JP7305399B2 - Metal wire for welding additive manufacturing by metal 3D printer - Google Patents

Description

The present invention relates to a metal wire for welding lamination molding by a metal 3D printer, and as a material for a metal 3D printer, it has sufficient thermal deformation characteristics, uniform material characteristics, and internal crack resistance even in repeated welding, heating, and cooling by lamination. , an austenitic stainless steel wire that can be used for highly reliable heavy duty parts with excellent intergranular corrosion resistance and toughness.

In recent years, metal 3D printers are expected to be an innovative production technology, and various technologies have been proposed. A case of using metal powder and a case of using metal wire have been proposed as main technical methods.

When metal powder is used, for example, a manufacturing method is disclosed in which powder of SUS630 is irradiated with an electron beam to be melted and solidified and laminated three-dimensionally (Patent Document 1). Further, a manufacturing method is disclosed in which SUS304 and SUS316 metal powders and a binder are three-dimensionally printed, followed by degreasing and sintering heat treatment to form parts (Patent Document 2). However, when metal powder is used, the cost of the raw material is high and the reliability of the parts is low due to the high porosity. Furthermore, when a binder is used, not only are degreasing and sintering processes required, but sintering also causes a large volume change, which tends to cause errors in the dimensional accuracy of the parts. In addition, it cannot be applied to structural parts, etc., which have low toughness and receive impacts.

On the other hand, in the case of using a metal wire, for example, a method of laminating welding beads of metal wire to form a three-dimensional part is disclosed (Patent Document 3). Further, a manufacturing method is disclosed in which stainless steel metal wires are welded by controlling an arc or plasma and laminated three-dimensionally (Patent Document 4). Furthermore, a manufacturing method is disclosed in which stainless steel metal wires are welded and laminated by two deposition apparatuses to reduce thermal deformation, stress, and internal cracks due to high heat during deposition (Patent Document 5). In addition, a manufacturing method related to highly efficient three-dimensional additive manufacturing by arc welding using a plurality of multi-wires is disclosed (Patent Document 6). When metal wires are welded and laminated three-dimensionally, dimensional variation is suppressed, but thermal deformation cannot be sufficiently reduced only by method control. Furthermore, there is also the problem that the metal structure changes due to heating and cooling due to repeated lamination, and the material becomes non-uniform. In particular, carbonitrides are precipitated, causing sensitization and deterioration of corrosion resistance (durability). In addition, repeated welding and lamination may leave a high residual stress and reduce the toughness.

In this way, conventional three-dimensional lamination technology suppresses dimensional fluctuations, thermal deformation, material non-uniformity, internal crack resistance, and intergranular corrosion resistance of parts, resulting in parts with high toughness, durability and reliability. is difficult to obtain.

JP 2018-176269 A Japanese Patent Application Laid-Open No. 2018-536770 JP 2003-266174 A JP 2018-507317 A JP 2018-87379 A JP 2018-187679 A

The problem to be solved by the present invention is to improve the durability and reliability of parts in a method for manufacturing metal parts by three-dimensional modeling by welding and laminating metals, based on modeling using metal wires that can suppress dimensional fluctuations. It is a metal wire for welding additive manufacturing by a metal 3D printer, which can obtain a uniform material, grain corrosion resistance and high toughness by suppressing thermal deformation and internal cracking of parts, and is suitable as a material for metal 3D printers. To provide an inexpensive austenitic stainless steel wire.

As a result of various studies to solve the above problems, the inventors of the present invention have found that in a method for manufacturing a 3D printer that performs three-dimensional modeling by welding and laminating metal wires, Cr, Ni, Mn, and Cu are contained and heat resistance, It has excellent toughness and thermal deformation resistance, and the composition is adjusted to stably obtain a single austenite phase during welding and prevent internal cracks, resulting in excellent material uniformity. We have found that the above problems can be solved by using inexpensive austenitic steel wires that are excellent in intergranular corrosion resistance.

The present invention has been made based on the above findings, and the gist thereof is as follows.
(1) in mass %,
C: 0.1% or less,
Si: 4.0% or less,
Mn: 25.0% or less,
S: 0.0002 to 0.4%,
P: 0.1% or less,
Ni: 30% or less,
Cr: 5.0 to 35.0%,
Mo: 8.0% or less,
Cu: 5.0% or less,
Mn+Ni+Cu: 8.0 to 30.0%,
0.05 to 2.0% in total of one or more of Nb, Ti, and V;
N: 0.1% or less,
O: 0.03% or less,
Welding by a metal 3D printer, characterized in that Al: 5.0% or less, the balance is Fe and unavoidable impurities, and the γ value represented by the formula (a) is 0% or less. Metal wire for additive manufacturing.
γ(%)=3Cr+Si+3Mo-3Ni-Mn-Cu-100C-50N-25 (a)
The element symbols in the above formula mean the content (% by mass) of the element.
(2) further in mass %,
Co: 8.0% or less,
B: The metal wire for welding additive manufacturing by a metal 3D printer according to (1), characterized by containing one or more of 1.0% or less.
(3) further in % by mass,
W: 8.0% or less,
Sn: 0.5% or less,
Sb: 0.5% or less,
Au: 0.5% or less,
The metal wire for welding additive manufacturing by a metal 3D printer according to the above (1) or (2), characterized by containing one or more of In: 0.5% or less.
(4) further in % by mass,
Mg: 0.02% or less,
Ca: 0.02% or less,
Hf: 0.02% or less,
REM: The metal wire for welding additive manufacturing by a metal 3D printer according to any one of (1) to (3), characterized by containing one or more of 0.02% or less.
(5) further in % by mass,
Ta: 2.0% or less,
Zr: The metal wire for welding additive manufacturing by a metal 3D printer according to any one of (1) to (4), characterized by containing one or more of 2.0% or less.
(6) further in % by mass,
Bi: 0.4% or less ,
Ag : 0.4% or less,
Se: 0.4% or less,
Te: 0.4% or less,
Zn: The metal wire for welding additive manufacturing by a metal 3D printer according to any one of (1) to (5), characterized by containing one or more of 0.1% or less.

According to the present invention, in the molding of a metal 3D printer, it is excellent in thermal deformation, internal cracking resistance, uniformity of material / metal structure, and stress corrosion cracking resistance, and can significantly reduce the cost by improving the reliability of parts. It is possible to provide a ferritic stainless steel wire for metal 3D printers that can exhibit its effects.

It is a perspective view of a metal part three-dimensionally modeled by a metal 3D printer.

Each requirement of the present invention will be described below. In addition, (%) in the following description is mass (%) unless otherwise specified.

The present invention is directed to metal wires for welding additive manufacturing by metal 3D printers. When three-dimensional modeling is performed by welding layered modeling with a metal 3D printer, it is necessary to ensure resistance to dimensional fluctuations and basic heat resistance (resistance to heat deformation). Using an austenitic stainless steel wire containing Cr, Mo, and W as a metal wire, and considering welding with the wire and layered manufacturing as a base, resistance to internal cracking, material uniformity, intergranular corrosion resistance, and stress corrosion cracking resistance In order to ensure low C, N, etc., the composition is designed so that a stable ferrite single phase structure can be obtained even if it is repeatedly welded, heated, and cooled, and is a material for metal 3D printers. It is suitable as

First, the essential component composition of the metal wire of the present invention will be described.
C and N are each limited to 0.10% or less in order to prevent sensitization by suppressing the precipitation of Cr carbonitrides to grain boundaries during welding and lamination and to ensure material uniformity and toughness. . Preferably, it is 0.06% or less. C and N are preferably as low as possible, and there is no lower limit.

Si is effective for deoxidizing during welding, but if it is added excessively, it promotes the precipitation of Cr carbonitrides at the grain boundaries during repeated welding, heating, and cooling processes, resulting in sensitization and deterioration of toughness. do. Therefore, it is limited to 4.0% or less. Preferably, it is 0.1% or more and 2.0% or less.

Mn is effective for deoxidizing during welding, and is added together with Ni and Cu in order to stably obtain an austenitic structure and ensure material uniformity and toughness. However, if it is added in excess of 25.0%, not only the effect is saturated, but also toughness deteriorates and internal cracks also deteriorate. Therefore, it is limited to 25.0% or less. Mn does not have to be contained. Preferably, it is 0.2% or more and 20% or less.

Ni is added together with Mn and Cu in order to stably obtain an austenite structure and ensure material uniformity and toughness. However, if the addition exceeds 30%, the effect not only saturates, but also internal cracks are promoted. Therefore, it is limited to 30% or less. Ni does not have to be contained. It is preferably 1.0% or more and 25% or less.

Cu is added together with Mn and Ni in order to stably obtain an austenite structure and ensure material uniformity and toughness. However, even if it is added in excess of 5.0%, the effect not only saturates, but also internal cracks are promoted. Therefore, it is limited to 5.0% or less. Cu does not have to be contained. It is preferably 0.05% or more and 3.5% or less.

Mn+Ni+Cu is added in an amount of 8.0% or more in order to stably obtain an austenitic structure and ensure material uniformity and toughness as described above. However, even if it is added in excess of 30.0%, the effect not only saturates but also promotes internal cracks. Therefore, it is limited to 30.0% or less. It is preferably 10.0 to 25.0% or less. At least one of Mn, Ni, and Cu should be contained and the total content should be 8.0% or more.

The S content is 0 in order to ensure the flowability of molten metal during welding and to form layers in a good shape so as not to deform the weld metal, and to improve the machinability during subsequent machining as necessary. .0002% or more is added. However, if it is added in excess of 0.4%, the fluidity of the molten metal is accelerated, and not only is it likely to deform during welding, but also the toughness is deteriorated and internal cracks are likely to occur, so the upper limit is set to 0.4%. . Preferably, it is 0.0004 to 0.10%.

P is limited to 0.1% or less in order to ensure toughness during welding and suppress internal cracks. Preferably, it is 0.05% or less. P is preferably as low as possible, and there is no lower limit.

Cr is added in an amount of 5.0% or more in order to ensure heat resistance (heat deformation) and corrosion resistance (durability) by forming a solid solution in the matrix. However, if the addition exceeds 35.0%, short nitrides and intermetallic compounds are formed during repeated welding, heating, and cooling steps, resulting in poor material uniformity, intergranular corrosion resistance, and toughness. Therefore, the upper limit is limited to 35.0%. Preferably, it is 11.0 to 28.0%.

Mo is added in order to secure heat resistance (heat deformation) and corrosion resistance (durability) by forming a solid solution in the matrix. However, if the content exceeds 8.0%, internal cracks tend to occur. Therefore, the upper limit is set to 8.0%. Preferably, it is 0.05% or more and 6.0% or less.

Nb, Ti, and V are selected from one of Nb, Ti, and V in order to suppress the precipitation of Cr carbonitrides on grain boundaries in repeated welding, heating, and cooling processes, thereby preventing sensitization and stress corrosion cracking. The seeds or more are added at a total of 0.05% or more. However, if the total content exceeds 2.0%, the toughness deteriorates and internal cracks occur. Therefore, the upper limit is limited to 2.0%. Preferably, Nb+Ti+V is 0.1-1.5%.

O is contained in an amount of 0.03% or less in order to appropriately ensure fluidity of molten metal at the time of welding and to laminate the weld metal. If the addition exceeds 0.03%, the toughness is lowered and internal cracks are likely to occur, so the upper limit is made 0.03%. Preferably, it is 0.001 to 0.02%.

Al is effective for heat resistance and deoxidation during welding. Therefore, the upper limit is set to 5.0%. Preferably, it is 0.001 to 2.5%.

The γ value represented by the formula (a) represents the degree of austenite structure formation in the weld metal. When the γ value is 0% or less, the weld metal exhibits a single austenite phase with an area ratio of 98%. On the other hand, if it exceeds 0%, a ferrite structure is formed and not only the material becomes non-uniform, but also carbonitrides are precipitated at the interface of the metal structure to sensitize the intergranular corrosion resistance. Therefore, the γ value represented by the formula (a) is limited to 0% or less. Preferably, the γ value is −2.0% or less.

Preferably, the metal wire of the present invention selectively contains the following components.
Co and B may be added as necessary in order to improve the toughness of the matrix. However, if the Co content exceeds 8.0%, an intermetallic compound is generated in repeated welding, heating, and cooling steps, degrading the material uniformity. Therefore, the upper limit of Co is set to 8.0%.
On the other hand, if the B content exceeds 1.0%, the toughness deteriorates and internal cracks are likely to occur. Therefore, the upper limit of B is limited to 1.0%. Preferably, Co: 4.0% or less and B: 0.3% or less.

W, Sn, Sb, Au, and In may be added as necessary in order to improve the corrosion resistance of the matrix. However, when W exceeds 8.0% and Sn, Sb, Au, and In exceed 0.5%, internal cracks tend to occur. Therefore, the upper limit of W is set to 8.0%, and the upper limits of Sn, Sn, Au, and In are set to 0.5%. Preferably, the upper limit of W is 6.0%, and the upper limit of Sn, Sb, Au, and In is 0.4% or less.

Mg, Ca, Hf, and REM are effective in deoxidizing during welding, and may be added as necessary. However, if it is added excessively, coarse oxides are formed in repeated welding processes, and internal cracks are likely to occur. Therefore, each is limited to 0.02% or less. Preferably, it is 0.01% or less.

Ta and Zr form fine precipitates in the matrix in repeated welding, heating, and cooling steps to improve heat resistance (heat deformation resistance), so they may be added as needed. However, if added in excess of 2.0% each, they form coarse precipitates and promote internal cracking. Therefore, the upper limit is set to 2.0%. Preferably, it is 1.0% or less.

Bi, Pb, Ag, Se, Te, and Zn may be added as necessary in order to impart machinability after 3D modeling. However, when each of Bi, Pb, Ag, Se and Te exceeds 0.4% and Zn exceeds 0.1%, internal cracks are promoted. Therefore, the upper limit of Bi, Pb, Ag, Se, and Te is set to 0.4%, and the upper limit of Zn is set to 0.1%. Preferably, Bi, Pb, Ag, Se and Te are 0.3% or less, and Ze is 0.1% or less.

The chemical composition of the metal wire of the present invention is composed of chemical components consisting of Fe and unavoidable impurities in addition to the elements described above.
Typical unavoidable impurities include Ge, Na, Be, F, Ga, and the like, and are usually mixed in the range of 0.01% or less as unavoidable impurities in the steel manufacturing process.
In addition, although typical optional additive elements are defined in the above (2) to (6), even elements not described in this specification are within a range that does not impair the effects of the present invention. can be contained in

The metal wire of the present invention is used for welding additive manufacturing applications with metal 3D printers. That is, it means a metal wire used as a material when forming a three-dimensional part by laminating weld beads of metal wire by a metal 3D printer.

According to the present invention described above, there is provided a metal wire for welding additive manufacturing by a metal 3D printer that suppresses dimensional fluctuation and thermal deformation, and has excellent uniformity in material and metal structure, stress corrosion cracking resistance, and toughness. Austenitic stainless steel wire can be provided at low cost.

Steels having the chemical compositions shown in Tables 1 to 3 were melted in a 45 kg vacuum melting furnace and processed into steel bars with a diameter of 11 mm by hot forging and hot extrusion. After that, wire drawing and annealing were repeated to make a trial metal wire with a diameter of 1.0 mm. In Tables 1 to 3, blanks mean that they were not intentionally added. In addition, numerical values outside the scope of the present invention are underlined.

Then, using an MIG arc welding machine as a robot, the metal wires prepared above are continuously laminated in a spiral shape and repeatedly welded, and laminated in the lamination direction 2 shown in FIG. A hollow quadrangular prism 1 (metal part 10) (one side: 50 mm, height: 80 mm) was manufactured as shown in FIG. The arc welding conditions were a welding current of 200 A, an arc voltage of 30 V, and a welding speed of 200 cm/min, using a shielding gas of Ar+3% oxygen.

After that, thermal deformation (heat resistance), internal cracks, internal voids, and material/metallographic uniformity of the manufactured square prism 1 were investigated. Tables 4 and 5 show the survey results.

Thermal deformation (heat resistance) was measured by measuring the maximum unevenness of the side surface of the quadrangular prism generated by thermal deformation during repeated lamination. If the maximum unevenness amount was 5 mm or less, it was evaluated as ⊚; When the metal wire of the present invention was used, the evaluation results were ⊚ and ◯, indicating excellent heat deformation resistance.

For internal cracks and internal voids, a cross section perpendicular to the stacking direction at any 10 points of the square prism 1 is used as the inspection target surface, the cut sample is embedded in resin, the inspection target surface is polished, and the internal cracks and internal voids are examined by optical microscope observation. Cracks and voids were observed. The case where internal cracks and voids existed on the surface to be inspected was evaluated as x, and the case where they did not exist was evaluated as ◯. When the metal wire of the present invention was used, the evaluation result was ◯, indicating excellent internal crack resistance and internal void resistance.

For material uniformity, the Hv hardness (1 kgf weight) was measured at 5 points of the embedded and polished sample, the bottom surface, the top surface of 1/4, 1/2, and 3/4 height of the layered manufacturing. bottom. The difference between the maximum and minimum values of HV at five points was defined as the variation in hardness ΔHv.
In order to confirm the presence of carbonitrides and sensitization, which adversely affect corrosion resistance (durability), as to the uniformity of the metallographic structure, the embedded and polished samples were subjected to an etch test according to JIS G 0571. A case where no groove-like structure was observed was evaluated as ◯, and a case where a groove-like structure was observed was evaluated as x.
When the metal wire of the present invention was used, both the uniformity of the material and the uniformity of the metal structure were evaluated as ◯, indicating that the uniformity of the material and the metal structure was excellent.

The toughness was measured from any five locations on a square prism according to JIS Z 2242, with a width of 2.5 mm, a height of 10 mm, and a length of 55 mm (the length direction and the stacking direction were the same). A V notch with a depth of 2 mm was cut out, and an impact test was performed at a normal temperature of 25°C to measure absorbed energy. An impact value of 100 J/cm ² or more was evaluated as ◯, and an impact value of less than 100 J/cm ² was evaluated as x.
When the metal wire of the present invention was used, ◯ was obtained, indicating excellent toughness.

On the other hand, the comparative steels of Examples 46 to 84 do not satisfy the specified range of the present invention and do not satisfy the required properties.

In molding a three-dimensional part using a metal 3D printer using a metal wire with excellent resistance to dimensional fluctuations, as is clear from the above examples, when forming a three-dimensional part by laminating welding beads of metal wires By using the metal wire of the present invention as a material, thermal deformation and internal cracks can be stably suppressed, the material and metal structure can be made uniform and toughness can be secured, and the reliability of parts can be improved. Extremely useful.

1 square pole 2 stacking direction 10 metal part

Claims (6)

in % by mass,
C: 0.1% or less,
Si: 4.0% or less,
Mn: 25.0% or less,
S: 0.0002 to 0.4%,
P: 0.1% or less,
Ni: 30% or less,
Cr: 5.0 to 35.0%,
Mo: 8.0% or less,
Cu: 5.0% or less,
Mn+Ni+Cu: 8.0 to 30.0%,
0.05 to 2.0% in total of one or more of Nb, Ti, and V;
N: 0.1% or less,
O: 0.03% or less,
Welding by a metal 3D printer, characterized in that Al: 5.0% or less, the balance is Fe and unavoidable impurities, and the γ value represented by the formula (a) is 0% or less. Metal wire for additive manufacturing.
γ(%)=3Cr+Si+3Mo-3Ni-Mn-Cu-100C-50N-25 (a)
The element symbols in the above formula mean the content (% by mass) of the element. Furthermore, in mass %,
Co: 8.0% or less,
B: The metal wire for welding additive manufacturing by a metal 3D printer according to claim 1, characterized by containing one or more of 1.0% or less. Furthermore, in mass %,
W: 8.0% or less,
Sn: 0.5% or less,
Sb: 0.5% or less,
Au: 0.5% or less,
3. The metal wire for welding additive manufacturing by a metal 3D printer according to claim 1 or 2, characterized by containing one or more kinds of In: 0.5% or less. Furthermore, in mass %,
Mg: 0.02% or less,
Ca: 0.02% or less,
Hf: 0.02% or less,
REM: The metal wire for welding additive manufacturing by a metal 3D printer according to any one of claims 1 to 3, characterized by containing one or more of 0.02% or less. Furthermore, in mass %,
Ta: 2.0% or less,
Zr: The metal wire for welding additive manufacturing by a metal 3D printer according to any one of claims 1 to 4, characterized by containing one or more of 2.0% or less. Furthermore, in mass %,
Bi: 0.4% or less ,
Ag : 0.4% or less,
Se: 0.4% or less,
Te: 0.4% or less,
6. The metal wire for welding additive manufacturing by a metal 3D printer according to any one of claims 1 to 5, characterized by containing one or more of Zn: 0.1% or less.

Images