FORMED PART WITH HIGH-TEMPERATURE PERSISTENCE AND LOW ANISOTROPY, FORMING METHOD AND FORMING POWDER

Abstract

A forming powder for a forming part with a low high-temperature durability anisotropy by additive manufacturing, which can be used for forming the forming part with low high-temperature durability anisotropy, a method for forming a forming part with a low high-temperature durability anisotropy, and a forming part with a low high-temperature durability anisotropy. The forming powder is composed of the following chemical components in terms of mass percentage (wt-%): 0.03%≤C≤0.09%, 20.50%≤Cr≤23.00%, 0.50%≤Co≤2.50%, 8.00%≤Mo≤10.00%, 0.20%≤W≤1.00%, 17.00%≤Fe≤20.00%, 0%≤B≤0.002%, 0%≤Mn≤1.00%, 0.0375%≤Si≤0.15%, 0%≤O≤0.02%, 0%≤N≤0.015%, the rest are Ni and inevitable impurities; wherein 0.2≤C/Si≤1.0.

Claims

1-10. (canceled)

11. A forming powder for a forming part with a low high-temperature durability anisotropy by additive manufacturing, wherein the forming powder is composed of the following chemical components in terms of mass percentage (wt-%): 0.03%≤C≤0.09%, 20.50%≤Cr≤23.00%, 0.50%≤Co≤2.50%, 8.00%≤Mo≤10.00%, 0.20%≤W≤1.00%, 17.00%≤Fe≤20.00%, 0%≤B≤0.002%, 0%≤Mn≤1.00%, 0.0375%≤Si≤0.15%, 0%≤O≤0.02%, 0%≤N≤0.015%, the rest are Ni and inevitable impurities; wherein 0.25≤C/Si≤1.0.

12. The forming powder for the forming part with low high-temperature durability anisotropy by additive manufacturing according to claim 11, wherein in terms of mass percentage: the carbon content is 0.05%≤C≤0.09%; the silicon content is 0.07%≤Si≤0.15%; wherein 0.335≤C/Si≤0.8.

13. The forming powder for the forming part with low high-temperature durability anisotropy by additive manufacturing according to claim 11, wherein the forming powder is obtained by gas atomization or rotary electrode atomization.

14. The forming powder for the forming part with low high-temperature durability anisotropy by additive manufacturing according to claim 11, wherein the powder particle size of the forming powder is from 15 μm to 150 μm.

15. A method for forming a forming part with a low high-temperature durability anisotropy, the forming part with low high-temperature durability anisotropy is formed by additive manufacturing process wherein: a forming powder used for the additive manufacturing process is any one of the forming powder for the forming part with low high-temperature durability anisotropy by additive manufacturing according to claim 11.

16. The method for forming the forming part with low high-temperature durability anisotropy according to claim 15, wherein the additive manufacturing process is a selective laser melting process.

17. The method for forming the forming part with low high-temperature durability anisotropy according to claim 15, wherein the forming method further comprises: performing stress relief annealing treatment on the forming part.

18. The method for forming the forming part with low high-temperature durability anisotropy according to claim 17, wherein after the stress relief annealing treatment, the forming method further comprises: performing wire cutting process on the forming part.

19. The method for forming the forming part with low high-temperature durability anisotropy according to claim 18, wherein after the wire cutting process, the forming method further comprises: performing hot isostatic pressing process on the forming part.

20. A forming part with a low high-temperature durability anisotropy, wherein the forming part is formed by any one of the methods for forming the forming part with low high-temperature durability anisotropy according to claim 15.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The specific features and performance of the invention is further described with reference to the following embodiments and drawings.

[0028] FIG. 1 shows a schematic diagram of the longitudinal specimen and transverse specimen used for the high-temperature durability test.

[0029] FIG. 2 shows the comparison of the transverse and longitudinal high-temperature durability property of the examples 1-4 and the contrast examples 1-3.

[0030] FIG. 3 shows the comparison diagram of the difference between the transverse high-temperature durability property and the longitudinal high-temperature durability property according to the measured values in FIG. 2.

DETAILED DESCRIPTION

[0031] In this disclosure, specific terms are used for describing the embodiments of the invention, such as ‘one embodiment’, ‘an embodiment’ and/or ‘some embodiments’ refers to a certain feature, structure or characteristics related to at least one embodiment of the invention. Therefore, it should be emphasized and noted that ‘one embodiment’ or ‘an embodiment’ mentioned two or more times in various places in the description do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics in one or more embodiments of the invention can be combined as appropriate. In addition, the use of terms such as ‘first’ and ‘second’ for defining components is only for the convenience of distinguishing the corresponding components, unless otherwise stated, the above terms do not have special meaning, and therefore cannot be considered as limitations on the scope of protection of the invention.

[0032] The effect of the composition of the forming powder on the anisotropic forming properties has been studied in the literature. For example, the anisotropy of Hastelloy-X metal powder in two batches which has a particle size of 15-45 μm are compared by Jing Wei et al. in ‘Effect of Hastelloy-X Powder Composition on Isotropic Forming Properties of Selective Laser Melting’ (Chinese Journal of Lasers, 2018, 045(012):135-141), where the effect of the C, Si element on anisotropy is reported. A composition of Hastelloy-X alloy is reported by Yongzhi Zhang et al. in ‘Microstructure and Anisotropy of the Tensile Properties of Hastelloy X Alloy by Laser Selective Melting’ (Journal of Aeronautical Materials, 2018, 038(006):50-56), and compared with the anisotropy of the forge pieces. The effect of the different C, Si element on the strength of anisotropy under the condition of additive manufacturing process is reported by Jiaqi Xue in ‘Effect of GH3536 Alloy Structure by Selective Laser Melting on Mechanical Properties’ (Laser & Optoelectronics Progress, 2019, 56(14)), which reveals the effect of C element is significant and the effect of Si element is not significant. In addition, there are a number of patents related to nickel-based alloys, which can reduce the crack density and improve the crack susceptibility by controlling the composition of element. The patent document with publication number of CN105828983A discloses a nickel-based alloy that can reduce the crack density. The patent document with publication number of CN106513660A discloses a composition of nickel-based alloy, where the high temperature tensile plasticity can be improved and the crack susceptibility can be reduced by controlling the content of various elements: 20.5-23.0Cr, 17.0-20.0Fe, 8.0-10.0Mo, 0.50-2.50Co, 0.20-1.00W, 0.04-0.10C, 0-0.5Si, 0-0.5Mn, 0-0.008B, and the content ratio of the elements C/B>5. The patent document with publication number of US20180073106A discloses that the tendency of cracking can be reduced without the expense of strength by determining 8.0-8.5Cr, 9.0-9.5Co, 0.4-0.6Mo, 9.3-9.7W, 2.9-3.6Ta, 4.9-5.6Al, 0.2-1.0Ti, and other elements. The patent document with publication number of CN107486555A discloses a nickel-based alloy with C/Hf>1.55, 0.01%<C<0.2%, which can reduce the crack susceptibility.

[0033] High-temperature durability is an important mechanical property index of the nickel-based superalloys under a long-term stress at a high temperature. The present disclosure further studies the composition of forming powder and high-temperature durability anisotropy to further optimize and reduce the high-temperature durability anisotropy of the nickel-based alloy formed by additive manufacturing, providing a forming powder for a forming part with a low high-temperature durability anisotropy by additive manufacturing, wherein the high-temperature durability property refers to the durability of the part at a temperature >500° C.

[0034] The nickel-based alloy forming powder is composed of the following chemical components in terms of mass percentage (wt-%):

[0035] 0.03%≤C≤0.09%, 20.50%≤Cr≤23.00%, 0.50%≤Co≤2.50%, 8.00%≤Mo≤10.00%, 0.20%≤W≤1.00%, 17.00%≤Fe≤20.00%, 0%≤B≤0.002%, 0%≤Mn≤1.00%, 0.0375%≤Si≤0.15%, 0%≤O≤0.02%, 0%≤N≤0.015%, the rest are Ni and inevitable impurities;

[0036] wherein the mass percentage ratio of carbon and silicon satisfies 0.2≤C/Si≤1.0.

[0037] In the prior art, the effect of the content of carbon and silicon in the forming powder on the properties of the forming part has already been known, wherein as disclosed in the background art literature, the carbon content has a significant effect on the number of intragranular carbides and carbides at the grain boundaries, and the carbides at the grain boundaries has a more significant inhibiting effect on the growth of grain size. Adding silicon will lead to the formation of more crack sources, resulting in a decrease in tensile strength. Boron plays an important role in the mechanical properties of nickel-based superalloys, so nickel-based alloys generally contain a trace amount of boron. Adding boron can improve the high temperature mechanical properties, the grain boundary shape and the processing properties of the alloy. In terms of the strengthening mechanism of boron, a theoretical study believes that boron can enrich the recrystallization boundary, fill the vacancies of the material and the lattice defects, reducing the diffusion process of the grain boundary and the speed of dislocation climbing, thereby improving the strength of the alloy. Another study holds that boron on the grain boundary can inhibit the early aggregation of carbides, thereby delaying the formation of cracks at the grain boundary. However, if too much boron is added, borides can be easily formed at the grain boundaries, which may reduce the mechanical properties.

[0038] Although the effect of carbon, silicon and boron content in the forming powder on the mechanism of the crack initiation on the forming part and the tensile strength of the part has been discussed in the prior art, there is a lack of research on the chemical element that plays an important role in high-temperature durability anisotropy in the prior art.

[0039] The forming powder for the nickel-based alloy of the invention is further optimized by the composition content of the chemical elements that play an important role in high-temperature durability anisotropy, and in terms of mass percentage, it is determined that 0.03%≤C≤0.09%, 0.0375%≤Si≤0.15%, 0%≤B≤0.002%, the mass percentage ratio of carbon and silicon is 0.2≤C/Si≤0.8. When the mass percentages and the mass percentage ratio of carbon, silicon and baron are controlled to be in the above ranges respectively, the part formed by additive manufacturing with the powder mentioned above has a low high-temperature durability anisotropy.

[0040] It can be understood that the high-temperature durability anisotropy mentioned herein refers to the anisotropy of the stress rupture properties of the forming part at the temperature >500° C., which is not directly related to the strength of the high-temperature durability properties of the part. It is the difference in the results of the longitudinal and transverse high-temperature durability test of the part, where the longitudinal direction is the same as the forming direction of the part and the transverse direction is perpendicular to the forming direction.

[0041] Further, in a preferred embodiment, in terms of mass percentage, the carbon content is 0.05%≤C≤0.09%, the silicon content is 0.07%≤Si≤0.15%, and the mass percentage ratio of carbon and silicon satisfies 0.33≤C/Si≤0.8, the three conditions are further satisfied concurrently by the element content of the forming powder, so as to further reduce the high-temperature durability anisotropy of the part formed by additive manufacturing with the powder mentioned above.

[0042] In one or more embodiment of the nickel-based alloying powder, the nickel-based alloying powder is obtained by gas atomization or rotary electrode atomization, so as to ensure that spherical powder with smooth surface can be obtained. In other embodiments, the nickel-based alloying powder can also be obtained by other suitable methods.

[0043] In one or more embodiment of the nickel-based alloying powder, the powder particle size of the nickel-based alloying powder is from 15 μm to 150 μm. In some embodiments, different ranges of particle size are selected based on different types of additive manufacturing processes.

[0044] Another aspect of the invention is to provide a method for forming a forming part with a low high-temperature durability anisotropy, where the forming part with a low high-temperature durability anisotropy is formed by additive manufacturing process with the nickel-based alloying powder according to one or more embodiment mentioned above.

[0045] In one embodiment of the forming method, the additive manufacturing process is a selective laser melting process (SLM). In some different embodiment, the additive manufacturing process can also be a laser melting deposition process (LMD).

[0046] In one embodiment of the forming method, the forming part formed by additive manufacturing is a blank part, and the forming method further comprises performing stress relief annealing treatment on the forming part to further reduce the high-temperature durability anisotropy.

[0047] In one embodiment of the forming method, the forming method further comprises performing wire cutting process on the forming part after performing the stress relief annealing treatment on the forming part to remove burrs on the surface of the part, further improving the forming quality of the outer surface of the part.

[0048] In one embodiment of the forming method, the forming method further comprises performing hot isostatic pressing process on the forming part after performing the wire cutting process on the forming part to further reduce the transverse organizational differences and the longitudinal organizational differences of the part, thereby reducing the high-temperature durability anisotropy.

[0049] Another aspect of the invention is to provide a forming part with a low high-temperature durability anisotropy, which is formed by the forming method according to one or more embodiment mentioned above

[0050] The part with a low high-temperature durability anisotropy formed by the nickel-based alloying powder is further described in the following embodiment.

[0051] An embodiment:

[0052] In this embodiment, 4 examples and 3 contrast examples are provided, wherein the present nickel-based alloying powder is used in the embodiments 1-4, the nickel-based alloying powder according to the preferred embodiments is used in the embodiment 1-3. The mass percentage of carbon and C/S in the contrast example 1, the mass percentage of silicon and C/S in the contrast example 2, the mass percentage of boron and C/S in the contrast example 3 are out of the range of the element range according to the invention respectively.

[0053] Table 1 shows the chemical element composition of the examples 1-4 and the contrast examples 1-3 (in terms of mass percentage):

TABLE-US-00001 TABLE 1 Contrast Contrast Contrast Example example Example example Example example Example Element 1 1 2 2 3 4 4 C 0.065 0.12 0.064 0.05 0.055 0.082 0.055 Cr 21.582 21.72 21.266 21.35 21.338 21.55 21.31 Co 1.577 1.45 1.561 1.58 1.522 1.64 1.51 Mo 8.983 8.85 9.325 9.15 9.114 9.11 9.07 W 0.653 0.58 0.808 0.62 0.584 0.62 0.59 Fe 18.785 18.51 18.606 18.57 18.648 18.53 18.65 B 0.001 <0.001 0.002 <0.002 0.001 0.003 0.001 Mn 0.033 0.012 0.011 0.006 0.015 0.014 0.015 Si 0.127 0.059 0.112 0.37 0.074 0.075 0.056 O 0.008 0.01 0.009 0.02 0.01 0.02 0.009 N 0.006 0.006 0.006 0.01 0.007 0.01 0.007 C/Si 0.51 2.03 0.57 0.14 0.74 1.09 0.996 Ni The rest The rest The rest The rest The rest The rest The rest

[0054] Selective laser melting process is performed on the powder of the above examples 1-4 and contrast examples 1-3 using the EOS M280 device for formation. The forming parameters are: layer thickness of 20 μm, laser scanning rate of 180W and rotation angle of 67° between layers (which can prevent the generation of transverse anisotropy). A longitudinal specimen 1 and a transverse specimen 2 as shown in FIG. 1 is formed according to the examples 1-4 and the contrast examples 1-3, wherein both the longitudinal specimen 1 and the transverse specimen 2 are formed along a forming direction a.

[0055] Postprocessing is performed after the forming process has been completed, the steps of stress relief annealing treatment, wire cutting process and hot isostatic pressing process are performed in sequence, and the high-temperature durability test is performed according to the standard. Specifically, the high-temperature durability test is performed on the longitudinal specimen 1 along a first direction y that is the same as the forming direction a, and the high-temperature durability test is performed on the transverse specimen 2 along a second direction x that is perpendicular to the forming direction a.

[0056] FIG. 2 shows the comparison of the transverse and longitudinal high-temperature durability property of the examples 1-4 and the contrast examples 1-3. FIG. 3 is the difference between the transverse high-temperature durability property and the longitudinal high-temperature durability property according to the measured values in FIG. 2.

[0057] Specifically, it can be seen from FIG. 2 and FIG. 3 that the example 1 of the forming part formed by the forming powder provided by the invention has a transverse high-temperature durability lifetime of 23.2 h (which is an average value of 3 sets of results) and a longitudinal high-temperature durability lifetime of 24.6 h (which is an average value of 3 sets of results) at a temperature of 815° C. and stress of 105 MPa, and the difference between the longitudinal high-temperature durability lifetime and the transverse high-temperature durability lifetime is 1.4 h.

[0058] The example 2 has a transverse high-temperature durability lifetime of 38.6 h (which is an average value of 3 sets of results) and a longitudinal high-temperature durability lifetime of 37.9 h (which is an average value of 3 sets of results) at a temperature of 815° C. and stress of 105 MPa, and the difference between the longitudinal high-temperature durability lifetime and the transverse high-temperature durability lifetime is −0.7 h.

[0059] The example 3 has a transverse high-temperature durability lifetime of 21.7 h (which is an average value of 3 sets of results) and a longitudinal high-temperature durability lifetime of 23.1 h (which is an average value of 3 sets of results) at a temperature of 815° C. and stress of 105 MPa, and the difference between the longitudinal high-temperature durability lifetime and the transverse high-temperature durability lifetime is 1.4 h.

[0060] The example 4 has a transverse high-temperature durability lifetime of 23.1 h (which is an average value of 3 sets of results) and a longitudinal high-temperature durability lifetime of 25.4 h (which is an average value of 3 sets of results) at a temperature of 815° C. and stress of 105 MPa, and the difference between the longitudinal high-temperature durability lifetime and the transverse high-temperature durability lifetime is 2.3 h.

[0061] The contrast example 1 has a transverse high-temperature durability lifetime of 11.3 h (which is an average value of 3 sets of results) and a longitudinal high-temperature durability lifetime of 36.8 h (which is an average value of 3 sets of results) at a temperature of 815° C. and stress of 105 MPa, and the difference between the longitudinal high-temperature durability lifetime and the transverse high-temperature durability lifetime is 25.6 h.

[0062] The contrast example 2 has a transverse high-temperature durability lifetime of 33.0 h (which is an average value of 3 sets of results) and a longitudinal high-temperature durability lifetime of 91.9 h (which is an average value of 3 sets of results) at a temperature of 815° C. and stress of 105 MPa, and the difference between the longitudinal high-temperature durability lifetime and the transverse high-temperature durability lifetime is 58.9 h.

[0063] The contrast example 3 has a transverse high-temperature durability lifetime of 29.9 h (which is an average value of 3 sets of results) and a longitudinal high-temperature durability lifetime of 37.0 h (which is an average value of 3 sets of results) at a temperature of 815° C. and stress of 105 MPa, and the difference between the longitudinal high-temperature durability lifetime and the transverse high-temperature durability lifetime is 7.1 h.

[0064] It can be seen from the above comparison that for the forming part formed by the forming powder provided by the invention, the difference between the longitudinal high-temperature durability lifetime and the transverse high-temperature durability lifetime at high temperature is reduced significantly, and the high-temperature durability anisotropy is reduced significantly, particularly suitable for manufacturing a part where the direction of the force applied does not have an obvious directionality and the part is used in a high temperature working condition.

[0065] Although the present invention is disclosed above with the preferred embodiments, it is not intended to limit the invention, and any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes and alternatives made to the above embodiments according to the technical essence of the invention without departing from the content of the technical solutions of the invention shall all fall within the scope of protection defined by the claims of the invention.