U.S. patent application number 17/424671 was filed with the patent office on 2022-04-21 for method for manufacturing a part from aluminium alloy, the alloy comprising at least zirconium and magnesium.
The applicant listed for this patent is C-TEC CONSTELLIUM TECHNOLOGY CENTER. Invention is credited to Bechir CHEHAB, Ravi SHAHANI.
Application Number | 20220119926 17/424671 |
Document ID | / |
Family ID | 1000006104032 |
Filed Date | 2022-04-21 |
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United States Patent
Application |
20220119926 |
Kind Code |
A1 |
CHEHAB; Bechir ; et
al. |
April 21, 2022 |
METHOD FOR MANUFACTURING A PART FROM ALUMINIUM ALLOY, THE ALLOY
COMPRISING AT LEAST ZIRCONIUM AND MAGNESIUM
Abstract
An object of the invention is a method for manufacturing a part
including a formation of successive metallic layers (20.sub.1, . .
. 20.sub.n), superimposed on one another, each layer being formed
by the deposition of a filler metal (15, 35), the filler metal
being subjected to an energy supply so as to melt and constitute,
when solidifying, said layer, the method being characterized in
that the filler metal (15, 35) is an aluminum alloy including the
following alloy elements, in weight percents: Mg: 0%-6%; Zr:
0.7%-2.5%, preferably according to a first variant >1% and
.ltoreq.2.5%; or preferably according to a second variant 0.7-2%;
and possibly 0.7-1.6%; and possibly 0.7-1.4%; and possibly
0.8-1.4%; and possibly 0.8-1.2%; at least one alloy element
selected from Fe, Cu, Mn, Ni and/or La: at least 0.1%, preferably
at least 0.25%, more preferably at least 0.5% per element;
impurities: <0.05% individually, and preferably <0.15% all in
all.
Inventors: |
CHEHAB; Bechir; (Voiron,
FR) ; SHAHANI; Ravi; (Voreppe, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
C-TEC CONSTELLIUM TECHNOLOGY CENTER |
Voreppe |
|
FR |
|
|
Family ID: |
1000006104032 |
Appl. No.: |
17/424671 |
Filed: |
January 24, 2020 |
PCT Filed: |
January 24, 2020 |
PCT NO: |
PCT/FR2020/050107 |
371 Date: |
July 21, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B33Y 70/00 20141201;
C22C 21/06 20130101; C22F 1/047 20130101; B23K 26/342 20151001;
B33Y 40/20 20200101; B22F 10/28 20210101; B33Y 10/00 20141201; B22F
10/64 20210101; B22F 2301/052 20130101 |
International
Class: |
C22C 21/06 20060101
C22C021/06; B33Y 10/00 20060101 B33Y010/00; B33Y 70/00 20060101
B33Y070/00; B22F 10/28 20060101 B22F010/28; B22F 10/64 20060101
B22F010/64; B33Y 40/20 20060101 B33Y040/20; C22F 1/047 20060101
C22F001/047; B23K 26/342 20060101 B23K026/342 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 24, 2019 |
FR |
1900598 |
Claims
1. A method for manufacturing a part comprising forming a formation
of successive metallic layers, superimposed on one another, each
layer being formed by the deposition of a filler metal, the filler
metal being subjected to an energy supply so as to melt and
constitute, when solidifying, said layer, wherein the filler metal
is an aluminum alloy including the following alloy elements, in
weight percent: Mg: 0%-6%; Zr: 0.7%-2.5%, optionally according to a
first variant >1% and .ltoreq.2.5%; or optionally according to a
second variant 0.7-2%; and optionally 0.7-1.6%; and optionally
0.7-1.4%; and optionally 0.8-1.4%; and optionally 0.8-1.2%; at
least one alloy element selected from Fe, Cu, Mn, Ni and/or La: at
least 0.1%, optionally at least 0.25%, optionally at least 0.5% per
element; impurities: <0.05% individually, and optionally
<0.15% all in all.
2. The method according to claim 1, wherein the aluminum alloy
includes from 0.2 to 6%, optionally from 1 to 5%, optionally from 2
to 5%, optionally from 3 to 5%, still optionally from 3.5 to 5% by
weight of Mg.
3. The method according to claim 1, wherein the aluminum alloy
includes a Mg content lower than 3.5%, optionally lower than 3%,
optionally lower than 2%, optionally lower than 1%, still
optionally lower than 0.05% by weight.
4. The method according to claim 1, wherein the aluminum alloy
includes at least one other alloy element, selected from: Si, Hf,
V, Cr, Ta, Nb, W, Ti, Y, Yb, Ce, Co, Mo, Nd and/or Er, the content
of the other alloy element or of each other alloy element being
from 0.05 to 5%, or from 0.1 to 3%, or from 0.1 to 2%, or from 0.1
to 1%, or from 0.1 to 0.5%.
5. The method according to claim 1, wherein the method includes,
after formation of the layers, and/or after the formation of the
part, an application of at least one heat treatment, the
temperature of the heat treatment being optionally from 300.degree.
C. to 600.degree. C.
6. The method according to claim 1, including no quenching-type
heat treatment following formation of the layers, and/or following
formation of the part.
7. The method according to claim 1, wherein the filler metal is in
the form of a powder, whose exposure to a beam of light or of
charged particles results in a local melting followed by a
solidification, so as to form a solid layer.
8. The method according to claim 1, wherein the filler metal is
derived from a filler wire, whose exposure to a heat source results
in local melting followed by solidification, so as to form a solid
layer.
9. A part obtained by a method of claim 1.
10. A powder, intended to be used as a filler material of an
additive manufacturing method, the powder being intended to be
heated, so as to form, under the effect of heating, a layer, the
layer resulting from melting followed by solidification, the powder
including aluminum alloy particles, wherein the aluminum alloy
includes the following alloy elements, in weight percent: Mg:
0%-6%; Zr: 0.7%-2.5%, optionally according to a first variant
>1% and .ltoreq.2.5%; or optionally according to a second
variant 0.7-2%; and optionally 0.7-1.6%; and optionally 0.7-1.4%;
and optionally 0.8-1.4%; and optionally 0.8-1.2%; at least one
alloy element selected from Fe, Cu, Mn, Ni and/or La: at least
0.1%, optionally at least 0.25%, optionally at least 0.5% per
element; impurities: <0.05% individually, and optionally
<0.15% all in all.
11. A filler wire, intended to be used as a filler material of an
additive manufacturing method, wherein said wire comprises an
aluminum alloy including the following alloy elements, in weight
percent: Mg: 0%-6%; Zr: 0.7%-2.5%, optionally according to a first
variant >1% and .ltoreq.2.5%; or optionally according to a
second variant 0.7-2%; and optionally 0.7-1.6%; and optionally
0.7-1.4%; and optionally 0.8-1.4%; and optionally 0.8-1.2%; at
least one alloy element selected from Fe, Cu, Mn, Ni and/or La: at
least 0.1%, optionally at least 0.25%, optionally at least 0.5% per
element; impurities: <0.05% individually, and optionally
<0.15% all in all.
12. A product comprising a powder according to claim 10 or a filler
wire made from said powder, adapted for a manufacturing method
selected from the group consisting of: cold spray consolidation
(CSC), laser metal deposition (LMD), additive friction stir (AFS),
spark plasma sintering (FAST) or rotary friction welding (IRFW),
optionally cold spray consolidation (CSC).
Description
TECHNICAL FIELD
[0001] The technical field of the invention is a method for
manufacturing a part made of an aluminum alloy, implementing an
additive manufacturing technique.
PRIOR ART
[0002] Since the 80s, additive manufacturing techniques have been
developed. These consist in shaping a part by addition of matter,
which is in contrast with machining techniques, aiming to remove
the matter. Formerly restricted to prototyping, additive
manufacturing is now operational for manufacturing industrial
products in mass production, including metallic parts.
[0003] The term "additive manufacturing" is defined according to
the French standard P E67-001 as a "set of processes allowing
manufacturing, layer after layer, by addition of matter, a physical
object based on a digital object". The standard ASTM F2792 (January
2012) defines additive manufacturing too. Different additive
manufacturing approaches are also defined and described in the
standard ISO/ASTM 17296-1. Resort to an additive manufacture to
make an aluminum part, with low porosity, has been described in the
document WO2015/006447. In general, the application of successive
layers is carried out by application of a so-called filler
material, and then melting or sintering of the filler material
using an energy source such as a laser beam, an electron beam, a
plasma torch or an electric arc. Regardless of the additive
manufacturing approach that is applied, the thickness of each added
layer is in the range of a few tens or hundreds of microns. The
filler material may be in the form of a powder or a wire.
[0004] Amongst additive manufacturing methods that could be used,
mention may be made for example, and without limitation, of melting
or sintering of a filler material in the form of a powder. This may
consist of laser melting or sintering. The patent application
US20170016096 describes a method for manufacturing a part by local
melting obtained by exposure of a powder to an energy beam such as
an electron beam or a laser beam, the method being also referred to
by the acronyms SLM standing for "Selective Laser Melting" or
"EBM", standing for "Electron Beam Melting". The powder is
constituted by an aluminum alloy whose copper content is from 5 to
6 weight %, the magnesium content being from 2.5 to 3.5 weight
%.
[0005] The document WO2018185259 describes an alloy, intended to be
used in the form of a powder, in a SLM-type additive manufacturing
method. In particular, the alloy may contain from 2 to 7 weight %
of Mg. It may also contain a weight fraction of Zr from 0 to
1%.
[0006] The document WO 2018009359 describes an aluminum alloy, in
the form of a powder, including a weight fraction of Mg from 1 to
10%, as well as a weight fraction of Zr from 0.3 to 3%. The alloy
may also include Zn, Mn, Cr, Si, Fe, Cu, but these elements are
then present in the form of unavoidable impurities, whose content
is lower than 500 ppm.
[0007] The mechanical properties of the aluminum parts obtained by
additive manufacturing depend on the alloy forming the filler
metal, and more specifically on its composition as well as on the
heat treatments applied following the implementation of the
additive manufacture.
[0008] The inventors have determined an alloy composition which,
when used in an additive manufacturing method, allows obtaining
parts with remarkable mechanical performances, in particular in
terms of hardness. An advantage of the composition defined by the
inventors is that it is not necessary to implement heat treatments
such as dissolution and quenching. Moreover, the composition
described hereinafter allows forming layers having a low porosity
level. Furthermore, it is suited to an implementation of an
additive manufacturing method according to high power and speed.
Thus, it enables the manufacture of parts with a high manufacturing
yield.
DISCLOSURE OF THE INVENTION
[0009] A first object of the invention is a method for
manufacturing a part including a formation of successive metallic
layers, superimposed on one another, each layer being formed by the
deposition of a filler metal, the filler metal being subjected to
an energy input so as to melt and constitute, when solidifying,
said layer, the method being characterized in that the filler metal
is an aluminum alloy including the following alloy elements, in
weight percents: [0010] Mg: 0-6%; [0011] Zr: 0.7%-2.5%, preferably
according to a first variant >1% and 2.5%; or preferably
according to a second variant 0.7-2%; and possibly 0.7-1.6%; and
possibly 0.7-1.4%; and possibly 0.8-1.4%; and possibly 0.8-1.2%;
[0012] at least one alloy element selected from Fe, Cu, Mn, Ni
and/or La: at least 0.1%, preferably at least 0.25%, more
preferably at least 0.5% per element; [0013] impurities: <0.05%
individually, and preferably <0.15% all in all.
[0014] Preferably, the remainder of the alloy is aluminum.
Preferably, the alloy according to the present invention comprises
a weight fraction of at least 85%, more preferably of at least 90%,
of aluminum.
[0015] As regards the amount of Zr, it should be noted that the
first variant is particularly suited in the presence of Mn.
[0016] Melting of the filler metal may be partial or total.
Preferably, from 50 to 100% of the exposed filler metal melts, more
preferably from 80 to 100%.
[0017] In particular, each layer may feature a pattern defined from
a digital model.
[0018] According to a variant of the invention, the Mg content may
be lower than 3.5%, preferably lower than 3%, preferably lower than
2%, more preferably lower than 1%, still more preferably lower than
0.05% by weight.
[0019] According to this variant, the alloys according to the
invention seem to be particularly advantageous by having a good
trade-off at room temperature between the (thermal or electrical)
conductivity and the mechanical strength. Indeed, the (electrical
or thermal) conductivity of the alloys according to the invention
at room temperature seems to continuously increase with the
duration of holding at the hardening annealing temperature, for
example at 400.degree. C. In turn, the mechanical strength at room
temperature, seems to rise at first to reach a peak between 0 and
10 h of holding (for example at 400.degree. C.) before starting to
decrease. Thus, depending on the pursued trade-offs, the time of
holding at the hardening annealing temperature seems to require
adjustment.
[0020] The hardening annealing temperature may be from 300 to
500.degree. C.
[0021] A Mg content >3.5%, and possibly 3%, and possibly 2% by
weight seems to be advantageous for mechanical strength but seems
to degrade the (thermal or electrical) conductivity.
[0022] According to another variant of the invention, the alloy may
include from 0.2 to 6%, preferably from 1 to 5%, preferably from 2
to 5%, more preferably from 3 to 5%, still more preferably from 3.5
to 5% by weight of Mg.
[0023] Preferably, according to a first variant, the Zr content is
from 1.2 to 2%, and possibly from 1.2 to 1.8%.
[0024] Preferably, according to a second variant, the Zr content is
from 0.7 to 2%; and possibly from 0.7 to 1.6%; and possibly from
0.7 to 1.4%; and possibly from 0.8 to 1.4%; and possibly from 0.8
to 1.2%.
[0025] The aluminum alloy may include Cu: from 0.1 to 5%,
preferably from 0.1 to 4%, preferably from 0.5 to 3%, and for
example 1 or 2%.
[0026] The aluminum alloy may include Fe: from 0.1 to 5%,
preferably from 0.1 to 4%, preferably from 0.5 to 3%, and for
example 1 or 2%.
[0027] The aluminum alloy may include Ni: from 0.1 to 5%,
preferably from 0.5 to 3%, and for example 1 or 2%.
[0028] The aluminum alloy may include La: from 0.1 to 5%,
preferably from 0.5 to 3%, and for example 1 or 2%.
[0029] The aluminum alloy may include Mn: from 0.1 to 5%,
preferably from 0.5 to 3%, and for example 1 or 2%.
[0030] Preferably, the cumulative content of the aforementioned
alloy elements is strictly higher than 0.1%. It may be from 0.1% to
5%. Preferably, it is lower than 10%.
[0031] The aluminum alloy may include at least one other alloy
element. The term "other alloy element" refers to an additive,
different from the alloy elements listed hereinbefore. The other
alloy element or each other alloy element is selected from: Si, Hf,
V, Cr, Ta, Nb, W, Ti, Y, Yb, Ce, Co, Mo, Nd and/or Er, the content
of the other alloy element or of each other alloy element being
from 0.05 to 5%, or from 0.1 to 3%, or from 0.1 to 2%, or from 0.1
to 1%, or from 0.1 to 0.5%. Preferably, the cumulative content of
the other alloy elements is lower than 10%, and preferably lower
than 5%.
[0032] The method may include, after the formation of the layers,
that is to say after the formation of the final part, an
application of at least one heat treatment, the temperature of the
heat treatment being preferably from 300.degree. C. to 600.degree.
C. The heat treatment may consist of annealing or tempering.
Preferably, the method does not include any quenching-type heat
treatment following the formation of the layers, that is to say
following the formation of the final part. According to one
embodiment, the filler metal is in the form of a powder, whose
exposure to a beam of light or of charged particles and more
generally a heat source, results in a local melting followed by a
solidification, so as to form a solid layer.
[0033] According to another embodiment, the filler metal is derived
from a filler wire, whose exposure to a heat source, for example an
electric arc, results in a local melting followed by a
solidification, so as to form a solid layer.
[0034] A second object of the invention is a part obtained by a
method according to the first object of the invention.
[0035] A third object of the invention is a powder intended to be
used as a filler material of an additive manufacturing method, the
powder being intended to be heated, so as to form, under the effect
of heating, a layer, the layer resulting from a melting followed by
a solidification, the powder including aluminum alloy particles,
the powder being characterized in that the aluminum alloy includes
the following alloy elements, in weight percents: [0036] Mg: 0-6%;
[0037] Zr: 0.7%-2.5%, preferably according to a first variant
>1% and .ltoreq.2.5%; or preferably according to a second
variant 0.7-2%; and possibly 0.7-1.6%; and possibly 0.7-1.4%; and
possibly 0.8-1.4%; and possibly 0.8-1.2%; [0038] at least one alloy
element selected from Fe, Cu, Mn, Ni and/or La: at least 0.1%,
preferably at least 0.25%, more preferably at least 0.5% per
element; [0039] impurities: <0.05% individually, and preferably
<0.15% all in all.
[0040] The powder may be such that at least 80% of the particles
composing the powder have an average size within the following
range: from 5 to 100 .mu.m, preferably from 5 to 25 .mu.m, or from
20 to 60 .mu.m.
[0041] A fourth object of the invention is a a filler wire,
intended to be used as a filler material of an additive
manufacturing method, characterized in that it is constituted by an
aluminum alloy including the following alloy elements, in weight
percents: [0042] Mg: 0-6%; [0043] Zr: 0.7%-2.5%, preferably
according to a first variant >1% and .ltoreq.2.5%; or preferably
according to a second variant 0.7-2%; and possibly 0.7-1.6%; and
possibly 0.7-1.4%; and possibly 0.8-1.4%; and possibly 0.8-1.2%;
[0044] at least one alloy element selected from Fe, Cu, Mn, Ni
and/or La: at least 0.1%, preferably at least 0.25%, more
preferably at least 0.5% per element; [0045] impurities: <0.05%
individually, and preferably <0.15% all in all.
[0046] When the filler material is in the form of a wire, the
diameter of the wire may in particular be from 0.5 to 3 mm, and
preferably from 0.5 to 2 mm, and still preferably from 1 to 2 mm.
The alloy implemented in the third and fourth objects of the
invention may have the features of the alloy described in
connection with the first object of the invention, considered
separately or according to technically feasible combinations.
[0047] A fifth object of the invention is the use of a powder or of
a filler wire as described hereinbefore and in the rest of the
description in a manufacturing method selected amongst: cold spray
consolidation (CSC), laser metal deposition (LMD), additive
friction stir (AFS), spark plasma sintering (FAST) or rotary
friction welding (IRFW), preferably cold spray consolidation
(CSC).
FIGURES
[0048] FIG. 1 is a diagram representing an additive manufacturing
method by selective laser melting (SLM);
[0049] FIG. 2 represents the evolution of the liquidus temperature
(ordinate axis) as a function of the Zr content (abscissa axis)
[0050] FIG. 3 shows a micrograph of a cross-section of a sample
after surface scanning with a laser, cut and polished with two
Knoop hardness indents in the re-melted layer.
[0051] FIGS. 4A to 4D illustrate Knoop hardness values (ordinate
axis) of samples made using compositions according to the invention
as a function of a duration of a heat post-treatment at 400.degree.
C. (abscissa axis).
[0052] FIGS. 5A to 5F show a section of a sample of a reference
alloy having been exposed to a laser beam according to different
scan speeds, the power of the laser being respectively 250 W, 300
W, 350 W, 400 W, 450 W and 500 W.
[0053] FIGS. 6A to 6F show a section of a sample according to the
present invention of an alloy Al-4% Mg-1.5% Zr-2% Cu having been
exposed to a laser beam according to different scan speeds, the
power of the laser being respectively 250 W, 300 W, 350 W, 400 W,
450 W and 500 W.
[0054] FIGS. 7A to 7F show a section of a sample according to the
present invention of an alloy Al-4% Mg-1.5% Zr-2% Ni having been
exposed to a laser beam according to different scan speeds, the
power of the laser being respectively 250 W, 300 W, 350 W, 400 W,
450 W and 500 W.
[0055] FIGS. 8A to 8F show a section of a sample according to the
present invention of an alloy Al-4% Mg-1.5% Zr-2% Fe having been
exposed to a laser beam according to different scan speeds, the
power of the laser being respectively 250 W, 300 W, 350 W, 400 W,
450 W and 500 W.
[0056] FIGS. 9A to 9F show a section of a sample according to the
present invention of an alloy Al-4% Mg-1.5% Zr-2% Mn having been
exposed to a laser beam according to different scan speeds, the
power of the laser being respectively 250 W, 300 W, 350 W, 400 W,
450 W and 500 W.
[0057] FIGS. 10A to 10F show a section of a sample according to the
present invention of an alloy Al-4% Mg-1.5% Zr-2% La having been
exposed to a laser beam according to different scan speeds, the
power of the laser being respectively 250 W, 300 W, 350 W, 400 W,
450 W and 500 W.
[0058] FIG. 11 is a diagram representing a Wire Arc Additive
Manufacturing method, commonly referred to by the acronym WAAM.
[0059] FIG. 12 is a diagram of the specimen used according to the
examples.
DISCLOSURE OF PARTICULAR EMBODIMENTS
[0060] Unless stated otherwise, in the description: [0061] the
designation of the aluminum alloys is compliant with the
nomenclature of The Aluminum Association; [0062] the contents of
the chemical elements are reported in % and represent weight
fractions. The x %-y % notation means higher than or equal to x %
and lower than or equal to y %.
[0063] FIG. 1 represents a SLM-type additive manufacturing device,
mentioned in connection with the prior art. The device uses an
aluminum alloy, forming a filler material, and provided in the form
of a powder 15, lying on a support 10. An energy source, in this
instance a laser source 11, emits a laser beam 12. The laser source
is coupled to the filler material by an optical system 13, whose
movement is determined according to a digital model M. The laser
beam 12 follows a movement according to the longitudinal plane XY,
describing a pattern depending on the digital model. The movement
is performed according to a scan speed, which represents the speed
of displacement of the beam relative to the powder. The interaction
of the laser beam 12 with the powder 15 causes a selective melting
of the latter, followed by a solidification, resulting in the
formation of a layer 20.sub.1 . . . 20.sub.n. Once a layer has been
formed, it is covered with powder 15 and another layer is formed,
superimposed on the layer made before. For example, the thickness
of the powder forming a layer may be from 10 to 200 .mu.m.
[0064] For aluminum alloys, the support 10 or tray may be heated up
to a temperature ranging up to 350.degree. C. In general, machines
that are currently available on the market enable heating of the
tray up to 200.degree. C. For example, the heating temperature of
the tray may be about 50.degree. C., 100.degree. C., 150.degree. C.
or 200.degree. C. In general, heating of the tray allows reducing
the humidity at the powder bed and also reducing the residual
stresses on the parts being manufactured. The humidity level at the
powder bed seems to have a direct effect on the porosity of the
final part. Indeed, it seems that the higher the humidity of the
powder, the higher will be the porosity of the final part. It
should be noted that heating of the tray is one of the existing
possibilities to carry out a hot additive manufacturing. However,
the present invention should not be limited to the use of this
heating means alone. All other heating means may be used in the
context of the present invention to heat up and monitor the
temperature, for example an infrared lamp. Thus, the method
according to the present invention may be carried out at a
temperature ranging up to 350.degree. C.
[0065] The powder may have at least one of the following
characteristics: [0066] average particle size from 5 to 100 .mu.m,
preferably from 5 to 25 .mu.m, or from 20 to 60 .mu.m. The given
values mean that at least 80% of the particles have an average size
within the specified range. [0067] spherical shape. For example,
the sphericity of a powder may be determined using a
morphogranulometer. [0068] good castability. For example, the
castability of a powder may be determined according to the standard
ASTM B213 or the standard ISO 4490:2018. According to the standard
ISO 4490:2018, the flow time is preferably shorter than 50 s.
[0069] low porosity, preferably from 0 to 5%, more preferably from
0 to 2%, still more preferably from 0 to 1% by volume. In
particular, the porosity may be determined by optical microscopy or
scanning electron microscope or by helium pycnometry (cf. the
standard ASTM B923). [0070] absence or small amount (less than 10%,
preferably less than 5% by volume) of small particles (1 to 20% of
the average size of the powder), called satellites, which stick to
the larger particles.
[0071] The inventors have looked for an alloy composition, forming
the filler material, allowing obtaining acceptable mechanical
properties without requiring the application of heat treatments,
subsequent to the formation of the layers, that is to say after the
formation of the final part, which might induce a distortion. In
particular, these consist of heat treatments involving an abrupt
variation of the temperature. Thus, the invention allows obtaining,
by additive manufacturing, a part whose mechanical properties are
satisfactory, in particular in terms of hardness. Depending on the
selected additive manufacturing method type, the filler material
may be in the form of a powder, as described before. In this case,
the exposure of the powder (15) to a beam of light (12) or of
charged particles results in a local melting followed by a
solidification, so as to form a solid layer (20.sub.1 . . .
20.sub.n).
[0072] According to one variant, the filler metal may also be in
the form of a wire, as described in connection with FIG. 11. In
this case, the exposure of the filler wire (35) to a heat source
(32) results in a local melting followed by a solidification, so as
to form a solid layer (20.sub.1 . . . 20.sub.n).
[0073] The inventors have noticed that a part having satisfactory
mechanical properties could be obtained using an aluminum alloy
combining: [0074] a magnesium content from 0 to 6% and preferably
from 1 to 6%, and preferably from 3 to 4.5%. A magnesium content
lower than 3.5% may also be advantageous, in particular for
corrosion resistance after thermal exposure. [0075] a zirconium
content according to a first variant from 1 to 2.5%, and preferably
from 1 to 2%, while being strictly higher than 1%. A Zr content
from 1.2 to 2% or from 1.2 to 1.8% is considered to be optimum. Or
according to a second variant from 0.7 to 2%; and possibly from 0.7
to 1.6%; and possibly from 0.7 to 1.4%; and possibly from 0.8 to
1.4%; and possibly from 0.8 to 1.2%. [0076] an alloy element, whose
content is higher than 0.1%, or higher than 0.25% or 0.5%, the
alloy element being selected amongst Fe, Cu, Ni, Mn and/or La.
Preferably, the content of each alloy element is lower than 5%,
more preferably lower than 3%. Preferably, the cumulative content
of each alloy element is from 0.1 to 5%. It may be lower than
10%.
[0077] The use of such an alloy in an additive manufacturing method
is accompanied with the following advantages: [0078] a good
compatibility with additive manufacturing methods, in particular
the SLM method: this is reflected by the absence of cracks at the
layers formed successively; [0079] a good corrosion resistance, in
particular when the magnesium content is from 3 to 4.5%, or when
the latter is lower than 3.5%. [0080] a melting (liquidus) point
lower than 1050.degree. C., and preferably lower than 1000.degree.
C., which limits the evaporation of Mg during the fusion. When the
Mg content is 4%, the liquidus temperature is lower than
1050.degree. C. when the Zr content is lower than 2.2%. When the Zr
content is lower than 1.6%, the liquidus temperature is lower than
1000.degree. C. With such an alloy, a part featuring a high
hardness is obtained. For these reasons, a Zr content from 0.7 to
2% or from 1 to 2% or from 1.2 to 1.8%, is optimum when the Mg
content is in the range of 4% and preferably in the presence of
Mn.
[0081] FIG. 2 represents an evolution of the liquidus temperature
as a function of the Zr content, for an aluminum alloy including 4%
of Mg. This curve has been obtained using the FactSage 7.1 software
using the VLAB database. It shows that a Zr content lower than 2.2%
allows keeping the liquidus temperature lower than or equal to
1050.degree. C. Moreover, a Zr content lower than or equal to 0.7%,
and possibly 1% is considered to be non-advantageous, the
mechanical properties then being insufficient, for example a
maximum hardness lower than 120 HK0.05. A Zr content close to 1.5%,
that is to say from 1 to 2%, or from 1.2 to 2% or from 1.2 to 1.8%,
seems to be optimum, according to a first variant, preferably in
the presence of Mn.
[0082] The alloy may include other alloy elements, selected from:
Si, Hf, V, Cr, Ta, Nb, W, Ti, Y, Yb, Ce, Co, Mo, Nd and/or Er, the
content of the other alloy element or of each other alloy element
being from 0.05 to 5%, or from 0.1 to 3%, or from 0.1 to 2%, or
from 0.1 to 1%, or from 0.1 to 0.5%. The weight fraction of the
other alloy elements, considered as a whole, is preferably lower
than 10%, and preferably lower than 5%, and preferably lower than
3% and even 2%. Such elements may generate an increase in the
hardness by a solid solution effect and/or by the formation of
dispersoids or fine intermetallic phases.
[0083] The alloy may include other elements selected amongst Sr,
Ba, Sb, Bi, Ca, P, B, In, Sn, according to a weight fraction lower
than or equal to 1%, and preferably lower than or equal to 0.1%,
and still preferably lower than or equal to 700 ppm for each
element. Preferably, the total weight fraction of these elements is
lower than 2%, and preferably lower than 1%. It may be preferable
to avoid an excessive addition of Bi, the preferred weight fraction
being lower than 0.05%, and preferably lower than 0.01%.
[0084] The alloy may include other elements such as: [0085] Ag,
according to a weight fraction from 0.06 to 1%; [0086] and/or Li,
according to a weight fraction from 0.06 to 2%; [0087] and/or Zn,
according to a weight fraction from 0.05 to 5%, preferably from 0.1
to 3%.
[0088] According to one embodiment, the alloy may also comprise at
least one element for refining the grains and avoiding a coarse
columnar microstructure, for example AITiC or AlTiB.sub.2, for
example a refining agent in the ATSB or AT3B form, according to an
amount smaller than or equal to 50 kg/ton, and preferably smaller
than or equal to 20 kg/ton, still more preferably equal 12 kg/ton
for each element, and smaller than or equal to 50 kg/ton, and
preferably smaller than or equal to 20 kg/ton for all these
elements.
[0089] Subsequently to the formation of the layers, that is to say
subsequently to the formation of the final part, the method may
include a heat treatment, referred to by the term post-treatment.
It may include a dissolution followed by quenching and tempering.
However, as previously described, quenching may cause a deformation
of the part formed by additive manufacturing, in particular, when
the dimensions of the latter are large. Henceforth, when a heat
treatment is applied, it is preferable that its temperature is from
300 to 600.degree. C., preferably lower than 500.degree. C. or more
preferably lower than or equal to 450.degree. C., and for example
from 100.degree. C. to 450.degree. C. In particular, it may consist
of hardening tempering or annealing. In general, the heat treatment
may enable a relief of the residual stresses and/or an additional
precipitation of hardening phases.
[0090] Preferably, the method according to the present invention
does not include any quenching-type heat treatment following the
formation of the layers, that is to say following the formation of
the final part.
[0091] According to one embodiment, the method may include a hot
isostatic pressing (HIP). In particular, the HIP treatment may
allow improving the elongation properties and the fatigue
properties. The hot isostatic pressing may be carried out before,
after or instead of the heat treatment. Advantageously, the hot
isostatic pressing is carried out at a temperature from 250.degree.
C. to 550.degree. C. and preferably from 300.degree. C. to
450.degree. C., at a pressure from 500 to 3000 bars and over a
duration from 0.5 to 10 hours. Depending on the pursued properties,
the temperature of the HIP treatment will not exceed 450.degree.
C., and possibly 400.degree. C., because the increase of the
temperature reduces the mechanical strengths.
[0092] In particular, the possible heat treatment and/or the hot
isostatic pressing allows increasing the hardness of the obtained
product, under some conditions, in particular temperature
conditions.
[0093] According to another embodiment, suited to alloys with
structural hardening, it is possible to carry out a dissolution
followed by quenching and tempering of the formed part and/or a hot
isostatic pressing. In this case, the hot isostatic pressing may
advantageously replace the dissolution.
[0094] However, the method according to the invention is
advantageous, because it preferably does not require any
dissolution treatment followed by quenching. The dissolution may
have a detrimental effect on the mechanical strength in some cases
by participating in an enlargement of dispersoids or fine
intermetallic phases.
[0095] According to one embodiment, the method according to the
present invention further includes, optionally, a machining
treatment, and/or a chemical, electrochemical or mechanical surface
treatment, and/or a vibratory finishing. In particular, these
treatments may be carried out to reduce the roughness and/or
improve the corrosion resistance and/or improve the resistance to
fatigue cracking.
[0096] Optionally, it is possible to carry out a mechanical
deformation of the part, for example after the additive manufacture
and/or before the heat treatment.
[0097] The tests described in the following description show that
the use of the alloy according to the invention allows obtaining
parts having a high hardness. This allows avoiding resort to
post-manufacture heat treatments involving an abrupt variation of
temperature, and which might induce a distortion, as mentioned
before.
[0098] The inventors have also noticed that the alloy as previously
described is particularly suited to be applied in an additive
manufacturing method, during which the alloy undergoes a local
melting followed by a solidification. In particular, the alloy is
suited to a method combining high power and high scan speed. Thus,
the alloy is suitable for an efficient implementation of an
additive manufacturing method.
EXAMPLES
[0099] Tests 1.
[0100] The tested alloys have been cast in a copper mold using an
Induthem VC 650V machine to obtain ingots with a 130 mm height, a
95 mm width and a 5 mm thickness.
[0101] The alloys as described in Table 1 hereinbefore have been
tested by a rapid prototyping method. Samples have been machined
for scanning of the surface with a laser, in form of strips having
60.times.22.times.3 mm dimensions, from the ingots obtained
hereinbefore. The strips have been placed in a SLM machine and
scans of the surface have been performed with a laser following the
same scanning strategy and process conditions representative of
those used for the SLM process. Indeed, it has been noticed that,
in this manner, it was possible to assess the capability of the
alloys of the SLM method and in particular the surface quality, the
sensitivity to hot cracking, the hardness at the raw state and the
hardness after heat treatment.
[0102] Under the laser beam, the metal melts in a bath having a 10
to 350 .mu.m thickness. After passage of the laser, the metal
rapidly cools down as in the SLM method. After laser scanning, a
fine surface layer having a 10 to 350 .mu.m thickness has molten
and then solidified. The properties of the metal in this layer are
close to the properties of the metal at the core of a part
manufactured by SLM, because the scanning parameters are properly
selected. Laser scanning of the surface of the different samples
has been performed using a selective laser melting machine ProX300
of the trademark 3DSystems. The laser source had a 250 W power, the
scattering vector was 60 .mu.m, the scan speed was 300 mm/s and the
diameter of the beam was 80 .mu.m.
[0103] Knoop Hardness Measurement
[0104] Hardness is a major property for alloys. Indeed, if the
hardness of the layer re-melted by scanning of the surface with a
laser is high, a part manufactured with the same alloy would
probably have a high tensile strength.
[0105] To assess the hardness of the re-melted layer, the strips
obtained hereinbefore have been cut in the plane perpendicular to
the direction of the passes of the laser and have been polished
afterwards. After polishing, hardness measurements have been
performed in the re-melted layer. The hardness measurement has been
performed with a Durascan model apparatus from Struers. The 50 g
Knoop hardness method with the large diagonal of the indent placed
parallel to the plane of the re-melted layer has been selected to
keep enough distance between the indent and the edge of the sample.
15 indents have been positioned at mid-thickness of the re-melted
layer. FIG. 3 shows an example of the hardness measurement. The
reference numeral 1 corresponds to the re-melted layer and the
reference numeral 2 corresponds to a Knoop hardness indent.
[0106] The hardness has been measured according to Knoop's scale
with a 50 g load after laser treatment (in the raw state) and after
an additional heat treatment at 400.degree. C. over variable
durations, allowing assessing in particular the ability of the
alloy to be hardened during a heat treatment and the effect of a
possible CIC treatment on the mechanical properties.
[0107] Following each test, a heat post-treatment has been applied
on some samples. The heat treatment consists of a hardening
annealing, at a temperature of 400.degree. C., and that being so
during 1 hour, or 4 hours, or 10 hours.
[0108] A reference alloy including aluminum, as well as the
following alloy elements, has been used: Mg (4%); Zr (1.5%). The
reference alloy is as described in the publication WO2018/185259.
The composition of the tested aluminum alloys is reported in Table
1 hereinafter, in weight percents:
TABLE-US-00001 TABLE 1 Com- position No. Mg Zr Cu Fe Mn Ni La Ref
4% 1.5% 1 4% 1.5% 2% 2 4% 1.5% 1% 3 4% 1.5% 2% 4 4% 1.5% 1% 1% 5 4%
1.5% 2% 6 4% 1.5% 2% 7 4% 1.5% 1% 1% 8 4% 1.5% 1% 9 4% 1.5% 2% 10
4% 1.5% 1% 1%
[0109] Table 2 hereinafter shows the Knoop 0.05 hardness values
measured for each alloy, namely after laser treatment, in a raw
state (column 0h), after hardening annealing at 400.degree. C.,
carried out after the laser treatment, for 1 hour (column 1h), or
over 4 hours (column 4h), or over 10 hours (column 10h). The max
column indicates the maximum hardness level measured on the
different tested samples. The values in bold indicate the heat
treatment having led to the highest hardness value.
TABLE-US-00002 TABLE 2 Com- position No. liquidus 0 h 1 h 4 h 10 h
max Ref 990 93 111 124 114 124 1 995 104 148 148 133 148 2 993 116
143 160 148 160 3 996 136 157 171 170 171 4 995 125 165 168 153 168
5 987 121 143 151 137 151 6 995 127 123 165 156 165 7 991 125 164
156 139 164 8 994 108 115 140 136 140 9 998 119 125 164 142 164 10
996 119 129 163 147 163
[0110] FIG. 4A shows the obtained results relating to the
compositions 2 (1% Fe), 3 (2% Fe) and 4 (1% Fe, 1% Cu), as well as
with the reference composition. Notice that the compositions 2, 3
and 4 allow obtaining a hardness higher than the reference
composition, irrespective of the duration of the heat treatment.
The highest hardness values are obtained with a heat treatment
duration of 4h. The highest values are obtained with the
compositions 3 (2% Fe) and 4 (1% Fe-1% Cu).
[0111] FIG. 4B shows the obtained results relating to the
compositions 8 (1% La), 9 (2% La) and 10 (1% La, 1% Cu), as well as
with the reference composition. Notice that the compositions 8, 9
and 10 allow obtaining a hardness higher than the reference
composition, irrespective of the duration of the heat treatment.
The highest hardness values are obtained with a heat treatment
duration of 4h. The highest values are obtained with the
compositions 9 (2% La) and 10 (1% La-1% Cu).
[0112] FIG. 4C shows the obtained results relating to the
compositions 5 (2% Ni), 7 (1% Cu, 1% Ni) as well as with the
reference composition. Notice that the compositions 5 and 7 allow
obtaining a hardness higher than the reference composition,
irrespective of the duration of the heat treatment. The highest
hardness values are obtained with a heat treatment duration of 4
hours for the composition 7 and 1 hour for the composition 5. The
highest values are obtained with the composition 7 (1% Cu-1%
Ni).
[0113] FIG. 4D shows the obtained results relating to the
compositions 1 (2% Cu), 6 (2% Mn) as well as with the reference
composition. Notice that the compositions 1 and 6 allow obtaining a
hardness higher than the reference composition, irrespective of the
duration of the heat treatment. The highest values are obtained
with the composition 6 (2% Mn).
[0114] These results show that: [0115] Resorting to at least one
alloy element, selected from Fe, Cu, Ni, Mn, La, with a content
higher than or equal to 0.1% individually, allows increasing
hardness in comparison with the reference composition, devoid of
these alloy elements; [0116] The application of a hardening
annealing, in particular at a temperature of 400.degree. C.,
improves hardness, the optimum duration being obtained by
implementing a heat treatment according to a duration from 1h to
8h, for example equal to 4h. [0117] The compositions 3 (2% Fe), 4
(1% Cu-1% Fe), 6 (2% Mn), 7 (1% Cu, 1% Ni), 9 (2% La) and 10 (1%
La-1% Cu) lead to the highest hardness values. [0118] The
compositions featuring Fe and/or Cu, with a cumulated content of
2%, seem to be particularly suitable.
[0119] Tests 2
[0120] Samples have been machined in form of strips having
60.times.22.times.3 mm dimensions, from the ingots obtained
hereinbefore (cf. Tests 1). During a second series of tests, these
samples have undergone a scanning using a laser beam, according to
different powers (between 250 W and 500 W) and different speeds
(between 300 mm/s and 2500 mm/s). The size of the laser beam was 80
.mu.m. The speed range has been adapted to the power. Thus: [0121]
at a power of 250 W, the speed has varied between 300 mm/s and 1500
mm/s, by 200 mm/s increments; [0122] at a power of 300 W, the speed
has varied between 500 mm/s and 1700 mm/s, by 200 mm/s increments;
[0123] at a power of 350 W, the speed has varied between 700 mm/s
and 1900 mm/s, by 200 mm/s increments; [0124] at a power of 400 W,
the speed has varied between 900 mm/s and 2100 mm/s, by 200 mm/s
increments; [0125] at a power of 450 W, the speed has varied
between 1100 mm/s and 2300 mm/s, by 200 mm/s increments; [0126] at
a power of 500 W, the speed has varied between 1300 mm/s and 2500
mm/s, by 200 mm/s increments.
[0127] The objective of these tests was to analyze the morphology
of the superficial portion of each sample after the melting and
solidification phases. The superficial portion having undergone
these phase changes is referred to by the term "molten area". It is
considered as representative of the morphology of the layers formed
by additive manufacturing. The tests have allowed characterizing
the surface condition of the samples, in particular porosity and
roughness. Each sample has undergone a section across the thickness
thereof, the latter having been characterized using an optical
microscope. The results of the characterizations, for different
compositions, are represented in FIGS. 5A to 5F, 6A to 6F, 7A to
7F, 8A to 8F, 9A to 9F, 10A to 10F. Each figure corresponds to a
section carried out at constant power, while making the scan speed
vary between a minimum speed, indicated to the left of the figure,
and a maximum speed, indicated to the right of the figure. Thus,
each figure shows the profiles of the surface exposed to the laser
beam for different speeds, at the same power. At each power level,
7 speeds, with 4 lines per speed, have been tested. The portions of
the samples corresponding to the same scan speed have been
represented with a brace. In the figures, it is observed that the
lines corresponding to the same speed (i.e. within the same brace)
partially overlap.
[0128] FIGS. 5A, 5B, 5C, 5D, 5E and 5F show the sections obtained
with samples whose composition corresponds to the reference
composition described in Table 1, respectively for the powers 250
W, 300 W, 350 W, 400 W, 450 W, 500 W.
[0129] FIGS. 6A, 6B, 6C, 6D, 6E and 6F show the sections obtained
with samples whose composition corresponds to the composition No. 1
described in Table 1 (4% Mg; 1.5% Zr-2% Cu), respectively for the
powers 250 W, 300 W, 350 W, 400 W, 450 W, 500 W.
[0130] FIGS. 7A, 7B, 7C, 7D, 7E and 7F show the sections obtained
with samples whose composition corresponds to the composition No. 5
described in Table 1 (4% Mg; 1.5% Zr-2% Ni), respectively for the
powers 250 W, 300 W, 350 W, 400 W, 450 W, 500 W.
[0131] FIGS. 8A, 8B, 8C, 8D, 8E and 8F show the sections obtained
with samples whose composition corresponds to the composition No. 3
described in Table 1 (4% Mg; 1.5% Zr-2% Fe), respectively for the
powers 250 W, 300 W, 350 W, 400 W, 450 W, 500 W.
[0132] FIGS. 9A, 9B, 9C, 9D, 9E and 9F show the sections obtained
with samples whose composition corresponds to the composition No. 6
described in Table 1 (4% Mg; 1.5% Zr-2% Mn), respectively for the
powers 250 W, 300 W, 350 W, 400 W, 450 W, 500 W.
[0133] FIGS. 10A, 10B, 10C, 10D, 10E and 10F show the sections
obtained with samples whose composition corresponds to the
composition No. 9 described in Table 1 (4% Mg; 1.5% Zr-2% La),
respectively for the powers 250 W, 300 W, 350 W, 400 W, 450 W, 500
W.
[0134] The compositions having undergone the tests reported in
FIGS. 6 to 10 correspond to those resulting in most favorable
hardness values throughout the first series of tests. It is
observed that these compositions allow obtaining a smoother and
less porous surface condition, than the reference composition.
Hence, they are best suited to be implemented in an additive
manufacturing method. In addition, these compositions allow
obtaining satisfactory surface conditions at high speed and high
power. They are particularly suited to an implementation of an
additive manufacturing method with high build rates.
[0135] Tests 3
[0136] Test parts have been made by SLM, using an alloy 11, whose
weight composition measured by ICP included: Al; Zr 1.64%; Fe
2.12%; Mg 2.56%; impurities: <0.05% each with cumulated
impurities <0.15%.
[0137] These tests have been carried out using a E0S290 SLM
(supplier EOS) type machine.
[0138] This machine enables a heating of the tray up to a
temperature of 200.degree. C. The tests have been carried out at a
heating temperature of 200.degree. C. but complementary tests have
demonstrated the good processability of the alloys according to the
present invention at lower heating temperatures, for example
25.degree. C., 50.degree. C., 100.degree. C. or 150.degree. C.
[0139] The power of the laser was 370 W. The scan speed was equal
to 1250 mm/s. The deviation between two adjacent scan lines,
usually referred to by the term "scattering vector" was 0.111 mm.
The layer thickness was 60 .mu.m.
[0140] The used powder had a particle size essentially comprised
from 3 .mu.m to 100 .mu.m, with a median of 38 .mu.m, a 10%
fractile of 14 .mu.m and a 90% fractile of 78 .mu.m.
[0141] The test parts have been made, in the form of solid
cylinders vertical (direction Z) with respect to the construction
tray which forms the base thereof in the plane (X-Y). The cylinders
have a diameter of 11 mm and a height of 46 mm. All parts have been
subjected to a SLM post-manufacture relaxation treatment of 4 hours
at 300.degree. C.
[0142] Some parts have been subjected to a post-manufacture heat
treatment at 400.degree. C. for a treatment duration comprised
between 1 h to 4 h. All parts (with and without the
post-manufacture heat treatment) have been machined to obtain
cylindrical tensile specimens having the following characteristics
in mm (cf. Table 3 and FIG. 12):
[0143] In FIG. 12 an Table 3, 0 represents the diameter of the
central portion of the specimen, M the width of the two ends of the
specimen, LT the total length of the specimen, R the radius of
curvature between the central portion and the ends of the specimen,
Lc the length of the central portion of the specimen and F the
length of the two ends of the specimen.
TABLE-US-00003 TABLE 3 Type .0. M LT R Lc F TOR 4 4 8 45 3 22
8.7
[0144] These cylindrical specimens have been tested in tension at
room temperature in the direction of manufacture Z according to the
standard NF EN ISO 6892-1 (2009-10).
[0145] Table 4 hereinafter summarizes the tensile properties (yield
strength, tensile strength and elongation at break) as a function
of the conditions of the post-manufacture heat treatment (duration,
temperature).
TABLE-US-00004 TABLE 4 Duration Temperature Rp0.2 Rm A (h)
(.degree. C.) (MPa) (MPa) (%) 0 -- 303 369 15.6 1 400 455 457 6.1 4
400 474 475 5.2
[0146] Tests 4
[0147] A fourth test similar to the test 3 has been carried out
using the alloy 4 whose weight composition measured by ICP included
Al; Zr 1.3%; Mn 4.47%; Mg 2.53%; impurities: <0.05% each with
cumulated impurities <0.15%.
[0148] The used powder had a particle size essentially comprised
from 3 .mu.m to 100 .mu.m, with a median of 40 .mu.m, a 10%
fractile of 14 .mu.m and a 90% fractile of 84 .mu.m.
[0149] Table 5 hereinafter summarizes the tensile properties (yield
strength, tensile strength and elongation at break) as a function
of the conditions of the post-manufacture heat treatment (duration,
temperature).
TABLE-US-00005 TABLE 5 Duration Temperature Rp0.2 Rm A (h)
(.degree. C.) (MPa) (MPa) (%) 0 -- 372 445 6.9 1 400 424 488 3.8 4
400 435.5 500 3.75
[0150] Tests 5
[0151] A fifth test similar to the tests 3 and 4 has been carried
out using the alloy 5 whose weight composition measured by ICP
included Al; Zr 1.13%; Mn 4.45%; Mg 1.09%; impurities: <0.05%
each with cumulated impurities <0.15%.
[0152] The used powder had a particle size essentially comprised
from 3 .mu.m to 100 .mu.m, with a median of 25 .mu.m, a 10%
fractile of 9.6 .mu.m and a 90% fractile of 52 .mu.m.
TABLE-US-00006 TABLE 6 Duration Temperature Rp0.2 Rm A (h)
(.degree. C.) (MPa) (MPa) (%) 0 -- 314.5 376 11.6 1 400 393 440 5.7
4 400 391 442 5.1
[0153] Although described in connection with a SLM-type additive
manufacturing method, which corresponds to the preferred method,
the previously-described compositions may be used in other types of
tests.
[0154] FIG. 11 represents a WAAM-type additive manufacturing
device, mentioned in connection with the prior art. An energy
source 31, in this instance a torch, forms an electric arc 32. In
this device, the torch 31 is held by a welding robot 33. The part
to be manufactured is disposed on a support 10. In this example,
the manufactured part is a wall extending according to a transverse
axis Z perpendicular to a longitudinal plane XY defined by the
support 10. Under the effect of the electric arc 32, the filler
wire 35 melts so as to form a welding bead. The welding robot is
controlled by a digital model M. The filler wire is moved so as to
form different layers 20.sub.1 . . . 20.sub.n, stacked on one
another, forming the wall 20, each layer corresponding to a welding
bead. Each layer 20.sub.1 . . . 20.sub.n extends in the
longitudinal plane XY, according to a pattern defined by the
digital model M.
[0155] Preferably, the diameter of the filler wire is smaller than
3 mm. It may be from 0.5 mm to 3 mm and is preferably from 0.5 mm
to 2 mm, and possibly from 1 mm to 2 mm. For example, it is 1.2
mm.
[0156] Moreover, other manufacturing methods may be considered, for
example, and without limitation: [0157] Selective Laser Sintering
(or SLS); [0158] Direct Metal Laser Sintering (or DMLS); [0159]
Selective Heat Sintering (or SHS); [0160] Electron Beam Melting (or
EBM); [0161] Direct Energy Deposition (or DED); [0162] Direct Metal
Deposition (or DMD); [0163] Direct Laser Deposition (or DLD);
[0164] Laser Deposition Technology; [0165] Laser Engineering Net
Shaping; [0166] Laser Cladding Technology; [0167] Laser Freeform
Manufacturing Technology (or LFMT); [0168] Laser Metal Deposition
(or LMD); [0169] Cold Spray Consolidation (or CSC); [0170] Additive
Friction Stir (or AFS); [0171] Field Assisted Sintering Technology
(FAST) or spark plasma sintering; [0172] Inertia Rotary Friction
Welding (or IRFW).
* * * * *