Technical Field
[0001] The present disclosure relates to a plated steel sheet
for hot press forming (HPF) having excellent hydrogen
embrittlement resistance and hot press formed parts, used as
5 vehicle body parts, and manufacturing methods thereof.
[0002]
Background Art
[0003] Hot press formed parts have recently been widely used
in structural members such as vehicles for the purpose of
10 improving fuel efficiency and protecting passengers by reducing
the weight of vehicles, and have been particularly widely used
in bumpers, doors, or filler reinforcement materials that
require ultra-high strength or energy absorbency.
Specifically, when hot press formed parts are used, plated steel
15 sheets of which the surface is plated to ensure corrosion
resistance have been widely used.
[0004]
[0005] Patent Document 1 is representative technology for the
hot press forming technique. According to Patent Document 1,
20 after heating an Al-Si plated steel sheet at 850°C or higher,
a hot press forming process and a cooling process by a press
are performed to form the structure of a member in a martensite
phase, thus securing ultra-high strength. When the ultra-high
strength is secured by using such a hot press forming technique,
25 since components are molded at high temperatures, it is possible
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to easily mold complex shapes. In addition, a lightweight
effect may be expected simultaneously with high strength
through an increase in strength according to rapid cooling in
the mold.
5 [0006]
[0007] However, it is known that the martensite structure has
low resistance to hydrogen embrittlement. Specifically, when
residual stress is present due to rapid cooling after heating
and the amount of diffusible hydrogen in steel increases,
10 components manufactured after a hot press forming process may
be subject to delayed fracture caused by hydrogen embrittlement,
which may limit the application of components. Therefore,
there is a need for a method to solve such problems.
[0008]
15 [0009] Patent Document 1: U.S. Patent No. 6296805
[0010]
Summary of Invention
Technical Problem
[0011] An aspect of the present disclosure is to provide a
20 plated steel sheet for hot press forming (HPF) having excellent
hydrogen embrittlement resistance and hot press formed parts
manufactured using the plated steel sheet, and manufacturing
methods thereof, due to reduced occurrence of delayed fracture
caused by hydrogen embrittlement of the hot press formed parts.
25 [0012]
Page 4
[0013] The subject of the present disclosure is not limited to
the above. A person skilled in the art will have no difficulty
understanding the further subject matter of the present
disclosure from the general content of this specification.
5 [0014]
Solution to Problem
[0015] According to an aspect of the present disclosure, a
plated steel sheet for hot press forming having excellent
hydrogen embrittlement resistance may include: a base steel
10 sheet; and
[0016] an Al-based plating layer formed on a surface of the base
steel sheet,
[0017] wherein an average Ni content in the Al-based plating
layer is 0.05 to 0.35 wt%.
15 [0018]
[0019] According to another aspect of the present disclosure,
a method of manufacturing a plated steel sheet for hot press
forming having excellent hydrogen embrittlement resistance may
include:
20 [0020] preparing a base steel sheet;
[0021] plating the prepared base steel sheet with Ni in a
coating weight of 150 to 2500 mg/m2; and
[0022] continuously annealing the Ni-plated cold rolled steel
sheet, followed by Al-based plating.
25 [0023]
Page 5
[0024] According to another aspect of the present disclosure,
hot press formed parts having excellent hydrogen embrittlement
may include: base iron;
[0025] and an alloy plating layer formed on the base iron,
5 [0026] wherein a Ni content at a point (Nimax) in which the Ni
content is the highest, up to 15 μm in a depth direction from
a surface of the alloy plating layer, is 0.1 to 0.75% wt%.
[0027]
[0028] According to another aspect of the present disclosure,
10 a method of manufacturing hot press formed parts having
excellent hydrogen embrittlement resistance may include:
[0029] providing a blank including a base steel sheet and an
Al-based plating layer formed on a surface of the base steel
sheet, wherein an average Ni content in the Al-based plating
15 layer is 0.05 to 0.35 wt%;
[0030] heating the blank in a temperature range of Ac3 to 975°C;
and transferring and molding the heated blank to a press, and
[0031] cooling the blank at a cooling rate of 20°C/s or higher.
[0032]
20 Advantageous Effects of Invention
[0033] According to an aspect of the present disclosure, when
a plated steel sheet for hot press forming is hot press formed,
the amount of diffusible hydrogen in steel can be reduced to
provide hot press formed parts having excellent hydrogen
25 embrittlement resistance.
Page 6
[0034] The various and beneficial advantages and effects of the
present disclosure are not limited to the aforementioned
description, and will be more easily understood in the process
of describing specific embodiments of the present disclosure.
5 [0035]
Brief Description of Drawings
[0036] FIG. 1 is a graph of analyzing contents of Fe and Ni of
an Al-based plating layer in a plated steel sheet for hot press
forming of Invention Example 1 in example embodiments by Glow
10 Discharge Optical Emission Spectroscopy (GDS).
[0037] FIG. 2 is a graph of analyzing the content of Ni in an
alloy plating layer of hot press formed parts of Invention
Example 3 in example embodiments by the GDS, through which a
Ni-concentrated layer is illustrated.
15 [0038] FIG. 3 is a graph of analyzing the content of Ni in the
alloy plating layer of the hot press formed parts of Invention
Examples 1 to 3 and Comparative Example 2 in the example
embodiments by the GDS.
[0039] FIG. 4 is a graph of illustrating results of measuring
20 the content of Ni and the amount of diffusible hydrogen of each
part at a Nimax point of the hot press formed parts of Invention
Examples 1 to 8 and Comparative Examples 1 to 2 in the example
embodiments.
[0040]
25 Best Mode for Invention
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[0041] The terminology used herein is for the purpose of
describing particular embodiments only and is not intended to
be limiting of the invention. Furthermore, in this
specification, the singular also includes the plural unless
5 specifically stated otherwise in the phrase.
[0042] As used herein, “comprises” and/or “comprising”
embodies one or more other components and/or elements and does
not exclude the presence or addition of other components.
[0043] Unless otherwise defined, all terms (including
10 technical and scientific terms) used in the present
specification may be used in a sense that can be commonly
understood by those skilled in the art. In addition, it will
be further understood that terms, such as those defined in
commonly used dictionaries, should be interpreted as having a
15 meaning that is consistent with their meaning in the context
of the relevant art.