A composite heat treatment process and heat treatment device for reducing the cracking tendency of a component

Abstract

The present application relates to a kind of composite heat treatment process and heat treatment device for reducing the cracking tendency of component, belong to additive manufacturing technical field, solve the problem that existing process needs special equipment and process is complicated.Composite heat treatment process includes the following steps: step 1: component is placed in the furnace body of heat treatment device;Step 2: set heat treatment process parameters;Step 3: start heat treatment device, heat component, and fill gas into furnace body to apply pressure to component;Step 4: heat preservation, cooling.The heat treatment device includes furnace body, heating unit, pressurizing unit, monitoring unit and control unit.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and in particular to a composite heat treatment process and heat treatment apparatus for reducing the cracking tendency of irregularly shaped large-sized components. Background Technology

[0002] Selective laser melting (SLM) additive manufacturing technology boasts advantages such as high energy density, high manufacturing precision, and excellent overall performance, making it particularly effective in manufacturing refractory metals and complex structures. It has been widely applied in the aerospace field. However, the high temperature gradient and residual stress accumulation during SLM forming can significantly increase the cracking tendency of high-strength alloys, especially in large and complex components, severely limiting the widespread application of this technology.

[0003] Due to the high temperature gradient and residual stress accumulation during selective laser melting (SLM), components formed using SLM additive manufacturing technology have a significantly increased tendency to crack. Therefore, SLM components need to undergo annealing heat treatment to release residual stress through deformation or even cracking. However, with the increase in component size and stress concentration caused by the distribution of characteristic structures, existing annealing heat treatments cannot effectively release the residual stress of large, complex, irregularly shaped components.

[0004] To address the aforementioned issues, existing technologies add an additional step after the annealing heat treatment process. For example, hot isostatic pressing (HIP) involves filling a sealed container with inert gas and applying it at a higher temperature (typically close to the material's forging temperature) and higher pressure (typically 100-140 MPa) to induce a metallurgical reaction in the product. This alters the product's microstructure, eliminating defects such as porosity and lack of fusion, and improving the product's density.

[0005] However, hot isostatic pressing (HIP) requires specialized equipment, which is expensive, resulting in high production costs. Furthermore, the high temperature and pressure involved in HIP lead to high energy consumption. Summary of the Invention

[0006] In view of the above analysis, the present invention aims to provide a composite heat treatment process and heat treatment device for reducing the cracking tendency of components, which can at least solve one of the following technical problems: (1) the existing process for reducing the cracking tendency of components has high energy consumption; (2) the existing process for reducing the cracking tendency of components requires special equipment, and the equipment is expensive and the production cost is high; (3) the existing process for reducing the cracking tendency of components is an additional process after the heat treatment process, and the process is cumbersome.

[0007] The objective of this invention is mainly achieved through the following technical solutions:

[0008] In a first aspect, the present invention provides a composite heat treatment process, comprising the following steps:

[0009] Step 1: Place the component inside the furnace of the heat treatment device;

[0010] Step 2: Set the heat treatment process parameters;

[0011] Step 3: Start the heat treatment device to heat the components and fill the furnace with gas to apply pressure to the components;

[0012] Step 4: Keep warm and cool.

[0013] Optionally, in step 3, the applied pressure is 20-80 MPa.

[0014] Optionally, in step 3, the heating temperature is 200-1200℃.

[0015] Optionally, in step 3, the heating rate is 5-30℃ / min.

[0016] Optionally, in step 4, the heat preservation time is 200-900 minutes.

[0017] Optionally, in step 3, the gas is an inert gas.

[0018] Optionally, the inert gas is helium and / or argon.

[0019] Optionally, in step 2, the heat treatment process parameters include heating rate, heating temperature, holding time, cooling rate, and applied pressure.

[0020] Optionally, in step 1, the component is an irregularly shaped component.

[0021] Secondly, the present invention provides a heat treatment apparatus for completing the above-mentioned composite heat treatment process, comprising a furnace body, a heating unit, a pressurizing unit, a monitoring unit, and a control unit;

[0022] The heating unit is used to heat the furnace body, the pressurizing unit is used to fill the furnace body with gas, the monitoring unit is used to detect the temperature and pressure inside the furnace body, and the control unit controls the working status of the heating unit and the pressurizing unit.

[0023] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0024] (1) The process of this invention is a novel composite heat treatment system with an external energy field. Without adding any additional processes, inert gas is introduced into the device during heat treatment to apply pressure to the component. This applied pressure resists the release of residual stress within the component during heat treatment, improving the residual stress elimination effect (resulting in lower residual stress, shorter heat treatment time, and increased efficiency), reducing the probability of component deformation and cracking, and improving product qualification rate. Specifically, components treated by the composite heat treatment process of this invention have internal residual stress reduced by more than 26% compared to those treated by existing heat treatment processes, and efficiency increased by more than 10%.

[0025] (2) Compared with hot isostatic pressing (HIP), the composite heat treatment process of this invention achieves the goal of improving residual stress elimination (resulting in lower residual stress, shorter heat treatment time, and increased efficiency) and reducing the probability of component deformation and cracking at lower temperatures (below the melting temperature of the alloy, while HIP requires temperatures close to the forging temperature of the alloy) and lower pressures (20-80 MPa, far lower than the 100-140 MPa of HIP), without any chemical reaction. Therefore, the composite heat treatment process of this invention has low energy consumption.

[0026] (3) The composite heat treatment process of the present invention only requires the addition of a pressurizing device that can apply pressure to the existing heat treatment device to realize the heat treatment process under low pressure. It does not require the purchase of special equipment, which helps to reduce production costs.

[0027] (4) This invention controls the insulation to be gradient insulation, and further ensures that the residual stress of the treated component is lower by controlling the gradient temperature, gradient segmentation method and pressure of the gradient insulation.

[0028] (5) The composite heat treatment process of the present invention applies pressure during the heat treatment process without the need for additional steps. Therefore, the process of the present invention is simple and conducive to improving production efficiency.

[0029] (6) The composite heat treatment process of the present invention is applicable to the heat treatment process of different types of additive manufacturing alloy components and has wide applicability. It is particularly suitable for the heat treatment of irregularly shaped large-sized (1m×1m×2m) alloy components.

[0030] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages will become apparent from the description or may be learned by practicing the invention. Attached Figure Description

[0031] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0032] Figure 1 This is a photograph of the component after processing, as shown in Comparative Example 1.

[0033] Figure 2 This is a photograph of the component after processing in Example 1. Detailed Implementation

[0034] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0035] In a first aspect, the present invention provides a composite heat treatment process, comprising the following steps:

[0036] Step 1: Place the components inside the furnace of the heat treatment device, center the components in the furnace, and arrange them symmetrically according to the structural characteristics of the components.

[0037] Step 2: Set the heat treatment process parameters;

[0038] Step 3: Start the heat treatment device to heat the components and fill the furnace with gas to apply pressure to the components;

[0039] Step 4: Keep warm and cool.

[0040] This invention utilizes the principle of hot isostatic pressing to perform heat treatment on large and complex high-temperature alloy components formed by laser selective melting and precipitation strengthening. By applying a certain pressure to the component, the residual stress of the component is offset, thus preventing the component from releasing stress through deformation or cracking during the heat treatment process.

[0041] In step 1, the heat treatment apparatus includes a furnace body, a heating unit, a pressurizing unit, a monitoring unit, and a control unit. The furnace body conforms to pressure vessel standards. The heating unit is used to heat the furnace body, the pressurizing unit is used to fill the furnace body with inert gas, the monitoring unit is used to detect the temperature and pressure inside the furnace body, and the control unit controls the operating status of the heating unit and the pressurizing unit. The inert gas can be, for example, helium and / or argon.

[0042] Specifically, in step 2, the heat treatment process parameters include heating rate, heating temperature, holding time, cooling rate, and applied pressure.

[0043] In step 3, during the heating process, pressure is gradually applied by filling the furnace with inert gas, so that the components are subjected to pressure while being heated.

[0044] Specifically, the heating rate is 5-30℃ / min, for example, 5℃ / min, 10℃ / min, 15℃ / min, 20℃ / min, 25℃ / min, 30℃ / min.

[0045] The heating temperature is 200-1200℃, for example, 200℃, 300℃, 400℃, 500℃, 600℃, 700℃, 800℃, 900℃, 1000℃, 1100℃, 1200℃.

[0046] The applied pressure is 20-80 MPa, for example, 20 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa.

[0047] In step 4, the heat preservation time is 200-900 minutes, for example, 200 minutes, 300 minutes, 400 minutes, 500 minutes, 600 minutes, 700 minutes, 800 minutes, and 900 minutes.

[0048] It should be noted that in step 4, the insulation is a gradient insulation, including:

[0049] Hold at 400℃ for 60-120 min (e.g., 60 min, 80 min, 100 min, 120 min) and at a pressure of 60 MPa;

[0050] Hold at 600-650℃ (e.g., 600℃, 610℃, 620℃, 630℃, 640℃, 650℃) for 60-200 min (e.g., 60 min, 80 min, 100 min, 120 min, 140 min, 160 min, 180 min, 200 min) and under a pressure of 60 MPa;

[0051] Hold at 600-850℃ (e.g., 600℃, 650℃, 700℃, 750℃, 800℃, 850℃) for 60-120 minutes (e.g., 60 minutes, 80 minutes, 100 minutes, 120 minutes) and under a pressure of 60 MPa.

[0052] Alternatively, in step 4, the insulation is a gradient insulation, including:

[0053] Hold at 400℃ for 60-120 min (e.g., 60 min, 80 min, 100 min, 120 min) and at a pressure of 60 MPa;

[0054] Hold at 600-650℃ (e.g., 600℃, 610℃, 620℃, 630℃, 640℃, 650℃) for 60-200 min (e.g., 60 min, 80 min, 100 min, 120 min, 140 min, 160 min, 180 min, 200 min) under a pressure of 60 MPa.

[0055] Hold at 600-850℃ (e.g., 600℃, 650℃, 700℃, 750℃, 800℃, 850℃) for 60-120 minutes (e.g., 60 minutes, 80 minutes, 100 minutes, 120 minutes) and at a pressure of 80 MPa.

[0056] Hold at 800-850℃ (e.g., 800℃, 810℃, 820℃, 830℃, 840℃, 850℃) for 60-80 minutes (e.g., 60 minutes, 70 minutes, 80 minutes) and at a pressure of 80 MPa.

[0057] Hold at 1000-1200℃ (e.g., 1000℃, 1100℃, 1200℃) for 80-120 minutes (e.g., 80 minutes, 90 minutes, 100 minutes, 120 minutes) and at a pressure of 80 MPa;

[0058] Hold at 600-650℃ (e.g., 600℃, 610℃, 620℃, 630℃, 640℃, 650℃) for 60-80 minutes (e.g., 60 minutes, 70 minutes, 80 minutes) and at a pressure of 80 MPa.

[0059] Hold at 800-850℃ (e.g., 800℃, 810℃, 820℃, 830℃, 840℃, 850℃) for 200 minutes under a pressure of 80MPa.

[0060] In step 4, pressure is stopped during the cooling process until the component cools to room temperature. The cooling rate is determined by the heat treatment regime. For example, it can be furnace cooling.

[0061] The process of this invention is a novel composite heat treatment system using an external energy field. Without adding any extra processes, it applies pressure to the component during heat treatment by introducing an inert gas into the device. This applied pressure resists the release of residual stress within the component during heat treatment, improving the residual stress elimination effect (resulting in lower residual stress, shorter heat treatment time, and increased efficiency), reducing the probability of component deformation and cracking, and improving product qualification rate. Specifically, components treated by the composite heat treatment process of this invention exhibit a reduction of internal residual stress of more than 26% compared to those treated by existing heat treatment processes, and an efficiency increase of more than 10%.

[0062] Compared to hot isostatic pressing (HIP), the composite heat treatment process of this invention achieves improved residual stress elimination (resulting in lower residual stress, shorter heat treatment time, and increased efficiency) and reduced component deformation and cracking probability at lower temperatures (below the melting temperature of the alloy, while HIP requires temperatures close to the forging temperature) and lower pressures (20-80 MPa, far lower than the 100-140 MPa of HIP), without any chemical reaction. Therefore, the composite heat treatment process of this invention has low energy consumption.

[0063] The composite heat treatment process of the present invention only requires the addition of a pressurizing device to the existing heat treatment equipment to achieve a low-pressure heat treatment process, without the need to purchase special equipment, which helps to reduce production costs.

[0064] This invention controls the insulation to be gradient insulation, and further ensures that the residual stress of the treated component is lower by controlling the gradient temperature, gradient segmentation method and pressure of the gradient insulation.

[0065] The composite heat treatment process of the present invention applies pressure during the heat treatment process without the need for additional steps. Therefore, the process of the present invention is simple and conducive to improving production efficiency.

[0066] The composite heat treatment process of this invention is applicable to the heat treatment of different types of additively manufactured alloy components and has wide applicability. It is particularly suitable for the heat treatment of irregularly shaped, large-sized (1m×1m×2m) alloy components.

[0067] The composite heat treatment process of the present invention will be described below with reference to specific embodiments.

[0068] Example 1

[0069] This embodiment describes the heat treatment of additively manufactured components based on Ti-based alloy TA15, including the following steps:

[0070] Step 1: Place the components inside the furnace of the heat treatment device, center the components in the furnace, and arrange them symmetrically according to the structural characteristics of the components.

[0071] Step 2: Set the heat treatment process parameters; wherein, the heating rate is 5℃ / min, the heating temperature is 850℃, and the applied pressure is 60MPa;

[0072] Step 3: Start the heat treatment device to heat and apply pressure to the component;

[0073] Step 4: Hold at 400℃ for 60 minutes at 60MPa, hold at 600℃ for 60 minutes at 60MPa, hold at 850℃ for 120 minutes at 60MPa, and then cool with the furnace.

[0074] Example 2

[0075] This embodiment describes the heat treatment of additively manufactured components made from Ni-based superalloy GH4099, including the following steps:

[0076] Step 1: Place the components inside the furnace of the heat treatment device, center the components in the furnace, and arrange them symmetrically according to the structural characteristics of the components.

[0077] Step 2: Set the heat treatment process parameters; wherein, the heating rate is 10℃ / min, the annealing temperature is 650℃, and the applied pressure is 60MPa; the solution temperature is 1200℃, and the applied pressure is 80MPa; the aging temperature is 850℃, and the applied pressure is 50MPa.

[0078] Step 3: Start the heat treatment device to heat and apply pressure to the component;

[0079] Step 4: Hold at 400℃ for 60 min at 60 MPa, hold at 650℃ for 80 min at 60 MPa; hold at 600℃ for 60 min at 80 MPa, hold at 850℃ for 60 min at 80 MPa, hold at 1200℃ for 100 min at 80 MPa; hold at 600℃ for 60 min at 80 MPa, hold at 850℃ for 200 min at 80 MPa; then cool with the furnace.

[0080] Comparative Example 1

[0081] The comparative example is basically the same as Example 1, except that no pressure is applied to the component during the heat treatment process, and the heat preservation is not gradient heat preservation, but heat preservation at 800°C for 4 hours.

[0082] Comparative Example 2

[0083] The comparative example is basically the same as Example 1, except that in step 4, instead of gradient heat preservation, it is heat preservation at 800℃ for 4 hours.

[0084] Comparative Example 3

[0085] The comparative example is basically the same as Example 1, except that the temperature of the gradient heat preservation is different, namely, heat preservation at 300℃ for 60 minutes at 60MPa, heat preservation at 700℃ for 60 minutes at 60MPa, and heat preservation at 900℃ for 120 minutes at 60MPa.

[0086] Comparative Example 4

[0087] The comparative example is basically the same as Example 1, except that the gradient segmentation method is different, namely, 400℃ for 60min and pressure of 60MPa, 600℃ for 60min and pressure of 60MPa, 700℃ for 60min and pressure of 60MPa, and 850℃ for 60min and pressure of 60MPa.

[0088] Comparative Example 5

[0089] The comparative example is basically the same as Example 1, except that the pressure of the gradient heat preservation is different, namely, 100MPa pressure for heat preservation at 400℃ for 60min, 100MPa pressure for heat preservation at 600℃ for 60min, and 100MPa pressure for heat preservation at 850℃ for 120min.

[0090] Residual stress tests were performed on the components of the embodiments and comparative examples under the same conditions, using the GB / T7704-2017 method for nondestructive testing X-ray stress determination. The results are listed in Table 1.

[0091] Table 1 Residual stress test results

[0092]

[0093]

[0094] As can be seen from Table 1, when the composite heat treatment process of the present invention is not used (Comparative Example 1), the residual stress of the component is 33.00 MPa, while when the composite heat treatment process of the present invention is used (Example 1), the residual stress of the component is only 24.23 MPa, and the residual stress is reduced by 26.6%.

[0095] As can be seen from the data of Example 1, Comparative Example 1 and 2, when gradient insulation is not used (Comparative Example 2), compared with the process of not applying pressure during heat treatment (Comparative Example 1), although the residual stress of the component can be reduced to a certain extent, the residual stress is still higher than that of the process of applying pressure during heat treatment + gradient insulation (Example 1). This proves that gradient insulation can further reduce the residual stress of the component and further ensure that the residual stress of the component after treatment is even lower.

[0096] Furthermore, as can be seen from the data of Comparative Examples 3-5 in Table 1, when different gradient temperature, gradient segmentation method, and pressure are used, such as 400℃ for 60-120 min and 60 MPa pressure, 600-650℃ for 60-200 min and 60 MPa pressure, and 600-850℃ for 60-120 min and 60 MPa pressure, the residual stress of the treated component is comparable to that of Comparative Example 2 (without gradient insulation), but is higher than that of the component treated in Example 1. This proves that using the above-mentioned gradient temperature, gradient segmentation method, and pressure is beneficial to further reduce the residual stress of the treated component.

[0097] Figure 1 This is a photograph of the component after processing, as shown in Comparative Example 1. Figure 1 It can be seen that the component has obvious cracks, and the product is unqualified.

[0098] Figure 2 This is a photograph of the component after processing in Example 1. (Source: [Insert Source Here]) Figure 2 It can be seen that the component has no cracks and no deformation, and the product is qualified.

[0099] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite heat treatment process, characterized in that, Composite heat treatment of additively manufactured components based on Ti-based alloy TA15 includes the following steps: Step 1: Place the components inside the furnace of the heat treatment device, center the components in the furnace, and arrange them symmetrically according to the structural characteristics of the components. Step 2: Set the heat treatment process parameters, including a heating rate of 5℃ / min, a heating temperature of 850℃, and an applied pressure of 60MPa; Step 3: Start the heat treatment device to heat the components and fill the furnace with inert gas to apply pressure to the components; Step 4: Hold at 400℃ for 60 min under 60 MPa pressure, hold at 600℃ for 60 min under 60 MPa pressure, hold at 850℃ for 120 min under 60 MPa pressure, and then cool with the furnace. The inert gas is helium and / or argon.

2. The composite heat treatment process according to claim 1, characterized in that, In step 1, the component is an irregularly shaped component.

3. A composite heat treatment process, characterized in that, Composite heat treatment is performed on additively manufactured components made of Ni-based superalloy GH4099, including the following steps: Step 1: Place the components inside the furnace of the heat treatment device, center the components in the furnace, and arrange them symmetrically according to the structural characteristics of the components. Step 2: Set the heat treatment process parameters, including a heating rate of 10℃ / min, an annealing temperature of 650℃, an applied pressure of 60MPa, a solution temperature of 1200℃, an applied pressure of 80MPa, and an aging temperature of 850℃, with an applied pressure of 50MPa. Step 3: Start the heat treatment device to heat the components and fill the furnace with inert gas to apply pressure to the components; Step 4: Hold at 400℃ for 60 min under 60 MPa pressure, hold at 650℃ for 80 min under 60 MPa pressure; hold at 600℃ for 60 min under 80 MPa pressure, hold at 850℃ for 60 min under 80 MPa pressure, hold at 1200℃ for 100 min under 80 MPa pressure; hold at 600℃ for 60 min under 80 MPa pressure, hold at 850℃ for 200 min under 80 MPa pressure; then cool with the furnace. The inert gas is helium and / or argon.

4. The composite heat treatment process according to claim 3, characterized in that, In step 1, the component is an irregularly shaped component.

Images