Wear-resistant and corrosion-resistant alloy screw and manufacturing process thereof

Abstract

The application relates to a wear-resistant and corrosion-resistant alloy screw rod, which comprises the following raw materials in mass fraction: nickel: 55-65%; chromium: 25-35%; vanadium: 1.8-2.5%; molybdenum: 0.5-1.8%; and the rest is a binder and unavoidable impurities; a carbon steel mandrel is arranged in the inner cavity of the alloy screw rod, a seamless steel pipe cavity matched with the length of the screw rod is selected, the carbon steel mandrel is arranged at the shaft center of the cavity, mixed powder with the above-mentioned mass ratio is injected into the cavity, and hot isostatic pressing process treatment is carried out in a vacuum environment; after grinding processing, the alloy screw rod product is obtained. Through the combination of material composition and manufacturing process, the reasonable proportioning of nickel and chromium endows the screw rod with good corrosion resistance, and the addition of vanadium and molybdenum enhances the wear resistance, so that the screw rod performs excellently in a humid or corrosive environment; the hot isostatic pressing furnace firing technology adopted ensures the uniformity and compactness of the alloy material, thereby improving the overall performance of the screw rod and guaranteeing the stability and long service life of the product.

Description

Technical Field

[0001] This application belongs to the field of alloy screw technology, and in particular relates to a wear-resistant and corrosion-resistant alloy screw and its manufacturing process. Background Technology

[0002] The screw is a crucial solvent injection component in injection molding machines. Existing alloy screws, due to material and manufacturing process factors, are susceptible to corrosion, especially in humid or corrosive environments. Prolonged repeated loading can lead to fatigue crack formation. Some alloys may experience performance degradation under high or low temperature conditions, and defects such as cracks and porosity may exist during manufacturing. Furthermore, friction and corrosion can easily cause wear and corrosion, thus affecting the normal operation and service life of the equipment. Therefore, developing a wear-resistant and corrosion-resistant alloy screw is of significant practical importance. Summary of the Invention

[0003] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and provide a wear-resistant and corrosion-resistant alloy screw and its manufacturing process, which aims to solve the problem of corrosion of plastic screws containing VO flame retardant in injection molding machines and increase the service life of the screw.

[0004] The technical solution adopted by this invention to solve its technical problem is:

[0005] A wear-resistant and corrosion-resistant alloy screw, the alloy screw comprising the following raw materials by mass fraction:

[0006] Nickel: 55%-65%;

[0007] Chromium: 25%-35%;

[0008] Vanadium: 1.8%-2.5%;

[0009] Molybdenum: 0.5%-1.8%;

[0010] The remainder consists of adhesives and unavoidable impurities;

[0011] The inner cavity of the alloy screw is also provided with a carbon steel core rod, which is used to enhance the bending strength of the alloy screw.

[0012] Select a seamless steel tube cavity that matches the length of the screw, place the carbon steel mandrel at the center of the cavity, inject the mixed powder according to the above mass ratio into the cavity, compact it, seal it and place it in a hot isostatic pressing furnace, process it in a vacuum environment using the hot isostatic pressing process, and after the bar is ground, obtain the finished alloy screw.

[0013] Preferably, in the wear-resistant and corrosion-resistant alloy screw of the present invention, the particle size requirements of each metal powder are as follows: nickel: 70-140μm, chromium: 70-140μm, vanadium: 20-50μm, molybdenum: 15-30μm, and other impurities not greater than 140μm.

[0014] Preferably, in the wear-resistant and corrosion-resistant alloy screw of the present invention, the purity requirements of each metal powder are as follows: nickel > 99.9%, chromium 99.5%, vanadium > 99.65%, and molybdenum > 99.9%.

[0015] Preferably, the manufacturing process of a wear-resistant and corrosion-resistant alloy screw according to the present invention includes the following steps:

[0016] Step 1: Ingredient preparation. Prepare powder according to the required mass fraction of the alloy screw and mix evenly.

[0017] Step 2: Prepare a seamless steel pipe with one end sealed, place the carbon steel mandrel into the core of the cavity, pour the mixed alloy powder into the cavity of the seamless steel pipe and compact it;

[0018] Step 3: Vacuum the seamless steel pipe and seal the ends;

[0019] Step 4: Heating and pressurizing. Place the sealed seamless steel pipe into a hot isostatic pressing furnace, gradually raise the temperature to 900℃-1000℃, pressurize to 180-220MPa, and maintain this temperature for no less than 5 hours.

[0020] Step 5: Cool down and depressurize, let the furnace cool to room temperature, and remove the alloy bar.

[0021] Step 6: Grind the alloy bar to produce a screw and perform quality inspection.

[0022] Preferably, in the manufacturing process of the wear-resistant and corrosion-resistant alloy screw of the present invention, the ratio of the outer diameter of the carbon steel core rod to the outer diameter of the alloy rod is 1:4.

[0023] Preferably, in the manufacturing process of the wear-resistant and corrosion-resistant alloy screw of the present invention, the lower end of the seamless steel pipe is sealed and welded with a lower cover, and a positioning seat for positioning and inserting a carbon steel core rod is provided on the inner wall of the lower cover.

[0024] Preferably, in the manufacturing process of the wear-resistant and corrosion-resistant alloy screw of the present invention, in step three, an upper cap is welded to the upper end of the seamless steel pipe, and the upper cap is provided with a vent hole for vacuuming.

[0025] The beneficial effects of this invention are:

[0026] (1) This invention aims to provide excellent wear resistance and corrosion resistance through the combination of material composition and manufacturing process. The superior ratio of nickel and chromium gives the screw excellent corrosion resistance, while the addition of vanadium and molybdenum enhances its wear resistance, making it perform well in humid or corrosive environments.

[0027] (2) The hot isostatic pressing furnace firing technology used in the manufacturing process of this invention ensures the uniformity and density of the alloy material, thereby improving the overall performance of the screw and ensuring the stability and long service life of the product. Attached Figure Description

[0028] The technical solution of this application will be further described below with reference to the accompanying drawings and embodiments.

[0029] Figure 1 This is a schematic diagram of the manufacturing process of an embodiment of this application;

[0030] Figure 2 This is a schematic diagram of the actual appearance of the alloy screw after salt spray test according to an embodiment of this application;

[0031] Figure 3 This is a schematic diagram of the cross-sectional appearance of the alloy screw after salt spray test according to an embodiment of this application. Detailed Implementation

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0033] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0034] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0035] The technical solution of this application will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] Example

[0037] This embodiment provides a wear-resistant and corrosion-resistant alloy screw, which comprises the following raw materials by mass fraction:

[0038] Nickel: 60%;

[0039] Chromium: 30%;

[0040] Vanadium: 2%;

[0041] Molybdenum: 1%;

[0042] The remainder consists of adhesives and unavoidable impurities;

[0043] The particle size requirements for each metal powder are as follows: nickel: 20-50μm, chromium: 20-50μm, vanadium: 20-50μm, molybdenum: 15-30μm, and other impurities not exceeding 90μm; the purity requirements for each metal powder are as follows: nickel >99.9%, chromium 99.5%, vanadium >99.65%, and molybdenum >99.9%.

[0044] High-purity nickel, chromium, and molybdenum can ensure that the products have better mechanical properties and corrosion resistance. At the same time, in order to improve the sintering effect and density of nickel, it is also necessary to pay attention to controlling the particle size and shape of nickel powder. When 50μm coarse molybdenum powder is used for pressing, the density is 7.2g / cm3; if 20μm fine molybdenum powder is used for pressing, the density can reach 7.4g / cm3. In this embodiment, metal powder with smaller particle size is selected to increase the density of the alloy.

[0045] A carbon steel mandrel is also installed in the inner cavity of the alloy screw. The carbon steel mandrel is used to strengthen the bending strength of the alloy screw. The carbon content of the carbon steel mandrel is between 0.2% and 0.3%, which has good plasticity and toughness and can withstand impact and deformation.

[0046] Select a seamless steel tube cavity that matches the screw length, weld and seal the lower end of the seamless steel tube, place the carbon steel mandrel at the center of the cavity, inject the mixed powder according to the above mass ratio into the cavity, compact and seal it and place it in a hot isostatic pressing furnace, process it in a vacuum environment using the hot isostatic pressing process, and after grinding the bar stock, obtain the finished alloy screw.

[0047] The manufacturing process of a wear-resistant and corrosion-resistant alloy screw in this embodiment is described in reference to... Figure 1 This includes the following steps:

[0048] Step 1: Batching. Prepare powder according to the required mass fraction of the alloy screw. Through the high-speed rotation of the high-energy ball mill, the metal powder is subjected to strong impact and friction, thereby refining the particles and promoting alloying.

[0049] Step 2: Prepare a seamless steel pipe, weld and seal the lower end of the seamless steel pipe, place the carbon steel mandrel into the core of the cavity, pour the pre-treated mixed alloy powder into the cavity of the seamless steel pipe and compact it; weld an end cap to the upper end of the seamless steel pipe, and set a small vacuum hole on the end cap.

[0050] Before loading the alloy powder into the packaging, the powder needs to be pretreated, such as dried, mixed, and sieved, to ensure its uniformity and flowability. Additionally, to prevent oxidation or volatilization at high temperatures, a protective film needs to be coated onto the powder surface.

[0051] Step 3: Vacuum the seamless steel pipe through the small hole on the end cap and weld the sealed port.

[0052] Step 4: Heating and pressurizing. Place the sealed seamless steel pipe into a hot isostatic pressing furnace, gradually raise the temperature to 900℃-1000℃, pressurize to 180-220MPa, and maintain this temperature for no less than 5 hours.

[0053] Step 5: Cool down and depressurize, let the furnace cool to room temperature, and remove the alloy bar.

[0054] Step 6: Grind the alloy bar to produce a screw and perform quality inspection.

[0055] The present invention also conducted a salt spray test on the finished alloy screw. The purpose of this salt spray test was to evaluate the corrosion resistance of the alloy screw in order to determine its service life and performance stability in harsh environments.

[0056] The testing process is as follows:

[0057] This test adopted the internationally recognized salt spray test method (ASTM B117-2013), exposing the alloy screw to a salt spray chamber containing sodium chloride and acidic solution. The corrosion resistance was evaluated by observing and measuring the degree of corrosion on the screw surface.

[0058] The temperature inside the salt spray test chamber is 35℃, the humidity is above 95%, the salt concentration is 5%, and the spraying time is 72 hours.

[0059] Test results:

[0060] The alloy screw was observed and measured after 72 hours of salt spray testing. The test results are as follows:

[0061] (1) Visual observation:

[0062] Reference Figure 2 and Figure 3 After the salt spray test, the surface of the alloy screw was bright and showed no signs of corrosion, but the cross-section of the carbon steel mandrel showed obvious corrosion and rust. The overall appearance of the screw surface still maintained a good gloss.

[0063] (2) Dimensional measurement:

[0064] The length, diameter, and pitch of the alloy screw were measured before and after the test. The results showed that the dimensional changes were small and no obvious dimensional deformation was observed.

[0065] (3) Mechanical property testing:

[0066] The alloy screw was subjected to hardness testing. First, multiple measurement points were selected on the surface of the alloy rod after molding and cooling for grinding and polishing to ensure that it was flat, smooth and free of obvious defects. The measurement points were placed on the measuring station of the Rockwell hardness tester, and the hardness value was obtained by measuring the indentations at different depths after applying a predetermined load to the material surface.

[0067] The following are the measured data values: HRC60.3, HRC60.9, HRC59.7, HRC59.9, HRC60.1, and HRC60.1. The test results show that the mechanical properties have not decreased significantly and still meet the design requirements.

[0068] Conclusion: Based on the results of this salt spray test, the alloy screw exhibits good corrosion resistance under harsh conditions. Although no signs of corrosion were observed, the overall appearance and dimensions showed minimal change, and the mechanical properties did not significantly deteriorate. Therefore, the alloy screw can be considered suitable for applications involving long-term exposure to salt spray environments.

[0069] Based on the above-described preferred embodiments according to this application, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A wear-resistant and corrosion-resistant alloy screw, characterized in that, The alloy screw comprises the following raw materials by mass fraction: Nickel: 55%-65%; Chromium: 25%-35%; Vanadium: 1.8%-2.5%; Molybdenum: 0.5%-1.8%; The remainder consists of adhesives and unavoidable impurities; The inner cavity of the alloy screw is also provided with a carbon steel core rod, which is used to enhance the bending strength of the alloy screw. The carbon content of the carbon steel core rod is 0.2%-0.3%. Select a seamless steel tube cavity that matches the length of the screw, place the carbon steel mandrel at the center of the cavity, inject the mixed powder according to the above mass ratio into the cavity, compact it, seal it and place it in a hot isostatic pressing furnace, process it in a vacuum environment using the hot isostatic pressing process, and after the bar is ground, obtain the finished alloy screw.

2. The wear-resistant and corrosion-resistant alloy screw according to claim 1, characterized in that, The particle size requirements for each metal powder are as follows: nickel: 70-140μm, chromium: 70-140μm, vanadium: 20-50μm, molybdenum: 15-30μm, and other impurities not larger than 140μm.

3. The wear-resistant and corrosion-resistant alloy screw according to claim 2, characterized in that, The purity requirements for each metal powder are as follows: nickel > 99.9%, chromium 99.5%, vanadium > 99.65%, molybdenum > 99.9%.

4. The manufacturing process of a wear-resistant and corrosion-resistant alloy screw according to any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Batching. Powder is prepared according to the required mass fraction of the alloy screw, and the metal powder is subjected to strong impact and friction through the high-speed rotation of the high-energy ball mill, thereby refining the particles and promoting alloying. Step 2: Prepare a seamless steel pipe with one end sealed, place the carbon steel mandrel into the core of the cavity, pour the mixed alloy powder into the cavity of the seamless steel pipe and compact it; Step 3: Vacuum the seamless steel pipe and seal the ends; Step 4: Heating and pressurizing. Place the sealed seamless steel pipe into a hot isostatic pressing furnace, gradually raise the temperature to 900℃-1000℃, pressurize to 180-220MPa, and maintain this temperature for no less than 5 hours. Step 5: Cool down and depressurize, let the furnace cool to room temperature, and remove the alloy bar. Step 6: Grind the alloy bar to produce a screw and perform quality inspection.

5. The manufacturing process of a wear-resistant and corrosion-resistant alloy screw according to claim 4, characterized in that, The ratio of the outer diameter of the carbon steel core rod to the outer diameter of the alloy rod is 1:

4.

6. The manufacturing process of a wear-resistant and corrosion-resistant alloy screw according to claim 4, characterized in that, The lower end of the seamless steel pipe is sealed with a lower cover, and a positioning seat for positioning and inserting a carbon steel core rod is provided on the inner wall of the lower cover.

7. The manufacturing process of a wear-resistant and corrosion-resistant alloy screw according to claim 4, characterized in that, In step three, an upper cap is welded to the upper end of the seamless steel pipe, and the upper cap is provided with a vent hole for vacuuming.

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