U.S. patent application number 15/762929 was filed with the patent office on 2018-10-18 for online-control cooling process for seamless steel tube for effectively refining grains and the method for manufacturing thereof.
The applicant listed for this patent is BAOSHAN IRON & STEEL CO., LTD.. Invention is credited to Yaoheng LIU, Dongxing WU, Zhonghua ZHANG.
Application Number | 20180298459 15/762929 |
Document ID | / |
Family ID | 58418385 |
Filed Date | 2018-10-18 |
United States Patent
Application |
20180298459 |
Kind Code |
A1 |
LIU; Yaoheng ; et
al. |
October 18, 2018 |
ONLINE-CONTROL COOLING PROCESS FOR SEAMLESS STEEL TUBE FOR
EFFECTIVELY REFINING GRAINS AND THE METHOD FOR MANUFACTURING
THEREOF
Abstract
An online-control cooling process for seamless steel tube for
effectively refining grains, comprising the following steps: when
the temperature of a crude tube is higher than Ar3, evenly spraying
water along the circumferential direction of the tube so as to
continuously cool the tube to T1.degree. C..about.T2.degree. C.,
the cooling rate being controlled to be N1.degree.
C./s.about.N2.degree. C./s, wherein
T1=810-360C-80(Mn+Cr)-37Ni-83Mo, T2=T1+115.degree. C.,
N1=55-80.times.C, N2=168*(0.8-C), and C, Mn, Cr, Ni and Mo in the
equations each represent the mass percentage of corresponding
elements in the seamless steel tube; then, cooling to the room
temperature at cooling rate no more than 10.degree. C./s.
Correspondingly, also provided are a method for manufacturing
seamless steel tube for effectively refining grains, and a seamless
steel tube. The online-control seamless steel tube cooling process
does not require adding too many alloying elements, which is simple
and can yield seamless steel tubes with good grain refinement and
better toughness.
Inventors: |
LIU; Yaoheng; (Shanghai,
CN) ; ZHANG; Zhonghua; (Shanghai, CN) ; WU;
Dongxing; (Shanghai, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BAOSHAN IRON & STEEL CO., LTD. |
Shanghai |
|
CN |
|
|
Family ID: |
58418385 |
Appl. No.: |
15/762929 |
Filed: |
September 21, 2016 |
PCT Filed: |
September 21, 2016 |
PCT NO: |
PCT/CN2016/099564 |
371 Date: |
March 23, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C22C 38/04 20130101;
C22C 38/002 20130101; C21D 9/085 20130101; C21D 9/08 20130101; C21D
6/005 20130101; C21D 6/008 20130101; C21D 2211/003 20130101; C21D
2211/008 20130101; C22C 38/02 20130101; C21D 1/18 20130101; C22C
38/12 20130101; C21D 2211/005 20130101; C22C 38/06 20130101; B21B
19/04 20130101; C21D 8/10 20130101; C22C 38/08 20130101; C21D
2211/002 20130101; C21D 2211/009 20130101; C21D 1/667 20130101;
C21D 8/105 20130101; C21D 11/005 20130101; C22C 38/40 20130101 |
International
Class: |
C21D 9/08 20060101
C21D009/08; C21D 8/10 20060101 C21D008/10; C22C 38/40 20060101
C22C038/40; C22C 38/08 20060101 C22C038/08; C22C 38/04 20060101
C22C038/04; C22C 38/12 20060101 C22C038/12 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 24, 2015 |
CN |
201510615737.9 |
Apr 26, 2016 |
CN |
201610265674.3 |
Aug 30, 2016 |
CN |
201610784964.9 |
Claims
1. An online-control cooling process for seamless steel tube for
effectively refining grains, comprising the following steps:
spraying water evenly along the circumferential direction of the
tube when the temperature of tube is higher than Ar3 so as to
continuously cool the tube to temperature of T1.degree.
C..about.T2.degree. C., and controlling; the cooling rate to
N1.degree. C./s to N2.degree. C./s, wherein
T1=810-360C-80(Mn+Cr)-37Ni-83Mo, T2=T1+115.degree. C.,
N1=55-80.times.C, and N2=168.times.(0.8-C), and wherein C, Mn, Cr,
Ni, and Mo in the equations each represents the mass percentage of
corresponding elements of the seamless steel tube; and cooling to
room temperature at a cooling rate no more than 10.degree.
C./s.
2. The online-control cooling process for seamless steel tube
according to claim 1, wherein the total amount of alloying elements
of the seamless steel tube is not more than 3% by mass, said
alloying elements being at least one selected from the group
consisting of C, Mn, Cr, Mo, Ni, Cu, V, Nb and Ti.
3. The online-control cooling process for seamless steel tube
according to claim wherein the total amount of alloying elements of
the seamless steel tube is 0.2% to 3% by mass.
4. A method for manufacturing seamless steel tube for effectively
refining grains, comprising the following steps: (1) manufacturing
a billet; (2) forming the billet into a tube; (3) cooling the tube
by the online-control cooling process for seamless steel tube
according to claim 1.
5. The method for manufacturing seamless steel tube according to
claim 4, wherein the obtained seamless steel tube has a grain size
grade of at least 7.5.
6. The method for manufacturing seamless steel tube according to
claim 4, wherein in step (2), the billet is heated to 1100.degree.
C. to 1130.degree. C. and maintained for 1 to 4 hours, and further
comprises piercing, rolling, stretch reducing or sizing, so as to
obtain the tube.
7. A seamless steel tube, which is prepared by the method for
manufacturing seamless steel tube according to claim 4.
8. The seamless steel tube according to claim 7, wherein the
microstructure of steel is mainly in form of pearlite and ferrite,
and the phase ratio of the pearlite and ferrite is not less than
80%.
9. The seamless steel tube according to claim 8, wherein the
microstructure further contains bainite and/or cementite.
10. A seamless steel tube, which is prepare e od for manufacturing
seamless steel tube according to claim 5.
11. The seamless steel tube according to claim 10, wherein the
microstructure of steel is mainly in form of pearlite and ferrite,
and the phase ratio of the pearlite and ferrite is not less than
80%.
12. The seamless steel tube according to claim 11, wherein the
microstructure further contains bainite and/or cementite
13. A seamless steel tube, which is prepared by the method for
manufacturing seamless steel tube according to claim 6.
14. The seamless steel tube according to claim 13, wherein the
microstructure of steel is mainly in form of pearlite and ferrite,
and the phase ratio of the pearlite and ferrite is not less than
80%.
15. The seamless steel tube according to claim 14, wherein the
microstructure further contains bainite and/or cementite
Description
FIELD
[0001] The present invention relates to a controlled cooling
process, in particular to an online control cooling process of a
seamless steel tube.
BACKGROUND
[0002] In the prior art, due to product shape and manufacturing
method limitations for hot-rolled seamless steel tubes, the product
performance has long been improved only by addition of alloying
elements and off-line heat treatment after rolling. Taking oil well
tubes for example, tubes having a degree of 555 MPa (80 Ksi) or
higher requires addition of more alloying elements in
manufacturing, which significantly increases the manufacturing
cost. Or, it can be made from conventional steel by off-line
quenching heat treatment, wherein the so-called off-line quenching
heat treatment means that hot-rolled seamless steel tubes are
air-cooled to the room temperature after rolling, and be put into a
tube bank firstly, then the pipes are heat-treated as needed.
However, this method also complicates the process and increases the
cost.
[0003] The performance of the steel is directly influenced by the
grain size. Fine grain strengthening is the only strengthening
mechanism that improves both strength and toughness of the steel at
the same time. In general, the cooling rate of a hot steel tube
(austenitic state) is accelerated by means of blowing or spraying
water, which increases the degree of widercooling of austenite,
promotes the nucleation of ferrite, and helps to improve grain
refinement and strength.
[0004] Although those skilled in the art already know that on-line
rapid cooling help the seamless steel tube obtain finer grain and
better performance, the on-line rapid cooling is still not used in
the prior art. This is because, cooling too fast will cause phase
transition of bainite and martensite, although the strength of the
seamless steel tube will increase significantly, rapid cooling
often leads to great changes in material properties, such as
decreasing in toughness and elongation, and increasing in yield
ratio, etc. Such changes may not satisfy the requirements. On the
other hand, the steel tube has a higher internal stress than that
of sheet products due to its unique cross section, cooling too fast
may lead to cracking and other problems.
[0005] Therefore, it is desired to obtain an online-control cooling
process for seamless steel tube, which utilizes the waste heat
after hot rolling of the steel pipe, wherein the online cooling
process is controlled, grains are effectively refined and the
toughness of seamless steel tube increases without non-equilibrium
phase transition of bainite, martensite, etc.
Invention Contents
[0006] One of purposes of the present invention is to provide an
online-control cooling process for effectively refining grain
seamless steel tube. By using said process, the seamless steel
tubes with good grain refinement can be obtained without adding
large amount of alloying elements.
[0007] Based on the above invention purpose, the present invention
provides an online-control cooling process for seamless steel tube
for effectively refining grains, comprising the following
steps:
[0008] when the temperature of tube is higher than Ar3, evenly
spraying water along the circumferential direction of the tube so
as to continuously cool the tube to temperature of T1.degree.
C..about.T2.degree. C., the cooling rate being controlled to
N1.degree. C./s.about.N2.degree. C./s, wherein
T1=810-360C-80(Mn+Cr)-37Ni-83Mo, T2=T1+115.degree. C.,
N1=55-80.times.C, N2=168.times.(0.8-C), and C, Mn, Cr, Ni, and Mo
in the equations each represents the mass percentage of
corresponding elements of the seamless steel tube;
[0009] Then, cool the tube to the room temperature at a cooling
rate no more than 10.degree. C./s.
[0010] As already explained above, the method of on-line rapid
cooling is not used to cool the steel pipe in the prior art,
because this cooling method will cause the phase transition of
hainite and martensitic, resulting in decreasing in toughness and
elongation of the steel pipe. In addition, since the internal
stress level of the seamless steel tube is much higher than those
of offline re-heated austenitizing after the thermal deformation of
the seamless steel tube, the seamless steel tube with online rapid
cooling is likely to crack. In order to solve this technical
problem, the inventors of the present invention conducted a lot of
research and found that in order to make the grain significantly
refined without the occurrence of phase transition of bainite or
martensitic transformation, it is required to strictly control the
quenching starting temperature, the final cooling temperature of
quenching and the cooling rate, so as to coordinate with the
element content of the steel effectively. Based on above, the
inventors of the present invention propose said technical
solution.
[0011] In this technical solution, the temperature of the tube
needs to be higher than the Ar3 temperature, this is because some
proeutectoid ferrite forms in the seamless steel tube if the
online-control cooling process for seamless steel tube begins at a
temperature below Ar3, which will deteriorate the grain refined
effect and performance of the seamless steel tube.
[0012] In addition, the temperature of the continuous cooling of
the tube is controlled from T1.degree. C. to T2.degree. C., wherein
T1=T1=810-360C-80(Mn+Cr)-37Ni-83Mo and T2=T1+115.degree. C. The
inventors found that, a better implementation effect can be
obtained when the final cooling temperature of the continuous
cooling of the tube is controlled in the said range. When the final
cooling temperature of the continuous cooling of the tube is higher
than T2.degree. C., the undercooling of the austenite is not
enough, and the effect of the refining grains is not enough. When
the final cooling temperature of the continuous cooling of the tube
is lower than T1.degree. C., the phase transition of bainite or
martensite occurs and has an negative effect on the final
performance of seamless steel tube. Therefore, in the said
online-control cooling process for the seamless steel tube
according to the present invention, the continuous cooling of the
tube is controlled from T1.degree. C. to T2.degree. C.
[0013] Moreover, the inventors of the present invention also found
that the seamless steel tube will obtain a better performance when
the cooling rate is controlled from N1.degree. C./s to N2.degree.
C./s, N1=55-80.times.C and N2=168.times.(0.8-C). When the cooling
rate is lower than N1.degree. C./s, subcooling of austenite is
insufficient, on the other hand, when the cooling rate higher than
N2.degree. C./s, the steel tube is likely to crack. Therefore, in
the online-control cooling process of the seamless steel tube
according to the present invention, the cooling rate is controlled
from N1.degree. C./s to N2.degree. C./s.
[0014] It should be noted that the Ar3 temperature is known to
those skilled in the art or can be obtained under technical
conditions. For example, it can be obtained by referring to a
manual or by thermal simulation experiment.
[0015] In addition, it should be noted that, in the above
equations, C, Mn, Cr, Ni and Mo each represents the mass percentage
of corresponding elements of the seamless steel tube. That is, the
numerical values of C, Mn, Cr, Ni and Mo substituted into the
equations are the numerical values before the percent %. For
example, in one embodiment where C is 0.17% by mass, the
substituted value of C into the equations is 0.17, rather than
0.0017. The substitution of other elements has same meaning and is
not further described.
[0016] It should also be noted that, the technical solution above
which defines the above equations do not mean that the seamless
steel tube must contain elements of C, Mn, Cr, Ni and Mo at the
same time. The equations are general and can be applied to the
seamless steel tube quenched by this method. Therefore, when one or
more of the elements involved in the equations is not contained,
zero should substitute into the equations.
[0017] In addition, in the present technical solution, grains are
further refined by setting a step of air-cooling after rapid
cooling. Since a high undercooling degree of the austenite is
formed during the rapid cooling in the air-cooling step of seamless
steel tube, the cooling rate for air-cooling cannot be too fast.
When the cooling rate of air-cooling exceeds 10.degree. C./s, it
brings significant phase transition of bainite. Therefore, in this
technical solution, the cooling rate in air cannot exceed
10.degree. C./s.
[0018] Further, in the online-control cooling process for seamless
steel tube according to the present invention, the total amount of
alloying elements of the seamless steel tube is not more than 3% by
mass, wherein alloying elements are at least one selected from C,
Mn, Cr, Mo, Ni, Cu, V, Nb and Ti. If the alloying elements of the
seamless steel tube exceed 3% by mass, the bainite/martensite phase
can be obtained by air-cooling, to which said method cannot apply.
In addition, the alloying element of the seamless steel tube in the
present technical solution is not limited to C, Mn, Cr, Mo, Ni, Cu,
V, Nb and Ti, and may be other alloying elements.
[0019] Further, in the online-control cooling process for seamless
steel tube according to the present invention, the total amount of
alloying elements of the seamless steel tube is 0.2% to 3% by
mass.
[0020] The technical solution is particularly suitable for
conventional carbon steel or low-alloy steel. By this process,
seamless steel tube that meets performance requirements can be
produced without adding excessive of alloying elements.
[0021] Accordingly, another purpose of the present invention is to
provide a. method of manufacturing a seamless steel tube for
effectively refining grains, comprising the steps of:
[0022] (1) manufacturing the Billet;
[0023] (2) forming the Billet into tube;
[0024] (3) cooling the tube by the online-control cooling process
for seamless steel tube.
[0025] In the method for producing an effectively refined grain
seamless steel tube according to the present invention, the
implementation effect of effectively refining the grain is achieved
by the online-control cooling process of the seamless steel tube
described above. Compared with the prior art, the seamless steel
tube can be austenitized without being reheated in the technical
solution of the present invention, and the seamless steel tube has
a better toughness by directly using online-control cooling process
for the seamless steel tube.
[0026] It should be noted that, in step (1), the billet can be
produced by casting the smelted molten steel into a round billet,
or can be produced by pouring first and then forging or rolling the
slab into the billet.
[0027] Further, in the manufacturing method for a seamless steel
tube according to the present invention, in step (2), the billet is
heated to 1100 to 1130.degree. C. and maintained for 1 to 4 hours,
followed by piercing, rolling, stretch reducing or sizing, so as to
obtain the tube.
[0028] In addition, another purpose of the present invention is to
provide a seamless steel tube which is prepared by the method said
above for manufacturing seamless steel tube.
[0029] Further, in the seamless steel tube of the present
invention, the grain size grade thereof is at least 7.5.
[0030] Further, in the seamless steel tube of the present
invention, the microstructure thereof is mainly in form of pearlite
and ferrite, and the phase ratio of the pearlite and ferrite is not
less than 80%.
[0031] Further, in the seamless steel tube of the present
invention, the microstructure thereof further contains bainite
and/or cementite.
[0032] The online-control cooling process and the manufacturing
method for the seamless steel tube for effectively refined grain
according to the present invention have the following advantages
and beneficial effects:
[0033] (1) The on-line control cooling process for the seamless
steel tube according to the present invention can effectively
refine the grains so that the grain size grade of the seamless
steel tube obtained reaches at least 7.5.
[0034] (2) The on-line control cooling process and the
manufacturing method for the seamless steel tube according to the
present invention can effectively improve the toughness of the
steel pipe and greatly reduce the amount of addition of the
alloying elements at the same performance level.
[0035] (3) The on-line control of the cooling process and the
manufacturing method for the seamless steel tube according to the
present invention can avoid the cracking phenomenon of seamless
steel tube which is unavoidable in the prior art and ensure the
qualified rate of the product.
DETAILED DESCRIPTION
[0036] The online-control cooling process for the seamless steel
tube for effectively refined grains according to the present
invention will be further explained and described accompanying
drawings and the specific Example as follow, and the this
explanation and description shall not be deemed to limit to the
technical solution of the present invention.
EXAMPLE A1-A7 AND COMPARATIVE EXAMPLE B1-B6
[0037] Seamless steel tubes in Example A1-A7 were manufactured
according to the following steps:
[0038] (1) Manufacturing the Billet: smelting according to the mass
percentage of each chemical element listed in Table 1, casting it
into an ingot and forging the ingot into the Billet.
[0039] (2) forming the Billet into tube: the Billet is heated to
1100.degree. C. to 1130.degree. C. and maintained for 1 to 4 hours,
followed by piercing, rolling, stretch reducing or sizing, so as to
obtain the tube.
[0040] (3) using the online-control cooling process: when the
temperature of tube is higher than Ar3, evenly spraying water along
the circumferential direction of the tube so as to continuously
cool the tube to temperature of T1.degree. C..about.T2.degree. C.,
the cooling rate being controlled to N1.degree.
C./s.about.N2.degree. C./s, wherein
T1=810-360C-80(Mn+Cr)-37Ni-83Mo, T2=T1+115.degree. C.,
N1=55-80.times.C, N2=168.times.(0.8-C), and C, Mn, Cr, Ni, and Mo
in the equations each represents the mass percentage of
corresponding elements of the seamless steel tube; then, cooling to
the room temperature at a cooling rate no more than 10.degree.
C./s.
[0041] In order to demonstrate the implementation effect of the
online-control cooling process of the present invention, the
process steps of manufacturing the billet and the tube for
Comparative Example B1-B6 are the same as that for Example of the
invention, whereas the process parameters of control cooling
process for Comparative Example B1-B6 are outside the protection
scope of the present technical solution.
[0042] Table 1 lists each mass percentage of the chemical elements
of the seamless steel tubes of Example A1 to A7 and Comparative
Example B1 to B6.
TABLE-US-00001 TABLE 1 (by wt %, the margin is Fe and other
unavoidable impurity elements) Steel No. model C Mn Cr Mo Ni A1
16Mn 0.17 1.65 -- -- -- A2 20# 0.2 0.5 -- -- -- A3 20# 0.2 0.5 --
-- -- A4 20# 0.2 0.5 -- -- -- A5 30Mn2 0.3 1.55 -- -- -- A6 20CrNi
0.2 0.55 0.9 -- 1.05 A7 15NiMo 0.15 0.6 0.2 0.60 B1 16Mn 0.17 1.65
-- -- -- B2 20# 0.2 0.5 -- -- -- B3 20# 0.2 0.5 -- -- -- B4 20# 0.2
0.5 -- -- -- B5 20# 0.2 0.5 -- -- -- B6 20# 0.2 0.5 -- -- --
[0043] Table 2 lists the specific process parameters for the
methods for manufacturing seamless steel tube of Example A1-A7 and
Comparative Example B1-B6.
TABLE-US-00002 TABLE 2 Quenching Final Heating heating Ar3 starting
cooling temperature time temperature temperature T1 T2 temperature
N1 N2 Cooling rate Cooling rate No. (.degree. C.) (h) (.degree. C.)
(.degree. C.) (.degree. C.) (.degree. C.) (.degree. C.) (.degree.
C./s) (.degree. C./s) (.degree. C./s) in air/.degree. C./s A1 1280
2.8 835 930 616.8 731.8 654 41.4 105.84 61 3 A2 1140 3.5 865 920
698 813 724 39 100.8 42 5 A3 1260 2.5 865 920 698 813 735 39 100.8
73 1.5 A4 1150 1.4 865 970 698 813 728 39 100.8 55 1.8 A5 1250 2.5
721 780 578 693 660 31 84 38 8 A6 1200 2 790 940 583.15 698.15 625
39 100.8 52 6 A7 1240 2.5 750 900 669.2 784.2 694 43 109.2 75 4.6
B1 1250 2 835 616.8 731.8 628 41.4 105.84 48 2.5 B2 1250 2 865 860
698 813 712 39 100.8 4 B3 1250 2 865 940 698 813 39 100.8 46 5 B4
1250 2 865 900 698 813 750 39 100.8 8 B5 1250 2 865 920 698 813 39
100.8 42 5 B6 1250 2 865 920 698 813 716 39 100.8 42
[0044] Various performance tests were conducted on the seamless
steel tubes of Example A1-A7 and Comparative Example B1-B6, and the
results are shown in Table 3. Wherein the yield strength data are
average value obtained according to the API standard after the
seamless steel tube of Example A1-A7 and the seamless steel tube of
Comparative Example B1-B6 are processed into API arc-shaped
samples. The impact sample was test by the standard impact sample
of the seamless steel tube of Example A1-A7 and Comparative Example
B1 to B6 processed into 10 mm*10 mm*55 mm size, V-notch at
0.degree. C. In addition, the hardness after quenching cooling of
each Example and Comparative Example was measured by a Rockwell
hardness test. The grain size was measured according to GB/T6394
standard after sampling, and the phase ratio was measured by the
metallographic method.
TABLE-US-00003 TABLE 3 Performance data for each Example and each
Comparative Example Impact energy Phase (full ratio Yield size Of
Strength sample) Pearlite + Crack/ Rp0.2 at 0.degree. C. Grain
ferrite yes No. (MPa) (J) size (%) or no A1 453 198 7.5 85 no A2
336 147 8 92 no A3 342 152 8 87 no A4 340 123 7.5 94 no A5 594 98 8
90 no A6 582 168 8.5 88 no A7 378 172 8.5 95 no B1 368 144 6 89 no
B2 253 97 6.5 92 no B3 262 108 6.5 87 no B4 -- -- -- -- yes B5 428
16 6.5 24 no B6 359 32 5.5 31 no
[0045] As can be seen from Table 3, the yield strength of the
seamless steel tubes for all Example A1-A7 is .gtoreq.336 MPa, the
impact energy at 0.degree. C. thereof is higher than 98J, and the
grain size grade is higher than 7.5, and the phase ratio of the
pearlite and ferrite in the microstructure of which is
.gtoreq.80%.
[0046] As can be seen from Table 2 and Table 1, the component
ratios of the chemical elements for all Example and Comparative
Example have no difference, but the method for manufacturing of the
Example and Comparative Example are significantly different.
Therefore, the performance of the seamless tube of Example A1-A7 is
superior to that of Comparative Example B1-B6 overall. in addition,
as can be seen from Table 2 and Table 3, the quenching starting
temperature of Comparative Example B1 is lower than the Ar3
temperature so that the steel of Comparative Example B1
precipitates proeutectoid ferrite, reducing its hardness after
quenching and affecting the strength of seamless steel tube also.
The cooling rate of Comparative Example B2 is lower than the
cooling rate range defined in the present technical solution, thus
the desired microstructure could not be obtained, which will affect
the performance. The final cooling temperature of Comparative
Example B3 was higher than the T2.degree. C. of the present
invention, thus the desired microstructure of seamless steel tube
could not be obtained in Comparative Example B3, which will affect
the performance. In addition, the cooling rate of Comparative
Example B4 is higher than the cooling rate range defined in the
present technical solution, so that the steel tube cracked, the
hardness is insufficient. The final cooling temperature of
Comparative Example 95 is lower than T1.degree. C. as defined in
the present technical solution, and the cooling rate in air of
Comparative Example B6 is higher than the cooling rate range
defined in the present technical solution, which results in a
significant phase transition of bainite in Comparative Example B5
and Comparative Example B6, and lack of toughness.
[0047] It is to be noted that the above Example are only a specific
embodiments of the present invention. Apparently, the invention is
not limited to the above embodiments, and there are may be many
similar variations. A person skilled in the art can directly derive
or associate all the variations from the content disclosed by the
invention, all of which shall be covered by the protection scope of
the invention.
* * * * *