Heat treatment toughening method suitable for indirect additive manufacturing of tungsten alloy components

Abstract

This invention relates to a heat treatment method for strengthening and toughening tungsten alloy parts manufactured through indirect additive manufacturing. The method includes the following steps: placing the indirectly additively manufactured tungsten alloy part in a quenching furnace and evacuating it; performing a first heating until the surface temperature or ambient temperature reaches 800℃~1200℃ and holding it at this temperature for a first preset time period; rapidly transferring it to a cooling medium for a second preset time period; repeating the step of placing the indirectly additively manufactured tungsten alloy part in the quenching furnace and evacuating it, and performing this cycle a preset number of times; transferring the indirectly additively manufactured tungsten alloy part to a vacuum solution furnace and evacuating it; performing a second heating until the surface temperature or ambient temperature reaches 800℃~1200℃ and holding it at this temperature for a third preset time period; and cooling it to room temperature in the furnace. This heat treatment strengthening and toughening method can achieve maximum improvement in strength and toughness while ensuring high dimensional accuracy of the indirectly additively manufactured tungsten alloy part, and is simple, has a short cycle time, and low cost.

Description

Technical Field

[0001] This invention relates to the field of indirect additive manufacturing technology, and in particular to a heat treatment method for strengthening and toughening tungsten alloy parts manufactured by intermittent additive manufacturing. Background Technology

[0002] Indirect additive manufacturing technology refers to a type of additive manufacturing technology that pre-fabricates raw material powder with a binder to create a green body, which is then densified by high-temperature debinding and sintering to obtain the final part. Based on different green body forming principles, it can be divided into four process routes: binder spraying, melt / slurry extrusion, photopolymerization, and selective laser sintering. Compared to direct additive manufacturing technologies using high-energy heat sources such as lasers, electron beams, and electric arcs, indirect additive manufacturing technology has more relaxed requirements for raw materials and higher forming efficiency. It is particularly suitable for low-cost, large-scale manufacturing of complex configurations of materials such as refractory metals, high-temperature ceramics, and metals with high laser reflectivity, and has enormous application potential in fields such as defense technology industries and consumer electronics.

[0003] Currently, the use of indirect additive manufacturing technology to form complex tungsten alloy structures has attracted widespread attention from researchers both domestically and internationally. However, due to the presence of binders and the significantly different forming principle compared to powder metallurgy, the mechanical properties of tungsten alloy parts manufactured through indirect additive manufacturing still lag behind those formed by powder metallurgy. Furthermore, it is impossible to significantly improve mechanical properties while maintaining the dimensional accuracy of the components through traditional heat treatment strengthening processes such as vacuum dehydrogenation, solution quenching, cyclic thermal shock, and deformation strengthening. This greatly limits the large-scale engineering application of this technology. Summary of the Invention

[0004] Therefore, it is necessary to provide a heat treatment intensive heating method suitable for indirect additive manufacturing of tungsten alloy parts.

[0005] A heat treatment method for strengthening and toughening tungsten alloy parts suitable for indirect additive manufacturing includes the following steps:

[0006] The tungsten alloy part manufactured by indirect additive manufacturing is placed in a quenching furnace and a vacuum is drawn.

[0007] The tungsten alloy part manufactured by indirect additive manufacturing in a vacuum environment is first heated until the surface temperature or ambient temperature of the tungsten alloy part is raised to 800°C to 1200°C, and then kept at that temperature for a first preset time period.

[0008] The indirect additive manufacturing tungsten alloy component, after being kept warm, is rapidly transferred to a cooling medium for cooling for a second preset time period.

[0009] Return to the step of placing the indirectly additively manufactured tungsten alloy part in the quenching furnace and drawing a vacuum, and repeat the process a preset number of times;

[0010] The indirect additive manufacturing tungsten alloy parts are transferred to a vacuum solution furnace and then evacuated.

[0011] The additively manufactured tungsten alloy in a vacuum environment is heated a second time until the surface temperature or ambient temperature of the indirectly additively manufactured tungsten alloy part rises to 800°C to 1200°C, and is held at that temperature for a third preset time period.

[0012] The indirect additive manufacturing tungsten alloy part, after being kept at a certain temperature, is cooled to room temperature in the furnace.

[0013] In one embodiment, prior to the steps of placing the indirectly additively manufactured tungsten alloy part in a quenching furnace and evacuating it, the method further includes the step of:

[0014] The indirect additive manufacturing tungsten alloy parts are cleaned to remove oil stains from their surfaces.

[0015] In one embodiment, the step of cleaning the indirect additive manufacturing tungsten alloy component is as follows: wiping and cleaning the oil stains on the surface of the indirect additive manufacturing tungsten alloy component with a cloth soaked in cleaning agent.

[0016] In one embodiment, prior to the step of transferring the indirectly additively manufactured tungsten alloy part into a vacuum solution furnace and evacuating it, the method further includes the step of removing the indirectly additively manufactured tungsten alloy part from the cooling medium and wiping the cooling medium off the surface of the indirectly additively manufactured tungsten alloy part.

[0017] In one embodiment, the step of placing the indirectly additively manufactured tungsten alloy part in a quenching furnace and evacuating the vacuum is as follows: placing the indirectly additively manufactured tungsten alloy part in a quenching furnace and evacuating the vacuum until the pressure inside the furnace is less than or equal to 10 Pa.

[0018] The step of placing the indirectly additively manufactured tungsten alloy component in a solution furnace and evacuating it is as follows: the indirectly additively manufactured tungsten alloy component is placed in a vacuum solution furnace and evacuated until the pressure inside the furnace is less than or equal to 10 Pa.

[0019] In one embodiment, the first preset time period is 1 min to 30 min, the second preset time period is 1 min to 10 min, and the third preset time period is 1 h to 3 h.

[0020] In one embodiment, the temperature rise rate during the first heating and the second heating is 1℃ / min to 10℃ / min.

[0021] In one embodiment, the transfer time when the indirect additive manufacturing tungsten alloy part is rapidly transferred to the cooling medium is ≤5 min.

[0022] In one embodiment, the cooling medium is ordinary quenching oil, bright quenching oil, high-speed quenching oil, or vacuum quenching oil.

[0023] In one embodiment, in the step of returning to perform the step of placing the indirectly additively manufactured tungsten alloy part in a quenching furnace and evacuating it, and repeating the step a preset number of times, the preset number of times is 2 to 20 times.

[0024] The aforementioned heat treatment strengthening method for indirect additive manufacturing (AIM) tungsten alloy parts, by repeatedly placing the AIM tungsten alloy part in a quenching furnace and applying vacuum, and performing this cycle a preset number of times, can achieve a more uniform distribution of the low-melting-point alloy phase within the AIM tungsten alloy part. This allows the phase to fully penetrate the tungsten-tungsten interface, causing the fracture mode of the AIM tungsten alloy part to shift from predominantly transgranular cleavage fracture of tungsten grains to predominantly binder-based ductile fracture. Vacuum solution purification of the tungsten-tungsten grain boundaries and suppression of phosphorus, oxygen, and other impurity element segregation reduce the hydrogen content within the AIM tungsten alloy part, thereby improving the toughness of the binder phase and the interfacial bonding strength between the tungsten and binder phases. Therefore, compared with existing tungsten alloy heat treatment processes, the above-mentioned heat treatment strengthening method can achieve maximum improvement in strength and toughness while maintaining high dimensional accuracy of the AIM tungsten alloy part. Furthermore, the process is simple, has a short cycle time, and low cost, making it promising for engineering applications. Attached Figure Description

[0025] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0026] Figure 1 This is a schematic flowchart of a heat treatment strengthening and toughening method for indirect additive manufacturing of tungsten alloy parts according to a preferred embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of the tensile stress-strain curves of the comparative example and Example 1 in one embodiment of the present invention;

[0028] Figure 3 The images show the fracture surface morphology of the tensile spline in one embodiment of the present invention, compared to that in Example 1. Detailed Implementation

[0029] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0031] When describing positional relationships, unless otherwise specified, when an element is referred to as being "on" another element, it may be directly on the other element or there may be intermediate elements. It is also understood that when an element is referred to as being "between" two elements, it may be the only one between the two elements, or there may be one or more intermediate elements.

[0032] When using the terms “including,” “having,” and “comprising” as described herein, another component may be added unless explicitly qualifying terms such as “only,” “consisting of,” etc. are used. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0033] Please see Figure 1 The heat treatment toughening method for tungsten alloy parts suitable for indirect additive manufacturing in a preferred embodiment of the present invention includes steps S100 to S700.

[0034] In step S100, the indirect additive manufacturing tungsten alloy part is placed in a quenching furnace and a vacuum is drawn.

[0035] Before performing step 100, the indirect additive manufacturing of tungsten alloy parts is a preform made from tungsten alloy powder and binder as raw materials, through processes such as binder spraying, melt extrusion, selective laser sintering, and molding.

[0036] Specifically, step S100 involves placing the indirectly additively manufactured tungsten alloy part in a quenching furnace and drawing a vacuum until the pressure inside the furnace is less than or equal to 10 Pa. This provides a vacuum environment for the heat treatment of the indirectly additively manufactured tungsten alloy part within the quenching furnace, reducing the influence of oxygen and other substances in the air on the heat treatment process.

[0037] Before step S100, the process further includes cleaning the indirectly additively manufactured tungsten alloy part to remove oil stains from its surface. This reduces the impact of oil stains adhering to the surface of the indirectly additively manufactured tungsten alloy part on the subsequent heat treatment process.

[0038] Specifically, the oil stains on the surface of the indirect additive manufacturing tungsten alloy part are wiped clean using a cloth dampened with a cleaning agent. More specifically, the cleaning agent is alcohol. Of course, in other embodiments, the cleaning agent can also be other solutions capable of quickly removing oil stains.

[0039] More specifically, the cleaning cloth, used as a cleaning tool, is made of clean non-woven fabric. Of course, in other embodiments, the cleaning cloth can also be made of other highly absorbent fabrics.

[0040] Step S200: The tungsten alloy part manufactured by indirect additive manufacturing in a vacuum environment is heated for the first time until the surface temperature or ambient temperature of the tungsten alloy part manufactured by indirect additive manufacturing rises to 800℃~1200℃, and is kept at this temperature for a first preset time period.

[0041] Specifically, the tungsten alloy parts manufactured through indirect additive manufacturing after the first heating are held at a temperature of 1 to 30 minutes.

[0042] Specifically, the tungsten alloy part manufactured by indirect additive manufacturing in a vacuum environment is heated for the first time, so that the surface temperature or ambient temperature of the tungsten alloy part manufactured by indirect additive manufacturing is increased to 800℃ to 1200℃ at a temperature rise rate of 1℃ / min to 10℃ / min.

[0043] Step S300 involves rapidly transferring the heat-preserved indirect additive manufacturing tungsten alloy part into a cooling medium for a second preset time period. Specifically, the heat-preserved indirect additive manufacturing tungsten alloy part is quickly removed from the quenching furnace and rapidly placed into a cooling medium for the second preset time period to achieve rapid cooling of the part after the initial heating. The cooling medium can be ordinary quenching oil, bright quenching oil, high-speed quenching oil, vacuum quenching oil, or other liquids capable of rapid cooling at high temperatures.

[0044] Specifically, the heat-insulated indirect additive manufacturing tungsten alloy parts are rapidly transferred to a cooling medium for cooling for 1 to 10 minutes.

[0045] Specifically, the transfer time during rapid transfer should be ≤5 minutes. That is, the time required to remove the heated indirect additive manufacturing tungsten alloy part from the quenching furnace and place it in the cooling medium should not exceed 5 minutes, in order to reduce the probability of the heated indirect additive manufacturing tungsten alloy part being exposed to air and undergoing oxidation.

[0046] Step S400: Return to the step of placing the indirectly additively manufactured tungsten alloy part in the quenching furnace and drawing a vacuum, and repeat this process a preset number of times. Specifically, the preset number of times is 2 to 20.

[0047] That is, step S400 is to return to the loop and execute steps S100 to S300 a preset number of times. Since steps S100 to S300 are the steps of quenching the tungsten alloy parts manufactured by indirect additive manufacturing, step S400 is to perform cyclic quenching treatment on the tungsten alloy parts manufactured by indirect additive manufacturing.

[0048] In step S500, the indirect additive manufacturing tungsten alloy part is transferred to a vacuum solution furnace and a vacuum is drawn. That is, the indirect additive manufacturing tungsten alloy part is removed from the cooling medium and placed into the vacuum solution furnace.

[0049] Specifically, the indirect additive manufacturing tungsten alloy parts are placed in a vacuum solution furnace and a vacuum is drawn until the pressure inside the furnace is less than or equal to 10 Pa. This provides a vacuum environment for the heat treatment of the indirect additive manufacturing tungsten alloy parts in the vacuum solution furnace, thereby reducing the influence of oxygen and other substances in the air on the heat treatment process.

[0050] Before step S500, the process further includes the step of removing the indirectly additively manufactured tungsten alloy part from the cooling medium and wiping the cooling medium off the surface of the indirectly additively manufactured tungsten alloy part. This ensures that the surface of the indirectly additively manufactured tungsten alloy part remains dry and clean before entering the vacuum solution furnace, thereby reducing the impact of the vacuum solution treatment of the cooling medium.

[0051] Step S600: The additive manufacturing tungsten alloy in a vacuum environment is heated a second time until the surface temperature or ambient temperature of the indirectly additive manufacturing tungsten alloy part rises to 800℃~1200℃, and is kept at that temperature for a third preset time period.

[0052] Specifically, the tungsten alloy parts manufactured through indirect additive manufacturing after the second heating are kept at a temperature of 1 to 3 hours.

[0053] Specifically, the tungsten alloy parts manufactured by indirect additive manufacturing in a vacuum environment are heated a second time, so that the surface temperature or ambient temperature of the tungsten alloy parts manufactured by indirect additive manufacturing is increased to 800℃ to 1200℃ at a temperature rise rate of 1℃ / min to 10℃ / min.

[0054] In step S700, the indirect additive manufacturing tungsten alloy part, after being kept at a certain temperature, is cooled to room temperature in the furnace.

[0055] By executing steps S100 to S700, heat treatment can be performed on the tungsten alloy parts manufactured by indirect additive manufacturing, and the execution sequence is consistent with the number sequence of the above steps. By executing steps S100 to S400, repeated quenching treatment can be performed on the tungsten alloy parts manufactured by indirect additive manufacturing. By executing steps S500 to S700, vacuum solution treatment can be performed on the tungsten alloy parts manufactured by indirect additive manufacturing.

[0056] Therefore, the aforementioned heat treatment strengthening and toughening method for tungsten alloy parts manufactured through indirect additive manufacturing comprises two parts: cyclic quenching and vacuum solution treatment. On one hand, cyclic quenching (i.e., repeated quenching) allows for a more uniform distribution of the low-melting-point alloy phase within the tungsten alloy part, enabling it to fully penetrate the tungsten-tungsten interface and shifting the fracture mode from predominantly transgranular cleavage fracture of tungsten grains to predominantly binder-based ductile fracture. On the other hand, vacuum solution treatment purifies the tungsten-tungsten grain boundaries, suppresses the segregation of impurities such as phosphorus and oxygen, reduces the hydrogen content within the tungsten alloy part, and improves the toughness of the binder phase and the interfacial bonding strength between the tungsten and binder phases. Therefore, compared to existing tungsten alloy heat treatment processes, this heat treatment strengthening and toughening method achieves maximum improvement in strength and toughness while maintaining high dimensional accuracy of the tungsten alloy part manufactured through indirect additive manufacturing. Furthermore, the process is simple, has a short cycle time, and low cost, making it promising for engineering applications.

[0057] To gain a more intuitive understanding of the mechanical properties of tungsten alloy parts modified by the above method in indirect additive manufacturing, several examples and corresponding mechanical property test results are listed below.

[0058] Comparative example: tungsten alloy parts manufactured by binder spraying.

[0059] In Example 1, in step S200, the heat preservation temperature is 1100℃ and the first preset time period is 20min; in step S300, the second preset time period is 5min; in step S400, the preset number of cycles is 2; in step S600, the heat preservation temperature is 1000℃ and the third preset time period is 2h.

[0060] In Example 2, in step S200, the heat preservation temperature is 1100℃ and the first preset time period is 20min; in step S300, the second preset time period is 5min; in step S400, the preset number of cycles is 4; in step S600, the heat preservation temperature is 1000℃ and the third preset time period is 2h.

[0061] In Example 3, in step S200, the heat preservation temperature is 1200℃ and the first preset time period is 20min; in step S300, the second preset time period is 5min; in step S400, the preset number of cycles is 4; in step S600, the heat preservation temperature is 900℃ and the third preset time period is 2h.

[0062] The tensile properties and impact toughness of the comparative examples and Examples 1-3 were tested according to the requirements of GB / T 228.1-2010 and GB / T 229-2020, respectively. The results are shown in the table below:

[0063]

[0064] The test data above show that the tungsten alloy parts modified using the heat treatment strengthening method suitable for indirect additive manufacturing of tungsten alloy parts have a tensile strength of 900 MPa to 1000 MPa, an elongation of 15% to 24%, and an impact toughness of 90 J / cm. 2 ~95J / cm 2 Compared with the untreated sample, the tensile strength and impact toughness can be increased by nearly 20% and 600%, respectively.

[0065] Furthermore, such as Figure 1 As shown, the fracture elongation of the tungsten alloy component modified by the above method in Example 1 is significantly improved; while... Figure 3 In the images, (a), (b), and (c) are comparative test images, and (d), (e), and (f) are test images of Example 1. It can be seen that the tungsten grain fracture surfaces in the comparative examples mostly exhibit radial cleavage morphology, with some debonding from the nickel-iron alloy binder phase. This indicates that grain boundaries are the main crack initiation points, and there is some dissipation in load transfer between the tungsten phase and the nickel-iron alloy binder phase. In contrast, the tungsten grain fracture surface in Example 1 is relatively smooth, with significantly reduced radial cleavage morphology. Simultaneously, the dimples of the nickel-iron alloy phase are more pronounced and tightly bonded to the tungsten. These morphological differences indicate that heat treatment can effectively purify tungsten grain boundaries, eliminate stress concentration caused by impurity phases, and promote a transformation in the fracture behavior of tungsten alloys towards greater toughness.

[0066] Therefore, the above-mentioned heat treatment strengthening and toughening method for tungsten alloy parts suitable for indirect additive manufacturing is simple to operate, has a significant strengthening and toughening effect, a short cycle, and a low cost. It can be combined with indirect additive manufacturing technology for the molding of high-performance tungsten alloy complex structural parts for the defense science and technology industry.

[0067] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0068] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A heat treatment method for strengthening and toughening tungsten alloy parts suitable for indirect additive manufacturing, characterized in that, Including the following steps: The tungsten alloy part manufactured by indirect additive manufacturing is placed in a quenching furnace and a vacuum is drawn. The tungsten alloy part manufactured by indirect additive manufacturing in a vacuum environment is first heated until the surface temperature or ambient temperature of the tungsten alloy part is raised to 800°C to 1200°C, and then kept at that temperature for a first preset time period. The indirect additive manufacturing tungsten alloy component, after being kept warm, is rapidly transferred to a cooling medium for cooling for a second preset time period. Return to the step of placing the indirectly additively manufactured tungsten alloy part in a quenching furnace and drawing a vacuum, then quickly transfer the heat-preserved indirectly additively manufactured tungsten alloy part to a cooling medium for a second preset time period, and repeat the process a preset number of times. The indirect additive manufacturing tungsten alloy parts are transferred to a vacuum solution furnace and then evacuated. The additively manufactured tungsten alloy in a vacuum environment is heated a second time until the surface temperature or ambient temperature of the indirectly additively manufactured tungsten alloy part rises to 800°C to 1200°C, and is held at that temperature for a third preset time period. The indirect additive manufacturing tungsten alloy part, after being kept at a certain temperature, is cooled to room temperature in the furnace.

2. The heat treatment strengthening and toughening method for tungsten alloy parts in indirect additive manufacturing according to claim 1, characterized in that, Before the step of placing the indirectly additively manufactured tungsten alloy part in a quenching furnace and evacuating it, the following step is also included: The indirect additive manufacturing tungsten alloy parts are cleaned to remove oil stains from their surfaces.

3. The heat treatment strengthening and toughening method for tungsten alloy parts manufactured by indirect additive manufacturing according to claim 2, characterized in that, The steps for cleaning the indirect additive manufacturing tungsten alloy parts are as follows: use a cloth dampened with cleaning agent to wipe and clean the oil stains on the surface of the indirect additive manufacturing tungsten alloy parts.

4. The heat treatment strengthening and toughening method for tungsten alloy parts manufactured by indirect additive manufacturing according to claim 1, characterized in that, Before the step of transferring the indirectly additively manufactured tungsten alloy part into a vacuum solution furnace and evacuating it, the method further includes the step of removing the indirectly additively manufactured tungsten alloy part from the cooling medium and wiping the cooling medium off the surface of the indirectly additively manufactured tungsten alloy part.

5. The heat treatment strengthening and toughening method for tungsten alloy parts manufactured by indirect additive manufacturing according to claim 1, characterized in that, The step of placing the indirectly additively manufactured tungsten alloy component in a quenching furnace and drawing a vacuum is as follows: the indirectly additively manufactured tungsten alloy component is placed in a quenching furnace and a vacuum is drawn until the pressure inside the furnace is less than or equal to 10 Pa. The step of placing the indirectly additively manufactured tungsten alloy component in a vacuum solution furnace and evacuating it is as follows: the indirectly additively manufactured tungsten alloy component is placed in a vacuum solution furnace and evacuated until the pressure inside the furnace is less than or equal to 10 Pa.

6. The heat treatment strengthening and toughening method for tungsten alloy parts manufactured by indirect additive manufacturing according to claim 1, characterized in that, The first preset time period is 1 min to 30 min, the second preset time period is 1 min to 10 min, and the third preset time period is 1 h to 3 h.

7. The heat treatment strengthening and toughening method for tungsten alloy parts in indirect additive manufacturing according to claim 1, characterized in that, The temperature rise rate during the first heating and the second heating is 1℃ / min to 10℃ / min.

8. The heat treatment strengthening and toughening method for tungsten alloy parts manufactured by indirect additive manufacturing according to claim 1, characterized in that, The transfer time for the indirect additive manufacturing tungsten alloy component to be rapidly transferred to the cooling medium is ≤5 min.

9. The heat treatment strengthening and toughening method for tungsten alloy parts manufactured by indirect additive manufacturing according to claim 1, characterized in that, The cooling medium is ordinary quenching oil, bright quenching oil, high-speed quenching oil, or vacuum quenching oil.

10. The heat treatment strengthening and toughening method for tungsten alloy parts manufactured by indirect additive manufacturing according to claim 1, characterized in that, In the step of returning to the execution of placing the indirectly additively manufactured tungsten alloy part in a quenching furnace and drawing a vacuum, to the step of rapidly transferring the heat-preserved indirectly additively manufactured tungsten alloy part to a cooling medium for cooling for a second preset time period, and repeating the step of ...

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