U.S. patent application number 11/240629 was filed with the patent office on 2006-04-06 for high hardness moulding plate and method for producing said plate.
This patent application is currently assigned to Corus Aluminium Walzprodukte GmbH. Invention is credited to Claus Jurgen Moritz, Jorgen Van De Langkruis.
Application Number | 20060070686 11/240629 |
Document ID | / |
Family ID | 34928545 |
Filed Date | 2006-04-06 |
United States Patent
Application |
20060070686 |
Kind Code |
A1 |
Moritz; Claus Jurgen ; et
al. |
April 6, 2006 |
High hardness moulding plate and method for producing said
plate
Abstract
Moulding plate of an aluminium wrought alloy including, in
weight percent: Si 1.4-2.1, Mn 0.8-1.2, Cu 0.45-0.9, Mg 0.7-1.2, Ti
<0.15, Zn <0.4, Fe <0.7, one or more of Zr, Cr, V each
<0.25, incidental elements and impurities, each <0.05, total
<0.25, the balance aluminium, and having a thickness of more
than 0.6 mm and in T6 temper condition having a hardness of more
than 105 HB. A method of making the plate is also disclosed.
Inventors: |
Moritz; Claus Jurgen;
(Koblenz, DE) ; Van De Langkruis; Jorgen;
(Amsterdam, NL) |
Correspondence
Address: |
STEVENS DAVIS MILLER & MOSHER, LLP
1615 L STREET, NW
SUITE 850
WASHINGTON
DC
20036
US
|
Assignee: |
Corus Aluminium Walzprodukte
GmbH
Koblenz
DE
|
Family ID: |
34928545 |
Appl. No.: |
11/240629 |
Filed: |
October 3, 2005 |
Current U.S.
Class: |
148/552 ;
420/532; 420/535 |
Current CPC
Class: |
C22C 21/02 20130101 |
Class at
Publication: |
148/552 ;
420/532; 420/535 |
International
Class: |
C22C 21/04 20060101
C22C021/04 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 5, 2004 |
EP |
04077781.7 |
Claims
1. Moulding plate of an aluminium wrought alloy comprising, in
weight percent: Si 1.4-2.1 Mn 0.8-1.2 Cu 0.45-0.9 Mg 0.7-1.2 Ti
<0.15 Zn <0.4 Fe <0.7 one or more of Zr, Cr, V each
<0.25 incidental elements and impurities, each <0.05, total
<0.25, the balance aluminium, and having a thickness of more
than 0.6 mm and in T6 temper condition having a hardness of more
than 105 HB.
2. Moulding plate according to claim 1, wherein Si is in the range
of 1.53-2.0%.
3. Moulding plate according to claim 1, wherein Si is in the range
of 1.55-1.9%.
4. Moulding plate according to claim 1, wherein Mn is in the range
of 0.85-1.10%.
5. Moulding plate according to claim 1, wherein Cu is in the range
of 0.5-0.7%.
6. Moulding plate according to claim 1, wherein Mg is in the range
of 0.9-1.1%.
7. Moulding plate according to claim 1, wherein Zn is below
0.3%.
8. Moulding plate according to claim 1, wherein Zn is in the range
of 0.17-0.3%.
9. Moulding plate according to claim 1, wherein the moulding plate
has a machinability rating of "B" or better.
10. Moulding plate according to claim 1, wherein the moulding plate
has a final thickness in the range of 5 to 300 mm.
11. Moulding plate according to claim 1, wherein the moulding plate
has a final thickness in the range of 5 to 260 mm.
12. Moulding plate according to claim 1, wherein the moulding plate
has been rolled to the final thickness by hot rolling only.
13. Moulding plate according to claim 1, having a hardness of more
than 115 HB.
14. Moulding plate according to claim 1, having a hardness of more
than 120 HB.
15. Method of manufacturing a moulding plate comprising the
sequential steps of: casting a composition comprising (in weight
percent): Si 1.4-2.1 Mn 0.8-1.2 Cu 0.45-0.9 Mg 0.7-1.2 Ti <0.15
Zn <0.4 Fe <0.7 one or more of Zr, Cr, V each <0.25
incidental elements and impurities, each <0.05, total <0.25,
balance aluminium, homogenising and preheating the cast
composition, working the homogenized and preheated cast composition
to form said plate to a final thickness, subjecting said plate to
heat treatment comprising solution heat treating followed by rapid
cooling, ageing said plate, wherein the cooling rate during said
rapid cooling is chosen to obtain a hardness of the moulding plate
of at least 105 HB.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This claims priority from European patent application no.
04077781.7, filed 5 Oct. 2004, incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The invention relates to moulding plate of an aluminium
wrought alloy. The invention further relates to a method for
producing said moulding plate.
BACKGROUND OF THE INVENTION
[0003] In the tooling and moulding plate market for blow moulding
and thermoforming of rubbers and plastic, a sustained effort in
reducing costs is made whilst maintaining satisfactory wear
resistance and repair weldability. These types of tooling plates
are also widely used in many other industrial applications,
including components produced by various machining operations such
as drilling, milling and turning. Commonly used tooling plates are
made from selected alloys from the AA2000 series alloys, the AA6000
series alloys or the AA7000-series alloys.
[0004] High wear resistance in combination with good machinability
are important properties of alloys for moulding plate. In typical
tooling plate wrought alloys this wear resistance is obtained by
alloying with copper (such as in the AA2000 series) or Zinc (such
as in the AA7000 series) or magnesium and silicon (such as in the
AA6000 series) in combination with a thermo-mechanical treatment.
In these heat treatable alloy classes, the typical way to achieve
high hardness is via precipitation hardening of coherent phases.
Additional hardening by relatively coarse particles, such as
primary Si and incoherent Mg.sub.2Si is often considered
inappropriate, because of the related risks of eutectic melting at
elevated temperatures. Also additional hardening by
.alpha.-Al(Fe,Mn,Cu)Si dispersoids is not readily applied, since it
is generally believed that they increase the quench sensitivity of
the alloy. Increased quench sensitivity is considered a
disadvantageous characteristic, in particular for thicker gauge
products.
[0005] Typically, with AA2000 and AA7000 alloys, higher hardness is
achieved than with AA6000 alloys. However, a disadvantage of the
AA2000 series is the high copper content which makes the alloy
expensive as well as very sensitive to the heat treatment. Also,
the weldability of the alloy is adversely affected by the high
copper content. Similar arguments are made for the AA7000 series
such as high residual stresses, and poor weldability and corrosion
performance which cause complications with dimensional tolerances,
repair weldability, and durability of the mould. The wear
resistance of an AA6000 series alloy in a T6 temper, such as
AA6010, AA6013, AA6061, AA6066, AA6070 and AA6082 is usually
adequate for normal industrial applications. However, for high
performance applications a higher wear resistance is desired,
without adversely affecting weldability and costs.
SUMMARY OF THE INVENTION
[0006] It is an object of the invention to provide a moulding plate
of an aluminium wrought alloy with an improved resistance to
wear.
[0007] The present invention provides a moulding plate of an
aluminium wrought alloy comprising, in weight percent: Si 1.4-2.1,
Mn 0.8-1.2, Cu 0.45-0.9, Mg 0.7-1.2, Ti <0.15, Zn <0.4, Fe
<0.7, one or more of Zr, Cr, V each <0.25, incidental
elements and impurities, each <0.05, total <0.25, the balance
aluminium, and having a thickness of more than 0.6 mm and in T6
temper condition having a hardness of more than 105 HB.
[0008] According to a further aspect of the invention, a method is
provided of manufacturing a moulding plate.
BRIEF DESCRIPTION OF THE DRAWING
[0009] FIG. 1, which is the sole figure, shows the hardness
profiles of plates with a composition according to Example 7 with
thicknesses of 80, 100 or 150 mm.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] According to the invention, the above-mentioned object is
reached by providing a moulding plate of an aluminium wrought alloy
comprising, in weight percent:
[0011] Si 1.4-2.1
[0012] Mn 0.8-1.2
[0013] Cu 0.45-0.9
[0014] Mg 0.7-1.2
[0015] Ti <0.15
[0016] Zn <0.4
[0017] Fe <0.7
[0018] one or more of Zr, Cr, V each <0.25, total preferably
<0.35
[0019] incidental elements and impurities, each <0.05, total
<0.25,
[0020] the balance aluminium, and
[0021] having a thickness of more than 0.6 mm and in T6 temper
condition having a hardness of more than 105 HB.
[0022] The increased hardness is reached by combining precipitation
hardening of Mg--Si--Cu phases, Fe- and Mn-containing
intermetallics and dispersoids, which are known to actually reduce
the age hardening effect in balanced AlMgSi(Cu) alloys through
their effect on the quench sensitivity, with a high excess of Si,
which decreases the Mg solute level, to minimise the negative
effect of Mn-containing dispersoids on the quench sensitivity. The
supersaturation level for Mg--Si phases is not yet so high that
particularly high quench sensitivities already result from the Mg-,
Si-, and Cu solute content. The balanced alloy composition
according to the invention is believed to combine the strength
increasing effect of a silicon addition with moderate amount of
copper, magnesium and manganese. It was found that this alloy
provides satisfactory weldability and a hardness of at least 105
HB. It should be noted that the hardness values are expressed in
the Brinell scale and were measured by a ball having a 2.5 mm
diameter loaded with a mass of 62.5 kg. The hardness tests were
performed according to ASTM E10 (version 2002).
[0023] In a preferred embodiment of the invention the hardness in
T6 temper condition is at least 115 HB, more preferably at least
120 HB. These hardness values imply an increased machinability as
well as wear resistance. The chemical composition in combination
with a heat treatment ensures that adequate weldability and thus
reparability is maintained: surprisingly it has been found that for
Cu levels of up to 0.9% the plate alloy shows very good
reparability with for instance a common 4043 filler wire.
[0024] In an embodiment the Si is in the range of 1.53-2.0%, more
preferably in the range of 1.55-1.9%. It was found that this range
of silicon provides a very good combination of the desirable
properties, through hardening by coherent Mg--Si--Cu phases, and by
primary Si, incoherent Mg.sub.2Si and .alpha.-Al(Fe,Mn,Cu)Si
intermetallic phases and dispersoids.
[0025] In an embodiment the Mn is in the range of 0.85-1.10%. It
was found that this range of manganese provides a very good
combination of the desirable properties, in particular by
stimulating the formation of .alpha.-Al(Fe,Mn,Cu)Si intermetallic
phases and dispersoids. At high Si levels, the tendency to form the
relatively brittle .beta.-AlFeSi intermetallic phase increases.
However, by ensuring the presence of suitable amounts of Mn and Cu
the more favourable .alpha.-Al(Fe,Mn,Cu)Si phase is stabilised.
[0026] In an embodiment the Cu is in the range of 0.5-0.7%. It was
found that this range of copper provides a very good combination of
the desirable properties through coherent Mg--Si--Cu phases and
stabilised .alpha.-Al(Fe,Mn,Cu)Si, whilst keeping alloying cost
down and ensuring good repair weldability.
[0027] In an embodiment the Zn is below 0.3%, preferably in the
range of 0.17-0.3%.
[0028] In an embodiment the Fe is preferably at least 0.2%, more
preferably in the range 0.2-0.5%, and even more preferably in the
range 0.3-0.5% to ensure the formation of sufficient amounts of
hardness increasing .alpha.-Al(Fe,Mn,Cu)Si intermetallics.
[0029] In an embodiment the Zr, Cr, V are each preferably below
0.18%, more preferably below 0.12% to further reduce the quench
sensitivity.
[0030] In an embodiment the moulding plate has a machinability
rating of "B" or better as defined in `ASM Specialty
Handbook--Aluminium and Aluminium Alloys (ed. J. R. Davis), ASM
International 1993, pages 328-331.
[0031] In an embodiment the moulding plate has a final thickness of
300 mm, in which the claimed hardness values can still be met in
the plate centre. Preferably the final thickness is in the range of
between 5 to 300 mm, more preferably in the range of between 5 to
260 mm. These thickness ranges allow the application of the
moulding plate for all practical application involving moulding
plate.
[0032] In an embodiment the moulding plate has been rolled to the
final thickness by hot rolling only.
[0033] According to a further aspect of the invention, a method is
provided of manufacturing a moulding plate comprising the
subsequent (in other words "sequential") steps of: [0034] casting
an ingot having a composition comprising (in weight percent):
[0035] Si 1.4-2.1 [0036] Mn 0.8-1.2 [0037] Cu 0.45-0.9 [0038] Mg
0.7-1.2 [0039] Ti <0.15 [0040] Zn <0.4 [0041] Fe <0.7
[0042] one or more of Zr, Cr, V each <0.25, total preferably
<0.35 [0043] incidental elements and impurities, each <0.05,
total <0.25, balance aluminium, and with preferred compositional
ranges as set out in the description hereinabove. [0044]
homogenising and/or preheating the ingot, [0045] working said plate
to a final thickness, preferably by hot rolling and/or cold
rolling, more preferably by hot rolling only, [0046] subjecting to
heat treatment comprising solution heat treating followed by rapid
cooling, [0047] ageing, [0048] wherein the cooling rate during said
rapid cooling is chosen so as to obtain a hardness of the moulding
plate of at least 105 HB.
[0049] By manufacturing a moulding plate according to the invention
a high hardness product with a high content of chip-breaking
intermetallics is obtained. The cooling rate during the rapid
cooling after solution heat treating is important because this
cooling rate determines the amount of solute content of Mg, Si and
Cu which were dissolved during the solution heat treatment.
[0050] In an embodiment of the invention the heat treatment after
hot rolling or hot pressing is a T6-treatment.
[0051] In an embodiment the homogenisation temperature is at least
450.degree. C., preferably at least 500.degree. C., more preferably
between 500 and 595.degree. C., preferably for between 1 to 25
hours, more preferably for between 10 to 16 hours. The pre-heat
temperature is at least 570.degree. C., between about 300.degree.
C. and 570.degree. C., preferably between 350 and 530.degree. C.,
preferably for between 1 to 25 hours, more preferably for between 1
and 10 hours.
[0052] In an embodiment the solution heat-treating temperature is
at least 500.degree. C., preferably at least 520.degree. C. and
more preferably at least 540.degree. C. In an embodiment the
cooling rate after solution heat-treating from the solution
heat-treating temperature to below 250.degree. C., preferably to
below 150.degree. C. and more preferably to below 100.degree. C.,
is at least 1.degree. C./s, preferably at least 2.degree. C./s more
preferably 5.degree. C./s, even more preferably at least 10.degree.
C./s. It should be noted that the cooling rate of the product
during quenching is dependent on the location within the product.
The centre of the product cools down more slowly than the surface
of the product. Consequently, since the final hardness is dependent
on the cooling rate, the hardness will be lower if the local
cooling rate during quenching is lower. The critical point in the
product is defined as the point where the cooling rate during
quenching is the lowest. The abovementioned cooling rates relate to
the cooling rate at the critical point.
[0053] In a further embodiment, the ageing process comprises
natural ageing for a maximum duration of 28 days, preferably for a
maximum duration of 14 days, more preferably for a maximum duration
of 7 days, even more preferably for a maximum duration of 2 days,
followed by an artificial ageing treatment equivalent to ageing at
about 180 to 200.degree. C. for about 1-10 hours. It is known to
the skilled person that time and temperature of an annealing are
usually not chosen independently. The ageing process is thermally
activated, resulting in the situation that a high temperature
coupled with a short time is equivalent to a lower temperature and
a longer time, i.e. the same metallurgical state is reached after
the ageing treatment.
[0054] In an embodiment of the invention the working step comprises
a rolling or pressing step. In a further embodiment the rolling
step comprises a hot rolling and/or a hot pressing step and/or
cold-rolling step. Preferably, the working step comprises hot
rolling and/or hot pressing only.
[0055] In an embodiment of the invention the casting step is a
near-net shape casting step, wherein the dimensions of the cast
product approximates the final product.
[0056] A particular embodiment of the invention will now be
explained by the following non-limitative examples and figure. It
should be noted that the chemical composition of the alloys was
varied by mixing cuttings of a brazing alloy, consisting mostly of
an AA3000-series core alloy clad with a Si-rich AA4000-series alloy
with technical purity Al 99.0 after which Cu and/or Mg and/or other
elements can be added to obtain the final chemistry. TABLE-US-00001
TABLE 1 Average composition of tested alloys and hardness in
T6-condition. content brazing Alloy Si Fe Cu Mn Mg Zn Ti HB alloy
(%) Al 99.0 0.4 0.6 0.03 0.03 0.03 0.07 -- -- 0 Brazing alloy 2.0
0.4 0.5 1.0 0.40 0.25 0.05 -- 100 Example 1 1.72 0.37 0.61 0.77
0.97 0.21 0.05 124 82 Example 2 1.70 0.39 0.91 0.95 0.85 0.21 0.05
124 81 Example 3 2.10 0.38 0.50 1.03 0.88 0.25 0.05 124 100 Example
4 1.68 0.41 0.40 0.78 0.98 0.21 0.05 123 80 Example 5 1.71 0.43
0.51 0.76 0.70 0.21 0.05 122 82 Example 6 1.59 0.38 0.61 0.81 0.98
0.10 0.03 123 75 Example 7 1.60 0.39 0.64 0.95 0.91 0.02 0.05
80
[0057] These alloys were homogenised at a temperature above
510.degree. C., optionally hot rolled, solution heat treated at
550.degree. C., cooled down with at least 10.degree. C./s to
maximise the solute content of Mg, Si and Cu, stored for 14 days at
room temperature, and aged following an ageing treatment equivalent
to 190.degree. C. for 2-6 hours. In this way, a high-hardness
T6-temper product with a high content of chip-breaking
intermetallics is obtained, leading to a hardness of at least 120
HB. Example 7 was solution heat treated at 530.degree. C. and
stored at room temperature for a period of 1 day, the remainder of
the process conditions being as given above for the other
alloys.
[0058] The hardness profiles of plates with the composition
according to Example 7 with thicknesses of 80, 100 or 150 mm are
shown in FIG. 1. Along the X-axis the distance (L) to the centre of
the plate in the thickness direction in mm is given, and along the
Y-axis the hardness in HB values is given at different locations
over the thickness of the plate. All measured values show a
hardness value of at least 120 HB at every location over the
thickness of the plate.
[0059] It is of course to be understood that the present invention
is not limited to the described embodiments and examples described
above, but encompasses any and all embodiments within the scope of
the description and the following claims.
* * * * *