GH4742 alloy hot working method

Abstract

The invention provides a GH4742 alloy hot working method, and relates to the field of hot working, the method comprises the following steps: obtaining a GH4742 alloy blank; carrying out hot working on the GH4742 alloy blank according to a preset deformation thermal parameter range; wherein the preset deformation thermal parameter range comprises a deformation temperature range and a strain rate range; the deformation temperature ranges from 1080 DEG C to 1160 DEG C; the strain rate ranges from 0.001 s <-1 > to 1 s <-1 >. The method is suitable for a GH4742 alloy hot working process and is used for providing a reasonable GH4742 alloy hot working process system.

Description

Technical Field

[0001] The present application relates to the field of thermal processing, specifically to the field of thermal processing of marine parts and aircraft parts, and in particular to a method for thermal processing of GH4742 alloy. Background Art

[0002] GH4742 alloy is a precipitation-strengthened nickel-based deformable high-temperature alloy with a volume fraction of γ' phase exceeding 35%. It contains a certain amount of solid solution strengthening elements such as Mo, Cr, Co, W, V, and grain boundary strengthening elements such as La, B, Ce, and C. It has excellent resistance to hot corrosion of fuel gas and high temperature resistance. It is widely used in the manufacture of key components such as large integral turbine disks of marine gas turbines and aircraft engines.

[0003] Therefore, how to design the hot working process system of GH4742 alloy has become our need. Summary of the invention

[0004] The present application provides a GH4742 alloy heat processing method, which is used to provide a reasonable GH4742 alloy heat processing process system.

[0005] In a first aspect, the present application provides a GH4742 alloy hot working method, the method comprising: obtaining a GH4742 alloy billet; hot working the GH4742 alloy billet according to a preset deformation thermomechanical parameter range; wherein the preset deformation thermomechanical parameter range includes a deformation temperature range and a strain rate range; the deformation temperature range is 1080°C to 1160°C; the strain rate range is 0.001s -1 To 1s -1 .

[0006] Optionally, the preset deformation thermal parameter range includes a first parameter range, the first parameter range is 1080°C to 1160°C, 0.001s -1 To 0.018 -1 ; Hot processing the GH4742 alloy billet according to a preset deformation thermomechanical parameter range, including: hot processing the GH4742 alloy billet according to a first parameter range.

[0007] Optionally, the preset deformation thermal parameter range includes a second parameter range, the second parameter range is 1080°C to 1160°C, 0.018s -1 to 1 -1 ; Hot processing the GH4742 alloy billet according to a preset deformation thermomechanical parameter range, including: hot processing the GH4742 alloy billet according to a second parameter range.

[0008] Optionally, the method also includes: performing an isothermal constant strain rate compression test on the GH4742 alloy sample to obtain a power dissipation diagram and an instability diagram of the GH4742 alloy sample; the power dissipation diagram is used to represent the change of the GH4742 alloy sample with the deformation temperature and strain rate; the instability diagram is used to represent the change of the instability parameters of the GH4742 alloy sample with the deformation temperature and strain rate; according to the power dissipation diagram and the instability diagram, determining the processing diagram of the GH4742 alloy sample; according to the processing diagram, determining the preset deformation thermal parameter range.

[0009] Optionally, according to the processing diagram, a preset deformation thermal parameter range is determined, including: according to the processing diagram, determining a first window corresponding to a relatively sufficient dynamic recrystallization structure and a second window corresponding to a complete dynamic recrystallization structure; and taking the union of the deformation thermal parameter ranges corresponding to the first window and the second window as the preset deformation thermal parameter range.

[0010] Optionally, the method further includes: determining, according to the processing diagram, a third window corresponding to the unstable tissue and a fourth window corresponding to the transitional tissue.

[0011] Optionally, an isothermal constant strain rate compression test is performed on the GH4742 alloy sample, including: obtaining multiple temperature points and multiple strain rate points; compressing the GH4742 alloy sample at a height reduction rate of 60% under different combinations of temperature points and strain rate points, and naturally cooling to room temperature after compression; cutting the cooled sample in half, and observing the microstructure after grinding, polishing and etching.

[0012] Optionally, a plurality of temperature points are obtained, including: in the range of 950° C. to 1160° C., a temperature point is taken at intervals of 35° C. to obtain a plurality of temperature points.

[0013] Optionally, multiple strain rate points are acquired, including: -1 To 1s -1 In the interval, a strain rate point is taken every order of magnitude to obtain multiple strain rate points.

[0014] It should be understood that the experiment on GH4742 alloy shows that the optimal deformation thermomechanical parameter window conditions are roughly between deformation temperature 1080~1160℃ and strain rate 0.018~1s -1 The best deformation thermomechanical parameter window conditions are roughly deformation temperature 1080~1160℃, strain rate 0.001~0.018s -1 Better dynamic recrystallization can occur when hot working GH4742 alloy is performed within these two window conditions.

[0015] The GH4742 alloy hot working method provided in this application can set the deformation temperature range to 1080°C to 1160°C; the strain rate range to 0.001s -1 To 1s -1 The preset deformation thermomechanical parameter range, within which hot working can produce better dynamic recrystallization, thus providing a reasonable hot working process system for GH4742 alloy.

[0016] In a second aspect, the present application provides a GH4742 alloy hot-processed product, which is obtained by using the GH4742 alloy hot-processing method described in the first aspect above.

[0017] The beneficial effects of the second aspect above can be referred to those described in the first aspect above and will not be elaborated on again. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic diagram of the original structure of the GH4742 alloy provided in the embodiment of the present application; Figure 2 Flow stress curves of the GH4742 alloy provided in the embodiments of the present application at different strain rates when the deformation temperatures are 985°C and 1090°C; Figure 3 A schematic diagram showing the effect of deformation temperature and strain rate on power dissipation efficiency under different strains provided in an embodiment of the present application; Figure 4 The three-dimensional power dissipation diagram of GH4742 alloy under different strains provided in the embodiments of the present application; Figure 5 A schematic diagram of the variation of the instability parameters with deformation temperature and strain rate provided in the embodiment of the present application; Figure 6 The three-dimensional instability diagram of the GH4742 alloy under different strains provided in the embodiment of the present application; Figure 7 Processing diagram of GH4742 alloy under different strains provided in the embodiments of the present application; Figure 8 A schematic diagram of deformation thermomechanical parameter window conditions for different deformation structures of GH4742 alloy provided in the embodiments of the present application; Fig. 9A schematic diagram of the unstable deformation structure under different deformation thermomechanical parameters and a high reduction rate of 60% provided in the embodiment of the present application; Fig.10 A schematic diagram of the transition structure under different deformation thermomechanical parameters and a high reduction rate of 60% provided in the embodiment of the present application; Fig.11 A schematic diagram of a relatively complete dynamic recrystallization structure under different deformation thermomechanical parameters and a high reduction rate of 60% provided in an embodiment of the present application; Fig.12 A schematic diagram of a fully dynamic recrystallized structure under different deformation thermomechanical parameters and a high reduction rate of 60% provided in an embodiment of the present application; Fig.13 A schematic flow chart of the GH4742 alloy hot working method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0021] It should be noted that, in the embodiments of the present application, words such as "exemplarily" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplarily" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplarily" or "for example" is intended to present related concepts in a specific way.

[0022] In order to facilitate the clear description of the technical solutions of the embodiments of the present application, in the embodiments of the present application, the words "first", "second", etc. are used to distinguish the same items or similar items with basically the same functions and effects. Those skilled in the art can understand that the words "first", "second", etc. are not limiting the quantity and execution order.

[0023] GH4742 alloy is a precipitation-strengthened nickel-based deformable high-temperature alloy with a volume fraction of γ' phase exceeding 35%. It contains a certain amount of solid solution strengthening elements such as Mo, Cr, Co, W, V, and grain boundary strengthening elements such as La, B, Ce, and C. It has excellent resistance to hot corrosion of fuel gas and high temperature resistance. It is widely used in the manufacture of key components such as large integral turbine disks of marine gas turbines and aircraft engines.

[0024] Therefore, how to design the hot working process system of GH4742 alloy has become our need.

[0025] In order to study the hot working process system of GH4742 alloy, experiments and analysis can be carried out on GH4742 alloy, mainly including the following parts: (1) Experimental materials.

[0026] The experimental material is GH4742 (high temperature) alloy, and its composition (mass fraction, %) is: C 0.04-0.08, Cr 13.0-15.0, Mo 4.5-5.5, Co 9.0-11.0, Al 2.4-2.8, Ti 2.4-2.8, Nb 2.4-2.8, Ni balance.

[0027] For example, Figure 1 The original structure diagram of the GH4742 alloy provided in the embodiment of the present application is shown in FIG. Figure 1 As shown in the figure, the original structure of the GH4742 alloy material is relatively uniform, with an average grain size of about 120 microns (μm), and a certain amount of granular second phase exists near the grain boundary.

[0028] (2) Experimental methods

[0029] The isothermal constant strain rate compression test was carried out using a Gleeble-3550 thermal simulator. A cylindrical GH4742 alloy specimen with a diameter of 8 mm and a height of 12 mm was selected. In order to reduce friction and high-temperature adhesion, mica sheets were placed on both ends of the specimen before compression. The deformation temperature range was 950 degrees Celsius (℃) to 1160℃, with an interval of 35℃; the strain rate range was 0.001s -1 To 1s -1 , one order of magnitude apart; the height reduction rate is 60%. The sample is heated to different temperature points at a heating rate of 10℃ / s, and then compressed at different strain rate points after keeping warm for 5 minutes (min), and then naturally cooled to room temperature after compression. The compressed sample is cut in half along the axial direction using a wire cutting machine, ground, polished, and etched, and then the microstructure is observed on an XJP-9A metallographic microscope.

[0030] (3) Analysis of flow stress behavior.

[0031] For example, Figure 2 The flow stress curves of the GH4742 alloy provided in the embodiment of the present application at different strain rates when the deformation temperatures are 985°C and 1090°C. Since the change characteristics of the flow stress curves at deformation temperatures of 950, 1020 and 1055°C are similar to those at 985°C, the change characteristics of the flow stress curves at deformation temperatures of 1125 and 1160°C are similar to those at 1090°C. Therefore, Figure 2(a) shows the flow stress curves of GH4742 alloy at different strain rates when the deformation temperature is 985℃. Figure 2 (b) shows the flow stress curves of GH4742 alloy at different strain rates when the deformation temperature is 1090℃. Figure 2 The flow stress curves in (a) and (b) are 1s from top to bottom. -1 Flow stress curve under strain rate, 0.1s -1 Flow stress curve under strain rate, 0.01s -1 Flow stress curve under strain rate, and 0.001s -1 Flow stress curve under strain rate.

[0032] from Figure 2 It can be seen that in the initial stage of deformation, the flow stress curves under different deformation conditions all increase rapidly to the peak value; with the further increase of strain, the flow stress decreases to varying degrees, and dynamic softening occurs. The main reason is that in the initial stage of deformation, dislocations multiply quickly, dislocation density increases rapidly, and work hardening dominates, causing the flow stress to increase rapidly; as deformation continues, the accumulation of deformation energy storage promotes dynamic recovery and dynamic recrystallization to soften it, and the flow stress decreases.

[0033] from Figure 2 It can also be seen that at different deformation temperatures, the flow stress of GH4742 alloy increases with the increase of strain rate and the decrease of deformation temperature. The main reasons are: the dislocation density increases with the increase of strain rate, and the work hardening effect is enhanced; at the same time, the dynamic recovery and dynamic recrystallization softening time is shortened, which inhibits dynamic recovery and dynamic recrystallization, and increases the flow stress. With the increase of deformation temperature, the thermal activation energy of the material increases, and the dynamic recovery or dynamic recrystallization softening is enhanced; the kinetic energy of alloy atoms increases, and the sliding resistance is further reduced; and the deformation coordination between grains is improved, and the softening mechanism is obvious, which reduces the flow stress. Considering only from the perspective of reducing deformation resistance, it is more appropriate for GH4742 alloy to select higher deformation temperature and lower strain rate hot working.

[0034] (4) Theoretical analysis of processing diagrams The dynamic material model can be regarded as a bridge between the mechanics of large plastic flow continuum and the evolution of dissipative microstructure. According to the theory of dynamic material model, the mechanical power absorbed by the unit volume of the component during hot working can be dissipated in two ways: Formula (1) In formula (1), It indicates the mechanical power absorbed per unit volume of a component during hot working. represents flow stress. Represents the equivalent strain rate. represents the power dissipation caused by plastic deformation, . It indicates the power dissipation related to the microstructure evolution during deformation, such as superplastic deformation, dynamic recrystallization, dynamic recovery, etc. It can also be called power dissipation coefficient. It can be expressed as the following formula (2): Formula (2) So the strain rate sensitivity index Decided exist and distribution between.

[0035] definition is the power dissipation efficiency, To express, then It can be expressed as the following formula (3): Formula (3) is a dimensionless parameter that represents the relative entropy generation rate due to microstructural evolution, which forms a power dissipation diagram as a function of deformation temperature and strain rate. The high-value region has more energy for microstructure evolution and often corresponds to the region with better plastic processing performance.

[0036] Considering the power dissipation coefficient It is related to the evolution of the microstructure of the metallurgical process. According to the irreversible thermodynamic extreme principle of large plastic flow continuum mechanics, the criterion for the flow instability of the material can be expressed as the following formula (4): Formula (4) In formula (4), represents the instability parameter, that is, when formula (4) is satisfied, plastic flow instability deformation will occur. The instability parameter in formula (4) is The instability diagram is formed as the deformation temperature and strain rate change, and the processing diagram is constructed by superimposing the instability diagram on the power dissipation diagram.

[0037] (5) Power dissipation efficiency.

[0038] Using the GH4742 alloy compression test data, the power dissipation efficiency can be calculated according to the above formula (3): .

[0039] For example, Figure 3This is a schematic diagram of the effect of deformation temperature and strain rate on power dissipation efficiency under different strains provided in the embodiments of the present application. Figure 3 As shown in (a), the influence of deformation temperature and strain rate on power dissipation efficiency under a strain of 0.1; Figure 3 As shown in (b), the influence of deformation temperature and strain rate on power dissipation efficiency under a strain of 0.3; Figure 3 As shown in (c), the influence of deformation temperature and strain rate on power dissipation efficiency under a strain of 0.5; Figure 3 As shown in (d) in the figure, the influence of deformation temperature and strain rate on power dissipation efficiency under a strain of 0.7; Figure 3 As shown in (e), the influence of deformation temperature and strain rate on power dissipation efficiency under a strain of 0.92.

[0040] from Figure 3 It can be seen that the power dissipation efficiency It changes significantly with the deformation temperature, strain rate and strain, indicating It is very sensitive to deformation thermal parameters. Figure 3 It can also be seen that under different strain conditions, with the increase of deformation temperature and the decrease of strain rate, The overall trend is increasing; especially when the strain rate is high, The trend of increasing with increasing deformation temperature is more significant. The main reason may be that under high temperature and low strain rate conditions, the alloy is more likely to undergo dynamic recovery and dynamic recrystallization, so more energy is dissipated in the evolution of the microstructure, making Higher.

[0041] For example, Figure 4 The three-dimensional power dissipation diagram of GH4742 alloy under different strains provided in the embodiment of the present application. One axis of the three-dimensional power dissipation diagram is the lg value of the strain rate, the other axis is the temperature / ℃, and the third axis is the power dissipation rate. Figure 4 As shown in (a), it is a three-dimensional power dissipation diagram under a strain of 0.1; Figure 4 As shown in (b), it is a three-dimensional power dissipation diagram under a strain of 0.3; Figure 4 As shown in (c), it is a three-dimensional power dissipation diagram under a strain of 0.5; Figure 4 As shown in (d) in the figure, it is a three-dimensional power dissipation diagram under a strain of 0.7; Figure 4 (e) shows the three-dimensional power dissipation diagram under a strain of 0.92.

[0042] from Figure 4 It can be seen that when the strain is small ( Figure 4 (a) and (b) in The higher area is mainly concentrated in the high deformation temperature range; deformation temperature 985℃, strain rate, The value is also high, indicating that under this deformation thermal parameter condition, more energy is dissipated in the evolution of the microstructure. Figure 4 (c), (d), (e)), power dissipation efficiency The higher area is mainly concentrated in the high deformation temperature and low strain rate range; the main reason may be that when the deformation temperature is high and the strain rate is low, dynamic recrystallization is more likely to occur, so When the strain rate is high, dynamic recrystallization is difficult to occur, and the deformation heat effect and temperature effect are more obvious, and the energy converted into viscoplastic heat increases, resulting in However, when the deformation temperature is 1125~1160℃ and the strain rate is 0.001s-1, The phenomenon is relatively low, and its value is only about 0.05; the main reason may be that under this deformation condition, when the strain is small, the alloy undergoes dynamic recrystallization, and then due to the high deformation temperature and low strain rate, the dynamic recrystallization grains grow, and the energy consumed in the growth process is relatively small, so Lower.

[0043] (6) Instability parameters.

[0044] Using the GH4742 alloy compression test data, the instability parameter can be calculated according to formula (4): The value of .

[0045] For example, Figure 5 Schematic diagram of the variation of the instability parameters with deformation temperature and strain rate provided in the embodiment of the present application. Figure 5 The instability parameter of the horizontal dashed line is 0. Figure 5 As shown in (a), the influence of deformation temperature and strain rate on the instability parameters under the strain of 0.1; Figure 5 As shown in (b), the influence of deformation temperature and strain rate on the instability parameters under the strain of 0.3; Figure 5 As shown in (c), the influence of deformation temperature and strain rate on the instability parameters under the strain of 0.5; Figure 5 As shown in (d) in the figure, the influence of deformation temperature and strain rate on the instability parameters under the strain of 0.7; Figure 5 As shown in (e), the influence of deformation temperature and strain rate on the instability parameters under the strain of 0.92.

[0046] from Figure 5 It can be seen that The value changes significantly with the change of deformation thermal parameters, indicating The value is also very sensitive to the deformation thermal parameters. Figure 5 It can also be seen that when the deformation temperature is higher and the strain rate is lower, The value is mostly greater than 0; when the deformation temperature is low and the strain rate is high, The values ​​are mostly less than 0, indicating that low deformation temperature and high strain rate deformation are more likely to cause plastic instability.

[0047] For example, Figure 6 The three-dimensional instability diagram of the GH4742 alloy under different strains provided in the embodiment of the present application. One axis of the three-dimensional instability diagram is the lg value of the strain rate, the other axis is the temperature, and the third axis is the power dissipation rate. Figure 6 As shown in (a), it is a three-dimensional instability diagram under a strain of 0.1; Figure 6 As shown in (b), it is the three-dimensional instability diagram under the strain of 0.3; Figure 6 As shown in (c) in the figure, it is a three-dimensional instability diagram under a strain of 0.5; Figure 6 As shown in (d) in the figure, it is a three-dimensional instability diagram under a strain of 0.7; Figure 6 (e) in the figure shows the three-dimensional instability diagram under a strain of 0.92.

[0048] from Figure 6 It can be seen that under different strain conditions, the instability parameter The lower value areas are mainly concentrated in the low deformation temperature and high strain rate range, indicating that under this deformation thermomechanical parameter condition, the energy dissipated in viscoplastic heat is high, that is, the power dissipation G is high, and the lattice distortion can be maintained at a high level at this time, resulting in microstructural defects and distortion, and inhibiting the generation of dynamic recovery and dynamic recrystallization; while the instability parameter The higher value areas are mainly concentrated in the high deformation temperature and low strain rate range. There is a clear physical meaning, that is, the rate at which the system generates entropy should at least match the rate at which external entropy is applied, otherwise local flow will occur, leading to flow instability; that is, The smaller the value, the easier it is to produce plastic flow instability. This shows that in order to obtain defect-free components of GH4742 alloy, it is advisable to select higher deformation temperature and lower strain rate for hot working.

[0049] (7) Optimization of processing diagram and deformation thermal parameters.

[0050] The instability diagram is superimposed on the power dissipation diagram to form the processing diagram.

[0051] For example, Figure 7 The processing diagram of GH4742 alloy under different strains provided in the embodiment of the present application. Figure 7 As shown in (a), it is the processing diagram under the strain of 0.1; Figure 7 As shown in (b), it is the processing diagram under the strain of 0.3; Figure 7 As shown in (c), it is the processing diagram under the strain of 0.5; Figure 7 As shown in (d) in the figure, it is the processing diagram under the strain of 0.7; Figure 7 (e) in the figure shows the processing diagram under a strain of 0.92.

[0052] Figure 7 The curve in the figure is the power dissipation efficiency The contour lines of value; Figure 7 The shaded area in the figure is the unstable deformation area, while the other areas are the stable deformation areas. Figure 7 It can be seen that with the increase of deformation, the instability zone tends to increase; in addition, the instability zone mainly appears in the low temperature zone below 1055℃; with the increase of strain rate, the deformation temperature range of the instability zone increases towards the high temperature zone.

[0053] from Figure 7 It can also be seen that the power dissipation diagrams under different deformation amounts have roughly the same characteristics. The value is less than 0.3, and the deformation temperature is higher than 1055℃ The value is mostly greater than 0.3, and there are two obvious power dissipation efficiency pattern characteristics in this area, namely Figure 7 As shown in window I and window II of (e) in FIG. For the power dissipation efficiency pattern of window I, the power dissipation efficiency value is mostly greater than 0.35, and The value gradually increases toward the center of the pattern, which means that more obvious dynamic recrystallization occurs in this window area; because dynamic recrystallization nucleation requires a large amount of power dissipation, and the strain rate in this window area is high, more energy is dissipated per unit time under the same deformation amount, which may be the reason for its The reason why the power dissipation efficiency pattern of window II is relatively large and gradually increases towards the center of the pattern. The value gradually decreases from 0.35 toward the center of the pattern, which means that complete dynamic recrystallization has occurred in this window area, and the dynamic recrystallization grains have obvious growth. Since the driving force for the growth of dynamic recrystallization grains comes from the reduction of the total free energy of the system after the grain boundary moves, and the strain rate in this window area is low, the energy dissipated per unit time is less under the same deformation amount, which may be its The reason why the value decreases gradually from 0.35 toward the center of the pattern. Figure 7 Zone III marked in (e) is the area outside the unstable zone and zones I and II. The deformation structure of this area is uncertain, and both unstable and stable structures may appear.

[0054] According to the processing diagram and its analysis, under the deformation thermomechanical parameter conditions studied, the deformation microstructure of GH4742 alloy can be roughly divided into instability deformation structure (Instability microstructure), transitional structure (Transitional microstructure), relatively fully dynamic recrystallization (Dynamic Recrystallization, DRX) structure (Relatively fully DRX microstructure) and fully dynamic recrystallization structure (Fully DRXmicrostructure).

[0055] For example, Figure 8 Schematic diagram of deformation thermomechanical parameter window conditions for different deformation structures of GH4742 alloy provided in the embodiment of the present application. Figure 8 As shown in the figure, the window conditions corresponding to each type of deformed tissue are as follows: Unstable deformation structure: Its deformation thermomechanical parameter window condition is roughly 950℃ to 20 (lg (strain rate) + 54)℃, 0.001s -1 To 1s -1 This window condition is a harmful processing area, and hot processing in this area should be avoided in actual production.

[0056] Transition structure: Its deformation thermomechanical parameter window condition is roughly 20 (lg (strain rate) + 54) ℃ to 1080 ℃, 0.001s -1 To 1s -1 Only a small amount of dynamic recrystallization may occur during hot working in this area, and even unstable structure may occur. Therefore, it is generally not advisable to perform hot working under the conditions of this deformation thermomechanical parameter window.

[0057] More fully dynamically recrystallized structure: its deformation thermomechanical parameter window conditions are roughly 1080℃ to 1160℃, 0.018s -1 To 1s -1 This window condition is the best hot working area. Hot working in this area can cause sufficient dynamic recrystallization behavior, which reduces the flow stress (see Figure 2 ), the alloy exhibits good plastic deformation ability and can obtain a more sufficient dynamic recrystallization structure.

[0058] Complete dynamic recrystallization structure: its deformation thermomechanical parameter window condition is roughly 1080℃ to 1160℃, 0.001s -1 To 0.018s -1This window condition is the optimal hot working area. Hot working in this area can cause complete dynamic recrystallization, which significantly reduces the flow stress (see Figure 2 ), the alloy exhibits good plastic deformation ability and can obtain a complete dynamic recrystallization structure.

[0059] (8) Verification of processing diagram prediction results.

[0060] In order to verify the accuracy and reliability of the unstable deformation, transition deformation, optimal deformation and optimal deformation thermal parameter window conditions determined by the above-mentioned processing map technology, the deformation microstructure under different conditions is observed and analyzed.

[0061] For example, Fig. 9 Schematic diagram of unstable deformation structure under different deformation thermomechanical parameters with a high reduction rate of 60% provided in the embodiment of the present application.

[0062] like Fig. 9 (a) shows the GH4742 alloy at a high reduction rate of 60%, 950℃, 0.1s -1 Schematic diagram of the unstable deformation organization under these conditions. Under these conditions, the deformed microstructure shows obvious adiabatic shear phenomenon.

[0063] like Fig. 9 (b) shows the GH4742 alloy at a high reduction rate of 60%, 1055℃, 1s -1 Schematic diagram of the unstable deformation organization under these conditions. Under these conditions, the deformed microstructure shows obvious local flow (Flow localization) phenomenon.

[0064] from Fig. 9 It can be seen that the plastic deformation mechanism occurring within the thermomechanical parameter window of unstable microstructure deformation is mainly adiabatic shear and local flow. At the same time, since most of the energy of adiabatic shear deformation is dissipated in the plastic flow zone in the form of heat energy, Also lower. Fig. 9 The results also show that the unstable microstructure deformation thermomechanical parameter window conditions predicted by the processing map are correct. Adiabatic shear and local flow will lead to uneven deformation, reduce the plastic deformation capacity of the alloy, cause uneven microstructure and performance, and be harmful to plastic processing. Therefore, hot processing should be avoided in the unstable microstructure deformation thermomechanical parameter window area.

[0065] For example, Fig.10 This is a schematic diagram of the transition structure under different deformation thermomechanical parameters with a high reduction rate of 60% provided in the embodiment of the present application.

[0066] like Fig.10(a) shows the GH4742 alloy at a high reduction rate of 60%, 1055℃, 0.01s -1 Schematic diagram of transitional organization in the case of Fig.10 (b) shows the GH4742 alloy at a high reduction rate of 60%, 1055℃, 0.001s -1 Schematic diagram of the transition organization in this case.

[0067] from Fig.10 It can be seen that slight adiabatic shear or local flow appeared in the deformed microstructure under these two conditions; in addition, obvious DRX small grains appeared near the flattened original austenite grain boundaries. This shows that the deformation mechanism in the transitional microstructure deformation thermomechanical parameter window is a mixture of adiabatic shear / local flow and DRX deformation mechanisms. Fig.10 The results also show that the transition structure deformation thermomechanical parameter window conditions predicted by the processing diagram are correct. Since hot working in the transition structure deformation thermomechanical parameter window area may only cause a small amount of dynamic recrystallization, the deformation resistance is large, and a certain degree of adiabatic shear or local flow instability may occur, it is not advisable to choose to perform hot working in this deformation thermomechanical parameter window area.

[0068] For example, Fig.11 This is a schematic diagram of a relatively complete dynamic recrystallization structure under different deformation thermomechanical parameter conditions with a high reduction rate of 60% provided in an embodiment of the present application.

[0069] like Fig.11 (a) shows the GH4742 alloy at a high reduction rate of 60%, 1090℃, 1s -1 Schematic diagram of a more complete dynamic recrystallization structure under the condition; Fig.11 (b) shows the GH4742 alloy at a high reduction rate of 60%, 1160℃, 0.1s -1 Schematic diagram of a more complete dynamic recrystallization structure under the condition.

[0070] from Fig.11 It can be seen that in addition to the clearly visible dynamic recrystallized grains (DRX grains), subgrains are vaguely visible, which means that there is both dynamic recrystallization and dynamic recovery behavior during the deformation process; that is, the deformation mechanism in this window area is mainly dynamic recrystallization and dynamic recovery, which shows that the more sufficient dynamic recrystallization deformation thermomechanical parameter window conditions predicted by the processing diagram are correct. The more sufficient dynamic recrystallization deformation thermomechanical parameter window is the best hot working condition, and hot working can be selected under this window condition.

[0071] For example, Fig.12This is a schematic diagram of the complete dynamic recrystallization structure under different deformation thermomechanical parameters with a high reduction rate of 60% provided in the embodiment of the present application.

[0072] like Fig.12 (a) shows the GH4742 alloy at a high reduction rate of 60%, 1090℃, 0.001s -1 Schematic diagram of the complete dynamic recrystallization structure under the condition; Fig.12 (b) shows the GH4742 alloy at a high reduction rate of 60%, 1160℃, 0.01s -1 Schematic diagram of the fully dynamic recrystallization structure under the condition.

[0073] from Fig.12 It can be seen that under these deformation conditions, complete dynamic recrystallization behavior occurred, and the size of the dynamic recrystallized grains grew to a certain extent with the increase of deformation temperature and the decrease of strain rate, especially at 1160℃ / 0.001s -1 The grain growth is more obvious under these conditions. Fig.12 The results show that the thermodynamic parameter window conditions of complete dynamic recrystallization deformation predicted by the processing map are correct. Dynamic recrystallization is a beneficial deformation mechanism in plastic processing. It can eliminate the original metallurgical defects through grain reconstruction, significantly reduce the flow stress, and thus significantly improve the plastic deformation capacity of the alloy. Therefore, the thermodynamic parameter window of complete dynamic recrystallization deformation is the best hot working condition, and actual hot working should be carried out under this window condition as much as possible.

[0074] Based on the understanding of the above embodiments, an embodiment of the present application provides a GH4742 alloy hot working method. Fig.13 The following is a schematic diagram of the process of hot working of GH4742 alloy provided in the embodiment of the present application. Fig.13 As shown, the method includes the following steps: S101. Obtain GH4742 alloy billet.

[0075] For example, as described in the experimental materials section (1) above, the composition (mass fraction, %) of the GH4742 alloy billet is: C 0.04-0.08, Cr 13.0-15.0, Mo 4.5-5.5, Co 9.0-11.0, Al 2.4-2.8, Ti 2.4-2.8, Nb 2.4-2.8, Ni balance.

[0076] S102, hot processing is performed on the GH4742 alloy billet according to a preset deformation thermal parameter range.

[0077] The preset deformation thermal parameter range includes deformation temperature range and strain rate range. The deformation temperature range is 1080℃ to 1160℃; the strain rate range is 0.001s -1 To 1s -1 .

[0078] It can be understood that the preset deformation thermomechanical parameter range is the deformation thermomechanical parameter range represented by the union of the window corresponding to the relatively sufficient dynamic recrystallization structure and the window corresponding to the complete dynamic recrystallization structure.

[0079] In a possible implementation, hot working can be performed within the range of deformation thermomechanical parameters represented by the window corresponding to the more fully dynamically recrystallized structure. In this case, the preset deformation thermomechanical parameter range may include a first parameter range, wherein the first parameter range is 1080°C to 1160°C, 0.001s -1 To 0.018 -1 The above S102 may specifically include: hot working the GH4742 alloy billet according to the first parameter range.

[0080] In another possible implementation, hot working can also be performed in the deformation thermomechanical parameter range represented by the window corresponding to the fully dynamically recrystallized structure. In this case, the preset deformation thermomechanical parameter range may include a second parameter range, and the second parameter range is 1080°C to 1160°C, 0.018s -1 to 1 -1 The above S102 may specifically include: hot working the GH4742 alloy billet according to the second parameter range.

[0081] It should be understood that the above experiments on GH4742 alloy show that the optimal deformation thermomechanical parameter window conditions are roughly between deformation temperature 1080~1160℃ and strain rate 0.018~1s -1 The best deformation thermomechanical parameter window conditions are roughly deformation temperature 1080~1160℃, strain rate 0.001~0.018s -1 Better dynamic recrystallization can occur when hot working GH4742 alloy is performed within these two window conditions.

[0082] The GH4742 alloy hot working method provided in the embodiment of the present application can set the deformation temperature range to 1080°C to 1160°C; the strain rate range to 0.001s -1 To 1s -1 The preset deformation thermomechanical parameter range, within which hot working can produce better dynamic recrystallization, thus providing a reasonable hot working process system for GH4742 alloy.

[0083] In some possible embodiments, before the above S101, a preset deformation thermal parameter range may be experimentally determined. In this case, before the above S101, the method may further include the following steps: Step 1: Perform an isothermal constant strain rate compression test on the GH4742 alloy sample to obtain a power dissipation diagram and an instability diagram of the GH4742 alloy sample.

[0084] The power dissipation diagram is used to show the variation of the GH4742 alloy specimen with deformation temperature and strain rate. The instability diagram is used to show the variation of the instability parameters of the GH4742 alloy specimen with deformation temperature and strain rate.

[0085] In a possible implementation, the above step 1 may specifically include: Step 1.1, obtain multiple temperature points and multiple strain rate points.

[0086] For example, a plurality of temperature points may be obtained by taking a temperature point at intervals of 35° C. within a range of 950° C. to 1160° C.

[0087] Exemplarily, the multiple temperature points may specifically include: 950°C, 985°C, 1020°C, 1055°C, 1090°C, 1125°C and 1160°C.

[0088] For example, you can use 0.001s -1 To 1s -1 In the interval, a strain rate point is taken every order of magnitude to obtain multiple strain rate points.

[0089] For example, the multiple strain rate points may specifically include: 0.001s -1 , 0.1s -1 , and 1s -1 .

[0090] Step 1.2: Under different combinations of temperature and strain rate points, the GH4742 alloy sample is compressed at a height reduction rate of 60%, and then naturally cooled to room temperature after compression.

[0091] Step 1.3: Cut the cooled sample in half, grind, polish and etch it, and then observe the microstructure.

[0092] Step 2: Determine the processing diagram of the GH4742 alloy sample based on the power dissipation diagram and the instability diagram.

[0093] Step 3: Determine the preset deformation thermal parameter range according to the processing drawing.

[0094] In a possible implementation, the above step 3 may specifically include the following steps: Step 3.1: According to the processing diagram, determine the first window corresponding to the relatively sufficient dynamic recrystallization structure and the second window corresponding to the complete dynamic recrystallization structure.

[0095] Step 3.2: The union of the deformation thermal parameter ranges corresponding to the first window and the second window is used as the preset deformation thermal parameter range.

[0096] In some possible embodiments, the method may further include: determining a third window corresponding to the unstable structure and a fourth window corresponding to the transitional structure according to the processing diagram, so as to avoid performing thermal processing within the deformation thermal parameter range corresponding to the third window and the fourth window.

[0097] The specific process of steps 1 to 3 and determining the third window and the fourth window can refer to the above-mentioned experiment and analysis of GH4742 alloy, which will not be repeated here.

[0098] The above is an introduction to the technical solution provided by the embodiment of the present application from the perspective of the method. In an exemplary embodiment, the embodiment of the present application also provides a GH4742 alloy hot-working product, which is obtained by using the GH4742 alloy hot-working method provided in the above method embodiment.

[0099] Based on the understanding of the above embodiments, the following conclusions can be drawn: (1) The flow stress of GH4742 alloy is sensitive to deformation temperature and strain rate, and its value increases with the decrease of deformation temperature and the increase of strain rate. Selecting higher deformation temperature and lower strain rate conditions for hot working can significantly reduce the deformation resistance.

[0100] (2) The deformation thermomechanical parameters have a significant effect on the power dissipation efficiency and instability parameters of GH4742 alloy. With the increase of deformation temperature and the decrease of strain rate, the power dissipation efficiency generally increases; at low deformation temperature and high strain rate, the instability parameters are generally small.

[0101] (3) The processing diagrams of GH4742 alloy under different strains were constructed. The thermal parameter window of unstable microstructure deformation is roughly between deformation temperature 950~20 (lg (strain rate) + 54) ℃ and strain rate 0.001~1s -1 The main instability phenomena are adiabatic shear and local flow. The thermal parameter window of transitional microstructure deformation is roughly between deformation temperature 20 (lg (strain rate) + 54) ~ 1080 °C and strain rate 0.001 ~ 1s -1 In this area, only a small amount of dynamic recrystallization may occur, and even plastic instability may occur. (4) Based on the processing diagram, the optimal deformation thermomechanical parameter window conditions of GH4742 alloy are determined to be roughly between deformation temperature 1080~1160℃ and strain rate 0.018~1s -1 The best deformation thermomechanical parameter window conditions are roughly deformation temperature 1080~1160℃, strain rate 0.001~0.018s -1 range, in which hot working can cause complete dynamic recrystallization.

[0102] (5) The organizational verification results show that the deformation thermomechanical parameter window conditions and the optimized deformation thermomechanical parameter range predicted based on the dynamic material model and processing map technology are correct.

[0103] Although the present application has been described in conjunction with specific features and embodiments thereof, it is obvious that various modifications and combinations may be made thereto without departing from the spirit and scope of the present application. Accordingly, this specification and the drawings are merely exemplary illustrations of the present application as defined by the appended claims, and are deemed to have covered any and all modifications, variations, combinations or equivalents within the scope of the present application. Obviously, those skilled in the art may make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

[0104] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A GH4742 alloy hot working method, characterized in that: The method comprises: Obtain GH4742 alloy billet; Hot working the GH4742 alloy billet according to a preset deformation thermomechanical parameter range; The preset deformation thermal parameter range includes a deformation temperature range and a strain rate range; the deformation temperature range is 1080°C to 1160°C; the strain rate range is 0.001s -1 To 1s -1 .

2. The method according to claim 1, characterized in that The preset deformation thermal parameter range includes a first parameter range, the first parameter range is 1080°C to 1160°C, 0.001s -1 To 0.018 -1 ; The hot working of the GH4742 alloy blank according to the preset deformation thermomechanical parameter range comprises: The GH4742 alloy billet is hot worked according to the first parameter range.

3. The method according to claim 1, characterized in that The preset deformation thermal parameter range includes a second parameter range, and the second parameter range is 1080°C to 1160°C, 0.018s -1 to 1 -1 ; The hot working of the GH4742 alloy blank according to the preset deformation thermomechanical parameter range comprises: The GH4742 alloy billet is hot worked according to the second parameter range.

4. The method according to claim 1, characterized in that The method further comprises: An isothermal constant strain rate compression test is performed on the GH4742 alloy sample to obtain a power dissipation diagram and an instability diagram of the GH4742 alloy sample; the power dissipation diagram is used to indicate the change of the GH4742 alloy sample with deformation temperature and strain rate; the instability diagram is used to indicate the change of the instability parameter of the GH4742 alloy sample with deformation temperature and strain rate; Determining a processing diagram of the GH4742 alloy sample according to the power dissipation diagram and the instability diagram; According to the processing diagram, the preset deformation thermal parameter range is determined.

5. The method according to claim 4, characterized in that Determining the preset deformation thermal parameter range according to the processing diagram includes: According to the processing diagram, determining a first window corresponding to a relatively sufficient dynamic recrystallization structure and a second window corresponding to a complete dynamic recrystallization structure; The union of the deformation thermal parameter ranges corresponding to the first window and the second window is used as the preset deformation thermal parameter range.

6. The method according to claim 5, characterized in that The method further comprises: According to the processing diagram, a third window corresponding to the unstable tissue and a fourth window corresponding to the transitional tissue are determined.

7. The method according to claim 4, characterized in that The isothermal constant strain rate compression test on the GH4742 alloy sample comprises: Obtain multiple temperature points and multiple strain rate points; Under different combinations of temperature points and strain rate points, the GH4742 alloy sample is compressed at a height reduction rate of 60%, and then naturally cooled to room temperature after compression; The cooled specimens were cut in half and the microstructure was observed after grinding, polishing and etching.

8. The method according to claim 7, characterized in that The obtaining of multiple temperature points includes: In the range of 950° C. to 1160° C., a temperature point is taken at every 35° C. interval to obtain the plurality of temperature points.

9. The method according to claim 7, characterized in that: The obtaining of multiple strain rate points comprises: In 0.001s -1 To 1s -1 In the interval, a strain rate point is taken every order of magnitude to obtain the multiple strain rate points.

10. A GH4742 alloy hot-working product, characterized in that: The GH4742 alloy hot-processed product is obtained by hot processing using the method described in any one of claims 1 to 9.

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