Sintering process for 420 stainless steel metal powder injection molding part
By adopting a sintering process of multiple heating and heat preservation in a vacuum degreasing sintering furnace, and using nitrogen and argon environments, the problem of unsatisfactory product density and hardness caused by the sintering process of 420 stainless steel metal powder injection molding process in the existing technology is solved. problem, achieving higher density and hardness.
Patent Information
- Application Number
- CN202411600101.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-11
- Publication Date
- 2025-01-21
Smart Images
Figure CN119328138A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of sintering technology of 420 metal injection molded parts, in particular to a sintering technology of 420 stainless steel metal powder injection molded parts. Background Art
[0002] 420 stainless steel is a typical martensitic stainless steel with high hardness, strength and wear resistance, so it is widely used in the fields of cutting tools, measuring tools and surgical medical equipment. Metal powder injection molding is an advanced metal forming technology, which is currently widely used. The manufacturing of 420 stainless steel products based on metal powder injection molding technology is a near-net forming technology that can effectively reduce resource and energy consumption.
[0003] In the prior art 420 stainless steel metal powder injection molding process, firstly, 420 stainless steel powder and a binder are mixed at a certain ratio, and then granulated on a granulating device to obtain a granular raw material. Subsequently, the molding mold is installed on the injection machine, and the granular raw material is added to the hopper of the injection machine. The raw material enters the barrel through the hopper, and the raw material gradually melts and turns into a melt in the barrel, and then is injected into the mold cavity through the screw. After a period of cooling, a green body of a 420 stainless steel product is obtained. The green body of the 420 stainless steel metal powder injection molding part formed by the injection machine is degreased to obtain a degreased blank, and then the degreased blank is placed in a sintering furnace for sintering to obtain the final sintered product.
[0004] The sintering process has a great influence on the final product quality. The density and hardness of the products produced by the existing sintering process are not ideal. Summary of the invention
[0005] The invention provides a sintering process for a 420 stainless steel metal powder injection molding part, so as to solve the problem of unsatisfactory product density and hardness in the sintering process of the prior art 420 stainless steel metal powder injection molding process.
[0006] In order to achieve the above object, the technical solution adopted by the present invention is: A sintering process for 420 stainless steel metal powder injection molded parts, comprising the following steps: Step 1, placing the 420 stainless steel metal powder injection molded part to be sintered in a vacuum degreasing sintering furnace, and evacuating the vacuum degreasing sintering furnace; Step 2: While introducing the first protective gas into the vacuum debinding sintering furnace, use the slide valve pump to evacuate the gas. At a heating rate of 3°C±0.1°C / min, raise the temperature in the vacuum debinding sintering furnace from room temperature to 200°C±3°C, and then keep it warm; Step 3: While introducing the first protective gas into the vacuum debinding sintering furnace, use the slide valve pump to evacuate the gas. At a heating rate of 2°C±0.2°C, raise the temperature in the vacuum debinding sintering furnace from 200°C±3°C to 400°C±3°C, and then keep it warm; Step 4: While introducing the first protective gas into the vacuum debinding sintering furnace, use the slide valve pump to evacuate the gas. At a heating rate of 3°C±0.1°C / min, raise the temperature in the vacuum debinding sintering furnace from 400°C±3°C to 600°C±3°C, and then keep it warm; Step 5: While introducing the first protective gas into the vacuum debinding sintering furnace, use the slide valve pump to evacuate the gas. At a heating rate of 3°C±0.1°C / min, raise the temperature in the vacuum debinding sintering furnace from 400°C±3°C to 800°C±3°C, and then keep it warm; Step 6, the first protective gas in the vacuum degreasing sintering furnace is evacuated to a vacuum state, and then the temperature in the vacuum degreasing sintering furnace is increased from 800°C±3°C to 1050°C±3°C at a heating rate of 2.5°C±0.2°C / min, and then the temperature is kept constant; Step 7, introducing a second protective gas into the vacuum degreasing sintering furnace, and then under the second protective gas environment, raising the temperature in the vacuum degreasing sintering furnace from 1050°C±3°C to 1380°C±3°C at a heating rate of 2.5°C±0.2°C / min, and then keeping the temperature; Step 8, under the second protective gas environment, cool the vacuum degreasing sintering furnace from 1380°C±3°C to 1050°C±3°C at a cooling rate of 3.5°C±0.2°C / min; Step 9, under the second protective gas environment, cool the vacuum degreasing sintering furnace from 1050°C±3°C to 800°C±3°C at a cooling rate of 4°C±0.2°C / min; Step 10, introducing the second protective gas into the vacuum degreasing sintering furnace again for forced cooling, the gas pressure is 85KPa±3KPa, and the forced cooling time is 30min±3min; Step 11: Leave it for a while to ensure that the vacuum degreasing sintering furnace is completely cooled, and then the sintered product can be obtained.
[0007] Furthermore, in steps 2 to 5, the insulation time is 30 minutes.
[0008] Furthermore, in step 6, the insulation time is 90 minutes.
[0009] Furthermore, in step 7, the insulation time is 180 minutes.
[0010] Furthermore, in steps 2 to 6, the first protective gas is nitrogen.
[0011] Furthermore, in step 7 to step 10, the second protective gas is argon.
[0012] The sintering process of the present invention can significantly improve the hardness of the final sintered product and further improve the density of the product. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 It is a sintering process diagram of an embodiment of the present invention. DETAILED DESCRIPTION
[0014] The present invention is further described below in conjunction with the accompanying drawings and embodiments.
[0015] like Figure 1 As shown, this embodiment discloses a sintering process for 420 stainless steel metal powder injection molding parts, comprising the following steps: Step 1: Use a metal injection molding vacuum degreasing sintering furnace as the sintering equipment, place a ceramic plate on the graphite plate in the vacuum degreasing sintering furnace, and then place the 420 stainless steel metal powder injection molded parts to be sintered on the ceramic plate in the vacuum degreasing sintering furnace. When there are multiple 420 stainless steel metal powder injection molded parts to be sintered, the molded parts should be staggered and not overlapped, and the vacuum degreasing sintering furnace should be vacuumed.
[0016] Step 2: While introducing the first protective gas into the vacuum debinding sintering furnace, the sliding valve pump is used to evacuate the gas. Then, in a nitrogen environment, the temperature in the vacuum debinding sintering furnace is raised from room temperature to 200°C±3°C at a heating rate of 3°C±0.1°C / min, and then kept at this temperature for 30 minutes.
[0017] Step 3: While introducing the first protective gas into the vacuum degreasing sintering furnace, the sliding valve pump is used to evacuate the gas. The temperature in the vacuum degreasing sintering furnace is raised from 200°C±3°C to 400°C±3°C at a heating rate of 2°C±0.2°C, and then kept at this temperature for 30 minutes.
[0018] Step 4: While introducing the first protective gas into the vacuum debinding sintering furnace, the sliding valve pump is used to evacuate the gas. The temperature in the vacuum debinding sintering furnace is raised from 400°C±3°C to 600°C±3°C at a heating rate of 3°C±0.1°C / min, and then kept at this temperature for 30 minutes.
[0019] Step 5: While introducing the first protective gas into the vacuum debinding sintering furnace, use the slide valve pump to evacuate the gas. At a heating rate of 3°C±0.1°C / min, raise the temperature in the vacuum debinding sintering furnace from 400°C±3°C to 800°C±3°C, and then keep the temperature for 30 minutes.
[0020] Step 6: Pump out the nitrogen in the vacuum degreasing sintering furnace to make it vacuum, then raise the temperature in the vacuum degreasing sintering furnace from 800°C±3°C to 1050°C±3°C at a heating rate of 2.5°C±0.2°C / min, and then keep it warm for 90 minutes.
[0021] Step 7, introduce argon gas into the vacuum debinding sintering furnace, and then in the argon environment, increase the temperature in the vacuum debinding sintering furnace from 1050°C±3°C to 1380°C±3°C at a heating rate of 2.5°C±0.2°C / min, and then keep it warm for 180 minutes.
[0022] Step 8: In an argon environment, cool the vacuum debinding sintering furnace from 1380°C±3°C to 1050°C±3°C at a cooling rate of 3.5°C±0.2°C / min.
[0023] Step 9: In an argon environment, cool the vacuum debinding sintering furnace from 1050°C±3°C to 800°C±3°C at a cooling rate of 4°C±0.2°C / min.
[0024] Step 10: introduce argon gas into the vacuum degreasing sintering furnace again for argon forced cooling. The forced cooling time is 30 min ± 3 min. The pressure of the second protective gas introduced is 85 KPa ± 3 KPa.
[0025] Step 11: Leave it for a while to ensure that the vacuum degreasing sintering furnace is completely cooled, and then the sintered product can be obtained.
[0026] Compared with the sintering process of the original 420 stainless steel metal powder injection molding process, the density, compactness and hardness of the product obtained by the sintering process of this embodiment are improved, as shown in Table 1.
[0027] Table 1 Comparison of the invented sintering process and the original sintering process data
[0028] It can be seen from Table 1 that the density of the 420 stainless steel metal powder injection molded part after the sintering process of this embodiment is 98.45%, which is 0.91% higher than that of the original process; the hardness of the product obtained by the process of this embodiment reaches 17.4HRB, which is 15.5% higher than that of the original process.
[0029] It can be seen from Table 1 that the product of the sintering process of this embodiment has advantages in density and hardness.
[0030] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. The embodiments described in the present invention are merely descriptions of the preferred embodiments of the present invention, and do not limit the concept and scope of the present invention. The various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction, and such combinations should also be regarded as the contents disclosed in the present disclosure as long as they do not violate the concept of the present invention. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.
[0031] The present invention is not limited to the specific details of the above-mentioned embodiments. Within the technical concept of the present invention and without departing from the design concept of the present invention, various modifications and improvements made to the technical solution of the present invention by technical personnel in this field should fall within the protection scope of the present invention. The technical contents for which protection is sought in the present invention have been fully recorded in the claims.
Claims
1. A sintering process for 420 stainless steel metal powder injection molded parts, characterized in that: The following steps are involved: Step 1, placing the 420 stainless steel metal powder injection molded part to be sintered in a vacuum degreasing sintering furnace, and evacuating the vacuum degreasing sintering furnace; Step 2: While introducing the first protective gas into the vacuum debinding sintering furnace, use the slide valve pump to evacuate the gas. At a heating rate of 3°C±0.1°C / min, raise the temperature in the vacuum debinding sintering furnace from room temperature to 200°C±3°C, and then keep it warm; Step 3: While introducing the first protective gas into the vacuum debinding sintering furnace, use the slide valve pump to evacuate the gas. At a heating rate of 2°C±0.2°C, raise the temperature in the vacuum debinding sintering furnace from 200°C±3°C to 400°C±3°C, and then keep it warm; Step 4: While introducing the first protective gas into the vacuum debinding sintering furnace, use the slide valve pump to evacuate the gas. At a heating rate of 3°C±0.1°C / min, raise the temperature in the vacuum debinding sintering furnace from 400°C±3°C to 600°C±3°C, and then keep it warm; Step 5: While introducing the first protective gas into the vacuum debinding sintering furnace, use the slide valve pump to evacuate the gas. At a heating rate of 3°C±0.1°C / min, raise the temperature in the vacuum debinding sintering furnace from 400°C±3°C to 800°C±3°C, and then keep it warm; Step 6, the first protective gas in the vacuum degreasing sintering furnace is evacuated to a vacuum state, and then the temperature in the vacuum degreasing sintering furnace is increased from 800°C±3°C to 1050°C±3°C at a heating rate of 2.5°C±0.2°C / min, and then the temperature is kept constant; Step 7, introducing a second protective gas into the vacuum degreasing sintering furnace, and then under the second protective gas environment, raising the temperature in the vacuum degreasing sintering furnace from 1050°C±3°C to 1380°C±3°C at a heating rate of 2.5°C±0.2°C / min, and then keeping the temperature; Step 8, under the second protective gas environment, cool the vacuum degreasing sintering furnace from 1380°C±3°C to 1050°C±3°C at a cooling rate of 3.5°C±0.2°C / min; Step 9, under the second protective gas environment, cool the vacuum degreasing sintering furnace from 1050°C±3°C to 800°C±3°C at a cooling rate of 4°C±0.2°C / min; Step 10, introducing the second protective gas into the vacuum degreasing sintering furnace again, the gas pressure is 85±3Kpa, and strong cooling is performed, and the strong cooling time is 30min±3min; Step 11: Leave it for a while to ensure that the vacuum degreasing sintering furnace is completely cooled, and then the sintered product can be obtained.
2. The sintering process of a 420 stainless steel metal powder injection molded part according to claim 1, characterized in that: In step 2 to step 5, the heat preservation time is 30 minutes.
3. The sintering process of 420 stainless steel metal powder injection molded parts according to claim 1, characterized in that: In step 6, the heat preservation time is 90 minutes.
4. The sintering process of 420 stainless steel metal powder injection molded parts according to claim 1, characterized in that: In step 7, the heat preservation time is 180 minutes.
5. A sintering process for 420 stainless steel metal powder injection molded parts according to any one of claims 1 to 4, characterized in that: In step 2 to step 6, the first protective gas is nitrogen.
6. A sintering process for 420 stainless steel metal powder injection molded parts according to any one of claims 1 to 4, characterized in that: In step 7 to step 10, the second protective gas is argon.