U.S. patent application number 13/830371 was filed with the patent office on 2014-06-12 for compacted graphite iron, engine cylinder head and vehicle.
This patent application is currently assigned to Hyundai Motor Company. The applicant listed for this patent is HYUNDAI MOTOR COMPANY. Invention is credited to Jeong Seop Lee, Duk Hyun Nam.
Application Number | 20140161657 13/830371 |
Document ID | / |
Family ID | 50881145 |
Filed Date | 2014-06-12 |
United States Patent
Application |
20140161657 |
Kind Code |
A1 |
Lee; Jeong Seop ; et
al. |
June 12, 2014 |
COMPACTED GRAPHITE IRON, ENGINE CYLINDER HEAD AND VEHICLE
Abstract
A compacted graphite iron having composition comprising: Fe as a
major ingredient, C: of about 3.4.about.4.2 wt %, Si: of about
1.5.about.2.5 wt %, P: 0.10 wt % or less (not including 0), S: of
about 0.10 wt % or less (not including 0), Cr: of about 0.10 wt %
or less (not including 0), Mn: of about 0.1.about.0.6 wt %, Cu: of
about 0.2.about.1.6 wt %, Sn: of about 0.1 wt % or less (not
including 0), Mg: of about 0.05 wt % or less (not including 0), Mo:
of about 0.05.about.0.5 wt %, at least one ingredient of V: of
about 0.05.about.0.5 wt % and Ti: of about 0.05.about.0.5 wt %, and
other inevitable impurities; an engine cylinder head; and a
vehicle.
Inventors: |
Lee; Jeong Seop; (Seoul,
KR) ; Nam; Duk Hyun; (Osan, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HYUNDAI MOTOR COMPANY |
Seoul |
|
KR |
|
|
Assignee: |
Hyundai Motor Company
Seoul
KR
|
Family ID: |
50881145 |
Appl. No.: |
13/830371 |
Filed: |
March 14, 2013 |
Current U.S.
Class: |
420/15 |
Current CPC
Class: |
C22C 37/06 20130101;
C22C 37/10 20130101 |
Class at
Publication: |
420/15 |
International
Class: |
C22C 37/10 20060101
C22C037/10; C22C 37/06 20060101 C22C037/06 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 12, 2012 |
KR |
10-2012-0144952 |
Claims
1. A compacted graphite iron having composition comprising: Fe as a
major ingredient, C: of about 3.4.about.4.2 wt %, Si: of about
1.5.about.2.5 wt %, P: of about 0.10 wt % or less (not including
0), S: of about 0.10 wt % or less (not including 0), Cr: of about
0.10 wt % or less (not including 0), Mn: of about 0.1.about.0.6 wt
%, Cu: of about 0.2.about.1.6 wt %, Sn: of about 0.1 wt % or less
(not including 0), Mg: of about 0.05 wt % or less (not including
0), Mo: of about 0.05.about.0.5 wt %, at least one ingredient of V:
of about 0.05.about.0.5 wt % and Ti: of about 0.05.about.0.5 wt %,
and other inevitable impurities.
2. An engine cylinder head manufactured with the composition
comprising the compacted graphite iron according to claim 1.
3. A vehicle equipped with an engine cylinder head manufactured
with the composition comprising the compacted graphite iron
according to claim 1.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims under 35 U.S.C. .sctn.119(a) the
benefit of Korean Patent Application No. 10-2012-0144952 filed on
Dec. 12, 2012 the entire contents of which are incorporated herein
by reference.
BACKGROUND
[0002] (a) Technical Field
[0003] The present invention relates to a CGI (compacted graphite
iron), which is suitable to be used to vehicle parts and the like
such as engine cylinder heads, particularly to a compacted graphite
iron having excellent tensile strength and thermo-mechanical
fatigue life, an engine cylinder head formed with the compacted
graphite iron, and a vehicle equipped with the engine cylinder
head.
[0004] (b) Background Art
[0005] Vehicle parts such as engine cylinder heads are required to
have proper tensile strength and thermo-mechanical fatigue life to
endure pressure and heat emitted by the engine while driving.
Further, there is a need to satisfy demands for improving output
and the like.
[0006] Particularly, a cylinder head, which is understood by those
skilled in the art as a cover covering the top of the cylinder, is
installed at a cylinder block with a bolt across a head gasket, and
forms a combustion chamber together with a piston and a cylinder. A
water cooled type engine head is casted in one piece as a whole
cylinder or as several divided cylinders, and includes a water
jacket for cooling. An air cooled type engine head is separately
manufactured per cylinder, and a cooling plate is installed
thereto. Further, there are the combustion chamber and a valve
sheet below the cylinder head, or in the upper part thereof, there
is a spark plug for a gasoline engine or there are apertures of
bores for installation of a glow plug and a spray nozzle and a part
for installation of a valve open-close device for a diesel
engine.
[0007] This cylinder head, which forms part of a combustion
chamber, is exposed to higher temperature and higher pressure
expansion gas. Accordingly, a material having excellent
thermo-mechanical fatigue life should be used to be operated under
enough strength and at a certain temperature (200.about.500.degree.
C.).
[0008] On the other hand, aluminum alloy is generally used for a
gasoline engine or a light duty diesel engine, but when a heavy
duty diesel engine, whose combustion pressure is high, flake-type
graphite cast iron or CGI is used as a material for a cylinder
head. Among them, the CGI having better tensile strength than the
flake-type graphite cast iron is mainly used for the cylinder head
of high output heavy duty diesel engine. However, CGI has a demerit
of low thermo-mechanical fatigue life due to lower thermal
conductivity than the flake-type graphite cast iron, and
accordingly, it is very important to secure the thermo-mechanical
fatigue life in order to secure competitiveness of the CGI.
Therefore, the CGI material for a cylinder head needs improvements
of tensile strength and thermo-mechanical fatigue life.
[0009] Conventional "CGI cast iron" typically includes iron (Fe) as
a major component, carbon (C) of 3.45.about.3.55 wt %, silicon (Si)
of 2.30.about.2.40 wt %, magnesium (Mg) of 0.002.about.0.008 wt %,
copper (Cu) of 0.10.about.0.90 wt %, tin (Sn) of 0.01.about.0.09 wt
%, chromium (Cr) of 0.03.about.0.07 wt %, manganese (Mn) of
0.30.about.0.35 wt %, phosphorus (P) of 0.1 wt % or less, and
sulfur (S) of 0.1 wt % or less, wherein the carbon equivalent (CE)
is 4.3.+-.0.05."
[0010] However, the above composition is not enough to secure the
appropriate tensile strength and thermo-mechanical fatigue life.
Accordingly, a composition of compacted graphite iron with improved
properties is urgently needed.
[0011] The description provided above as a related art of the
present invention is just for helping understanding the background
of the present invention and should not be construed as being
included in the related art known by those skilled in the art.
SUMMARY OF THE DISCLOSURE
[0012] The present invention has been made in an effort to solve
the above-described problems associated with prior art. The present
invention provides a CGI (compacted graphite iron), which is
suitable to be used to vehicle parts and the like such as engine
cylinder heads, particularly to a compacted graphite iron having
excellent tensile strength and thermo-mechanical fatigue life, an
engine cylinder head formed with the compacted graphite iron, and a
vehicle equipped with the engine cylinder head.
[0013] In order to accomplish the said object, the compacted
graphite iron according to the present invention has composition
comprising: Fe as a major ingredient, C: of about 3.4.about.4.2 wt
%, Si: of about 1.5.about.2.5 wt %, P: of about 0.10 wt % or less
(not including 0), S: of about 0.10 wt % or less (not including 0),
Cr: of about 0.10 wt % or less (not including 0), Mn: of about
0.1.about.0.6 wt %, Cu: of about 0.2.about.1.6 wt %, Sn: of about
0.1 wt % or less (not including 0), Mg: of about 0.05 wt % or less
(not including 0), Mo: of about 0.05.about.0.5 wt %, at least one
ingredient of V: of about 0.05.about.0.5 wt % and Ti: of about
0.05.about.0.5 wt %, and other inevitable impurities.
[0014] Further, the engine cylinder head of the present invention
is manufactured with the composition comprising the compacted
graphite iron. Additionally, the vehicle of the present invention
is equipped with the engine cylinder head manufactured with the
composition comprising the compacted graphite iron.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The above and other features of the present invention will
now be described in detail with reference to certain exemplary
embodiments thereof illustrated the accompanying drawings which are
given hereinbelow by way of illustration only, and thus are not
limitative of the present invention, and wherein:
[0016] FIGS. 1 and 2 are graphs showing the results of tensile
strength test and fatigue life test of the compacted graphite iron
according to one exemplary embodiment of the present invention and
a conventional compacted graphite iron.
[0017] It should be understood that the appended drawings are not
necessarily to scale, presenting a somewhat simplified
representation of various preferred features illustrative of the
basic principles of the invention. The specific design features of
the present invention as disclosed herein, including, for example,
specific dimensions, orientations, locations, and shapes will be
determined in part by the particular intended application and use
environment.
[0018] In the figures, reference numbers refer to the same or
equivalent parts of the present invention throughout the several
figures of the drawing.
DETAILED DESCRIPTION
[0019] Hereinafter, the compacted graphite iron, the engine
cylinder head and the vehicle according to preferable embodiments
of the present invention now will be described in detail with
reference to the accompanying drawings.
[0020] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof. As
used herein, the term "and/or" includes any and all combinations of
one or more of the associated listed items.
[0021] Unless specifically stated or obvious from context, as used
herein, the term "about" is understood as within a range of normal
tolerance in the art, for example within 2 standard deviations of
the mean. "About" can be understood as within 10%, 9%, 8%, 7%, 6%,
5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated
value. Unless otherwise clear from the context, all numerical
values provided herein are modified by the term "about."
[0022] The compacted graphite iron (CGI) of the present invention
has composition comprises Fe as a major ingredient, C: of about
3.4.about.4.2 wt %, Si: of about 1.5.about.2.5 wt %, P: of about
0.10 wt % or less (not including 0), S: of about 0.10 wt % or less
(not including 0), Cr: of about 0.10 wt % or less (not including
0), Mn: of about 0.1.about.0.6 wt %, Cu: of about 0.2.about.1.6 wt
%, Sn: of about 0.1 wt % or less (not including 0), Mg: of about
0.05 wt % or less (not including 0), Mo: of about 0.05.about.0.5 wt
%, at least one ingredient of V: of about 0.05.about.0.5 wt % and
Ti: of about 0.05.about.0.5 wt %, and other inevitable
impurities.
[0023] The CGI of the present invention has very excellent tensile
strength and thermo-mechanical fatigue life compared with previous
materials having a CGI level. Accordingly, the CGI material of the
present invention can be used for high output cylinder head.
[0024] In the CGI of the present invention, thermo-mechanical
fatigue life is improved by adding Mo, V and Ti of chemical
ingredients, and excellent tensile strength is secured by
strengthening perlite structure as a matrix by adding Sn and by
securing fine perlite structure by adding Mo and regulating the
upper limit of the Si content.
[0025] The functions and contents of the ingredients contained in
the CGI according to the present invention are as follows.
[0026] The carbon (C) is an essential atom for forming the
high-temperature stable phase, and is preferably contained at the
amount of about 3.4.about.4.2 wt % in view of fluidity reduction
and primary graphite crystallization.
[0027] The silicon (Si) is contained at the amount of about
1.5.about.2.5 wt %. The silicon contributes to graphite
crystallization, and therefore, it is needed to be contained at the
amount of about 1.5 wt % or more. The silicon is a representative
atom interrupting perlite refining. Therefore, in order to improve
tensile strength through the perlite refining, the silicon content
should be as low as possible, and when the silicon content is high,
more perlite refining atoms (Mo and the like) should be added.
Accordingly, in the present invention, the silicon content was
determined to be about 2.5 wt % or less, which is the level which
would not interrupt the perlite refining.
[0028] Particularly, the silicon content was regulated to be about
2.5 wt % or less, the level not excessively demanding the addition
of perlite refining atoms (Mo and the like). In the case of
molybdenum, castability and machinability are decreased when its
content is over 0.5 wt %. Accordingly, the molybdenum was added to
improve tensile strength by refining the perlite structure, and the
content silicon (Si), which attributes to graphite crystallization,
was optimized to the level not interrupting the perlite refining at
the same time. On the other hand, the phosphorus (P) is contained
in the amount of 0.10 wt % or less. The phosphorus forms steadite
and affects to brittleness. Accordingly, it is preferred to limit
the amount to about 0.10 wt % or less.
[0029] The Sulfur (S) is contained at the amount of about 0.10 wt %
or less. The sulfur forms MnS by being combined with Mn so as to
improve machinability, but affects to brittleness when the amount
is over 0.10 wt %. Accordingly, it is preferred to limit the amount
to 0.10 wt % or less.
[0030] Further, the chromium (Cr) is contained at the amount of
about 0.10 wt % or less. When the amount is over 0.10 wt %,
machinability may be decreased. Accordingly, it is preferred to
limit the amount of chromium (Cr) to 0.10 wt % or less.
[0031] The manganese (Mn) is contained at the amount of
0.1.about.0.6 wt %, and improves tensile strength by strengthening
perlite matrix. However, when the amount is over 0.6 wt %,
machinability may be decreased. Accordingly, it is preferred to use
the manganese (Mn) in the amount of 0.1.about.0.6 wt %.
[0032] On the other hand, the copper (Cu) is contained at the
amount of about 0.2.about.1.6 wt %. The copper, an atom making
perlite matrix, strengthens the matrix and improves tensile
strength. However, when the amount is over 1.6 wt %, the effects
are saturated. Accordingly, it is preferred to use the copper (Cu)
at the amount of about 0.2.about.1.6 wt %.
[0033] The tin (Sn) is contained at the amount of about 0.1 wt % or
less. Because it has higher effects to on the perlite matrix than
the copper, tensile strength can be improved. However, when the
content is over 0.1 wt %, the effects may be saturated.
Accordingly, the tin (Sn) content is limited to about 0.1 wt % or
less.
[0034] The magnesium (Mg) is contained at the amount of about 0.05
wt % or less. The magnesium is an atom required to make graphite
form into compacted graphite, which is an intermediate form of
flake form and spheroidal form. However, when the magnesium content
is over 0.05 wt %, the graphite is spheroidized. Accordingly, it is
preferred to limit the magnesium (Mg) content to about 0.05 wt % or
less.
[0035] Particularly, the molybdenum (Mo) is contained in the amount
of 0.05.about.0.5 wt %. The molybdenum is an atom refining the
perlite matrix structure, and it should be contained because it
improves tensile strength by refining the perlite structure formed
by the copper (Cu) and the tin (Sn). Further, it forms Mo Carbide
by combining with the carbon (C), and then sometimes forms the high
temperature stable phase improving thermo-mechanical fatigue life.
However, when its content is over 0.5 wt %, castability and
machinability are decreased. Accordingly, it is preferred to use
the molybdenum (Mo) in the amount of about 0.0.about.0.5 wt %.
[0036] As described above, the silicon (Si) is contained in the
amount of about 1.5.about.2.5 wt % at the same time, thereby it
attributes to graphite crystallization and is regulated to the
level not interrupting the perlite refining.
[0037] On the other hand, at least one atom of vanadium (V) and
titanium (Ti) should be contained in the amount of 0.05.about.0.5
wt %. This atom forms V/Ti Carbide by combining with carbon (C),
and forms high-temperature stable phase improving thermo-mechanical
fatigue life. But, because castability and machinability are
decreased when the amount of at least one atom of vanadium (V) and
titanium (Ti) is over 0.5 wt %, it is preferred to limit the amount
of at least one atom of vanadium (V) and titanium (Ti) to
0.05.about.0.5 wt %.
[0038] Effects of the compacted graphite iron of the present
invention can be confirmed by comparing with Comparative Example,
and specific compositions of Comparative Example and Examples are
as follows.
TABLE-US-00001 TABLE 1 Composition (wt %) C Si P S Cr Mn Cu Sn Mg
Mo V Ti Fe Comp. 3.78 2.02 0.03 0.02 0.03 0.32 0.82 0.04 0.02 -- --
-- Rem. Example Example 3.67 1.95 0.04 0.03 0.04 0.29 0.79 0.09
0.02 0.3 -- -- Rem. 1 Example 3.71 2.03 0.02 0.02 0.02 0.33 0.83
0.09 0.02 0.2 -- 0.3 Rem. 2 Example 3.68 2.01 0.02 0.03 0.03 0.31
0.80 0.09 0.02 0.2 0.3 -- Rem. 3
[0039] The composition of Examples 1, 2 and 3 are the composition
of the compacted graphite iron suggested by the present invention,
and the composition of Comparative Example is the composition of
the compacted graphite iron having 400 MPa level of tensile
strength suggested as the conventional material for engine cylinder
heads.
[0040] Tensile tests were conducted according to KS B 0802 (tensile
test method of metallic materials). No. 8 test specimen was used as
a test specimen according to KS B 0801 (tensile test specimen of
metallic materials). As a result, as shown in FIG. 1, Examples 1, 2
and 3 showed higher tensile strength, which was improved 10% or
more than Comparative Example, and it is considered perlite matrix
strengthening effect by Sn and perlite matrix refining effect by
Mo. Namely, these were resulted from perlite strengthened by adding
more Sn than before, and from perlite refined by newly adding
Mo.
[0041] On the other hand, thermo-mechanical fatigue life was
conducted by controlling temperature condition to room temperature
.about.450.degree. C., stress strain rate to .+-.0.75% at 200
sec/cycle. As shown in FIG. 2, it was confirmed that
thermo-mechanical fatigue life of each of Examples 1, 2 and 3 was
increased, 20% or more, than Comparative Example, and it is
considered effect by generation of Mo/V/Ti Carbide, which is
high-temperature stable phase, according to adding Mo, V and
Ti.
[0042] According to the compacted graphite iron, the engine
cylinder head and the vehicle having the constitution described
above, Mo/V/Ti Carbide as high-temperature stable phase can be
formed by adding Mo, V and Ti atoms improving thermo-mechanical
fatigue life, by adding Sn atom improving tensile strength by
matrix strengthening, by adding Mo atom improving tensile strength
by perlite refining, and by optimizing other alloy ingredients,
compared with the conventional CGIs. Particularly, by selecting Si
in charge of graphite crystallization and Mo in charge of perlite
refining within a balanced range, both of the two effects can be
obtained.
[0043] Through this, a CGI having improved tensile strength of 10%
or more and thermo-mechanical fatigue life of 20% or more against
the conventional CGI materials can be obtained. Further, the CGI is
excellent on tensile strength and thermo-mechanical fatigue life by
forming good compacted graphite and fine perlite structure against
the conventional CGI, and therefore, it can be suitably used for
engine cylinder heads that requires power improvement.
[0044] The invention has been described in detail with reference to
preferred embodiments thereof. However, it will be appreciated by
those skilled in the art that changes or modifications may be made
in these embodiments without departing from the principles and
spirit of the invention, the scope of which is defined in the
appended claims and their equivalents.
* * * * *