Heat treatment method for preventing deformation and cracking of thick-wall additive manufacturing part

Abstract

The invention discloses a heat treatment method for preventing a thick-wall additive manufacturing part from deforming and cracking. The heat treatment method comprises the following steps that firstly, an effective thickness is determined, and the homogenization heat preservation time is determined according to the effective thickness; step 2, determining a second phase () precipitation amount-time relation curve graph of the additive manufacturing part at each temperature, and determining inflection point time of the curve at each temperature and a temperature at which the maximum precipitation amount of the second phase () is less than 10% at a high-temperature section; 3, determining a first temperature, a second temperature and a third temperature; fourthly, a heat treatment scheme of the additive manufacturing part is formulated, wherein the heat treatment scheme comprises low-temperature section heating and heat preservation; heating and preserving heat in a medium-temperature section; heating and preserving heat in a high-temperature section; and furnace cooling, wherein the temperature is reduced to 150 DEG C or below in a segmented mode. According to the method, the internal stress is eliminated through heat treatment, and the non-deformation and non-cracking additive manufacturing part is obtained.

Description

Technical Field

[0001] This invention relates to the field of mechanical metal 3D printing manufacturing technology, specifically to a heat treatment method for preventing deformation and cracking of thick-walled additive manufacturing parts. Background Technology

[0002] Additive manufacturing (also known as 3D printing), as an emerging manufacturing technology, constructs parts by building them point-by-point and layer-by-layer through computer-generated three-dimensional digital models. It has shown enormous application potential in numerous fields such as aerospace and automotive manufacturing. During additive manufacturing, a high-energy-density beam rapidly acts on metal powder, causing it to undergo rapid melting and solidification. This rapid heating and cooling results in extremely high temperature gradients and cooling rates. Furthermore, the repeated thermal effects of the building region on the already built region make the microstructure of the component highly complex due to the dynamic superposition effect of the heat-affected zones. Therefore, the additive manufacturing process is essentially a highly complex, non-equilibrium material evolution process involving the coupling of multiple physical fields such as heat, force, and phase transitions.

[0003] Crack-free, high-quality additive manufacturing of precipitation-hardening superalloys is challenging due to the narrow process range. Their susceptibility to cracking includes solidification cracking and stress cracking. The formation mechanism of solidification cracking is closely related to the various alloying elements present in the alloy. Under the high cooling rates of additive manufacturing, element segregation leads to the accumulation of low-melting-point eutectic phases at grain boundaries. When the molten pool solidifies, the final solidified liquid film is located at the grain boundaries, and solidification shrinkage causes solidification cracks to form at these locations. Stress cracking occurs when the high temperature gradient during additive manufacturing generates significant thermal stress within the component. Simultaneously, the cyclic thermal effects during additive manufacturing cause complex phase transformations in the alloy. The volume difference in these phase transformations further amplifies the internal stress. When the internal stress exceeds the fracture strength, stress cracking occurs.

[0004] In additive manufacturing practice, it has been found that the wall thickness of a part has a significant impact on residual stress. Thin-walled parts have small cross-sectional dimensions, resulting in rapid heat transfer and high cooling rates, which easily lead to large instantaneous temperature gradients and induce higher thermal stress. However, due to their low structural stiffness, some stress can be released through macroscopic deformation, resulting in a moderate level of residual stress, which is distributed in a gradient along the wall thickness direction with a significant difference between the surface and the core. In contrast, thick-walled components have a large heat capacity and a long heat conduction path, resulting in slower cooling and a gentler overall temperature gradient, leading to a lower initial thermal stress amplitude. However, their high rigidity strongly constrains thermal deformation, making stress difficult to release and prone to accumulation internally. The stress distribution is also more complex, often showing a transformation from surface compressive stress to core tensile stress, especially in the core where high tensile stress may form due to heat accumulation.

[0005] During additive manufacturing, the thick-walled sections of parts exhibit high residual internal stress, and areas with varying wall thicknesses and structures are prone to complex stress distributions and deformations. To prevent excessive deformation or even cracking during additive manufacturing, robust structural support structures are often used to increase local stiffness and prevent deformation and cracking. Therefore, although crack-free additively manufactured rough products may be obtained in engineering practice, the enormous residual internal stress in the components during additive manufacturing can lead to deformation and dimensional deviations, or even cracking, when the support is directly cut. Alternatively, during subsequent heat treatment, the residual stress may not be fully eliminated, resulting in increased temperature and decreased material strength, ultimately causing cracking. Therefore, after additive manufacturing, deformation control and heat treatment often become crucial factors in determining whether the part can be practically applied.

[0006] To address the aforementioned issues, existing technologies primarily focus on preventing cracking and reducing residual stress during 3D printing, as well as controlling deformation and cracking after printing to obtain usable, qualified parts. Preheating techniques and optimized process parameters are employed to reduce residual stress. Preheating involves heating the substrate or the entire forming environment to a specific temperature before printing, thereby reducing the rate and peak value of thermal stress generation by increasing the ambient temperature of the component. Optimized process parameters involve adjusting laser power, scanning speed, and strategies to control heat input and transfer, reducing temperature gradients and the heat-affected zone, and minimizing the accumulation of residual stress.

[0007] After printing, the component is placed in a specific temperature environment for heat preservation to release residual stress. Once the residual stress is released, the support and additive component can be cut from the printing substrate. Because there is no residual stress, the component undergoes minimal deformation during cutting, thus controlling the amount of deformation and ensuring dimensional accuracy. Another scenario involves residual stress that is difficult to eliminate after printing. In such cases, the part structure is not complex, and the amount of deformation can be predicted relatively accurately. In this case, an anti-deformation compensation design is adopted during the pre-printing digital model design, ensuring that the deformation of the component during cutting after printing achieves the correct dimensional accuracy.

[0008] However, for thick-walled precipitation-hardening, easily cracked high-temperature alloy parts, the residual stress threshold after 3D printing is relatively high, and they often contain a large amount of high-temperature alloying elements such as Hf and Ta. These elements, through grain boundary strengthening and high-temperature microstructure stability, make it difficult for residual stress to relax in the component. On the other hand, precipitation-hardening high-temperature alloys can produce a large proportion of [unclear - possibly related to stress reduction or cracking] in the high-temperature environment of heat treatment. Precipitated hardened phases such as carbides will generate additional internal stress during the precipitation process due to the volume difference between the precipitated phase and the matrix phase, causing the component to deform and crack during heat treatment. Summary of the Invention

[0009] The purpose of this invention is to provide a heat treatment method to prevent deformation and cracking of thick-walled additive manufacturing parts. By heat treatment, the internal stress that is difficult to eliminate in precipitation-hardening, easily cracked nickel-based high-temperature alloy thick-walled additive manufacturing parts is completely eliminated, and additive manufacturing parts without deformation and cracking are obtained.

[0010] To achieve the above-mentioned objectives, the technical solution adopted by this invention is: a heat treatment method for preventing deformation and cracking of thick-walled additive manufacturing parts, comprising the following steps: Step 1: Determine an effective thickness based on the wall thickness uniformity of the additively manufactured part. And according to the effective thickness Determine the homogenization and heat preservation time : Where k is the alloy coefficient; Step 2: Determine the second phase of the additively manufactured part at various temperatures. Data on the relationship between precipitation amount and time were collected, and the inflection point time of the curve at each temperature was determined. And the second phase at high temperatures ( The temperature at which the maximum precipitation amount is less than 10% ; Step 3, determine the first temperature Second temperature and the third temperature ; Step four: Develop a heat treatment plan for the additively manufactured part, including: Low-temperature heating and heat preservation: heating from room temperature to the first temperature. and at the first temperature Insulation at the bottom; Medium-temperature range heating and heat preservation: from the first temperature Heat to the second temperature And at the second temperature Insulation at the bottom; High-temperature section heating and heat preservation: First, divide the second temperature into sections. Increase the temperature to the third temperature And at the third temperature Keep warm, then raise the temperature to And keep warm; Furnace cooling: The temperature is reduced in stages from Reduce to below 150℃.

[0011] Furthermore, in step one, when the wall thickness uniformity of the additively manufactured part is good, the average wall thickness of the additively manufactured part is... Defined as effective thickness ; When the wall thickness uniformity of the additively manufactured part is poor and the proportion of thick walls is large, the maximum wall thickness of the additively manufactured part should be... Defined as effective thickness ; When the wall thickness uniformity of the additively manufactured part is poor and the proportion of thin walls is large, the minimum wall thickness of the additively manufactured part should be adjusted. Defined as effective thickness .

[0012] Furthermore, through the formula: Determine the wall thickness uniformity of the additively manufactured part, among which It refers to the local volume of different areas of an additively manufactured part. It refers to the local surface area of ​​different regions of the additively manufactured part. These are empirical coefficients for each region. =1; The closer to the average wall thickness of the additively manufactured part The better the uniformity of the wall thickness of the additively manufactured part, the better.

[0013] Furthermore, the first temperature Second temperature Determined in the following ways: Through formula middle = The corresponding temperature value is determined. Value, in °C; Through formula Determine the second temperature Value, in °C; Through formula Determine the first temperature The unit is ℃.

[0014] Furthermore, through the formula Determine the third temperature The unit is ℃.

[0015] Furthermore, in step four, with The heating rate will raise the room temperature to the first temperature. and at the first temperature Under-insulation .

[0016] Furthermore, in step four, with The heating rate will reach the first temperature Heat to the second temperature And at the second temperature Under-insulation .

[0017] Furthermore, in step four, the temperature is increased from... Gradually reduced to The second temperature is divided into segments. Increase the temperature to the third temperature And at the third temperature Lower insulation 0.5 ; by The heating rate will affect the third temperature. Heat up to and in Under-insulation .

[0018] Furthermore, in step four, the temperature is increased in three stages from... Reduce to below 150°C: In the first stage, the temperature was changed from... furnace cooled to and in Under-insulation ; In the second stage, the temperature will be changed from... furnace cooled to and in Under-insulation ; In the third stage, the temperature will be changed from... The furnace was cooled to below 150°C.

[0019] Furthermore, The determination process is as follows: Through formula middle = The corresponding temperature value is determined. Value, in °C; Through formula ,Sure Value, in °C.

[0020] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: Precipitation-hardening nickel-based superalloy components undergo significant precipitation of γ' phase and carbides under high-temperature conditions. This precipitation, due to volume differences, generates additional internal stress, which, combined with existing residual stress, can lead to component cracking. In this invention, the maximum furnace temperature during heat treatment of additively manufactured parts is... , The second phase is in the high-temperature range. The maximum precipitation amount is less than 10% at the temperature value. Therefore, the heat treatment scheme of the present invention can ensure that precipitation-hardening nickel-based superalloy components will not precipitate γ' phase and carbide and other precipitate phases in a large proportion under high temperature environment, thereby reducing the generation of internal stress. At the same time, during the heating / cooling process of thick-walled parts, the large internal / external and upper / lower temperature gradients of the components will generate thermal stress. The heat treatment scheme of the present invention has multiple heating stages and segmented cooling to reduce the temperature gradient during the heating / cooling process of the components and avoid the generation of thermal stress due to the large temperature gradient. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first," "second," etc., used in the specification and claims of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate for the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate orientation or positional relationships. These terms are primarily used to better describe the invention and its embodiments and are not intended to limit the indicated devices, elements, or components to having a specific orientation or to be constructed and operated in a specific orientation.

[0024] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0025] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this invention can be combined with each other. The invention will now be described in detail with reference to the embodiments.

[0027] Example 1 This invention provides a heat treatment method for preventing deformation and cracking of thick-walled additively manufactured parts, comprising the following steps: Step 1: Determine an effective thickness based on the wall thickness uniformity of the additively manufactured part. And according to the effective thickness Determine the homogenization and heat preservation time : Where k is the alloy coefficient; Step 2: Determine the second phase of the additively manufactured part at various temperatures. Data on the relationship between precipitation amount and time were collected, and the inflection point time of the curve at each temperature was determined. And the second phase at high temperatures ( The temperature at which the maximum precipitation amount is less than 10% ; Step 3, determine the first temperature Second temperature and the third temperature ; Step four: Develop a heat treatment plan for the additively manufactured part, including: Low-temperature heating and heat preservation: heating from room temperature to the first temperature. and at the first temperature Insulation at the bottom; Medium-temperature range heating and heat preservation: from the first temperature Heat to the second temperature And at the second temperature Insulation at the bottom; High-temperature section heating and heat preservation: First, divide the second temperature into sections. Increase the temperature to the third temperature And at the third temperature Keep warm, then raise the temperature to And keep warm; Furnace cooling: The temperature is reduced in stages from Reduce to below 150℃.

[0028] Precipitation-hardening nickel-based superalloy components undergo significant precipitation of γ' phase and carbides under high-temperature conditions. This precipitation, due to volume differences, generates additional internal stress, which, combined with existing residual stress, can lead to component cracking. In this invention, the maximum furnace temperature during heat treatment of additively manufactured parts is... , The second phase is in the high-temperature range. The maximum precipitation amount is less than 10% at the temperature value. Therefore, the heat treatment scheme of the present invention can ensure that precipitation-hardening nickel-based superalloy components will not precipitate γ' phase and carbide and other precipitate phases in a large proportion under high temperature environment, thereby reducing the generation of internal stress. At the same time, during the heating / cooling process of thick-walled parts, the large internal / external and upper / lower temperature gradients of the components will generate thermal stress. The heat treatment scheme of the present invention has multiple heating stages and segmented cooling to reduce the temperature gradient during the heating / cooling process of the components and avoid the generation of thermal stress due to the large temperature gradient.

[0029] Furthermore, in step one, when the wall thickness uniformity of the additively manufactured part is good, the average wall thickness of the additively manufactured part is... Defined as effective thickness When the wall thickness uniformity of the additively manufactured part is poor and the proportion of thick walls is large, the maximum wall thickness of the additively manufactured part should be... Defined as effective thickness ; When the wall thickness uniformity of the additively manufactured part is poor and the proportion of thin walls is large, the minimum wall thickness of the additively manufactured part should be adjusted. Defined as effective thickness Effective thickness The unit is mm.

[0030] Furthermore, through the formula: Determine the wall thickness uniformity of the additively manufactured part, among which It refers to the local volume of different areas of an additively manufactured part. It refers to the local surface area of ​​different regions of the additively manufactured part. These are empirical coefficients for each region. When the thermal conductivity of a region is low, especially if the region is located inside the component or in a localized area, Based on experience, it usually increases. =1. Effective thickness Related to the thickness uniformity of additively manufactured parts, typically, The closer to the average wall thickness of the additively manufactured part The higher the uniformity of the wall thickness, the better the uniformity of the additively manufactured part; conversely, the lower the uniformity, the worse the uniformity. When the proportion of thick-walled portions is large, The value tends to increase and is greater than the average wall thickness. When the proportion of thin-walled sections is relatively large, The value tends to decrease and is less than the average wall thickness. .

[0031] Furthermore, the second phase of the component alloy at various temperatures was determined using DSC experiments or thermodynamic calculation software. The relationship between precipitation amount and time is shown in the graph.

[0032] Furthermore, the first temperature Second temperature Determined in the following ways: Through formula middle = The corresponding temperature value is determined. Value, in °C and The units are all in min; Through formula Determine the second temperature Value, in °C; Through formula Determine the first temperature The unit is ℃.

[0033] Furthermore, through the formula Determine the third temperature The unit is ℃.

[0034] Furthermore, in step four, with The heating rate will raise the room temperature to the first temperature. and at the first temperature Under-insulation .

[0035] Furthermore, in step four, with The heating rate will reach the first temperature Heat to the second temperature And at the second temperature Under-insulation .

[0036] Furthermore, in step four, the temperature is increased from... Gradually reduced to The second temperature is divided into segments. Increase the temperature to the third temperature And at the third temperature Lower insulation 0.5 ; by The heating rate will affect the third temperature. Heat up to and in Under-insulation .

[0037] Furthermore, in step four, the temperature is increased in three stages from... Reduce to below 150°C: In the first stage, the temperature was changed from... furnace cooled to and in Under-insulation ; In the second stage, the temperature will be changed from... furnace cooled to and in Under-insulation ; In the third stage, the temperature will be changed from... The furnace was cooled to below 150°C.

[0038] Furthermore, The determination process is as follows: Through formula middle = The corresponding temperature value is determined. Value, in °C; Through formula ,Sure Value, in °C.

[0039] Example 2 This invention provides a heat treatment method for preventing deformation and cracking of thick-walled additively manufactured parts, comprising the following steps: Step 1: Determine an effective thickness based on the wall thickness uniformity of the additively manufactured part. =15mm, let k=4, and according to the effective thickness Determine the homogenization and heat preservation time : =60min; Step 2: Determine the second phase of the additively manufactured part at various temperatures. Data on the relationship between precipitation amount and time were collected, and the inflection point time of the curve at each temperature was determined. And the second phase at high temperatures ( The temperature at which the maximum precipitation amount is less than 10% ; Step 3, determine the first temperature Second temperature and the third temperature ; Step four: Develop a heat treatment plan for the additively manufactured part, including: Low-temperature heating and heat preservation: heating from room temperature to the first temperature. and at the first temperature Insulation at the bottom; Medium-temperature range heating and heat preservation: from the first temperature Heat to the second temperature And at the second temperature Insulation at the bottom; High-temperature section heating and heat preservation: First, set the second temperature... Increase the temperature to the third temperature And at the third temperature Keep warm, then raise the temperature to And keep warm; Furnace cooling: The temperature is reduced in stages from Reduce to below 150℃.

[0040] The second phase at various temperatures was calculated using thermodynamic calculation software. In the data of the relationship between precipitation amount and time The relationship between temperature and temperature is shown in the table below:

[0041] According to the data in the table above, at 1180℃, The maximum precipitation amount is <10%, therefore =1180℃. When = =60min, The temperature value is 850℃.

[0042] Furthermore, through the formula Determine the second temperature =700℃; Through formula Determine the first temperature =400℃.

[0043] Furthermore, through the formula Determine the third temperature =1150℃, unit is ℃.

[0044] Furthermore, in step four, with The heating rate raises the room temperature from 30°C to 400°C and holds it at 400°C. .

[0045] Furthermore, in step four, with The heating rate was increased from 400℃ to 700℃, and then held at 700℃. .

[0046] Furthermore, in step four, firstly with The heating rate was increased from 700℃ to 950℃, and then... The heating rate was increased from 950℃ to 1100℃, and finally... The heating rate was increased from 1100℃ to 1150℃, and the temperature was held at 1150℃. ; by The heating rate was increased from 1150℃ to 1180℃, and the temperature was held at 1180℃. .

[0047] Furthermore, in step four, the temperature is reduced from 1180℃ to below 150℃ in three stages: In the first stage, the temperature was cooled from 1180℃ to... and in Under-insulation ; In the second stage, the temperature will be changed from... The furnace was cooled to 400°C and then held at 400°C. ; In the third stage, the temperature is cooled from 400℃ to below 150℃.

[0048] Furthermore, The determination process is as follows: Through formula middle = The corresponding temperature value is determined. value, =850℃.

[0049] Through formula ,Sure =750℃.

[0050] Furthermore, the heat treatment scheme in step four is shown in the table below:

[0051] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A heat treatment method for preventing deformation and cracking of thick-walled additively manufactured parts, characterized in that, Includes the following steps: Step 1: Determine an effective thickness based on the wall thickness uniformity of the additively manufactured part. And according to the effective thickness Determine the homogenization and heat preservation time : Where k is the alloy coefficient; Step 2: Determine the second phase of the additively manufactured part at various temperatures. Data on the relationship between precipitation amount and time were collected, and the inflection point time of the curve at each temperature was determined. And the second phase at high temperatures ( The temperature at which the maximum precipitation amount is less than 10% ; Step 3, determine the first temperature Second temperature and the third temperature ; Step four: Develop a heat treatment plan for the additively manufactured part, including: Low-temperature heating and heat preservation: heating from room temperature to the first temperature. and at the first temperature Insulation at the bottom; Medium-temperature range heating and heat preservation: from the first temperature Heat to the second temperature And at the second temperature Insulation at the bottom; High-temperature section heating and heat preservation: First, divide the second temperature into sections. Increase the temperature to the third temperature And at the third temperature Keep warm, then raise the temperature to And keep warm; Furnace cooling: The temperature is reduced in stages from Reduce to below 150℃.

2. The heat treatment method for preventing deformation and cracking of thick-walled additive manufacturing parts as described in claim 1, characterized in that, In step one, when the wall thickness uniformity of the additively manufactured part is good, the average wall thickness of the additively manufactured part is... Defined as effective thickness ; When the wall thickness uniformity of the additively manufactured part is poor and the proportion of thick walls is large, the maximum wall thickness of the additively manufactured part should be... Defined as effective thickness ; When the wall thickness uniformity of the additively manufactured part is poor and the proportion of thin walls is large, the minimum wall thickness of the additively manufactured part should be adjusted. Defined as effective thickness .

3. The heat treatment method for preventing deformation and cracking of thick-walled additive manufacturing parts as described in claim 2, characterized in that, Through the formula: Determine the wall thickness uniformity of the additively manufactured part, among which It refers to the local volume of different areas of an additively manufactured part. It refers to the local surface area of ​​different regions of the additively manufactured part. These are empirical coefficients for each region. =1; The closer to the average wall thickness of the additively manufactured part The better the uniformity of the wall thickness of the additively manufactured part, the better.

4. The heat treatment method for preventing deformation and cracking of thick-walled additive manufacturing parts as described in claim 1, characterized in that, First temperature Second temperature Determined in the following ways: Through formula middle = The corresponding temperature value is determined. Value, in °C; Through formula Determine the second temperature Value, in °C; Through formula Determine the first temperature The unit is ℃.

5. The heat treatment method for preventing deformation and cracking of thick-walled additive manufacturing parts as described in claim 1, characterized in that, Through formula Determine the third temperature The unit is ℃.

6. The heat treatment method for preventing deformation and cracking of thick-walled additive manufacturing parts as described in claim 1, characterized in that, In step four, with The heating rate will raise the room temperature to the first temperature. and at the first temperature Under-insulation .

7. The heat treatment method for preventing deformation and cracking of thick-walled additive manufacturing parts as described in claim 1, characterized in that, In step four, with The heating rate will reach the first temperature Heat to the second temperature And at the second temperature Under-insulation .

8. The heat treatment method for preventing deformation and cracking of thick-walled additive manufacturing parts as described in claim 1, characterized in that, In step four, the temperature is increased from... Gradually reduced to The second temperature is divided into segments. Increase the temperature to the third temperature And at the third temperature Lower insulation 0.5 ; by The heating rate will affect the third temperature. Heat up to and in Under-insulation .

9. The heat treatment method for preventing deformation and cracking of thick-walled additive manufacturing parts as described in claim 1, characterized in that, In step four, the temperature is increased in three stages from Reduce to below 150°C: In the first stage, the temperature was changed from... furnace cooled to and in Under-insulation ; In the second stage, the temperature will be changed from... furnace cooled to and in Under-insulation ; In the third stage, the temperature will be changed from... The furnace was cooled to below 150°C.

10. The heat treatment method for preventing deformation and cracking of thick-walled additively manufactured parts as described in claim 9, characterized in that, The determination process is as follows: Through formula middle = The corresponding temperature value is determined. Value, in °C; Through formula ,Sure Value, in °C.

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