CN116200689A

CN116200689A - Pre-forging heat treatment method for nickel-based alloy arc fuse additive prefabricated member

Info

Publication number: CN116200689A
Application number: CN202310083569.8A
Authority: CN
Inventors: 温东旭; 熊康祺; 李建军
Original assignee: Mianyang Daqi Technology Co ltd; Huazhong University of Science and Technology
Current assignee: Mianyang Daqi Technology Co ltd; Huazhong University of Science and Technology
Priority date: 2023-02-08
Filing date: 2023-02-08
Publication date: 2023-06-02

Abstract

The invention discloses a pre-forging heat treatment method of a nickel-based alloy arc fuse additive prefabricated member, and relates to the technical field of heat treatment processes. The method specifically comprises the following steps: performing primary heat treatment on the nickel-based alloy manufactured by the arc fuse additive, and then air-cooling to room temperature; and then continuously heating to the temperature of the second-stage heat treatment for the second-stage heat treatment, and then cooling to room temperature. According to the invention, delta phase capable of inhibiting grain growth is separated out through the first heat treatment, and impurity phase in the alloy is dissolved through the second heat treatment, so that the effects of eliminating harmful phase and inhibiting grain growth are achieved, and the structural performance of the alloy is improved. The method breaks through the traditional technological thought that the high-temperature alloy part can refine the grain structure only through plastic deformation, so that grains can be refined in the heat treatment process, and the pre-forging with more excellent performance is obtained, and has important research value.

Description

Pre-forging heat treatment method for nickel-based alloy arc fuse additive prefabricated member

Technical Field

The invention relates to the technical field of heat treatment processes, in particular to a pre-forging heat treatment method for a nickel-based alloy arc fuse additive prefabricated member.

Background

The nickel-base superalloy is an alloy material widely used in the field of high-temperature materials, takes nickel as a matrix, adds a large amount of iron and cobalt elements, and is a multi-element alloy of iron, nickel and cobalt. Compared with the traditional iron-based alloy, the nickel-based superalloy has better oxidation resistance, high temperature resistance and corrosion resistance, is widely used for manufacturing key hot end components in high-end equipment such as aeroengines, gas turbines and the like, and the forming manufacturing technology is an important basic stone for realizing independence and autonomy in the fields of supporting important strategic demands of countries such as aviation, aerospace, energy and the like. Large superalloy disc-shaped members, represented by turbine discs, turbine rotor support cone walls, and the like, have structural features such as significant wall thickness differences, large dimensions, and the like. Through dissecting and forming the forging, the parts such as the hub belong to thick-wall small deformation areas, deformation dead areas locally exist, the uniformity of local tissues is poor, the grain size level difference is serious, the control is difficult to be within 2 levels, the qualification rate of the high-pressure turbine disc forging manufactured by adopting domestic GH4169 alloy is less than 60%, and the qualification rate of the low-pressure turbine rotor supporting conical wall forging is less than 70% according to reliable statistics. Therefore, localized homogenization of forging structure has become a key challenge in high quality manufacturing of superalloy components.

The regulation and control of the precipitated phase are mainly realized through a heat treatment process, a proper heat treatment system is an essential means for enabling the high-temperature alloy part to reach the target mechanical property, and related researches are mainly based on the precipitation/dissolution dynamics characteristics of the precipitated phase, numerical simulation and the optimization of the heat treatment process. Cormier et al studied isothermal precipitation kinetics of the gamma' and gamma "phases of GH4169 alloys using in situ test techniques such as dynamic resonance and neutron diffraction, respectively. Semiatin et al, based on the theory of uniform nucleation and diffusion controlled growth, propose an average field model that can rapidly quantify the precipitation behavior of GH4169 alloy gamma 'and gamma'. With the deep understanding of the evolution mechanism of the high-temperature alloy structure, chen Mingsong and the like develop a double-stage heat treatment process of 'low Wen phase aging + high-temperature continuous cooling annealing', and successfully refine the GH4169 alloy deformed mixed crystal structure into an ASTM 12 grade equiaxed fine crystal structure. For the mixed structure of 'forging-material adding' of the high-temperature alloy, laves phase is eliminated by heat treatment before forging, and meanwhile, excessive growth of grain size is restrained, so that the interaction mechanism of precipitation and dissolution competition of Laves phase and delta phase and the rule of influence on grain growth behavior are extremely important, and related research reports are not seen at present.

The arc fuse additive manufacturing is a rapid forming technology which takes an arc generated by a metal wire as a heat source, melts the metal wire and stacks and forms metal components layer by layer, and the technology has the characteristics of high production efficiency, low production cost, large degree of freedom of formed parts and the like. However, the formed part has uneven microstructure and larger residual stress, so that the mechanical property of the further forged workpiece is poor, and engineering application standard is difficult to reach. How to promote nickel-base superalloy preforms produced by arc additive prior to forging is therefore a major concern for current researchers.

The prior art CN202010991832.X is a thermal processing method for improving the structural uniformity of nickel-base superalloy manufactured by additive, which discloses the unique advantages of fully utilizing electron beam fuse additive, incomplete homogenization treatment and thermal processing deformation, but adopts incomplete homogenization heat treatment, and cannot effectively control the grain size after homogenization heat treatment.

Disclosure of Invention

For the above reasons, in view of the problems or drawbacks of the prior art, an object of the present invention is to provide a method for heat treatment before forging of a nickel-based alloy arc fuse additive preform, which solves or at least partially solves the above technical drawbacks of the prior art: the pre-precipitation heat treatment adopted by the invention not only can eliminate harmful phases, but also can effectively control the grain size after homogenization heat treatment.

In order to achieve the above object, the present invention adopts the following technical scheme:

a pre-forging heat treatment method of a nickel-based alloy arc fuse additive preform, comprising the following steps:

performing primary heat treatment on the nickel-based alloy manufactured by the arc fuse additive, and then air-cooling to room temperature; and then continuously heating to the temperature of the second-stage heat treatment for the second-stage heat treatment, and then cooling to room temperature.

Further, according to the technical scheme, the temperature of the first-stage heat treatment is 850-980 ℃.

Further, according to the technical scheme, the heating rate adopted by the first-stage heat treatment is 5-100 ℃/min.

Further, according to the technical scheme, the time of the first-stage heat treatment is 6-48 hours.

In particular, according to the technical scheme, the first-stage heat treatment can lead a large amount of delta phase (Ni ₃ Nb), delta phase can control grain growth.

Further, according to the technical scheme, the temperature of the second-stage heat treatment is 1050-1250 ℃.

Further, according to the technical scheme, the temperature rising rate adopted by the second-stage heat treatment is 5-100 ℃/min.

Further, according to the technical scheme, the time of the second-stage heat treatment is 0.5-5 h.

Specifically, according to the technical scheme, the second-stage heat treatment can dissolve impurity phases in the nickel-based alloy, and make elements in the alloy more uniform, so that precipitation of a strengthening phase is facilitated. And due to the large amount of delta phase (Ni ₃ Nb), grain growth in this process is also effectively controlled, compared to conventional homogenization heat treatments. The purpose of air cooling after the first-stage heat treatment is as follows: the forging is cooled, and more delta phases are precipitated in the cooling process. The purpose of water cooling after the second stage heat treatment is to prevent re-precipitation of impurity phases during cooling. The alloy obtained by the method not only eliminates harmful phases, but also has finer grains, and creates good conditions for the subsequent forging process. The invention effectively improves the performance of the nickel-based alloy arc fuse additive prefabricated member before forging.

Compared with the prior art, the invention has the following beneficial effects:

the invention provides a novel heat treatment method aiming at the defects and shortcomings of the prior art, and provides a forging-material-increasing mixed structure homogenization heat treatment process method aiming at eliminating Laves phases and inhibiting grain growth on the basis of the traditional pre-forging/post-forging heat treatment process. The specific method is that delta phase capable of inhibiting the growth of crystal grains is separated out through the first heat treatment, and then impurity phase in the alloy is dissolved through the second heat treatment, so that the effects of eliminating harmful phase and inhibiting the growth of crystal grains are achieved, and the structural performance of the alloy is improved. The method breaks through the traditional technological thought that the high-temperature alloy part can refine the grain structure only through plastic deformation, so that grains can be refined in the heat treatment process, and the pre-forging with more excellent performance is obtained, and has important research value.

Drawings

FIG. 1 is a schematic flow diagram of a pre-forging heat treatment process for a nickel-based alloy arc fuse additive preform in accordance with the present invention;

FIG. 2 is a microstructure of a GH4169 alloy sample obtained in step (1) of example 1;

FIG. 3 is a microstructure of GH4169 alloy block prepared in step (1) of example 1 under electron microscopy;

FIG. 4 is a microstructure of a GH4169 alloy sample obtained in step (2) of example 1;

FIG. 5 is a microstructure of a GH4169 alloy sample of comparative example 1 directly subjected to a heat treatment at 1200℃ for 2 hours;

FIG. 6 is a microstructure of a GH4169 alloy sample obtained in step (2) of example 2;

FIG. 7 is a microstructure of a GH4169 alloy sample of comparative example 2 directly heat-treated at 1200℃ for 1.5 h.

Detailed Description

The invention is described in further detail below by way of examples. The present embodiment is implemented on the premise of the present technology, and a detailed embodiment and a specific operation procedure are now given to illustrate the inventive aspects of the present invention, but the scope of protection of the present invention is not limited to the following embodiments.

Various modifications to the precise description of the invention will be readily apparent to those skilled in the art from the information contained herein. It is to be understood that the scope of the invention is not limited to the defined processes, properties or components, as these embodiments, as well as other descriptions, are merely illustrative of specific aspects of the invention.

For a better understanding of the present invention, and not to limit its scope, all numbers expressing quantities, percentages, and other values used in the present application are to be understood as being modified in all instances by the term "about". Accordingly, unless specifically indicated otherwise, the numerical parameters set forth in the specification are approximations that may vary depending upon the desired properties sought to be obtained. Each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

The equipment and materials used in the present invention are commercially available or are commonly used in the art. The methods in the following examples are conventional in the art unless otherwise specified.

Example 1

The embodiment relates to a pre-forging heat treatment method of a nickel-based alloy arc fuse additive prefabricated member, which specifically comprises the following steps:

(1) Preparation of GH4169 alloy sample

GH4169 alloy wires with the diameter of l.2mm are used as raw materials, GH4169 alloy additive blocks with the dimensions of 120mm multiplied by 80mm multiplied by 30mm are piled up on a GH4169 alloy substrate, and the GH4169 alloy wires comprise the following components in percentage by weight: ni:52.91%, fe:19.43%, cr:19.01%, nb:4.43%, mo:2.68%, ti:0.97%, S:0.52%. The parameters for a particular arc additive manufacturing are as follows: the welding current was 160A, the lap rate was 40%, the welding rate was 16cm/min, and the remaining parameters were automatically given by the machine Yaskawa DX 200. And after arc additive parameters are set, manufacturing the GH4169 alloy block by adopting a layer-by-layer stacking method.

(2) Heat treatment of

And (3) heating the GH4169 alloy block sample obtained in the step (1) to 900 ℃ at a heating rate of 10 ℃/min, preserving heat for 24 hours, air-cooling to room temperature, heating to 1200 ℃ along with a furnace at a heating rate of 10 ℃/min, preserving heat for 2 hours, and cooling to room temperature by water to obtain the reinforced GH4169 alloy.

Comparative example 1

A method of pre-forging heat treatment of a nickel-based alloy arc fuse additive preform of this comparative example, which is substantially the same as in example 1, except that: the heat treatment in the step (2) of the comparative example is to heat up the GH4169 alloy block sample obtained in the step (1) to 1200 ℃ at a heating rate of 10 ℃/min, then heat-preserving for 2 hours, and water-cooling to room temperature.

Fig. 2 is a microstructure of the GH4169 alloy block obtained in step (1) of this example, and as can be seen from fig. 2, the alloy after arc addition is columnar crystals and has directionality.

FIG. 3 is a microstructure of the GH4169 alloy block prepared by step (1) under electron microscopy, and it can be seen that a large number of Laves phases occur in arc additive manufacturing.

Fig. 4 is a microstructure of the enhanced GH4169 alloy obtained in step (2) of this example, showing clear grain boundaries.

FIG. 5 is a microstructure of comparative example 1, a GH4169 alloy sample directly heat treated at 1200℃ for 2 hours, where sharp grain boundaries are visible and statistically significantly greater than FIG. 4.

As can be seen by comparing FIGS. 3, 4 and 5, the homogenization heat treatment eliminates the Laves phase. The average grain size of the pre-precipitation heat-treated sample of statistical example 1 was 769.6 μm, the average grain size of comparative example 1 was 1016.5 μm when heat-treated directly for 2 hours, and the grain size of the heat-treated sample of comparative example 1 was significantly reduced. It can be explained that the heat treatment method of the present invention is indeed capable of refining grains while dissolving the Laves phase.

Example 2

(1) Preparation of GH4169 alloy sample

GH4169 alloy wires with the diameter of l.2mm are used as raw materials, GH4169 alloy additive blocks with the dimensions of 120mm multiplied by 80mm multiplied by 30mm are piled up on a GH4169 alloy substrate, and the GH4169 alloy wires comprise the following components in percentage by weight: ni:52.91%, fe:19.43%, cr:19.01%, nb:4.43%, mo:2.68%, ti:0.97%, S:0.52%. The parameters for a specific arc additive manufacturing are as follows, welding current 160A, overlap ratio 40%, welding rate 16cm/min, the remaining parameters being given automatically by the machine Yaskawa DX 200. And after arc additive parameters are set, manufacturing the GH4169 alloy block by adopting a layer-by-layer stacking method.

(2) Heat treatment of

And (3) heating the GH4169 alloy sample obtained in the implementation step (1) to 900 ℃ at a heating rate of 10 ℃/min, preserving heat for 24 hours, air-cooling to room temperature, heating to 1200 ℃ along with a furnace at a heating rate of 10 ℃/min, preserving heat for 1.5 hours, and then cooling to room temperature by water to obtain the reinforced GH4169 alloy.

Comparative example 2

A method of pre-forging heat treatment of a nickel-based alloy arc fuse additive preform of this comparative example, which is substantially the same as in example 2, except that: the heat treatment in the step (2) of the comparative example is to heat up the GH4169 alloy block sample obtained in the step (1) to 1200 ℃ at a heating rate of 10 ℃/min, then heat-preserving for 1.5h, and water-cooling to room temperature.

Microstructure of GH4169 alloy sample example 1 is given, and fig. 6 is a microstructure of GH4169 alloy sample obtained in step (2) of example 2, in which clear grain boundaries are visible.

FIG. 7 is a microstructure plot of a GH4169 alloy sample from comparative example 2 directly heat treated at 1200℃ for 1.5h, where sharp grain boundaries are visible and statistically significantly greater than FIG. 6.

As can be seen from a comparison of fig. 3 and 6, the homogenization heat treatment eliminates the Laves phase, and the average grain size of the pre-precipitation heat treated sample in example 2 was 556.6 μm, whereas the average grain size of the direct heat treatment for 1.5h in comparative example 2 was 890.4 μm, in contrast to the significant reduction in the grains obtained by the heat treatment in example 2. It can be seen that the present invention does enable refinement of the grains while dissolving the Laves phase.

Example 3

A pre-forging heat treatment method of a nickel-based alloy arc fuse additive preform of the present embodiment, which is substantially the same as embodiment 1, differs only in that: the heat treatment process in step (2) of this embodiment is specifically as follows:

and (3) heating the GH4169 alloy sample obtained in the step (1) to 900 ℃ at a heating rate of 5 ℃/min, preserving heat for 24 hours, air-cooling to room temperature, heating to 1200 ℃ along with a furnace at a heating rate of 5 ℃/min, preserving heat for 2 hours, and cooling to room temperature by water to obtain the reinforced GH4169 alloy.

Example 4

and (3) heating the GH4169 alloy sample obtained in the step (1) to 850 ℃ at a heating rate of 5 ℃/min, preserving heat for 48 hours, air-cooling to room temperature, heating to 1200 ℃ along with a furnace at a heating rate of 5 ℃/min, preserving heat for 2 hours, and cooling to room temperature by water to obtain the reinforced GH4169 alloy.

Example 5

and (3) heating the GH4169 alloy sample obtained in the step (1) to 980 ℃ at a heating rate of 100 ℃/min, preserving heat for 6 hours, air-cooling to room temperature, heating to 1200 ℃ along with a furnace at a heating rate of 100 ℃/min, preserving heat for 2 hours, and cooling to room temperature by water to obtain the reinforced GH4169 alloy.

Example 6

and (3) heating the GH4169 alloy sample obtained in the step (1) to 900 ℃ at a heating rate of 5 ℃/min, preserving heat for 24 hours, air-cooling to room temperature, heating to 1250 ℃ along with a furnace at a heating rate of 5 ℃/min, preserving heat for 0.5 hour, and then cooling to room temperature by water to obtain the reinforced GH4169 alloy.

Example 7

and (3) heating the GH4169 alloy sample obtained in the step (1) to 900 ℃ at a heating rate of 5 ℃/min, preserving heat for 24 hours, air-cooling to room temperature, heating to 1050 ℃ along with a furnace at a heating rate of 10 ℃/min, preserving heat for 5 hours, and cooling to room temperature by water to obtain the reinforced GH4169 alloy.

Example 8

and (3) heating the GH4169 alloy sample obtained in the step (1) to 900 ℃ at a heating rate of 100 ℃/min, preserving heat for 24 hours, air-cooling to room temperature, heating to 1050 ℃ along with a furnace at a heating rate of 100 ℃/min, preserving heat for 5 hours, and cooling to room temperature by water to obtain the reinforced GH4169 alloy.

The reinforced GH4169 alloys obtained in examples 3-8 were also subjected to the same test as in example 1. The microstructure graphs show that the enhanced GH4169 alloys obtained in examples 3-8 all eliminate Laves phase by two-stage homogenization heat treatment. And the average grain size of the sample obtained by the two-stage heat treatment is smaller than that of the sample obtained by the one-stage heat treatment alone.

In summary, within the scope of the present invention, the heat treatment method of the present invention is capable of refining grains while dissolving the Laves phase.

Claims

1. A pre-forging heat treatment method of a nickel-based alloy arc fuse additive prefabricated member is characterized by comprising the following steps of: the method specifically comprises the following steps:

2. The method according to claim 1, characterized in that: the temperature of the first-stage heat treatment is 850-980 ℃.

3. The method according to claim 1, characterized in that: the heating rate adopted by the first-stage heat treatment is 5-100 ℃/min.

4. The method according to claim 1, characterized in that: the time of the first-stage heat treatment is 6-48 h.

5. The method according to claim 1, characterized in that: the temperature of the second-stage heat treatment is 1050-1250 ℃.

6. The method according to claim 1, characterized in that: the temperature rising rate adopted by the second-stage heat treatment is 5-100 ℃/min.

7. The method according to claim 1, characterized in that: the time of the second-stage heat treatment is 0.5-5 h.