JP7128916B2 - Additive manufacturing - Google Patents

Description

TECHNICAL FIELD The present invention relates to a Ni-based superalloy powder for additive manufacturing with good high-temperature properties. More specifically, the present invention relates to a Ni-based superalloy powder that provides a sintered body with good high-temperature characteristics even when sintered by a rapid melting, rapid cooling and solidification process such as additive manufacturing.

2. Description of the Related Art Conventionally, a method of producing a three-dimensional shaped object by irradiating a powder material with a laser or an electron beam (hereinafter referred to as powder sintering lamination method) is known. In this method, for example, as disclosed in Japanese Patent No. 4661842 (Patent Document 1), a powder layer made of metal powder is irradiated with a light beam to form a sintered layer, and the sintered layer is laminated. A method for producing a metal powder for metal stereolithography, which is used for metal stereolithography to obtain a three-dimensional shaped article, has been proposed.

On the other hand, one of the powders used in the powder sintering lamination method is Ni-based superalloy powder. Ni-based superalloys are widely used as materials for engine parts in the fields of space and aircraft. For example, as disclosed in Japanese Patent Application Laid-Open No. 2005-97650 (Patent Document 2), in terms of weight %, Cr: 20% or less, Mo: 10% or less, W: 15% or less, Al: 2 to 10%, A Ni-based superalloy having a composition containing Ta+Nb+Ti: 16% or less, Ru: 10% or less, and the balance being Ni and unavoidable impurities has been proposed. The present invention is particularly characterized by using Ru as an essential element.

Further, as disclosed in Japanese Patent Application Laid-Open No. 11-310839 (Patent Document 3), in weight %, Hf: 0 to 2%, Zr: 0 to 0.1, Cr: 2 to 25%, Al: 2-7%, Mo: 0-8%, W: 0-16%, Re: 0-16%, V: 0-4%, Nb: 0-8%, Ta: 0-16%, Co: ~ 15%, Ti: 0 to 7%, a total amount of 8% or less of one or more of Ru, Rh, Pd, Ir and Pt, and one or more of Sc, Y, La and Ce A high-strength Ni-based superalloy directionally solidified casting containing a total amount of 2% or less has been proposed. In the case of the present invention, Nb is not intentionally added in view of the examples.

Japanese Patent No. 4661842 JP-A-2005-97650 JP-A-11-310839

Currently, the cases disclosed in the above-mentioned Patent Documents 2 and 3 are often used in cast materials and forged materials, and from the viewpoint of difficult workability, the application of the powder sintering lamination method that can produce parts in near net shape is preferred. is underway. In addition, Ni-based superalloys generally have Al, Ti, and Nb in the crystal grains called γ' (gamma prime) phase, called Ni ₃ (Al, Ti), and γ'' (gamma double prime) phase. By finely precipitating a strengthening phase of Ni ₃ (Al, Ti, Nb), excellent mechanical properties are exhibited at high temperatures. Therefore, by increasing the amounts of γ' and γ'', the strength at high temperatures can be increased. The amount of γ′ and γ″ varies depending on the amount of Al, Ti, Nb, etc. added, and the amount of precipitation can be increased by increasing the amount of addition.

However, increasing the amount of Al and Ti, which are the forming elements of the γ' and γ″ phases, causes solidification cracking, and increasing the amount of Nb leads to a decrease in strength due to the formation of the Laves phase. Therefore, it has been difficult to produce a Ni-based superalloy powder that can be applied to the powder sintering lamination method involving a rapid melting, rapid cooling and solidification process, and that yields a sintered body with good high-temperature characteristics while increasing the strength of the alloy.

As a result of intensive studies on the above-mentioned problems, by adding one or more of Zr, Y, and Hf, a sintered structure is obtained by applying a rapid melting and rapid solidification process such as a powder additive manufacturing method. also found that it is possible to obtain a sintered body having good high-temperature properties, leading to the present invention.
The gist of the invention is
(1) In mass%, C: 0.001 to 0.3%, Cr: 9.0 to 25.0%, Ti + Al: 1.0 to 10.0%, Mo: 0.1 to 10.0% , Nb: 0.1 to 7.0%, at least one or more of Zr, Y, and Hf, Zr: 0.1 to 2.0%, Y: 0.2 to 2.0%, Hf: 0.1% to 2.0%. A Ni-based superalloy powder characterized by containing in an amount of 1 to 2.0%, the balance consisting of Ni and unavoidable impurities.

(2) Ni-based superalloy powder characterized by containing at least one or more of W, Co and Ta in a total amount of 0.1 to 40% in addition to the component (1). .

(3) In terms of properties after sintering in a rapid melting and rapid solidification process such as additive manufacturing, the tensile strengths at room temperature (TR) and at high temperature (TH) are A _TR , A _TH , 0.00. The Ni-based superalloy powder according to (1) or (2) above, which satisfies the following formula (1), where B _TR and B _TH are 2% yield strengths, and C _TR and C _TH are elongations.
However, TR indicates a temperature from 0°C to 50°C, and TH indicates a temperature from 50°C to 760°C. 0.4≦A _TH /A _TR , B _TH /B _TR , C _TH /C _TR ≦1.0 (1)

(4) The Ni-based superalloy powder according to any one of (1) to (3), wherein the ratio of average particle size D50 to tap density TD (D50/TD) satisfies 0.2-20.
The unit of D50 is μm ^, and the unit of TD is Mg/m3.

INDUSTRIAL APPLICABILITY As described above, the present invention provides a Ni-based superalloy powder capable of obtaining a sintered body having good high-temperature properties even when sintered by a rapid melting, rapid cooling and solidification process such as an additive manufacturing method. It can be used as a base material for additive manufacturing regardless of the irradiation method for sintering.

The present invention will be described in detail below.
Ni-based superalloys tend to deteriorate in properties in a high temperature range when shaped bodies are produced by rapid melting, rapid cooling, and solidification processes, as in the case of producing base metals by general casting and forging processes. As a result of investigating the state of this deterioration, it was found that very small inclusions and oxides, which cannot be detected at room temperature, exist at the grain boundaries at high temperatures. In the rapid quenching process, melting and solidification are repeated in a shorter period of time than in general casting and forging processes, so melting and solidification occur before impurity elements have completely diffused. Therefore, inclusions and oxides are segregated at the grain boundary interface, which is thought to be the cause of cracking in the high temperature range.

Therefore, as a result of intensive studies in order to develop excellent characteristics at high temperatures, at least one of Zr, Y, and Hf was added to Zr: 0.1% or more and 2.0% or less, Y: 0.2% or more 2 0% or less, and Hf: 0.1% or more and 2.0% or less, good high-temperature characteristics are exhibited. That is, in the rapid melting, rapid cooling and solidification process, by adding Zr, Y, and Hf, the compounds of Zr, Y, and Hf become thermally stable oxides and inclusions, and the pinning effect makes the fabric structure fine and stable. It was clarified that the high-temperature characteristics of the molded body itself are improved by making it more flexible.

The present invention finds that the addition of Zr, Y, and Hf to the Ni-based superalloy powder is effective for the deterioration of high-temperature properties in the rapid melting, rapid cooling, and solidification process. It is a realization of alloy molding.

The reasons for limiting the component composition of the present invention are described below.
C: 0.001-0.3%
_In the Ni-based superalloy powder of the present invention, C not only forms MC _- type carbides with Nb, Ti, etc., but also forms carbides such as _{M6C , M7C3} , M23C6 with Cr, Mo, W, etc. to form alloys. It is necessary to add 0.001% or more because of the effect of increasing the high-temperature strength of the steel. However, if a large amount of C is added, carbides are continuously precipitated at grain boundaries, weakening the grain boundaries and deteriorating corrosion resistance and toughness. Preferably, it is 0.05% or more and 0.1% or less.

Cr: 9.0-25.0%
In the Ni-based superalloy powder of the present invention, Cr is an essential element that contributes to solid solution strengthening and oxidation resistance improvement of the alloy. If it is less than 9.0%, the above effect cannot be obtained, and if it exceeds 25.0%, the δ phase is generated and the high-temperature strength and toughness are lowered. It is preferably 13.0% or more and 20.0% or less.

Ti+Al: 0.1 to 10.0%
In the Ni-based superalloy powder of the present invention, Ti and Al are elements that form a γ' phase and increase creep rupture strength and oxidation resistance. Since cracks are likely to occur during molding, the content is made 10.0% or less.

Mo: 0.1-10.0%
In the Ni-based superalloy powder of the present invention, Mo is an element that contributes to solid solution strengthening and is effective in increasing strength, so it must be contained in an amount of 0.1% or more. However, if the content is too large, it promotes the formation of μ phase or σ phase and causes embrittlement, so the content is made 10.0% or less.

Nb: 0.1-7.0%
In the Ni-based superalloy powder of the present invention, Nb forms carbides and reinforces the γ' phase to improve the strength, so the content should be 0.1% or more. However, if it is too large, a Laves phase is formed and the strength is lowered, so the content is made 7.0% or less.

Zr: 0.1-2.0%
In the Ni-based superalloy powder of the present invention, Zr reacts with oxides and carbides to form thermally stable Zr oxide particles and inclusion particles. must be included. However, if the amount is too large, the oxide particles and inclusion particles become coarse and the high-temperature strength is lowered, so the content is made 2.0% or less.

Y: 0.2-2.0%
In the Ni-based superalloy powder of the present invention, Y reacts with oxides and carbides to form thermally stable Y oxide particles and inclusion particles. must be included. However, if the content is too large, the oxide particles and inclusion particles become coarse and the high-temperature strength is lowered, so the content is preferably 2.0% or less.

Hf: 0.1-2.0%
Since Hf has the effect of improving oxidation resistance in the Ni-based superalloy powder of the present invention, it is necessary to contain 0.1% or more as necessary. However, if it is too large, a brittle phase is formed and the strength and toughness are lowered, so 2.0% or less is preferable.

0.1 to 40% in total of at least one or more of W, Co and Ta
In the Ni-based superalloy powder of the present invention, W is an element that contributes to solid solution strengthening and is effective in increasing strength, Co increases the solubility of the γ' phase in Ni solid solution to improve high temperature ductility and high temperature strength, and Ta forms carbides and strengthens the γ' phase to improve strength, so at least one or more of them can be added in a total amount of 0.1 to 40% as required. However, if the content is too large, it leads to embrittlement and strength reduction, so the total content is made 40.0% or less.

Tensile strength A at room temperature (TR) and high temperature (TH), 0.2% yield strength B, elongation C is 0.4 ≤ A _TH /A _TR , B _TH /B _TR , C _TH /C _TR <1 .0 metal powder ... (1)
In the Ni-based superalloy powder of the present invention, A _TH /A _TR , B _TH /B _TR , and C _TH /C _TR are from 0.4 to 1.0. However, if it is less than 0.4, even if the characteristics at room temperature are very good, it is not suitable for use at high temperatures. Greater than 1.0 is not possible in normal materials, under normal test conditions. Therefore, the range was set to 0.4 to 1.0.

Metal powder satisfying the ratio of average particle diameter D50 to tap density TD (D50/TD) of 0.2-20 In the Ni-based superalloy powder of the present invention, D50/TD is 0.2-20. If it is less than 0.2, the fluidity of the powder is reduced due to pulverization, and the density of the shaped body is reduced. If it is greater than 20, part of the powder remains undissolved and sintered during layered manufacturing, and remains as defects. Therefore, the range was set to 0.2-20.

EXAMPLES The present invention will be specifically described below with reference to Examples.
First, the effects of additive elements Zr, Hf, and Y on improvement of high-temperature characteristics were evaluated in detail. The base is three representative Ni-based superalloy steel types (Ni-19.0Cr-3.0Mo-5.0Nb-1.5 (Ti + Al)-0.05C, Ni-12.5Cr-4.2Mo-2Nb -6.9 (Ti + Al) -0.1Zr-0.1C, Ni-22.5Cr-1Nb-5.5 (Ti + Al) -19.0Co-2.0W-1.4Ta-0.15C) and added The amount of elemental Zr is changed in the range of 0.1 to 2.0%, the amount of Y is changed in the range of 0.2 to 2.0%, and the amount of Hf is changed in the range of 0.1 to 2.0%. ( _TH ) of each tensile strength ratio _ATR /ATH, 0.2% yield strength ratio _BTR / _BTH , elongation ratio CTR/ _CTH , ratio of average particle diameter D50 and tap density _TD (D50/TD ), and investigated the effective composition range of the amount of Zr, Hf, and Y added to the Ni-based superalloy (Table 1, Nos. 1 to 24).

Next, by changing the composition of the Ni-based superalloy, _ATR /ATH, _BTR / _{BTH, CTR/CTH ,} and D50/ _TD were evaluated, and C, _Cr , Ti+Al, and Mo of the Ni-based superalloy were evaluated. , Nb, Zr, Y, Hf, W, Co, and Ta were investigated (Table 1, Nos. 25 to 51).

[Preparation of test material]
A powder of prescribed components was produced by the gas atomization method and classified to a size of 63 μm or less. Gas atomization is performed by melting a raw material in a vacuum crucible made of alumina in a predetermined distribution by high-frequency induction heating, dropping the molten alloy from a nozzle with a diameter of about 5 mm under the crucible, and applying high-pressure argon or high-pressure gas to it. This was done by sparging with nitrogen. Using this as a raw material powder, a material to be subjected to each test was produced using a three-dimensional additive manufacturing apparatus (EOS-M280).

[Room temperature tensile properties]
A JIS14A φ5 test piece (φ5×GL25 mm) was prepared, and the maximum tensile stress σ applied during the tensile test was calculated as the tensile strength (σ=measured load F/cross-sectional area S). Also, the load and elongation were plotted on a graph, a straight line offset by 0.2% of the gauge length was drawn parallel to the elastic region, and the intersection with the load curve was calculated as the 0.2% yield strength. The elongation Z was calculated as a percentage ((Lf−L0)/L0×100) when the gauge length L0 became Lf after breakage.

[High temperature tensile properties]
A JIS G 0567 I-6 type test piece (φ6×GL30 mm) was prepared, and the same measurements as for normal temperature tensile properties were performed at 760° C. to calculate tensile strength, 0.2% proof stress and elongation.

[Particle size distribution measurement, tap density]
Average particle size was evaluated by laser diffraction method. About 50 g of spherical powder was packed into a cylinder with a volume of 100 cm ³ , and the tap density was evaluated by the packing density when the drop height was 10 mm and the number of taps was 200.

[Evaluation method]
(Evaluation 1) A _TH /A _TR , B _TH /B _TR , C _TH /C _TR : 0.9 to 1.0
D50/TD: 0.2-20
(Evaluation 2) A _TH /A _TR , B _TH /B _TR , C _TH /C _TR : 0.5 to less than 0.9
D50/TD: 0.2-20
(Evaluation 3) A _TH /A _TR , B _TH /B _TR , C _TH /C _TR : 0.4 to less than 0.5
D50/TD: 0.2-20
(Evaluation 4) A _TH /A _TR , B _TH /B _TR , C _TH /C _TR : less than 0.4
D50/TD: less than 0.2 or greater than 20
falls under any of
(Evaluation 5) The composition is outside the scope of the present invention.

表１または表２に示すように、Ｎｏ．１～２４は本発明例であり、Ｎｏ．２５～５１は比較例である。

As shown in Table 1 or Table 2, No. 1 to 24 are examples of the present invention; 25-51 are comparative examples.

Comparative example No. shown in Table 2. In 38, 41, 42, 45, 49, and 50, the contents of Zr, Y, and Hf, which are component compositions, are all outside the range, and one or two of C, Cr, Ti + Al, Mo, and Nb are contained. any of the amounts are out of range, plus no. In the case of No. 38, the total content of at least one or more of W, Co, and Ta is out of the range, so the evaluation is 5.

Comparative example No. shown in Table 2. 26, 30 to 35, 39, 43, 44, 48, and 51, the contents of Zr, Y, and Hf, which are component compositions, are all within the range, but one of C, Cr, Ti+Al, Mo, and Nb or Either of the two contents is outside the range, and in addition, No. In Nos. 31, 32, 33, 39, and 48, the total content of at least one of W, Co, and Ta or at least two of them was out of the range, so they were evaluated as 5.

Comparative example No. shown in Table 2. In Nos. 25 and 27, the contents of Zr, Y, and Hf, which are component compositions, are within the range of 1 or 2 types. In No. 25, the contents of C and Ti+Al are out of range. In No. 27, the contents of Cr and Ti+Al are out of the range, so the evaluation is 5.

Comparative example No. shown in Table 2. In Nos. 28 and 37, the contents of Zr, Y, and Hf, which are component compositions, are within the range of one type, but the content of Cr is low, so they are evaluated as 5.

Comparative example No. shown in Table 2. In Nos. 29, 36, 40, 46, and 47, the contents of Zr, Y, and Hf, which are component compositions, are within the range of one type, but the contents of Ti+Al are all outside the range. 29 is C, Mo is out of range, No. 40, C is out of range; 46 is Cr out of the range; 47 is rated 5 because Mo is out of range.

On the other hand, Example No. of the present invention. Since all of 1 to 24 satisfy the conditions of the present invention, it can be seen that the evaluation shows a value of 1 to 4.

As described above, the chemical composition of the Ni-based superalloy powder is regulated, and then Zr, Y, and Hf are added in order to improve the high-temperature properties of the Ni-based superalloy powder in the rapid melting and rapid solidification process. The compounds of Zr, Y, and Hf become thermally stable oxide particles and inclusion particles, and the pinning effect finely stabilizes the texture of the fabric, resulting in good high-temperature characteristics of the model itself. It is made clear that it will be

Claims (1)

A laminate-molded body whose material is a Ni-based superalloy,
The Ni-based superalloy, in mass%,
C: 0.001 to 0.3%,
Cr: 9.0 to 25.0%,
Ti + Al: 1.0 to 10.0%,
Mo: 0.1 to 10.0%,
and Nb: 0.1 to 7.0%,
contains
Zr: 0.1 to 2.0%,
Y: 0.2 to 2.0%,
and Hf: 0.1 to 2.0%
contains at least one of
Containing at least one of W, Co and Ta, the total content of these is 0.1 to 40.0%,
The balance consists of Ni and unavoidable impurities,
Tensile strength A _TR , 0.2% proof stress B _TR , and elongation C _TR obtained in normal temperature tensile test, and tensile strength A _TH obtained in tensile test at 760° C. , 0.2% proof stress A layered product whose B _TH and elongation C _TH satisfy the following three formulas.
0.4 ≤ _ATH / _ATR ≤ 1.0
0.4≦ _BTH / _BTR ≦1.0
0.4≦ _CTH / _CTR ≦1.0