with a plating weight not less than 5 g/m' and less than 40 g/ni ; wherein a galvanized layer of the hot stamp molded body is configured with 0 g/m2 to 15 g/m2 of a Zn-Ve inlermetallic compound and a Vc-Zn solid solution phase as a balance, and wherein, in the galvanized layer of the hot stamp molded body, 1x10 pes to IxIO4 pes of particulate matter with an average diameter of from 10 nni to 1 pin arc present per 1 mm length of the galvanized layer. [Claim 2j The hot stamp molded body according to claim 1, wherein the steel sheet comprises, by mass %, one, or two or more kinds of: Ti: from 0.001 to 0.200%, Nb: from 0.001 to 0.200%, Mo: from 0.01 to 1.00%, Cr: from 0.01 to 1.00%, 35 V: from 0.001 to 1.000%, Ni: from 0.01 to 3.00%, B: from 0.0002 to 0.0050%, Ca: from 0.0002 to 0.0050%, or Mg: from 0.0002 to 0.0050%. [Claim 3] The hot stamp molded body according to claim 1 or 2, wherein the particulate matter is one, or two or more kinds of oxides containing one, or two or more kinds out of Si, Mn, Cr or Al. [Claim 4] The hot stamp molded body according to any one of claims 1 to 3, wherein the electrogalvanized steel sheet is an electrolytic zinc alloy-coated steel sheet. [Claim 5] A method for producing a hot stamp molded body, in which a steel comprising as components, by mass %: C: Si: Al: Mn: P: S: N: Ti: Nb: Mo: Cr: V: Ni: B: Ca: Mg: from 0.10 to 0.35%, from 0.01 to 3.00%, from 0.01 to 3.00%, from 1.0 to 3.5%, from 0.001 to 0.100%, from 0.001 to .O.OJO.%, ..._-• from 0.0005 to 0.0100%, from 0.000 to 0.200%, from 0.000 to 0.200%, from 0.00 to 1.00%, from 0.00 to 1.00%, from 0.000 to 1.000%, from 0.00 to 3.00%, from 0.0000 to 0.0050%, from 0.0000 to 0.0050%, and from 0.0000 to 0.0050%, a balance being Fe and impurities, is subjected to a hot rolling step, a pickling step, a cold rolling step, a continuous annealing step, a temper rolling step, and an electrogalvanizing step to yield an electrogalvanized steel sheet, and the electrogalvanized steel sheet is subjected to a hot stamp molding step to produce a hot stamp molded body; wherein in the continuous annealing step, the steel sheet is subjected to repeated bending at a bending angle of from 90° to 220° four or more times during heating of the steel sheet in an atmosphere gas containing hydrogen at from 0.1 volume % to 30 volume %, and 36 H2O corresponding to a dew point of from -70°C to -20°C as well as nitrogen and impurities as a balance at a sheet temperature within a range of from 350°C to 700°C, wherein in the electrogalvanizing step, each face of the steel sheet is electrogalvanized with a plating weight of not less than 5 g/m and less than 40 g/m , and wherein in the hot stamp molding step, the electrogalvanized steel sheet is heated with an average temperature elevation rate of 50°C/sec or more to a temperature range of from 700°C to 1100°C, hot-stamped within 1 min from the initiation of the temperature elevation, and thereafter cooled to normal temperature. [Claim 6] The method for producing a hot stamp molded body according to claim 5, wherein the steel comprises, by mass %, one, or two or more kinds of: Ti: from 0.001 to 0.200%, Nb: from 0.001 to 0.200%, Mo: from 0.01 to 1.00%, Cr: from 0.01 to 1.00%, V: from 0.001 to 1.000%, Ni: from 0.01 to 3.00%, B: from 0.0002 to 0.0050%, Ca: from 0.0002.1O &Q05fi%,_Qr Mg: from 0.0002 to

Documents

Orders

Section Controller Decision Date

Application Documents

# Name Date
1 11362-DELNP-2015-RELEVANT DOCUMENTS [30-08-2023(online)].pdf 2023-08-30
1 Priority Document [14-12-2015(online)].pdf 2015-12-14
2 11362-DELNP-2015-RELEVANT DOCUMENTS [24-09-2022(online)].pdf 2022-09-24
2 Power of Attorney [14-12-2015(online)].pdf 2015-12-14
3 Form 5 [14-12-2015(online)].pdf 2015-12-14
3 11362-DELNP-2015-IntimationOfGrant02-08-2020.pdf 2020-08-02
4 Form 3 [14-12-2015(online)].pdf 2015-12-14
4 11362-DELNP-2015-PatentCertificate02-08-2020.pdf 2020-08-02
5 Form 18 [14-12-2015(online)].pdf 2015-12-14
5 11362-DELNP-2015-FORM-26 [24-07-2020(online)].pdf 2020-07-24
6 Form 1 [14-12-2015(online)].pdf 2015-12-14
6 11362-DELNP-2015-Written submissions and relevant documents [24-07-2020(online)].pdf 2020-07-24
7 Drawing [14-12-2015(online)].pdf 2015-12-14
7 11362-DELNP-2015-US(14)-HearingNotice-(HearingDate-17-07-2020).pdf 2020-06-26
8 Description(Complete) [14-12-2015(online)].pdf 2015-12-14
8 11362-DELNP-2015-ABSTRACT [05-12-2019(online)].pdf 2019-12-05
9 11362-DELNP-2015-CLAIMS [05-12-2019(online)].pdf 2019-12-05
9 11362-DELNP-2015.pdf 2015-12-15
10 11362-DELNP-2015-CORRESPONDENCE [05-12-2019(online)].pdf 2019-12-05
10 11362-delnp-2015-Form-1-(05-01-2016).pdf 2016-01-05
11 11362-delnp-2015-Correspondence Others-(05-01-2016).pdf 2016-01-05
11 11362-DELNP-2015-DRAWING [05-12-2019(online)].pdf 2019-12-05
12 11362-DELNP-2015-FER_SER_REPLY [05-12-2019(online)].pdf 2019-12-05
12 Other Document [04-02-2016(online)].pdf 2016-02-04
13 11362-DELNP-2015-OTHERS [05-12-2019(online)].pdf 2019-12-05
13 Marked Copy [04-02-2016(online)].pdf 2016-02-04
14 11362-DELNP-2015-Correspondence-120619.pdf 2019-06-20
14 Form 13 [04-02-2016(online)].pdf 2016-02-04
15 11362-DELNP-2015-OTHERS-120619.pdf 2019-06-20
15 Description(Complete) [04-02-2016(online)].pdf 2016-02-04
16 11362-delnp-2015-Form-3-(29-03-2016).pdf 2016-03-29
16 11362-DELNP-2015-Power of Attorney-120619.pdf 2019-06-20
17 11362-DELNP-2015-FORM 13 [10-06-2019(online)].pdf 2019-06-10
17 11362-delnp-2015-Correspondence Others-(29-03-2016).pdf 2016-03-29
18 11362-DELNP-2015-FER.pdf 2019-06-06
18 11362-DELNP-2015-RELEVANT DOCUMENTS [10-06-2019(online)].pdf 2019-06-10
19 11362-DELNP-2015-FER.pdf 2019-06-06
19 11362-DELNP-2015-RELEVANT DOCUMENTS [10-06-2019(online)].pdf 2019-06-10
20 11362-delnp-2015-Correspondence Others-(29-03-2016).pdf 2016-03-29
20 11362-DELNP-2015-FORM 13 [10-06-2019(online)].pdf 2019-06-10
21 11362-delnp-2015-Form-3-(29-03-2016).pdf 2016-03-29
21 11362-DELNP-2015-Power of Attorney-120619.pdf 2019-06-20
22 11362-DELNP-2015-OTHERS-120619.pdf 2019-06-20
22 Description(Complete) [04-02-2016(online)].pdf 2016-02-04
23 Form 13 [04-02-2016(online)].pdf 2016-02-04
23 11362-DELNP-2015-Correspondence-120619.pdf 2019-06-20
24 11362-DELNP-2015-OTHERS [05-12-2019(online)].pdf 2019-12-05
24 Marked Copy [04-02-2016(online)].pdf 2016-02-04
25 11362-DELNP-2015-FER_SER_REPLY [05-12-2019(online)].pdf 2019-12-05
25 Other Document [04-02-2016(online)].pdf 2016-02-04
26 11362-delnp-2015-Correspondence Others-(05-01-2016).pdf 2016-01-05
26 11362-DELNP-2015-DRAWING [05-12-2019(online)].pdf 2019-12-05
27 11362-DELNP-2015-CORRESPONDENCE [05-12-2019(online)].pdf 2019-12-05
27 11362-delnp-2015-Form-1-(05-01-2016).pdf 2016-01-05
28 11362-DELNP-2015-CLAIMS [05-12-2019(online)].pdf 2019-12-05
28 11362-DELNP-2015.pdf 2015-12-15
29 11362-DELNP-2015-ABSTRACT [05-12-2019(online)].pdf 2019-12-05
29 Description(Complete) [14-12-2015(online)].pdf 2015-12-14
30 Drawing [14-12-2015(online)].pdf 2015-12-14
30 11362-DELNP-2015-US(14)-HearingNotice-(HearingDate-17-07-2020).pdf 2020-06-26
31 Form 1 [14-12-2015(online)].pdf 2015-12-14
31 11362-DELNP-2015-Written submissions and relevant documents [24-07-2020(online)].pdf 2020-07-24
32 Form 18 [14-12-2015(online)].pdf 2015-12-14
32 11362-DELNP-2015-FORM-26 [24-07-2020(online)].pdf 2020-07-24
33 Form 3 [14-12-2015(online)].pdf 2015-12-14
33 11362-DELNP-2015-PatentCertificate02-08-2020.pdf 2020-08-02
34 Form 5 [14-12-2015(online)].pdf 2015-12-14
34 11362-DELNP-2015-IntimationOfGrant02-08-2020.pdf 2020-08-02
35 Power of Attorney [14-12-2015(online)].pdf 2015-12-14
35 11362-DELNP-2015-RELEVANT DOCUMENTS [24-09-2022(online)].pdf 2022-09-24
36 11362-DELNP-2015-RELEVANT DOCUMENTS [30-08-2023(online)].pdf 2023-08-30
36 Priority Document [14-12-2015(online)].pdf 2015-12-14

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