Hot stamping steel, hot stamping component, and method for manufacturing same

Abstract

The present invention provides a method for manufacturing a hot stamping component, the method comprising: a hot rolling step of hot rolling a slab to manufacture a hot rolled sheet; a cold rolling step of rolling the hot rolled sheet at a reduction ratio of 40% to 70% to manufacture a cold rolled sheet; a plating layer formation step of annealing the cold rolled sheet and then immersing the cold rolled sheet in a plating solution; a plating layer alloying step of heating the cold rolled sheet having a plating layer formed thereon to alloy the plating layer, thereby manufacturing hot stamping steel; and a hot stamping step of forming the hot stamping steel in a press after heat treatment thereof.

Description

Hot stamping steel, hot stamping parts and methods for manufacturing the same

[0001] The present invention relates to a hot stamping steel part with improved bendability and hydrogen embrittlement by controlling precipitation, and a method for manufacturing the same.

[0002] Automotive parts require high tensile strength to ensure passenger safety in the event of a collision. Therefore, hot stamping steel is widely used.

[0003] The hot stamping process is a process in which a blank produced by cutting steel plates is heated to a high temperature, press-formed using a mold while simultaneously cooling to create a desired shape, and finally trimmed or cut to manufacture the final hot-stamped part.

[0004] Through this hot stamping process, high-strength parts can be manufactured.

[0005] While increasing the carbon content of hot stamping steel can increase its strength, problems such as reduced bendability may occur when heated at a high dew point during the process.

[0006] If bendability is reduced, when manufactured into automotive parts, it may not be able to absorb shocks effectively, which could lead to a problem where passenger safety cannot be guaranteed.

[0007] The present invention is intended to solve various problems, including the problems mentioned above. According to one embodiment of the present invention, a hot stamping steel with improved bendability and hydrogen embrittlement by controlling precipitates and a method for manufacturing the same can be provided.

[0008] However, these tasks are exemplary and do not limit the scope of the invention.

[0009] According to one aspect of the present invention, carbon (C) 0.10 wt% or more and 0.48 wt% or less, silicon (Si) 0.05 wt% or more and 1.0 wt% or less, manganese (Mn) 0.3 wt% or more and 1.6 wt% or less, phosphorus (P) greater than 0 wt% and 0.020 wt% or less, sulfur (S) greater than 0 wt% and 0.008 wt% or less, titanium (Ti) 0.01 wt% or more and 0.05 wt% or less, chromium (Cr) 0.05 wt% or more and 1.5 wt% or less, boron (B) 0.001 wt% or more and 0.006 wt% or less, niobium (Nb) 0.001 wt% or more and 0.065 wt% or less, nitrogen (N) greater than 0 wt% and 0.01 wt% or less, and calcium (Ca) 0.0003 wt% or more and 0.0031 wt% A method for manufacturing a hot stamping part is provided, comprising: a hot rolling step of manufacturing a hot-rolled plate by hot rolling a slab containing a remainder of iron (Fe) and other unavoidable impurities, wherein the content of nitrogen, titanium, and niobium satisfies Formula 1 below; a cold rolling step of manufacturing a cold-rolled plate by rolling the hot-rolled plate with a reduction rate of 40% or more and 70% or less; a plating layer forming step of immersing the cold-rolled plate in a plating solution after annealing; a plating layer alloying step of manufacturing a hot-stamping steel by heating the cold-rolled plate with the plating layer formed thereon to alloy the plating layer; and a hot stamping step of forming the hot-stamping steel in a press after heat treatment.

[0010] <Equation 1>

[0011] 0.0017 ≤ (1.08*({N}-0.006))+[({Ti}+(0.7*{Nb}))] / 3.41 ≤ 0.033

[0012] According to one aspect of the present invention, as a hot stamping steel, carbon (C) 0.10 wt% or more and 0.48 wt% or less, silicon (Si) 0.05 wt% or more and 1.0 wt% or less, manganese (Mn) 0.3 wt% or more and 1.6 wt% or less, phosphorus (P) greater than 0 wt% and 0.020 wt% or less, sulfur (S) greater than 0 wt% and 0.008 wt% or less, titanium (Ti) 0.01 wt% or more and 0.05 wt% or less, chromium (Cr) 0.05 wt% or more and 1.5 wt% or less, boron (B) 0.001 wt% or more and 0.006 wt% or less, niobium (Nb) 0.001 wt% or more and 0.065 wt% or less, nitrogen (N) greater than 0 wt% and 0.01 wt% or less, and calcium (Ca) 0.0003 wt% or more A hot stamping steel is provided that contains 0.0031 weight% or less, the remainder being iron (Fe) and other unavoidable impurities, wherein the content of nitrogen, titanium, and niobium satisfies Formula 1 below, and the average size of the (TiNb)CN precipitates contained in the hot stamping steel is 0.01 μm or more and 3 μm or less.

[0013] <Equation 1>

[0014] 0.0017 ≤ (1.08*({N}-0.006))+[({Ti}+(0.7*{Nb}))] / 3.41 ≤ 0.033

[0015] According to one aspect of the present invention, as a hot stamping part, carbon (C) 0.10 wt% or more and 0.48 wt% or less, silicon (Si) 0.05 wt% or more and 1.0 wt% or less, manganese (Mn) 0.3 wt% or more and 1.6 wt% or less, phosphorus (P) greater than 0 wt% and 0.020 wt% or less, sulfur (S) greater than 0 wt% and 0.008 wt% or less, titanium (Ti) 0.01 wt% or more and 0.05 wt% or less, chromium (Cr) 0.05 wt% or more and 1.5 wt% or less, boron (B) 0.001 wt% or more and 0.006 wt% or less, niobium (Nb) 0.001 wt% or more and 0.065 wt% or less, nitrogen (N) greater than 0 wt% and 0.01 wt% or less, and calcium (Ca) 0.0003 wt% or more A hot stamping part is provided, comprising 0.0031 weight% or less, the remainder being iron (Fe) and other unavoidable impurities, wherein the content of nitrogen, titanium, and niobium satisfies Formula 1 below, and wherein the hot stamping part comprises a martensite structure of 80 volume% or more and a bainite structure of 20 volume% or less.

[0016] <Equation 1>

[0017] 0.0017 ≤ (1.08*({N}-0.006))+[({Ti}+(0.7*{Nb}))] / 3.41 ≤ 0.033

[0018] According to one embodiment of the present invention as described above, by controlling precipitates, a hot stamping steel with improved bendability and hydrogen embrittlement and a method for manufacturing the same can be provided. Of course, the scope of the present invention is not limited by these effects.

[0019] FIG. 1 is a flowchart illustrating a method for manufacturing hot stamping steel according to one embodiment of the present invention.

[0020] FIG. 2 is a flowchart showing a process including a hot rolling step according to one embodiment of the present invention.

[0021] The above hot rolling step includes a step of reheating the slab, a step of rolling the reheated slab, and a step of winding the rolled slab. In the step of reheating the slab, the section where the slab is first heated is called the first section, the heating section that starts after the end of the first section is called the second section, and the heating section that starts after the end of the second section until the step of reheating the slab is finished is called the third section. When the average heating rate of the slab in the first section is called the first heating rate, the average heating rate of the slab in the second section is called the second heating rate, and the average heating rate of the slab in the third section is called the third heating rate, the first heating rate and the second heating rate are different, and the second heating rate and the third heating rate may be different.

[0022] The third heating rate is less than or equal to the first heating rate, and the third heating rate may be less than or equal to the second heating rate.

[0023] The second heating rate in the second section is 0.013 ℃ / s or more and 0.60 ℃ / s or less, and the time for heating the slab in the second section may be 1,000 seconds or more and 10,000 seconds or less.

[0024] When the temperature of the slab at the time when the third section ends is referred to as the third final temperature, the third final temperature may be 1,150 ℃ or higher and 1,280 ℃ or lower.

[0025] The above hot rolling step comprises 20 (TiNb)CN precipitates / mm² with an average size of 0.01 μm or more and 3 μm or less, contained in the hot-rolled plate. 3 It can be made to be less than or equal to this.

[0026] The above method for manufacturing a hot stamping part can be such that the ratio of the length of the (TiNb)CN precipitate contained in the hot stamping steel that has undergone the plating layer alloying step to the length of the (TiNb)CN precipitate contained in the hot-rolled plate that has undergone the hot rolling step is 1 or more and 1.7 or less.

[0027] The tensile strength of the above hot stamping steel may be 500 MPa or more and 650 MPa or less, and the yield strength may be 300 MPa or more and 400 MPa or less.

[0028] The tensile strength of the above hot stamping part may be 1,400 MPa or more, and the yield strength may be 1,000 MPa or more.

[0029] The average austenite grain size of the austenite included in the above hot stamping part may be 15 μm or more and 25 μm or less.

[0030] The present invention will be described in detail below. However, in describing the present invention, if it is determined that a detailed description of related known technologies or configurations may unnecessarily obscure the essence of the present invention, such detailed description will be omitted.

[0031] In the following embodiments, terms such as first, second, etc. are used not in a limiting sense, but for the purpose of distinguishing one component from another component.

[0032] In the following examples, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0033] In the following embodiments, when various components such as layers, films, regions, and plates are described as being "on" another component, this includes not only cases where they are "directly on" another component, but also cases where another component is interposed between them.

[0034] In the drawings, the size of components may be exaggerated or reduced for convenience of explanation. For example, the size and thickness of each component shown in the drawings are depicted arbitrarily for convenience of explanation, and therefore the present invention is not necessarily limited to what is illustrated.

[0035] In the following embodiments, terms such as "include" or "have" mean that the features or components described in the specification are present, and do not preclude the possibility that one or more other features or components may be added.

[0036] In this specification, "A and / or B" indicates the case where it is A, B, or both A and B. Additionally, in this specification, "at least one of A and B" indicates the case where it is A, B, or both A and B.

[0037] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0038] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0039] FIG. 1 is a flowchart illustrating a method for manufacturing hot stamping steel according to one embodiment of the present invention.

[0040] Referring to FIG. 1, a method for manufacturing hot stamping steel according to one embodiment of the present invention may include a hot rolling step (S100), a cold rolling step (S200), a plating layer forming step (S300), and a plating layer alloying step (S400).

[0041] A hot stamping part can be manufactured by forming the hot stamping steel, which has undergone the plating layer alloying step (S400), into a desired shape through the hot stamping step (S500).

[0042] In a method for manufacturing hot stamping steel according to one embodiment of the present invention, the semi-finished product subject to hot rolling may be a slab. The slab in the semi-finished product state can be obtained through a continuous casting process after obtaining molten steel of a predetermined composition through a steelmaking process.

[0043] The slab contains carbon (C) 0.10 wt% or more and 0.48 wt% or less, silicon (Si) 0.05 wt% or more and 1.0 wt% or less, manganese (Mn) 0.3 wt% or more and 1.6 wt% or less, phosphorus (P) greater than 0 wt% and 0.020 wt% or less, sulfur (S) greater than 0 wt% and 0.008 wt% or less, titanium (Ti) 0.01 wt% or more and 0.05 wt% or less, chromium (Cr) 0.05 wt% or more and 1.5 wt% or less, boron (B) 0.001 wt% or more and 0.006 wt% or less, niobium (Nb) greater than 0 wt% and 0.065 wt% or less, nitrogen (N) greater than 0 wt% and 0.01 wt% or less, calcium (Ca) 0.0003 wt% or more and 0.0031 wt% or less, and the remainder of It may contain iron (Fe) and other unavoidable impurities.

[0044] In addition, the content of nitrogen (N), titanium (Ti), and niobium (Nb) contained in the slab can satisfy the following Equation 1.

[0045] <Equation 1>

[0046] 0.0017 ≤ (1.08*({N}-0.006))+[({Ti}+(0.7*{Nb}))] / 3.41 ≤ 0.033

[0047] (Here, {N} represents the nitrogen content (wt%) of the slab, {Ti} represents the titanium content (wt%) of the slab, and {Nb} represents the niobium content (wt%) of the slab)

[0048] The following explains why the numerical range of components included in the slab is limited.

[0049] Carbon (C)

[0050] Carbon can be added to increase the strength of the steel and to secure a hard phase. If the carbon content in the slab is less than 0.10 weight%, the strength decreases, and if the carbon content in the slab exceeds 0.48 weight%, brittleness may occur and bendability may decrease.

[0051] Silicon (Si)

[0052] Silicon homogenizes the hot stamping structure and finely disperses ferrite. Therefore, it is possible to control the non-uniformity of martensite strength, thereby improving the impact performance of hot stamping steel. If the silicon content in the slab is less than 0.05 wt%, cementite may form and coarsen during hot stamping, which may worsen bendability; and if the silicon content in the slab exceeds 1.0 wt%, the rolling load increases during hot and cold rolling, excessive scale may occur during the hot rolling process, and plating quality may deteriorate.

[0053] Manganese (Mn)

[0054] Manganese can improve the hardenability of steel sheets during heat treatment and increase the strength of steel sheets. If the manganese content in the slab is less than 0.3 weight%, the hardenability of the steel sheet is reduced, which may result in a lower fraction of the hard phase after hot stamping and a decrease in strength. If the manganese content in the slab exceeds 1.6 weight%, homogeneous microstructures such as manganese segregation and bands may occur, which may reduce formability and bendability.

[0055] Ph(P)

[0056] Phosphorus is an element that contributes to the improvement of the strength of steel plates. However, if the phosphorus content in the slab exceeds 0.020 weight%, iron phosphide compounds are formed, which lowers toughness and weldability, potentially causing cracks in the steel plate during processing and segregating at grain boundaries, thereby weakening the grain boundaries and causing a decrease in the toughness of the steel plate.

[0057] Yellow (S)

[0058] Sulfur can form inclusions such as MnS. If the sulfur content in the slab exceeds 0.008 weight%, coarse inclusions may be formed, which can deteriorate the physical properties of the steel sheet.

[0059] Titanium (Ti)

[0060] Titanium inhibits BN formation by forming precipitation strengthening and nitrides. If the titanium content in the slab is less than 0.01 weight%, intergranular brittleness may occur due to the formation of BN, and if the titanium content in the slab exceeds 0.05 weight%, elongation and bendability may decrease.

[0061] Niobium (Nb)

[0062] Niobium is a powerful carbide-forming element that has a grain refinement effect, improves hardenability, and increases the strength of steel sheets. If the niobium content in the slab exceeds 0.065 weight%, precipitates are excessively formed and coarsenic may occur, which may reduce elongation.

[0063] Chrome (Cr)

[0064] Chromium has the effect of refining grain size, improving hardenability, and increasing the strength of steel sheets. If the chromium content in the slab is less than 0.05 weight%, sufficient strength cannot be secured, and if the chromium content in the slab exceeds 1.5 weight%, the toughness of the steel sheet decreases and the manufacturing cost of the steel sheet may increase.

[0065] Boron (B)

[0066] Boron has the effect of improving hardenability and increasing the strength of steel plates. If the boron content in the slab is less than 0.001 weight%, the hardenability may not be sufficient, and if the boron content in the slab exceeds 0.006 weight%, hard phase intergranular brittleness may occur, which may reduce toughness and bendability.

[0067] Nitrogen (N)

[0068] Nitrogen combines with aluminum, titanium, niobium, etc. to form precipitates such as AiN, TiN, and NbN, and their size grows during the manufacture of high-temperature materials. If the nitrogen content in the slab exceeds 0.01 weight%, the elongation, formability, and bendability may decrease.

[0069] Calcium (Ca)

[0070] Calcium can control the size of MnS elongated inclusions by forming them into MnCaS-based shapes during the steelmaking process. If the calcium content in the slab is less than 0.0003 weight%, this effect may be negligible, and if the calcium content in the slab exceeds 0.0031 weight%, the quality of the slab may deteriorate.

[0071] It will be understood by anyone with ordinary knowledge in the art to which this invention pertains that, in addition to the components described above, various components included in non-oriented electrical steel sheets may be included as components of the non-oriented electrical steel sheet of this invention. Combinations of commonly known components and their applications naturally fall within the scope of this invention.

[0072] Hot rolling step (S100)

[0073] In the hot rolling step (S100), the above-mentioned slab can be hot-rolled to produce a hot-rolled plate.

[0074] In the hot rolling step (S100), the above-mentioned slab can be hot-rolled to produce a hot-rolled plate.

[0075] In one embodiment, the reduction rate in the hot rolling step (S100) may be 99% or more.

[0076] FIG. 2 is a flowchart showing a process including a hot rolling step (S100) according to one embodiment of the present invention.

[0077] Referring to FIG. 2, the hot rolling step (S100) may include a step of reheating the slab (S110), a step of rolling the reheated slab (S120), and a step of winding the rolled slab (S130).

[0078] In the step of reheating the slab (S110), the slab can be heated through three or more sections.

[0079] In the step (S110) of reheating a slab according to one embodiment of the present invention, the section where the slab is heated for the first time may be called the first section, the heating section that begins after the end of the first section may be called the second section, and the heating section that begins after the end of the second section and continues until the end of the step (S110) of reheating the slab may be called the third section.

[0080] The period from when the slab started to be heated until the first time (t1) is called the first period, and the average heating rate of the slab in the first period can be called the first heating rate (v1).

[0081] In addition, the period from the first time (t1) when the first period ends to the second time (t2) can be called the second period, and the average heating rate of the slab in the second period can be called the second heating rate (v2).

[0082] And, the period from the second time (t2), when the second section ends, to the third time (t3), when the slab reheating stage ends, is called the third section, and the average heating rate of the slab in the third section can be called the third heating rate (v3).

[0083] The first heating rate (v1) and the second heating rate (v2) may be different from each other, and the second heating rate (v2) and the third heating rate (v3) may be different from each other.

[0084] In one embodiment, the third heating rate (v3), which is the average heating rate of the slab in the third section, may be less than or equal to the first heating rate (v1), which is the average heating rate of the slab in the first section.

[0085] In one embodiment, the third heating rate (v3), which is the average heating rate of the slab in the third section, may be less than or equal to the second heating rate (v2), which is the average heating rate of the slab in the second section.

[0086] In one embodiment, the first heating rate (v1), which is the average heating rate of the slab in the first section, may be 0.01 ℃ / s or more and 0.2 ℃ / s or less. In one embodiment, the first heating rate (v1) may be 0.03 ℃ / s or more and 0.14 ℃ / s or less.

[0087] If the first heating rate (v1) in the first section is too low, the bendability of the final product may be deteriorated.

[0088] In one embodiment, the second heating rate (v2), which is the average heating rate of the slab in the second section, may be 0.013 ℃ / s or more and 0.60 ℃ / s or less. In one embodiment, the second heating rate (v2) may be 0.06 ℃ / s or more and 0.13 ℃ / s or less.

[0089] If the second heating rate (v2) in the second section is too low, the bendability of the final product may be deteriorated.

[0090] In one embodiment, the third heating rate (v3), which is the average heating rate of the slab in the third section, may be 0.0001 ℃ / s or more and 0.01 ℃ / s or less.

[0091] The time for heating the slab in the first section, i.e., the first section holding time, can be called the first holding time (dt1), the time for heating the slab in the second section, i.e., the second section holding time, can be called the second holding time (dt2), and the time for heating the slab in the third section, i.e., the third section holding time, can be called the third holding time (dt3).

[0092] At this time, since the time at which the slab started to be heated is the reference (0 seconds), the first holding time (dt1) may be the same as the first time (t1), the second holding time (dt2) may be the value obtained by subtracting the first time (t1) from the second time (t2) (t2 - t1), and the third holding time (dt3) may be the value obtained by subtracting the second time (t2) from the third time (t3) (t3 - t2).

[0093] In one embodiment, the first holding time (dt1), which is the time for heating the slab in the first section, may be 1,000 seconds or more and 10,000 seconds or less.

[0094] In one embodiment, the second holding time (dt2), which is the time for heating the slab in the second section, may be 1,000 seconds or more and 50,000 seconds or less.

[0095] In one embodiment, the third holding time (dt3), which is the time for heating the slab in the third section, may be 1,000 seconds or more and 10,000 seconds or less.

[0096] In other words, in the step (S110) of reheating the slab, the slab is heated at a first heating rate (v1) for a first holding time (dt1), then the slab is heated again at a second heating rate (v2) different from the first heating rate (v1) for a second holding time (dt2), and then the slab is heated again at a third heating rate (v3) different from the second heating rate (v2) for a second holding time (dt3).

[0097] Slab heating in the first, second, and third sections can be performed continuously.

[0098] At this time, the slab is heated at a first heating rate (v1) in the first section for a first holding time (dt1), and the temperature of the slab at the time when the first section ends can be called the first final temperature (T1).

[0099] Likewise, the temperature of the slab at the time when the second section ends can be called the second final temperature (T2), and the temperature of the slab at the time when the third section ends can be called the third final temperature (T3).

[0100] In one embodiment, the first final temperature (T1) may be 100°C or higher and the Ac3 point temperature [°C] or lower.

[0101] In one embodiment, the second final temperature (T2) may be 1,160 ℃ or higher and 1,394 ℃ or lower.

[0102] In one embodiment, the third final temperature (T3) may be 1,150 ℃ or higher and 1,280 ℃ or lower.

[0103] If the third final temperature (T3) is less than 1,150 ℃, the bendability of the final product may be deteriorated.

[0104] That is, the first heating rate (v1), the first holding time (dt1), the second heating rate (v2), the second holding time (dt2), the third heating rate (v3), and the third holding time (dt3) must be controlled within a range such that the first final temperature (T1) is 100 ℃ or higher and the Ac3 point temperature [℃] or lower, the second final temperature (T2) is 1,160 ℃ or higher and 1,394 ℃ or lower, and the third final temperature (T3) is 1,150 ℃ or higher and 1,280 ℃ or lower.

[0105] After reheating the slab, the heated slab can be rolled at a predetermined finishing delivery temperature (FDT). The finishing delivery temperature of the hot rolling step (S100) may be 800°C or higher and 1,000°C or lower.

[0106] If the finishing rolling temperature is less than 800 ℃, a non-uniform microstructure may occur depending on the width and thickness of the steel sheet, increasing in-plane anisotropy and potentially deteriorating formability. If the finishing rolling temperature exceeds 1,000 ℃, the grain size in the final product may increase, which may result in a decrease in strength.

[0107] After rolling the slab at a predetermined finishing rolling temperature, it can be cooled to a predetermined coiling temperature (CT) and coiled. According to one embodiment, the coiling temperature may be less than 650 ℃.

[0108] If the coiling temperature is 650℃ or higher, abnormal crystal grains may grow or crystal grains may grow excessively, which may worsen the formability and strength of the final product.

[0109] The hot-rolled plate that has undergone the hot rolling step (S100) may contain ferrite and pearlite structures.

[0110] (TiNb)CN precipitates may be formed in the hot-rolled plate during the hot rolling step (S100).

[0111] In one embodiment, the average size of (TiNb)CN precipitates contained in the hot-rolled plate may be 0.01 μm or more and 3 μm or less, and the hot-rolled plate contains 20 such (TiNb)CN precipitates / mm 3 The following may be included.

[0112] Cold rolling step (S200)

[0113] A cold rolling step (S200) may be performed after the hot rolling step (S100). In the cold rolling step (S200), the coiled hot-rolled steel sheet is pickled and then cold rolling is performed, at which time the cold reduction rate may be 40% or more and 70% or less.

[0114] In the cold rolling step (S200), the hot-rolled structure is deformed, and the deformed energy becomes the energy for the recrystallization process. If the cold reduction rate is less than 40%, this deformation effect is small, and if the cold reduction rate exceeds 70%, the load on the equipment is large, which not only makes rolling difficult but also increases the probability of cracks forming at the edges of the steel plate and plate breakage.

[0115] After the cold rolling step (S200), a plating layer generation step (S300) can be performed.

[0116] Plating layer formation step (S300)

[0117] In the plating layer formation step (S300), a plating layer can be formed on the cold-rolled plate.

[0118] In the plating layer formation step (S300), the cold-rolled plate is recrystallized by annealing it to an annealing temperature of 730°C or higher and 830°C or lower, and the annealed cold-rolled plate is cooled to a temperature similar to the temperature of the plating bath at a cooling rate of 1°C / s or higher and 40°C / s or lower, and then immersed in the plating solution in the plating bath.

[0119] In one embodiment, the plating amount is 40 g / m² on both sides. 2 200 g / m² or more 2 It may be less than.

[0120] The plating solution contained in the plating bath may contain aluminum and silicon.

[0121] After the plating layer formation step (S300), the plating layer alloying step (S400) can be performed.

[0122] Plating layer alloying step (S400)

[0123] In the plating layer alloying step (S400), the cold-rolled plate on which the plating layer is formed can be heated to a predetermined alloying temperature to induce a phase change in the plating layer. That is, hot stamping steel can be manufactured by alloying the plating layer.

[0124] In one embodiment, the alloying temperature may be 650°C or higher and 670°C or lower.

[0125] Heat resistance and weldability of the plating layer can be secured through the plating layer alloying step (S400).

[0126] A hot stamping step (S500) can be performed after the plating layer alloying step (S400).

[0127] A hot stamping steel according to one embodiment that has undergone a plating layer alloying step (S400) may include an elongated (TiNb)CN precipitate.

[0128] That is, as the (TiNb)CN precipitates contained in the hot-rolled plate undergo an additional rolling process such as a cold rolling step (S200), they may have a shape that is elongated in one direction.

[0129] In one embodiment, the average size of the (TiNb)CN precipitates contained in the hot stamping steel that has undergone the plating layer alloying step (S400) may be 0.01 μm or more and 3 μm or less.

[0130] However, the ratio of the length of the (TiNb)CN precipitate contained in the hot stamping steel that has undergone the alloy layer alloying step (S400) to the length of the (TiNb)CN precipitate contained in the hot-rolled plate that has undergone the hot rolling step (S100) may be 1.0 or more and 1.7 or less.

[0131] Hot stamping step (S500)

[0132] In the hot stamping step (S500), hot stamping steel can be heat-treated and stamped to manufacture hot stamping parts.

[0133] In the hot stamping step (S500), the hot stamping steel is heated to a temperature of 900°C or higher and 970°C or lower at a heating rate of 3°C / s or higher, then transferred to a press, and formed into a desired shape in the press.

[0134] At this time, cooling can be performed simultaneously while stamping the steel plate in the press.

[0135] In one embodiment, the cooling rate in the press may be 15 ℃ / s or higher, and the cooling end temperature may be Mf - 100℃ or higher and Mf + 100℃ or lower.

[0136] Here, the Mf temperature may be the temperature at which the martensite transformation ends.

[0137] When press forming, the desired shape can be manufactured by maintaining the cooling end temperature for 10 seconds or more and 20 seconds or less.

[0138] Hot Stamping River

[0139] In the present invention, hot stamping steel may refer to a steel plate that has undergone the above-described hot rolling step (S100), cold rolling step (S200), plating layer formation step (S300), and plating layer alloying step (S400).

[0140] Accordingly, the hot stamping steel according to one embodiment of the present invention comprises carbon (C) 0.10 wt% or more and 0.48 wt% or less, silicon (Si) 0.05 wt% or more and 1.0 wt% or less, manganese (Mn) 0.3 wt% or more and 1.6 wt% or less, phosphorus (P) greater than 0 wt% and 0.020 wt% or less, sulfur (S) greater than 0 wt% and 0.008 wt% or less, titanium (Ti) 0.01 wt% or more and 0.05 wt% or less, chromium (Cr) 0.05 wt% or more and 1.5 wt% or less, boron (B) 0.001 wt% or more and 0.006 wt% or less, niobium (Nb) greater than 0 wt% and 0.065 wt% or less, nitrogen (N) greater than 0 wt% and 0.01 wt% or less, and calcium (Ca) 0.0003 wt% or more and 0.003 wt% It may contain less than or equal weight percent, and the remainder may contain iron (Fe) and other unavoidable impurities.

[0141] In addition, the content of nitrogen (N), titanium (Ti), and niobium (Nb) contained in hot stamping steel can satisfy Equation 1.

[0142] <Equation 1>

[0143] 0.0017 ≤ (1.08*({N}-0.006))+[({Ti}+(0.7*{Nb}))] / 3.41 ≤ 0.033

[0144] (Here, {N} represents the nitrogen content (wt%) of the hot stamping steel, {Ti} represents the titanium content (wt%) of the hot stamping steel, and {Nb} represents the niobium content (wt%) of the hot stamping steel)

[0145] A hot stamping steel according to one embodiment of the present invention may include (TiNb)CN precipitates.

[0146] In one embodiment, the average size of the (TiNb)CN precipitates contained in the hot stamping steel may be 0.01 μm or more and 3 μm or less.

[0147] In one embodiment, the tensile strength of the hot stamping steel may be 500 MPa or more and 650 MPa or less.

[0148] In one embodiment, the yield strength of the hot stamping steel may be 300 MPa or more and 400 MPa or less.

[0149] In one embodiment, the elongation of the hot stamping steel may be 15% or more and 25% or less.

[0150] In the present invention, yield strength, tensile strength, and elongation were measured through tensile testing. Yield strength was measured using the 0.2% offset method, and the maximum strength during the tensile test was defined as the tensile strength. Elongation was defined as the elongation at break up to the point where the measured value decreased to 98% of the maximum load, and if it broke before the 98% reduction point, that point was defined as the elongation at break.

[0151] Hot stamping parts

[0152] In the present invention, a hot stamping part may refer to a hot stamping steel described above that is heat-treated and stamped in a hot stamping step (S500) to form a desired shape.

[0153] Accordingly, a hot stamping part according to one embodiment of the present invention comprises carbon (C) 0.10 wt% or more and 0.48 wt% or less, silicon (Si) 0.05 wt% or more and 1.0 wt% or less, manganese (Mn) 0.3 wt% or more and 1.6 wt% or less, phosphorus (P) greater than 0 wt% and 0.020 wt% or less, sulfur (S) greater than 0 wt% and 0.008 wt% or less, titanium (Ti) 0.01 wt% or more and 0.05 wt% or less, chromium (Cr) 0.05 wt% or more and 1.5 wt% or less, boron (B) 0.001 wt% or more and 0.006 wt% or less, niobium (Nb) greater than 0 wt% and 0.065 wt% or less, nitrogen (N) greater than 0 wt% and 0.01 wt% or less, and calcium (Ca) 0.0003 wt% or more and 0.003 wt% It may contain less than or equal weight percent, and the remainder may contain iron (Fe) and other unavoidable impurities.

[0154] In addition, the content of nitrogen (N), titanium (Ti), and niobium (Nb) contained in the hot stamping part can satisfy Equation 1.

[0155] <Equation 1>

[0156] 0.0017 ≤ (1.08*({N}-0.006))+[({Ti}+(0.7*{Nb}))] / 3.41 ≤ 0.033

[0157] (Here, {N} represents the nitrogen content (wt%) contained in the hot stamping part, {Ti} represents the titanium content (wt%) contained in the hot stamping part, and {Nb} represents the niobium content (wt%) contained in the hot stamping part)

[0158] In one embodiment, the hot stamping part may comprise a martensitic structure of 80 volume% or more, a bainite structure of 20 volume% or less, and the remainder being ferrite and retained austenite. In this case, the retained ferrite and retained austenite may be less than 5 volume%.

[0159] In one embodiment, the tensile strength of the hot stamping part may be 1,400 MPa or more.

[0160] In one embodiment, the yield strength of the hot stamping part may be 1,000 MPa or more.

[0161] In one embodiment, the elongation of the hot stamping part may be 6% or more.

[0162] In one embodiment, the bending angle of the hot stamping part (based on VDA238-100) may be 50° or more.

[0163] In one embodiment, the bending angle of the hot stamping part was measured through a bending test according to the VDA238-100 standard.

[0164] In one embodiment, the average austenite grain size (AGS) of the austenite included in the hot stamping part may be 15 μm or more and 25 μm or less.

[0165] Hereinafter, the structure and operation of the present invention will be explained in more detail through preferred embodiments of the present invention. However, these are presented as preferred examples of the present invention and should not be interpreted in any way as limiting the present invention.

[0166] Experimental Example

[0167] The present invention will be explained in more detail below through experimental examples. However, the following experimental examples are intended to explain the present invention more specifically, and the scope of the present invention is not limited by the following experimental examples. The following experimental examples may be appropriately modified or changed by those skilled in the art within the scope of the present invention.

[0168]

[0169] Example 1

[0170] Table 1 above is a table showing the component content [weight%] of the slabs used to manufacture the examples and comparative examples.

[0171] Example 1 produced a hot-rolled plate by hot-rolling a slab containing the components according to Table 1 above.

[0172] At this time, the first heating rate of the first section was 0.04 ℃ / s, the second heating rate of the second section was 0.06 ℃ / s, and the second holding time was 4,000 seconds, and the slab was heated such that the third heating rate of the third section was 0.006 ℃ / s and the third final temperature was 1,190 ℃.

[0173] In addition, the finish rolling temperature was 887 ℃, and the coiling temperature was 620 ℃.

[0174] After that, a cold-rolled sheet was manufactured by cold rolling with a reduction rate of 60%, and then recrystallized by annealing at a temperature of 780°C. After that, the cold-rolled sheet was immersed in a plating bath containing an AlSi plating solution to apply the plating solution at a rate of 200 g / m2 on both sides, and then the plating layer was alloyed at a temperature of 660°C to manufacture hot-stamping steel.

[0175] The manufactured hot stamping steel was heated to a temperature of 930 ℃ at a heating rate of 2 ℃ / s, then transferred to a press, and cooled at a cooling rate of 27 ℃ / s while forming.

[0176] At this time, the thickness of the steel plate was 1 mm.

[0177] Example 2

[0178] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.06 ℃ / s, the second heating rate of the second section was 0.09 ℃ / s, and the second holding time was 6,000 seconds, the third heating rate of the third section was 0.002 ℃ / s, and the third final temperature was 1,210 ℃, the finishing rolling temperature was 910 ℃, and the coiling temperature was 588 ℃.

[0179] Example 3

[0180] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.14 ℃ / s, the second heating rate of the second section was 0.017 ℃ / s, and the second holding time was 30,000 seconds, the third heating rate of the third section was 0.007 ℃ / s, and the third final temperature was 1,220 ℃, the finishing rolling temperature was 876 ℃, and the coiling temperature was 709 ℃.

[0181] Example 4

[0182] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.03 ℃ / s, the second heating rate of the second section was 0.07 ℃ / s, and the second holding time was 5,000 seconds, the third heating rate of the third section was 0.004 ℃ / s, and the third final temperature was 1,218 ℃, the finish rolling temperature was 885 ℃, the coiling temperature was 627 ℃, and the manufactured hot stamping steel was heated to a temperature of 870 ℃ at a heating rate of 2 ℃ / s.

[0183] Example 5

[0184] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.06 ℃ / s, the second heating rate of the second section was 0.08 ℃ / s, and the second holding time was 7,000 seconds, the third heating rate of the third section was -0.005 ℃ / s, and the third final temperature was 1,233 ℃, the finish rolling temperature was 914 ℃, the coiling temperature was 596 ℃, and the manufactured hot stamping steel was heated to a temperature of 870 ℃ at a heating rate of 2 ℃ / s.

[0185] Example 6

[0186] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.13 ℃ / s, the second heating rate of the second section was 0.014 ℃ / s, and the second holding time was 40,000 seconds, the third heating rate of the third section was 0.005 ℃ / s, and the third final temperature was 1,247 ℃, the finish rolling temperature was 879 ℃, the coiling temperature was 704 ℃, and the manufactured hot stamping steel was heated to a temperature of 870 ℃ at a heating rate of 2 ℃ / s.

[0187] Example 7

[0188] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.05 ℃ / s, the second heating rate of the second section was 0.07 ℃ / s, and the second holding time was 7,000 seconds, the third heating rate of the third section was 0.0066 ℃ / s, and the third final temperature was 1,220 ℃, the finishing rolling temperature was 884 ℃, and the coiling temperature was 618 ℃.

[0189] Example 8

[0190] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.06 ℃ / s, the second heating rate of the second section was 0.11 ℃ / s, and the second holding time was 5,000 seconds, the third heating rate of the third section was -0.0034 ℃ / s, and the third final temperature was 1,250 ℃, the finishing rolling temperature was 906 ℃, and the coiling temperature was 595 ℃.

[0191] Example 9

[0192] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.09 ℃ / s, the second heating rate of the second section was 0.028 ℃ / s, and the second holding time was 30,000 seconds, the third heating rate of the third section was 0.0024 ℃ / s, and the third final temperature was 1270 ℃, the finishing rolling temperature was 885 ℃, and the coiling temperature was 703 ℃.

[0193] Example 10

[0194] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.03 ℃ / s, the second heating rate of the second section was 0.09 ℃ / s, and the second holding time was 4,000 seconds, the third heating rate of the third section was 0.0057 ℃ / s, and the third final temperature was 1219 ℃, the finishing rolling temperature was 881 ℃, and the coiling temperature was 611 ℃.

[0195] Example 11

[0196] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.05 ℃ / s, the second heating rate of the second section was 0.13 ℃ / s, and the second holding time was 6,000 seconds, the third heating rate of the third section was -0.0021 ℃ / s, and the third final temperature was 1243 ℃, the finishing rolling temperature was 900 ℃, and the coiling temperature was 599 ℃.

[0197] Example 12

[0198] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.07 ℃ / s, the second heating rate of the second section was 0.043 ℃ / s, and the second holding time was 50,000 seconds, the third heating rate of the third section was 0.0043 ℃ / s, and the third final temperature was 1279 ℃, the finishing rolling temperature was 882 ℃, and the coiling temperature was 700 ℃.

[0199] Comparative Example 1

[0200] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.08 ℃ / s, the second heating rate of the second section was 0.07 ℃ / s, and the second holding time was 800 seconds, the third heating rate of the third section was 0.003 ℃ / s, and the third final temperature was 1,140 ℃, the finishing rolling temperature was 893 ℃, and the coiling temperature was 607 ℃.

[0201] Comparative Example 2

[0202] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.17 ℃ / s, the second heating rate of the second section was 0.028 ℃ / s, and the second holding time was 6,000 seconds, the third heating rate of the third section was -0.02 ℃ / s, and the third final temperature was 1,167 ℃, the finishing rolling temperature was 911 ℃, and the coiling temperature was 599 ℃.

[0203] Comparative Example 3

[0204] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.07 ℃ / s, the second heating rate of the second section was 0.06 ℃ / s, and the second holding time was 600 seconds, the third heating rate of the third section was 0.004 ℃ / s, and the third final temperature was 1,178 ℃, the finish rolling temperature was 898 ℃, the coiling temperature was 611 ℃, and the manufactured hot stamping steel was heated to a temperature of 870 ℃ at a heating rate of 2 ℃ / s.

[0205] Comparative Example 4

[0206] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.19 ℃ / s, the second heating rate of the second section was 0.026 ℃ / s, and the second holding time was 7,000 seconds, the third heating rate of the third section was -0.022 ℃ / s, and the third final temperature was 1,195 ℃, the finish rolling temperature was 914 ℃, the coiling temperature was 603 ℃, and the manufactured hot stamping steel was heated to a temperature of 870 ℃ at a heating rate of 2 ℃ / s.

[0207] Comparative Example 5

[0208] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.08 ℃ / s, the second heating rate of the second section was 0.09 ℃ / s, and the second holding time was 700 seconds, the third heating rate of the third section was 0.004 ℃ / s, and the third final temperature was 1,180 ℃, the finishing rolling temperature was 896 ℃, and the coiling temperature was 605 ℃.

[0209] Comparative Example 6

[0210] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.17 ℃ / s, the second heating rate of the second section was 0.028 ℃ / s, and the second holding time was 6,000 seconds, the third heating rate of the third section was -0.022 ℃ / s, and the third final temperature was 1,197 ℃, the finishing rolling temperature was 907 ℃, and the coiling temperature was 587 ℃.

[0211] Comparative Example 7

[0212] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.06 ℃ / s, the second heating rate of the second section was 0.08 ℃ / s, and the second holding time was 800 seconds, the third heating rate of the third section was 0.005 ℃ / s, and the third final temperature was 1,171 ℃, the finishing rolling temperature was 894 ℃, and the coiling temperature was 600 ℃.

[0213] Comparative Example 8

[0214] The slab was heated in the same manner as in Example 1, except that the first heating rate of the first section was 0.20 ℃ / s, the second heating rate of the second section was 0.037 ℃ / s, and the second holding time was 7,000 seconds, the third heating rate of the third section was -0.018 ℃ / s, and the third final temperature was 1,192 ℃, the finishing rolling temperature was 902 ℃, and the coiling temperature was 583 ℃.

[0215]

[0216] Table 2 above shows the average size [㎛] and number per unit volume (pieces / mm²) of (TiNb)CN precipitates contained in the hot-rolled plates of the Examples and Comparative Examples after the hot-rolling step. 3 This is a table representing ).

[0217] Referring to Table 2, it can be seen that the example satisfies the condition that the average size of the (TiNb)CN precipitates is 0.01 μm or more and 3 μm or less, while the comparative example does not satisfy this condition.

[0218] In addition, the comparative example also has more than 20 crystals per unit volume.

[0219]

[0220] Table 3 above is a table showing the average size [μm] of the (TiNb)CN precipitates contained in the hot stamping steel that has undergone the alloy layer alloying step (S400) according to the examples and comparative examples, and the ratio of the length of the (TiNb)CN precipitates contained in the hot stamping steel to the length of the (TiNb)CN precipitates contained in the hot-rolled plate.

[0221] Referring to Table 3, it can be seen that the comparative examples do not satisfy the length ratio of 1.0 or more and 1.7 or less, which is the target of the present invention.

[0222]

[0223] Table 4 above shows the results of the bendability test, hydrogen embrittlement test, and average austenite grain size observation of the examples and comparative examples.

[0224] In this experiment, the bending angle of the hot stamping parts was measured through a bending test according to the VDA238-100 standard, and the bending angle [°] of each specimen was measured.

[0225] Examples 1 to 12 satisfy the conditions of the first to third sections described above, and thus exhibit good bendability of 50° or more.

[0226] In this experiment, the hydrogen embrittlement test was performed by applying bending stress with a constant force to the examples and comparative examples and immersing them in 0.1N hydrochloric acid for 200 hours to observe whether fracture occurred.

[0227] At this time, for Examples 1 to 6, no fracture occurred even when the above experiment was conducted by applying a bending stress of 110% of the yield strength of each example, for Examples 7 to 9, no fracture occurred even when the above experiment was conducted by applying a bending stress of 140% of the yield strength of each example, and for Examples 10 to 12, no fracture occurred even when the above experiment was conducted by applying a bending stress of 120% of the yield strength of each example.

[0228] On the other hand, Comparative Example 1 was lower than 1,150°C, exhibiting a bending angle of less than 50° and fracture occurring even when only 90% of the yield strength was applied as a bending stress, indicating that it is susceptible to hydrogen embrittlement.

[0229] Likewise, Comparative Examples 2 to 8 also do not satisfy the process conditions of the present invention, so they exhibit an inferior bending angle of less than 50° and fracture occurs even when only 90% of the yield strength is applied as bending stress, making them susceptible to hydrogen embrittlement.

[0230] The embodiments of the present invention are merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true scope of technical protection of the present invention should be determined by the technical spirit of the appended claims.

Claims

1. Carbon (C) 0.10 wt% or more and 0.48 wt% or less, Silicon (Si) 0.05 wt% or more and 1.0 wt% or less, Manganese (Mn) 0.3 wt% or more and 1.6 wt% or less, Phosphorus (P) greater than 0 wt% and 0.020 wt% or less, Sulfur (S) greater than 0 wt% and 0.008 wt% or less, Titanium (Ti) 0.01 wt% or more and 0.05 wt% or less, Chromium (Cr) 0.05 wt% or more and 1.5 wt% or less, Boron (B) 0.001 wt% or more and 0.006 wt% or less, Niobium (Nb) 0.001 wt% or more and 0.065 wt% or less, Nitrogen (N) greater than 0 wt% and 0.01 wt% or less, Calcium (Ca) 0.0003 wt% or more and 0.0031 wt% or less, A hot rolling step for manufacturing a hot-rolled plate by hot rolling a slab containing residual iron (Fe) and other unavoidable impurities, wherein the content of nitrogen (N), titanium (Ti), and niobium (Nb) satisfies Formula 1 below; A cold rolling step for manufacturing a cold rolled plate by rolling the above hot rolled plate with a reduction rate of 40% or more and 70% or less; A plating layer formation step in which the above cold-rolled plate is immersed in a plating solution after annealing; A plating layer alloying step of manufacturing hot stamping steel by heating the cold-rolled plate on which the plating layer is formed to alloy the plating layer; and A hot stamping step of forming the above hot stamping steel in a press after heat treatment; A method for manufacturing a hot stamping part, comprising <Equation 1> 0.0017 ≤ (1.08*({N}-0.006))+[({Ti}+(0.7*{Nb}))] / 3.41 ≤ 0.033 2. In Paragraph 1, The hot rolling step comprises the steps of reheating the slab, rolling the reheated slab, and coiling the rolled slab. In the step of reheating the slab, the section where the slab is heated for the first time is called the first section, the heating section that begins after the end of the first section is called the second section, and the heating section that begins after the end of the second section and continues until the step of reheating the slab is finished is called the third section. When the average heating rate of the slab in the first section is called the first heating rate, the average heating rate of the slab in the second section is called the second heating rate, and the average heating rate of the slab in the third section is called the third heating rate, A method for manufacturing a hot stamping part, wherein the first heating rate and the second heating rate are different, and the second heating rate and the third heating rate are different.

3. In Paragraph 2, A method for manufacturing a hot stamping part, wherein the third heating rate is less than or equal to the first heating rate, and the third heating rate is less than or equal to the second heating rate.

4. In Paragraph 2, A method for manufacturing a hot stamping part, wherein the second heating rate in the second section is 0.013 ℃ / s or more and 0.60 ℃ / s or less, and the time for heating the slab in the second section is 1,000 seconds or more and 10,000 seconds or less.

5. In Paragraph 4, When the temperature of the slab at the point where the above third section ends is referred to as the third final temperature, A method for manufacturing a hot stamping part, wherein the third final temperature is 1,150 ℃ or higher and 1,280 ℃ or lower.

6. In Paragraph 1, The above hot rolling step comprises 20 (TiNb)CN precipitates / mm² with an average size of 0.01 μm or more and 3 μm or less, contained in the hot-rolled plate. 3 A method for manufacturing a hot stamping part such that the following applies.

7. In Paragraph 6, The above hot stamping part manufacturing method is, A method for manufacturing a hot stamping part, wherein the ratio of the length of the (TiNb)CN precipitate contained in the hot stamping steel that has undergone the plating layer alloying step to the length of the (TiNb)CN precipitate contained in the hot-rolled plate that has undergone the hot rolling step is 1 or more and 1.7 or less.

8. As hot stamping steel, Carbon (C) 0.10 wt% or more and 0.48 wt% or less, Silicon (Si) 0.05 wt% or more and 1.0 wt% or less, Manganese (Mn) 0.3 wt% or more and 1.6 wt% or less, Phosphorus (P) greater than 0 wt% and 0.020 wt% or less, Sulfur (S) greater than 0 wt% and 0.008 wt% or less, Titanium (Ti) 0.01 wt% or more and 0.05 wt% or less, Chromium (Cr) 0.05 wt% or more and 1.5 wt% or less, Boron (B) 0.001 wt% or more and 0.006 wt% or less, Niobium (Nb) 0.001 wt% or more and 0.065 wt% or less, Nitrogen (N) greater than 0 wt% and 0.01 wt% or less, Calcium (Ca) 0.0003 wt% or more and 0.0031 wt% or less, and the remainder of It contains iron (Fe) and other unavoidable impurities, and the content of nitrogen (N), titanium (Ti), and niobium (Nb) satisfies the following Formula 1, A hot stamping steel having an average size of (TiNb)CN precipitates contained in the hot stamping steel of the above, ranging from 0.01 μm to 3 μm. <Equation 1> 0.0017 ≤ (1.08*({N}-0.006))+[({Ti}+(0.7*{Nb}))] / 3.41 ≤ 0.033 9. In Paragraph 8, The hot stamping steel has a tensile strength of 500 MPa or more and 650 MPa or less, and a yield strength of 300 MPa or more and 400 MPa or less.

10. As a hot stamping part, Carbon (C) 0.10 wt% or more and 0.48 wt% or less, Silicon (Si) 0.05 wt% or more and 1.0 wt% or less, Manganese (Mn) 0.3 wt% or more and 1.6 wt% or less, Phosphorus (P) greater than 0 wt% and 0.020 wt% or less, Sulfur (S) greater than 0 wt% and 0.008 wt% or less, Titanium (Ti) 0.01 wt% or more and 0.05 wt% or less, Chromium (Cr) 0.05 wt% or more and 1.5 wt% or less, Boron (B) 0.001 wt% or more and 0.006 wt% or less, Niobium (Nb) 0.001 wt% or more and 0.065 wt% or less, Nitrogen (N) greater than 0 wt% and 0.01 wt% or less, Calcium (Ca) 0.0003 wt% or more and 0.0031 wt% or less, and the remainder of It contains iron (Fe) and other unavoidable impurities, and the content of nitrogen (N), titanium (Ti), and niobium (Nb) satisfies the following Formula 1, The above hot stamping part is a hot stamping part comprising a martensitic structure of 80 volume% or more and a bainite structure of 20 volume% or less. <Equation 1> 0.0017 ≤ (1.08*({N}-0.006))+[({Ti}+(0.7*{Nb}))] / 3.41 ≤ 0.033 11. In Paragraph 10, A hot stamping part having a tensile strength of 1,400 MPa or more and a yield strength of 1,000 MPa or more.

12. In Paragraph 10, A hot stamping part comprising austenite, wherein the average austenite grain size of the austenite included in the hot stamping part is 15 μm or more and 25 μm or less.

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