阅读说明：本技术 造形体制造方法及造形体 (Method for producing molded article and molded article ) 是由 冈田龙太朗 野村嘉道 井头贤一郎 于 2020-03-09 设计创作，主要内容包括：造形体制造方法是通过使用由γ′析出强化型Ni基合金构成的粉末的粉末床熔融法制造造形体的方法,Ni基合金含有质量百分率为10～16%的Cr、4.5～7.5%的Al、2.8～6.2%的Mo、0.8～4%的Nb＋Ta、0.01～2%的Ti、0.01～0.3%的Zr、0.01～0.3%的C,在由粉末构成的层(3)上沿着互相平行的多条扫描线(4)照射激光时,扫描线(4)的间隔除以激光点径时的值为0.2以上1.0以下。(A method for producing a molded body by a powder bed melting method using a powder composed of a gamma' -precipitation-strengthened Ni-based alloy, wherein the Ni-based alloy contains 10 to 16 mass% of Cr, 4.5 to 7.5 mass% of Al, 2.8 to 6.2 mass% of Mo, 0.8 to 4 mass% of Nb + Ta, 0.01 to 2 mass% of Ti, 0.01 to 0.3 mass% of Zr, and 0.01 to 0.3 mass% of C, and when a layer (3) composed of the powder is irradiated with a laser along a plurality of scanning lines (4) parallel to each other, the value of the interval between the scanning lines (4) divided by the diameter of the laser spot is 0.2 to 1.0.)

1. A method for producing a molded body, characterized in that,

a method for producing a molded body by a powder bed melting method using a powder composed of a γ' precipitation-strengthening Ni-based alloy;

the Ni-based alloy contains 10 to 16 mass% of Cr, 4.5 to 7.5 mass% of Al, 2.8 to 6.2 mass% of Mo, 0.8 to 4 mass% of Nb + Ta, 0.01 to 2 mass% of Ti, 0.01 to 0.3 mass% of Zr, and 0.01 to 0.3 mass% of C;

when a laser is irradiated onto a layer made of the powder along a plurality of scanning lines parallel to each other, the value obtained by dividing the interval between the plurality of scanning lines by the diameter of the laser spot is 0.2 to 1.0.

2. A shaped body, characterized in that,

a shaped body made of a Ni-based alloy and containing a dendritic structure;

the Ni-based alloy contains 10 to 16 mass% of Cr, 4.5 to 7.5 mass% of Al, 2.8 to 6.2 mass% of Mo, 0.8 to 4 mass% of Nb + Ta, 0.01 to 2 mass% of Ti, 0.01 to 0.3 mass% of Zr, and 0.01 to 0.3 mass% of C;

the distance between branches of the primary dendrite of the dendrite structure is less than 3 μm;

the maximum value of the pole density of the positive pole spot diagram measured by the EBSD method is 6 or more.

Technical Field

The present invention relates to a method for producing a shaped body and a shaped body obtained by the method.

Background

Conventionally, there has been known a method of producing a molded body by a Powder bed melting method (Powder bed fusion) using a Powder made of a Ni-based alloy. The shaped body made of a Ni-based alloy produced by such a production method is used, for example, as a high-temperature component of a gas turbine engine or the like.

As the Ni-based alloy constituting the powder, γ' (gamma prime) precipitation strengthening Ni-based alloy may be used. The γ 'precipitation-strengthened Ni-based alloy is γ' (Ni) for strengthening the precipitation strength of the produced shaped article by heat treatment₃(Al, Ti)) phase, and the composition thereof.

It is known that when the total content of Al (2 Al + Ti) is 6% or more, which is 2 times the content of Al and the content of Ti, in an Ni-based alloy containing Al and Ti, cracks are likely to occur during welding. For example, micro-cracks having a length exceeding several micrometers to several hundred micrometers may be formed in a molded body produced by the powder bed melting method.

As a technique for suppressing the occurrence of cracks during welding of γ' precipitation-strengthened Ni-based alloys, for example, patent document 1 describes that the Si content and the Zr content are each limited to less than 0.03% by mass.

Prior art documents:

patent documents:

patent document 1: japanese patent laid-open No. 2017-508877.

Disclosure of Invention

The invention aims to solve the problems that:

in contrast, it is preferable to suppress the occurrence of cracks in the γ' precipitation-strengthened Ni-based alloy during welding, and particularly to reduce the occurrence of cracks in a molded article produced by the powder bed melting method, regardless of whether the Si content and the Zr content in the Ni-based alloy are limited.

Accordingly, an object of the present invention is to provide a method for producing a shaped body capable of reducing cracks formed in a shaped body produced by a powder bed melting method using a powder made of a γ' precipitation-strengthening Ni-based alloy, and a shaped body obtained by the method for producing a shaped body.

Means for solving the problems:

in order to solve the above problems, the inventors of the present invention have made extensive studies and found that in a powder bed melting method in which a laser beam is irradiated onto a layer made of powder along a plurality of scanning lines parallel to each other, a value obtained by dividing the interval between the scanning lines by the spot diameter of the laser beam is correlated with the formation of cracks in a molded body. The present invention has been made in view of the above points.

That is, the method for producing a shaped body of the present invention is a method for producing a shaped body by a powder bed melting method using a powder made of a γ' precipitation-strengthened Ni-based alloy; the Ni-based alloy contains 10 to 16 mass% of Cr, 4.5 to 7.5 mass% of Al, 2.8 to 6.2 mass% of Mo, 0.8 to 4 mass% of Nb + Ta, 0.01 to 2 mass% of Ti, 0.01 to 0.3 mass% of Zr, and 0.01 to 0.3 mass% of C; when a laser is irradiated onto a layer made of the powder along a plurality of scanning lines parallel to each other, the value obtained by dividing the interval between the plurality of scanning lines by the diameter of the laser spot is 0.2 to 1.0.

According to the above structure, cracks formed in the molded body can be reduced.

The shaped article of the present invention is a shaped article comprising a dendritic structure made of a Ni-based alloy; the Ni-based alloy contains 10 to 16 mass% of Cr, 4.5 to 7.5 mass% of Al, 2.8 to 6.2 mass% of Mo, 0.8 to 4 mass% of Nb + Ta, 0.01 to 2 mass% of Ti, 0.01 to 0.3 mass% of Zr, and 0.01 to 0.3 mass% of C; the distance between branches of the primary dendrite of the dendrite structure is less than 3 μm; the maximum value of the pole density of the positive pole point diagram measured by the EBSD (Electron Backscatter diffraction) method is 6 or more.

Here, the "pole Density of the positive pole spot diagram" is obtained by calculating how many times the frequency of each crystal orientation appears in the measurement plane with reference to a state where all crystal orientations appear at a Uniform Density (uniformity Density) (that is, a completely randomly oriented structure), and is calculated as mud (multiples of a uniformity Density) by analysis of software attached to the EBSD apparatus. The larger MUD indicates that the crystal orientation of the measurement surface is more biased toward a specific crystal.

As a method for producing a cast product having a large MUD by casting, unidirectional solidification casting, single crystal casting, and the like are known, but in these cast products, the intervals between primary dendrite branches of the dendrite structure are as large as more than about 40 μm. In contrast, the interval between the primary dendrite branches of the dendrite structure in the formed body produced by the powder bed melting method using a laser as a heat source is as small as less than 3 μm. When the value obtained by dividing the interval between the plurality of scanning lines by the laser spot diameter in the powder bed fusion method is 0.2 to 1.0 as described above, the maximum value of the pole density (i.e., MUD) in the positive pole spot diagram measured by the EBSD method is 6 or more. Therefore, the molded body having the above structure is a molded body with less cracks.

The invention has the following effects:

according to the present invention, cracks formed in a molded body produced by a powder bed melting method using a powder made of a γ' precipitation-strengthening Ni-based alloy can be reduced.

Drawings

FIG. 1 is a diagram illustrating a method of manufacturing a shaped body by a powder bed fusion process;

FIG. 2 is a graph showing the maximum values of MUDs and the amount of cracking for examples 1-6 and comparative examples 1, 2;

FIG. 3 is a photomicrograph of example 4;

fig. 4 is a photomicrograph of comparative example 1.

Detailed Description

The method for producing a shaped body according to an embodiment of the present invention is a method for producing a shaped body by a powder bed melting method using a powder made of a γ' precipitation-strengthened Ni-based alloy. The heat source for melting the powder in the powder bed melting method may be an electron beam, and in the present embodiment, the heat source is a laser.

As shown in fig. 1, the powder bed melting method forms a layer 3 made of powder on a stage 1, and irradiates the layer 3 with laser light along a plurality of scanning lines 4 parallel to each other. The laser light is irradiated in a form of being condensed near the surface of the layer 3. The position, shape and length of each scanning line 4 are determined according to the cross-sectional shape of the molded body to be manufactured. For example, the scanning line 4 may be a straight line or a curved line.

Fig. 1 shows an example of manufacturing a square-shaped molded body. In fig. 1, the scanning directions of the laser beams in the adjacent scanning lines 4 are opposite to each other, but the scanning directions of the laser beams in all the scanning lines 4 may be the same direction.

By the laser light irradiated on the layer 3, a part or the whole of the layer 3 is melted and solidified. Thereafter, the stage 1 is lowered by the thickness of the layer 3, a new layer (hereinafter, referred to as an uppermost layer) 3 made of powder is formed on the layer 3 formed at the latest (hereinafter, referred to as a latest layer), and the uppermost layer 3 is irradiated with laser light along a plurality of scanning lines 4 parallel to each other. Further, the bed 2 contains the existing molded part having the uppermost layer 3 formed on the latest layer 3 and the non-melted powder.

The scanning lines 4 may be oriented in the same direction in the uppermost layer 3 and in the latest layer 3, or may be oriented in different directions. When the directions of the scanning lines 4 in the uppermost layer 3 and the latest layer 3 are different, the angle (hereinafter referred to as a scanning rotation angle) of the scanning line 4 of the uppermost layer 3 with respect to the scanning line 4 of the latest layer 3 can be determined as appropriate. For example, in fig. 1, the scan rotation angle is 90 degrees.

The above-described operation is repeated, and finally the non-melted powder is removed from the bed 2, thereby producing a shaped body. The interval between the branches of the primary dendrites of the dendrite structure in such a shaped body is as small as less than 3 μm.

The particle size distribution of the powder used in the powder bed melting method is, for example, 10 to 60 μm, preferably 10 to 45 μm. The thickness of the layer 3 is, for example, 3 times or more the median of the particle size distribution of the powder and 3 times or less the median of the particle size distribution of the powder.

The Ni-based alloy constituting the powder may contain, as essential components other than Ni, 10 to 16 mass% of Cr, 4.5 to 7.5 mass% of Al, 2.8 to 6.2 mass% of Mo, 0.8 to 4 mass% of Nb + Ta, 0.01 to 2 mass% of Ti, 0.01 to 0.3 mass% of Zr, and 0.01 to 0.3 mass% of C. The Ni-based alloy may contain 0.001 to 0.03% of B as an essential component. Examples of the Ni-based alloy include IN713C (IN is abbreviated as Inconel (registered trademark) and the same shall apply hereinafter), IN713LC, and the like. In addition, the Ni-based alloy may not contain any one of Nb and Ta with respect to Nb and Ta.

The content of each essential component is more preferably Cr: 11-14%, Al: 5.5-6.5%, Mo: 3.8 to 5.2%, Nb + Ta: 1.65-2.65%, Ti: 0.5 to 1.0%, Zr: 0.05-0.15%, C: 0.02-0.2%.

The Ni-based alloy may contain, as other optional components, at least one of Co in an amount of less than 1%, Cu in an amount of less than 0.5%, Fe in an amount of less than 0.5%, and Si in an amount of less than 0.5%. The remainder of the Ni-based alloy other than the above components is Ni and inevitable impurities.

In the present embodiment, when the laser is irradiated to each layer 3, the value (L/D) obtained by dividing the interval L of the scanning lines 4 by the laser spot diameter D is 0.2 to 1.0. The laser spot diameter D means that the intensity of the laser is reduced from the peak value to 1/e²In other words, a position of about 13.5% of the peak value. In the powder bed melting apparatus using a laser, there are some apparatuses in which the laser spot diameter can be set by the apparatus user and some apparatuses in which the setting cannot be made.

The laser spot diameter D is, for example, 0.02 to 0.20mm, preferably 0.05 to 0.15 mm. The interval L between the scanning lines 4 is, for example, 0.02mm to 0.08 mm. Preferably, the L/D is 0.3 to 0.9.

The scanning speed of the laser is, for example, 500 to 3000mm/s, preferably 600 to 2000mm/s, and more preferably 700 to 1500 mm/s. The laser output is, for example, 100 to 400W, preferably 130 to 350W, and more preferably 150 to 300W.

As described above, by setting the value (L/D) obtained by dividing the interval L of the scanning lines 4 by the laser spot diameter D when the laser beam is irradiated on each layer 3 to be 0.2 to 1.0, cracks formed in the molded body can be reduced. In the molded article with few cracks thus produced, the maximum value of MUD (pole density of した positive pole point diagram measured by EBSD method で) was 6 or more (10 or more depending on the conditions).

Examples

The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

(example 1)

A cubic shaped body having a side of 10mm was produced by a powder bed melting method using powder having an alloy composition corresponding to IN 713C. The particle size distribution of the powder is 16 to 45 μm. The alloy composition of the powder was analyzed, and the content of the components other than Ni was Cr: 12.41%, Al: 5.94%, Mo: 4.36%, Nb: 1.94%, Ta: 0.009%, Ti: 0.68%, Zr: 0.11%, C: 0.06%, B: 0.01%, Co: 0.18%, Cu: 0.02%, Fe: 0.20%, Si: 0.03% (the content of inevitable impurities is omitted).

As the powder bed melting apparatus, EOS M290 manufactured by EOS was used. In this apparatus, the laser spot diameter D was set to 0.08mm by the manufacturer. The thickness of each layer was 40 μm when the molded body was produced, the interval of scanning lines was 0.03mm when the layers were irradiated with laser light, the laser scanning speed was 1000mm/s, the laser output was 180W, and the scanning rotation angle was 90 degrees.

(example 2)

A molded body was produced in the same manner as in example 1, except that the interval between scanning lines was 0.04mm when each layer was irradiated with a laser beam.

(example 3)

A molded body was produced in the same manner as in example 1, except that the interval between scanning lines was 0.05mm when each layer was irradiated with a laser beam.

(example 4)

A molded body was produced in the same manner as in example 1, except that the interval between scanning lines was 0.06mm when each layer was irradiated with laser light.

(example 5)

A molded body was produced in the same manner as in example 4, except that the scanning rotation angle was 67 degrees.

(example 6)

A molded body was produced in the same manner as in example 1, except that the interval between scanning lines was 0.07mm when each layer was irradiated with a laser beam.

Comparative example 1

A molded body was produced in the same manner as in example 1, except that the interval between scanning lines was 0.09mm, the laser scanning speed was 1250mm/s, and the laser output was 270W when the layers were irradiated with laser light.

Comparative example 2

A molded body was produced in the same manner as in example 1, except that the interval between scanning lines when the laser light was irradiated on each layer was 0.11mm, the laser scanning speed was 960mm/s, the laser output was 285W, and the scanning rotation angle was 67.

The production conditions of the shaped bodies of examples 1 to 6 and comparative examples 1 and 2 are shown in table 1. Also, table 1 shows the value (L/D) of the scanning line interval L divided by the laser spot diameter D.

[ Table 1]

。

(test)

The molded bodies of examples 1 to 6 and comparative examples 1 and 2 were cut along a plane parallel to the stacking direction (vertical direction in fig. 1), and a photomicrograph of the cut plane was taken. Fig. 3 is a photomicrograph of example 4, and fig. 4 is a photomicrograph of comparative example 1. In examples 1 to 6 and comparative examples 1 and 2, the length of the crack per unit area observed in the cut surface was calculated as the amount of the crack.

In each of examples 1 to 6 and comparative examples 1 and 2, the electrode density in the positive electrode dot pattern was measured by the EBSD method on the cut surface of the molded body cut on the surface perpendicular to the stacking direction. In this measurement, SEM-SU5000 manufactured by Hitachi, Inc. and Pegasus Digiview5 manufactured by EDAX/TSL, Inc. were used as EBSD devices.

More specifically, the measurement of the pole density of the positive pole dot pattern was carried out by preparing a mechanical polishing of a cut surface using water-resistant sandpaper and diamond abrasive grains, and then carrying out a final polishing using colloidal silica. This preliminary preparation is used to reduce points that cannot be measured and to ensure measurement accuracy, and is often used for Ni-based alloys. Next, the Kikuchi line was measured in a 3 μm step size for a 300 μm × 300 μm area in the cut surface, and analyzed by using Analysis software (OIM Data Collection/OIM Analysis ver.8 manufactured by EDAX/TSL Co., Ltd.) to obtain a { 100 } pole point diagram of the projected { 100 } pole. MUD is calculated from the positive pole diagram. When MUD was calculated, the number of expansions was 16 and the half width was 5 degrees by the Spherical Harmonics (Spherical Harmonics) method.

The maximum values of MUD and the amount of cracking in examples 1 to 6 and comparative examples 1 and 2 are shown in table 2. The maximum values and the crack amounts of MUD in examples 1 to 6 and comparative examples 1 and 2 are shown in the graph of fig. 2.

[ Table 2]

。

As is apparent from table 1 and fig. 2, the crack amount was very large in comparative examples 1 and 2 in which the interval between scanning lines when the layers were irradiated with laser light was more than 0.08mm, that is, L/D was more than 1.0. On the other hand, in examples 1 to 6 in which the interval between the scanning lines when the layers were irradiated with the laser was adjusted so that the L/D was 0.3 to 0.9 (i.e., 0.2 to 1.0), the amount of cracks was very small.

The maximum value of MUD in comparative examples 1 and 2 was less than 6, while MUD in examples 1 to 6 was 10 or more (i.e., 6 or more). Therefore, a molded article having a maximum MUD value of 6 or more is a molded article with few cracks.

Description of the symbols:

1 platform

2 bed

3 layers of

4 scan lines.