U.S. patent application number 13/171267 was filed with the patent office on 2011-12-15 for steel and coupler made from the same.
This patent application is currently assigned to MUDANJIANG JINYUAN COUPLER AND DRAFT GEAR MANUFACTURING CO., LTD.. Invention is credited to Yang Lu, XIAOFENG QIN, Chunguo Tao, Xunqian Wei, Baoli Wen, Limin Xiao.
Application Number | 20110305593 13/171267 |
Document ID | / |
Family ID | 45096359 |
Filed Date | 2011-12-15 |
United States Patent
Application |
20110305593 |
Kind Code |
A1 |
QIN; XIAOFENG ; et
al. |
December 15, 2011 |
STEEL AND COUPLER MADE FROM THE SAME
Abstract
The present invention provides a type of steel and a coupler
made from same, comprising the following compositions in
percentages by weight: carbon: 0.24-0.32%, silicon: 0.20-0.50%,
manganese: 1.30-1.70%, phosphorus: less than or equal to 0.02%,
sulphur: less than or equal to 0.02%, copper: less than or equal to
0.30%, chromium: 0.50-0.80%, nickel: 0.40-0.70%, molybdenum:
0.25-0.45%, aluminium: 0.02-0.08%, and the remainders are iron and
other inevitable elements. The steel of the present invention is
advantaged in high strength and excellent toughness and therefore
the mechanical property thereof is better than the standard of
conventional grade E steel.
Inventors: |
QIN; XIAOFENG;
(Heilongjiang, CN) ; Tao; Chunguo; (Heilongjiang,
CN) ; Lu; Yang; (Heilongjiang, CN) ; Xiao;
Limin; (Heilongjiang, CN) ; Wen; Baoli;
(Heilongjiang, CN) ; Wei; Xunqian; (Heilongjiang,
CN) |
Assignee: |
MUDANJIANG JINYUAN COUPLER AND
DRAFT GEAR MANUFACTURING CO., LTD.
Heilongjiang
CN
QIQIHAR RAILWAY ROLLING STOCK CO., LTD.
Heilongjiang
CN
|
Family ID: |
45096359 |
Appl. No.: |
13/171267 |
Filed: |
June 28, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/CN2010/074332 |
Jun 23, 2010 |
|
|
|
13171267 |
|
|
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|
Current U.S.
Class: |
420/91 |
Current CPC
Class: |
C22C 38/06 20130101;
C22C 38/44 20130101; C22C 38/02 20130101; C22C 38/42 20130101; C22C
38/58 20130101 |
Class at
Publication: |
420/91 |
International
Class: |
C22C 38/42 20060101
C22C038/42; C22C 38/44 20060101 C22C038/44; C22C 38/06 20060101
C22C038/06; C22C 38/58 20060101 C22C038/58; C22C 38/02 20060101
C22C038/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 13, 2010 |
CN |
201010202732.0 |
Claims
1. A steel, characterized by comprising the following compositions
in percentages by weight: carbon: 0.24-0.32%, silicon: 0.20-0.50%,
manganese: 1.30-1.70%, phosphorus: less than or equal to 0.02%,
sulphur: less than or equal to 0.02%, copper: less than or equal to
0.30%, chromium: 0.50-0.80%, nickel: 0.40-0.70%, molybdenum:
0.25-0.45%, aluminium: 0.02-0.08%, and the remainders are iron and
other inevitable elements.
2. The steel in claim 1, characterized in that: the percentage of
the carbon by weight is 0.25-0.29%.
3. The steel in claim 2, characterized in that: the percentage of
the carbon by weight is 0.25-0.28%.
4. The steel in claim 1, characterized in that: the percentage of
the manganese by weight is 1.35-1.60%.
5. The steel in claim 4, characterized in that: the percentage of
the manganese by weight is 1.35-1.55%.
6. The steel in claim 1, characterized in that: the percentage of
the phosphorus by weight is less than or equal to 0.015%.
7. The steel in claim 1, characterized in that: the percentage of
the sulphur by weight is less than or equal to 0.015%.
8. The steel in claim 1, characterized in that: the percentage of
the aluminium by weight is 0.02-0.06%.
9. The steel in claim 8, characterized in that: the percentage of
the aluminium by weight is 0.02-0.05%.
10. A coupler made of the steel in the claim 1.
11. A coupler made of the steel in the claim 2.
12. A coupler made of the steel in the claim 3.
13. A coupler made of the steel in the claim 4.
14. A coupler made of the steel in the claim 5.
15. A coupler made of the steel in the claim 6.
16. A coupler made of the steel in the claim 7.
17. A coupler made of the steel in the claim 8.
18. A coupler made of the steel in the claim 9.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of international
application No. PCT/CN2010/074332 filed on Jun. 23, 2010, which
claims the priority benefit of China Patent Application No.
201010202732.0, filed on Jun. 13, 2010. The contents of the above
identified applications are incorporated herein by reference in
their entirety.
FIELD OF THE TECHNOLOGY
[0002] The present invention relates to metallurgical technology,
in particular to a type of steel with higher mechanical property
and to a coupler made from the same.
BACKGROUND
[0003] Along with the development of industry, the requirement to
the mechanical property of steel material becomes higher and
higher. For example, during the development of "speed-rising and
heavy-haul" of railway wagon, total traction weight of railway
wagon has been increased greatly and therefore the requirement to
the quality of components on wagon also becomes higher and higher;
as a connection part between wagons, the coupler bears large
tensile stress and impact force in a running railway wagon; the
coupler knuckle of the coupler is a weak link of a railway wagon
and easy to be fractured in a running railway wagon. The fracture
of the coupler knuckle in a running railway wagon is generally
fatigue fracture, for which the reasons include poor toughness,
insufficient strength etc. of the materials for coupler
knuckle.
[0004] Therefore, the strength and toughness of steel should be
improved to meet the constantly increasing industry requirements,
such as prolonging the fatigue life of a wagon coupler.
SUMMARY
[0005] The present invention aims at providing a type of steel and
a coupler made from the same, so as to improve mechanical property
of steel, in particular the strength and toughness thereof, and to
therefore provide a coupler with excellent mechanical property.
[0006] In order to achieve the above purposes, the present
invention provides a steel, comprising the following compositions
in percentages by weight: carbon: 0.24-0.32%, silicon: 0.20-0.50%,
manganese: 1.30-1.70%, phosphorus: less than or equal to 0.02%,
sulphur: less than or equal to 0.02%, copper: less than or equal to
0.30%, chromium: 0.50-0.80%, nickel: 0.40-0.70%, molybdenum:
0.25-0.45%, aluminium: 0.02-0.08%, and the remainders are iron and
other inevitable elements.
[0007] Wherein, the percentage of carbon by weight is preferably
0.25-0.29%, and more preferably 0.25-0.28%.
[0008] The percentage of manganese by weight is preferably
1.35-1.60%, and more preferably 1.35-1.55%.
[0009] The percentage of phosphorus by weight is preferably: less
than or equal to 0.015%.
[0010] The percentage of sulphur by weight is preferably: less than
or equal to 0.015%. And
[0011] The percentage of aluminium by weight is preferably
0.02-0.06%, and more preferably 0.02-0.05%.
[0012] In order to achieve the above purpose, the present invention
further provides a coupler made of the steel provided by the
present invention.
[0013] The steel and the coupler made from the same are advantaged
in high strength and excellent toughness and therefore the
mechanical property thereof is better than the standard of
conventional grade E steel.
DETAILED DESCRIPTION
[0014] The technical solution of the present invention is further
described in detail in connection with embodiments.
[0015] The present invention provides a steel, comprising the
following compositions in percentages by weight: carbon:
0.24-0.32%, silicon: 0.20-0.50%, manganese: 1.30-1.70%, phosphorus:
less than or equal to 0.02%, sulphur: less than or equal to 0.02%,
copper: less than or equal to 0.30%, chromium: 0.50-0.80%, nickel:
0.40-0.70%, molybdenum: 0.25-0.45%, aluminium: 0.02-0.08%, and the
remainders are iron and other inevitable elements.
[0016] Wherein, the percentage of carbon by weight is preferably
0.25-0.29%, and more preferably 0.25-0.28%; the percentage of
manganese by weight is preferably 1.35-1.60%, and more preferably
1.35-1.55%; the percentage of phosphorus by weight is preferably:
less than or equal to 0.015%; the percentage of sulphur by weight
is preferably: less than or equal to 0.015%; and the percentage of
aluminium by weight is preferably 0.02-0.06%, and more preferably
0.02-0.05%.
[0017] The percentage of silicon by weight is preferably
0.20-0.40%, and more preferably 0.21-0.39%; the percentage of
chromium by weight is preferably 0.50-0.65%, and more preferably
0.50-0.60%; the percentage of nickel by weight is preferably
0.40-0.60%, and more preferably 0.40-0.55%; and the percentage of
molybdenum by weight is preferably 0.25-0.35%, and more preferably
0.25-0.30%.
[0018] The chemical compositions of steel substantially decide the
mechanical property thereof; by improving the purity of molten
steel and reducing the content of gas and harmful elements therein,
the metallurgical process can create a good condition for the
subsequent processing of the steel material; the heat treatment
process after smelting process can achieve best potential of the
mechanical property of the steel material. Therefore, chemical
compositions play an important role in improving the mechanical
property of steel. Among all compositions, carbon and manganese are
major elements to improve the strength of material; the toughness
of material can be improved by reducing the content of harmful
elements P and S and properly increasing the content of nickel; the
hardenability of material can be improved by properly increasing
the content of manganese, chromium and molybdenum; meanwhile, the
increasing of the content of molybdenum can effectively restrict
the temper brittleness of material; the content of aluminium can be
controlled to refine grains in subsequent heat treatment.
[0019] The present invention further provides a coupler made of the
steel provided by the present invention. The couple has excellent
mechanical property such as high strength and good toughness and
can bear larger tensile stress and impact force. The wagon coupler
can be applied to multiple applications, for example, to the
railway wagon or railway carriage.
EMBODIMENTS
[0020] The chemical compositions of the steel of the embodiments
1-1 to 1-10 provided by the present invention are shown in Table 1;
the mechanical properties of the steel of embodiments 1-1 to 1-10
are shown in Table 2. Wherein the heat treatment process of
embodiments 1-1 to 1-10 is the conventional heat treatment process,
namely thermal refining (including quenching and tempering
processes), in which the quenching temperature is 910 DEG C, the
temperature holding time is 2 hours, and the cooling method is
water quenching; and the tempering temperature is 560 DEG C, the
temperature holding time is 3.5 hours, and the cooling method is
wind cooling.
TABLE-US-00001 TABLE 1 Embodiments C % Si % Mn % P % S % Cr % Ni %
Mo % Cu % Al % 1-1 0.27 0.39 1.48 0.014 0.012 0.59 0.48 0.29 0.08
0.04 1-2 0.28 0.38 1.50 0.011 0.013 0.60 0.52 0.30 0.09 0.05 1-3
0.26 0.40 1.52 0.010 0.011 0.62 0.53 0.33 0.10 0.04 1-4 0.29 0.35
1.49 0.012 0.013 0.58 0.51 0.31 0.07 0.05 1-5 0.28 0.41 1.54 0.013
0.011 0.61 0.54 0.32 0.08 0.03 1-6 0.27 0.38 1.53 0.010 0.011 0.63
0.49 0.34 0.09 0.04 1-7 0.26 0.36 1.55 0.012 0.010 0.60 0.50 0.32
0.010 0.06 1-8 0.28 0.37 1.46 0.011 0.012 0.57 0.55 0.28 0.08 0.05
1-9 0.27 0.39 1.47 0.010 0.012 0.58 0.53 0.30 0.09 0.04 1-10 0.29
0.40 1.50 0.014 0.012 0.61 0.49 0.32 0.08 0.05
TABLE-US-00002 TABLE 2 Yield strength Tensile strength Reduction of
Impact energy Embodiment MPa MPa Elongation % cross section % J(-40
DEG C.) 1-1 835 930 17.0 53.5 55.3 1-2 855 945 16.5 46.0 47.0 1-3
845 930 18.0 53.5 57.0 1-4 840 930 17.5 53.5 51.0 1-5 850 940 17.5
55.0 52.3 1-6 855 965 17.0 50.5 39.7 1-7 860 960 17.0 49.5 47.7 1-8
840 940 17.5 51.5 53.0 1-9 850 955 18.0 53.5 48.7 1-10 845 945 17.5
50.5 49.3 Grade E More than or More than or More than or More than
or More than or steel equal to 690 equal to 830 equal to 14 equal
to 30 equal to 27
[0021] Table 1 and Table 2 show that the mechanical property of the
steel provided by the present invention is significantly better
than that of grade E steel; for example, the yield strength is 20%
higher than that of grade E steel; the tensile strength is 13%
higher than that of grade E steel; the impact energy is 90% higher
than that of grade E steel; in addition, the elongation and
reduction of cross section are also much higher than those of grade
E steel; hereinto, higher impact energy means higher toughness of
steel.
[0022] According to standard M201 of American AAR (Association of
American Railroads), steel is classified into the following grades
on the basis of strength thereof: grade A steel, grade B steel,
grade B+ steel, grade C steel, and grade E steel, in which the
grade E is the highest grade.
[0023] Due to the above chemical compositions, the steel provided
by the present invention has excellent mechanical property,
including high strength and good toughness, and the mechanical
property is better than that of grade E steel.
[0024] In order to further improve the mechanical property of
material, the steel material of the present invention can be
obtained through the following heat treatment process, which
includes pre-heat treatment and thermal refining; the pre-heat
treatment comprises normalizing treatment; the thermal refining
comprises quenching and tempering procedures. Specifically, the
process comprises the following steps:
[0025] Step 1: performing pre-heat treatment to steel, wherein the
normalizing temperature is 900-960 DEG C, the temperature holding
time is 3-5 hours, and the cooling method is air cooling or wind
cooling; the normalizing temperature is preferably 920-950 DEG C,
and more preferably 930-950 DEG C; the temperature holding time is
preferably 3.5-4.5 hours, and more preferably 4 hours.
[0026] Step 2: quenching the steel after the pre-heat treatment of
step 1, wherein the quenching temperature is 900-920 DEG C, the
temperature holding time is 2-3 hours, and the cooling method is
water quenching.
[0027] Step 3: tempering the steel after quenching of step 2,
wherein the tempering temperature is 520-580 DEG C, the temperature
holding time is 3-5 hours, and the cooling method is water cooling;
the tempering temperature may also be 550-570 DEG C or 530-550 DEG
C.
[0028] After the pre-heat treatment procedure to the steel provided
by the present invention, the as-cast structure of steel can be
eliminated and the crystalline grain can be refined, so as to
prepare for the thermal refining; furthermore, water cooling is
adopted in the tempering procedure to eliminate the temper
brittleness, and therefore the mechanical property of steel can be
greatly improved.
[0029] Before the heat treatment to steel, metallurgy procedure
should also be executed. The metallurgy procedure can be ex ecuted
using the conventional metallurgy process, for example, including
the following steps:
[0030] Step a1: preparing raw material: according to the
requirements of compositions of steel to be melted, weighing the
iron alloy necessary in smelting process, conveying it beside arc
furnace, and also conveying various slagging materials,
carburetant, oxidizing material and reduction materials beside the
furnace.
[0031] Step a2: feeding material: feeding the cut and selected
waste steel, of which the size and weight meet the requirements of
furnace, into the hopper of furnace, according to the arrangement
of "large, medium, small and light"; adding carburetant and a part
of iron alloy to the steel; conveying all materials to charging bay
via battery truck; weighing these materials; and feeding the
materials in batches into the arc furnace.
[0032] Step a3: electrifying the furnace to melt the materials:
electrifying the arc furnace after the waste steel is fed
thereinto, where different currents and voltages can be adopted to
covert electric energy into heat energy and therefore to melt the
waste steel into molten steel. In order to speed up the smelting,
oxygen can be blown to accelerate the melting when the arc furnace
is electrified.
[0033] Step a4: oxidizing: adding the slagging materials to make a
layer of slag cover on the surface of molten steel after the waste
steel is melted into molten steel; and adding oxidizing material
when the molten steel is at a proper temperature, to boil the
molten steel under the reaction of carbon and oxygen, so as to
eliminate gas from the molten steel. Since the molten steel is
boiled, the molten steel can contact with slag fully, and therefore
the harmful element phosphorus can be transferred from the molten
steel to the slag. The compositions of the molten steel can be
checked for 2-3 times during the oxidizing process. At the end of
the oxidizing process, steel ladle can be dried.
[0034] Step a5: removing slag: at the end of oxidizing, under the
condition that all compositions and temperature comply with the
technical requirements, shutting off the power and removing all
slag generated in the oxidizing process, so as to prevent the
harmful element, phosphorus, from entering molten steel again.
[0035] Step a6: reduction: after all slag generated in oxidizing
process is removed, electrifying the arc furnace and adding
slagging materials rapidly; removing oxygen element from the molten
steel by diffusible desoxydation method and precipitation
desoxydation method; and adding iron alloy into the molten steel in
sequence according to oxidability of iron alloy. In reduction
process, inert gas can be adopted for mixing so as to make the
molten steel flow and contact with the slag fully and therefore
transfer the harmful element sulphur from the molten steel into the
slag. The temperature of molten steel is continuously improved to
prepare for tapping during deoxygenation, desulfuration and
adjustment of molten steel compositions.
[0036] Step a7: tapping: on the basis that compositions of molten
steel are qualified, the temperature of molten steel and drying of
steel ladle are in accordance with requirements and desoxydation
experiment of molten steel is under good condition, the power can
be shut off and the tapping can be executed.
[0037] And step a8: refining molten steel: during the tapping
process, blowing inert gas into the steel ladle and keeping it for
a certain time; and after the end of tapping, feeding deoxidant
into steel ladle.
[0038] In order to ensure the reliability and safety of vehicles
running at a high load, more requirement to the mechanical property
of material for making coupler has been proposed by mine
manufacturer; the requirement is even higher than grade E; the
steel hereafter meets the requirement is classified as grade E+
steel; the requirement to the mechanical property of grade E+ steel
is shown in Table 3.
TABLE-US-00003 TABLE 3 Mechanical Yield strength Tensile strength
Reduction of Impact energy property MPa MPa Elongation % cross
section % J(-40 DEG C.) Grade E More than or More than or More than
or More than or More than or steel equal to 690 equal to 830 equal
to 14 equal to 30 equal to 27 Grade E+ More than or More than or
More than or More than or More than or steel equal to 760 equal to
910 equal to 14 equal to 30 equal to 33
[0039] As shown in Table 3, the mechanical property of grade E+
steel is higher than that of grade E steel; the yield strength and
tensile strength of grade E+ steel are 10% higher than those of
grade E steel; and the impact energy is 20% higher than that of
grade E steel.
[0040] The mechanical property of grade E steel part can be
obtained as shown in Table 4 from the grade E steel (embodiments
2-1 to 2-10) through the conventional heat treatment process.
Wherein, the raw material of embodiments 2-1 to 2-10 can be either
commercial grade E steel or the grade E steel made by manufacturer
according to the requirements thereof.
TABLE-US-00004 TABLE 4 Yield strength Tensile strength Reduction of
cross Impact energy Embodiments MPa MPa Elongation % section %
J(-40 DEG C.) 2-1 855 945 16.5 46.0 25.6 2-2 855 945 18.0 52.5 31.3
2-3 865 945 17.0 52.5 39.7 2-4 845 935 19.0 52.5 32.7 2-5 865 955
16.5 51.5 30.7 2-6 865 945 18.0 50.5 36.5 2-7 845 935 17.0 51.5
40.5 2-8 870 955 17.5 55.0 41.3 2-9 870 960 17.5 52.5 24.0 2-10 855
955 18.0 53.5 38.7 Grade E+ 760 910 14 30 33 steel standard
values
[0041] Wherein, the heat treatment process of the conventional
grade E steel part comprises: quenching temperature is 910 DEG C,
the temperature holding time is 2 hours and the quenching method is
water quenching; the tempering temperature is 560 DEG C, the
temperature holding time is 3.5 hours and the cooling method is
wind cooling.
[0042] As shown in Table 4, with the increasing of strength (yield
strength and tensile strength), the parameter of impact energy
(toughness) of grade E steel part reduces and cannot be stabilized.
Compared with the requirement of grade E+ steel, the mechanical
property can only meet 50% of the requirement thereof.
[0043] The mechanical property of the steel (embodiments 3-1 to
3-10) with new compositions provided by the present invention,
after smelting process and through the heat treatment process
provided by the present invention is shown in Table 5:
TABLE-US-00005 TABLE 5 Yield strength Tensile strength Reduction of
cross Impact energy Embodiments MPa MPa Elongation % section %
J(-40 DEG C.) 3-1 840 945 19.0 55.0 81.3 3-2 880 955 18.5 48.5 65.7
3-3 850 940 18.5 51.5 78.3 3-4 875 960 20.0 52.0 66.3 3-5 875 955
19.0 58.0 65.0 3-6 865 945 18.5 52.0 71.7 3-7 855 945 19.5 52.5
70.0 3-8 880 970 18.5 54.0 71.3 3-9 865 955 19.0 57.0 72.3 3-10 875
975 16.0 42.5 60.3 Grade E+ 760 910 14 30 33 steel standard
values
[0044] Wherein, the specific compositions of the steel in
embodiments 3-1 to 3-10 are shown in Table 6.
TABLE-US-00006 TABLE 6 Embodiments C % Si % Mn % P % S % Cr % Ni %
Mo % Cu % Al % 3-1 0.27 0.39 1.48 0.014 0.012 0.59 0.48 0.29 0.08
0.04 3-2 0.28 0.38 1.50 0.011 0.013 0.60 0.52 0.30 0.09 0.05 3-3
0.26 0.40 1.52 0.010 0.011 0.62 0.53 0.33 0.10 0.04 3-4 0.29 0.35
1.49 0.012 0.013 0.58 0.51 0.31 0.07 0.05 3-5 0.28 0.41 1.54 0.013
0.011 0.61 0.54 0.32 0.08 0.03 3-6 0.27 0.38 1.53 0.010 0.011 0.63
0.49 0.34 0.09 0.04 3-7 0.26 0.36 1.55 0.012 0.010 0.60 0.50 0.32
0.010 0.06 3-8 0.28 0.37 1.46 0.011 0.012 0.57 0.55 0.28 0.08 0.05
3-9 0.27 0.39 1.47 0.010 0.012 0.58 0.53 0.30 0.09 0.04 3-10 0.29
0.40 1.50 0.014 0.012 0.61 0.49 0.32 0.08 0.05
[0045] As shown in Table 5, the mechanical property of the steel,
with new compositions, provided by the present invention after the
heat treatment process provided by the present invention is
noticeably higher than that of grade E+ steel (in particular the
impact energy) and completely meets the requirement thereof.
Compared with the conventional grade E steel shown in Table 4, the
mechanical property provided by the present invention is greatly
higher than that of grade E steel.
[0046] As shown in Table 5 and Table 2, the mechanical property of
the steel with new compositions provided by the present invention
after special heat treatment process (Table 5) is noticeably higher
than that of the steel only executed with the conventional heat
treatment process; especially, based on keeping the strength, the
impact energy is greatly improved; namely, the toughness of the
steel with new compositions provided by the present invention is
also improved on the basis of keeping or even improving the
strength thereof.
[0047] The present invention provides a steel material with high
strength and excellent toughness, the steel can be applied to
multiple fields, such as coupler of railway wagon, in order to meet
the requirement of "speed-rising and heavy-haul" of railway
wagon.
[0048] Finally, it should be understood that the above embodiments
are only used to explain, but not to limit the technical solution
of the present invention. In despite of the detailed description of
the present invention with referring to above preferred
embodiments, it should be understood that various modifications,
changes or equivalent replacements can be made by those skilled in
the art without departing from the scope of the present invention
and covered in the claims of the present invention.
* * * * *