Method for improving wettability of melt on surface of riser tube and prolonging service life of riser tube

Abstract

The embodiment of the invention provides a method for improving the wettability of melt on the surface of a riser tube and prolonging the service life of the riser tube. The method comprises the steps that the riser tube is subjected to acid pickling treatment; carrying out surface treatment on the riser tube subjected to acid pickling treatment; the surface treatment comprises shot blasting treatment, ion nitriding treatment and vacuum high-temperature diffusion. The riser tube is subjected to acid pickling treatment to remove surface oxide skin, shot blasting treatment to enhance the surface strength and roughness and improve the ion nitriding effect, a 5-10 [mu] m nitriding layer is formed on the surface of the riser tube through ion nitriding treatment, an austenite and martensite matrix and a 30-50 [mu] m nitriding layer are formed after vacuum high-temperature diffusion, the surface nitriding layer can effectively improve the melt wettability, and the melt wettability is improved. The service life of the riser tube can be prolonged from 25 times to more than 60 times, fire-resistant paint is not needed, and the risk that the paint falls off is avoided. The riser tube treated by the method has the advantages of low cost, good melt wettability, excellent service life and the like.

Description

Technical Field

[0001] The present application relates to the technical field of material casting, and in particular to a method for improving the wettability of the melt on the surface of a riser tube and improving the service life of the riser tube. Background Art

[0002] The riser is one of the key components in the anti-gravity pouring equipment for aluminum or magnesium alloys. When working, the lower end is placed in a closed crucible containing aluminum solution (temperature 700-800℃) in the anti-gravity pouring equipment for aluminum or magnesium alloys. Under the action of gas pressure, the molten metal enters the crucible from the crucible through the riser; after the pressure is released, the unsolidified molten metal also flows back to the crucible through the riser. As an important component in the pouring system, the riser has the functions of diversion and shrinkage compensation. Its material is required to have the properties of high temperature resistance, non-wetting with the melt, good service life, and low cost of use.

[0003] However, the riser in the prior art cannot meet the requirements. Summary of the invention

[0004] The embodiment of the present application provides a method for improving the wettability of the melt on the surface of a riser tube and the service life of the riser tube, so as to improve the wettability of the melt on the surface of the riser tube and the service life of the riser tube.

[0005] The embodiment of the present application provides a method for improving the wettability and service life of the melt on the surface of a riser tube, comprising:

[0006] Pickling the riser tube;

[0007] Performing surface treatment on the pickled riser tube;

[0008] The surface treatment includes shot peening, ion nitriding and vacuum high temperature diffusion.

[0009] In a feasible implementation, the pickling treatment includes:

[0010] The pickling liquid is a hydrochloric acid solution with a concentration of 5%-20%;

[0011] In a feasible implementation, the pickling treatment includes:

[0012] The pickling temperature range is 20℃-80℃.

[0013] In a feasible implementation, the pickling treatment includes:

[0014] The pickling time ranges from 2min to 15min.

[0015] In a feasible implementation, the diameter of the balls subjected to the shot peening treatment ranges from 1 mm to 5 mm, and the shot peening treatment time ranges from 5 min to 60 min.

[0016] In a feasible implementation, the ion nitriding treatment includes:

[0017] Using an ion nitriding furnace to perform the ion nitriding treatment on the riser tube in a nitrogen environment;

[0018] The ion nitriding furnace is evacuated to a target vacuum range, and the riser tube is powered on for ion bombardment. After the arc is broken, nitrogen is continuously introduced into the ion nitriding furnace, and the riser tube is treated within the nitriding temperature range and the nitriding time range. The ion nitriding furnace is then evacuated to a low vacuum, and the riser tube is removed from the furnace after cooling to a specified temperature.

[0019] In one possible implementation,

[0020] The target vacuum range is 100Pa-500Pa;

[0021] And / or, the nitriding temperature ranges from 400°C to 800°C;

[0022] And / or, the nitriding time ranges from 8h to 20h.

[0023] In a feasible implementation, the vacuum high temperature diffusion includes:

[0024] The riser tube after ion nitriding treatment is placed in a vacuum furnace for high-temperature diffusion treatment, specifically including: raising the temperature in the vacuum furnace to a specified temperature range, maintaining the temperature within a target time range, and then cooling the vacuum furnace to room temperature.

[0025] In a feasible implementation, the specified temperature range is 800° C.-1200° C.;

[0026] In a feasible implementation, the target duration ranges from 2 hours to 8 hours.

[0027] The embodiment of the present application provides a method for improving the surface wettability and service life of the riser tube, including pickling the riser tube; performing surface treatment on the pickled riser tube; the surface treatment includes shot peening, ion nitriding and vacuum high-temperature diffusion. The riser tube is pickled to remove the surface oxide scale, and the shot peening strengthens the surface strength and roughness, improves the ion nitriding effect, and after the ion nitriding, a 5-10μm nitriding layer is formed on the surface of the riser tube, and an austenite + martensite matrix and a 30-50μm nitriding layer are formed after vacuum high-temperature diffusion. The surface nitriding layer can effectively improve the wettability of the melt, and the service life of the riser tube can be increased from 25 times to more than 60 times, without the need to use refractory coatings, and there is no risk of coating shedding. The riser tube treated by this method has the advantages of low cost, good melt wettability, and excellent service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present application and do not constitute improper limitations on the present invention.

[0029] In the attached picture:

[0030] Figure 1 It is a flow chart of a method for improving the wettability and service life of the melt on the surface of a riser tube provided in one embodiment of the present application. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solutions in this application, the following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0032] In the description of the embodiments of the present application, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "plurality" means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0033] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0034] The riser is one of the key components in the anti-gravity pouring equipment for aluminum or magnesium alloys. When working, the lower end is placed in a closed crucible containing aluminum solution (temperature 700-800℃) in the anti-gravity pouring equipment for aluminum or magnesium alloys. Under the action of gas pressure, the molten metal enters the crucible from the crucible through the riser; after the pressure is released, the unsolidified molten metal also flows back to the crucible through the riser. As an important component in the pouring system, the riser has the functions of diversion and shrinkage compensation. Its material is required to have the properties of high temperature resistance, non-wetting with the melt, good service life, and low cost of use.

[0035] In the prior art, the riser tubes for counter-gravity casting mainly include metal riser tubes and ceramic riser tubes.

[0036] (1) Metal riser: It is mainly made of seamless steel pipe welding / cast iron casting, and the inner and outer layers are brushed with refractory materials. The metal riser has good mechanical properties and air tightness, is easy to process, and is inexpensive. The disadvantages are that the thermal expansion coefficients of metal and coating are very different, the coating is easy to fall off, the metal riser is easy to corrode, and the alloy liquid is polluted. In addition, the metal riser is severely deformed during use, which affects the flow rate and direction of the metal liquid. At the same time, the metal riser has a short service life, which affects production efficiency and increases production costs.

[0037] (2) Ceramic riser tube: It is mainly made of aluminum titanate ceramic / silicon nitride and other materials. It has the advantages of low expansion coefficient, good heat shock resistance, excellent high temperature mechanical properties, strong resistance to metal corrosion, etc. However, it is expensive and not conducive to large-scale industrial use.

[0038] In order to solve the above problems, the embodiment of the present application provides a method for improving the wettability and service life of the melt on the surface of the riser tube, so as to improve the wettability and service life of the melt on the surface of the riser tube. The scheme provided by the embodiment of the present application will be described below in conjunction with the drawings of the specification.

[0039] Figure 1 It is a flow chart of a method for improving the wettability and service life of the melt on the surface of a riser tube provided in one embodiment of the present application.

[0040] Reference Figure 1 As shown, the embodiment of the present application provides a method for improving the wettability and service life of the melt on the surface of the riser tube, comprising:

[0041] S100: The riser pipe is pickled to remove the surface oxide scale.

[0042] For example, the pickling treatment uses a hydrochloric acid solution with a concentration of 5%-20%. The pickling temperature ranges from 20° C. to 80° C. The pickling time ranges from 2 min to 15 min.

[0043] S200: performing surface treatment on the pickled riser pipe, wherein the surface treatment includes shot peening, ion nitriding and vacuum high temperature diffusion.

[0044] The shot peening treatment enhances the surface strength and roughness and improves the ion nitriding effect. For example, the diameter of the shot peening balls ranges from 1 mm to 5 mm, and the shot peening time ranges from 5 min to 60 min.

[0045] Exemplarily, in some examples, the ion nitriding treatment includes: using an ion nitriding furnace to perform the ion nitriding treatment on the riser tube in a nitrogen environment; placing the riser tube, thermocouple, etc. properly, then sealing the ion nitriding furnace, starting the vacuum pump to evacuate, and at the same time starting the cooling water system to evacuate the ion nitriding furnace to a target vacuum range, powering on the riser tube for ion bombardment, and after the arc is broken, continuously introducing nitrogen into the ion nitriding furnace, and the flow rate of the nitrogen introduced can be 0.5L / min-2L / min. The riser tube is treated within the nitriding temperature range and the nitriding time range, and then the ion nitriding furnace is evacuated to a low vacuum, and the riser tube is taken out of the furnace after cooling to a specified temperature with the furnace. Among them, the target vacuum range is 100Pa-500Pa; and / or, the nitriding temperature range is 400℃-800℃; and / or, the nitriding time range is 8h-20h.

[0046] The vacuum high temperature diffusion includes placing the riser tube after ion nitriding treatment into a vacuum furnace for high temperature diffusion treatment, specifically including: raising the temperature in the vacuum furnace to 800°C-1200°C, and maintaining the temperature for 2h-8h, and then cooling the vacuum furnace to room temperature. It should be noted that room temperature can specifically refer to 25°C.

[0047] After ion nitriding treatment, a 5-10μm nitride layer is formed on the surface of the riser tube, and after vacuum high-temperature diffusion, an austenite + martensite matrix and a 30-50μm nitride layer are formed. The surface nitride layer can effectively improve the wettability of the melt, and the service life of the riser tube can be increased from 25 times to more than 60 times. There is no need to use refractory coatings, and there is no risk of coating shedding. The riser tube treated by this method has the advantages of low cost, good melt wettability, and excellent service life.

[0048] Example

[0049] The present invention provides a method for improving the wettability and service life of the surface of a metal riser tube for counter-gravity casting, and the process method is as follows:

[0050] Step 1: Pickling

[0051] The SUS430 liquid-lifting pipe is placed in a pickling tank for pickling treatment and then ultrasonically cleaned.

[0052] The pickling solution is a 15% hydrochloric acid solution, the pickling temperature is 60°C, and the pickling time is 10 minutes.

[0053] Step 2: Shot Peening

[0054] Place the riser tube into the shot blasting machine working chamber for shot blasting.

[0055] The shot peening is performed using SUS304 stainless steel balls, the diameter of the balls is within the range of 3 mm, and the shot peening time is 30 minutes.

[0056] Step 3: Ion nitriding

[0057] Ion nitriding treatment, using an ion nitriding furnace to carry out the ion nitriding step on the riser tube after the above treatment, put the riser tube, thermocouple, etc. in place, then seal the ion nitriding furnace, start the vacuum pump to evacuate the ion nitriding furnace, and turn on the cooling water system at the same time. When the vacuum degree in the ion nitriding furnace reaches a certain value, power on to bombard the riser tube with ions to eliminate the residual dirt on the surface of the riser tube that cannot be cleaned with high-efficiency detergents. After the arc is basically broken, nitrogen gas with an appropriate flow rate is continuously introduced into the ion nitriding furnace. After the treatment is completed under certain nitriding temperature and nitriding time conditions, the ion nitriding furnace is evacuated to a low vacuum, and the riser tube is removed from the furnace when it cools to a certain temperature with the furnace.

[0058] The vacuum degree reaches a certain value, and the vacuum degree range is 300Pa.

[0059] The nitrogen gas is continuously introduced into the ion nitriding furnace at an appropriate flow rate of 2 L / min.

[0060] The treatment is carried out under certain nitriding temperature and nitriding time conditions, the nitriding temperature range is 600° C., and the nitriding time range is 12 hours.

[0061] The furnace is cooled to a certain temperature, and the temperature range is 150°C.

[0062] Step 4: Vacuum high temperature diffusion

[0063] The nitrided riser tube is placed in a vacuum furnace for high-temperature diffusion, the furnace temperature is raised to a certain temperature, the diffusion is carried out for a certain time, and then the furnace is cooled to room temperature.

[0064] The furnace temperature is raised to a certain temperature, and the temperature range is 1000°C.

[0065] The diffusion is carried out for a certain period of time, and the diffusion time is 6 hours.

[0066] After the above steps, the surface of the obtained riser tube is smooth and free of crack defects, and an austenite + martensite matrix and a 30-50μm nitride layer are formed on the surface. The surface nitride layer can effectively improve the wettability of the melt, and the service life is increased from 25 times to more than 60 times. There is no need to use refractory coating, and at the same time, the manual coating process is reduced, there is no risk of coating falling off, the production efficiency is improved, the quality of the product is guaranteed, and the production cost is reduced.

[0067] It is easy to understand that those skilled in the art can combine, split, reorganize, etc. the embodiments of the present application to obtain other embodiments based on the several embodiments provided in the present application, and these embodiments do not exceed the protection scope of the present application.

[0068] The above specific implementation methods further explain in detail the purpose, technical solutions and beneficial effects of the embodiments of the present application. It should be understood that the above are only specific implementation methods of the embodiments of the present application and are not used to limit the protection scope of the embodiments of the present application. Any modifications, equivalent substitutions, improvements, etc. made on the basis of the technical solutions of the embodiments of the present application should be included in the protection scope of the embodiments of the present application.

Claims

1. A method for improving the wettability and service life of a riser tube surface melt, characterized in that: include: Pickling the riser tube; Performing surface treatment on the pickled riser tube; The surface treatment includes shot peening, ion nitriding and vacuum high temperature diffusion.

2. The method for improving the wettability and service life of the riser tube surface according to claim 1, characterized in that: The pickling treatment comprises: The pickling solution is a hydrochloric acid solution with a concentration of 5%-20%.

3. The method for improving the wettability and service life of the riser tube surface according to claim 1, characterized in that: The pickling treatment comprises: The pickling temperature range is 20℃-80℃.

4. The method for improving the wettability and service life of the riser tube surface according to claim 1, characterized in that: The pickling treatment comprises: The pickling time ranges from 2min to 15min.

5. The method for improving the wettability and service life of the riser tube surface according to claim 1, characterized in that: The diameter of the balls subjected to the shot peening treatment ranges from 1 mm to 5 mm, and the shot peening treatment time ranges from 5 min to 60 min.

6. The method for improving the wettability and service life of the riser tube surface according to claim 1, characterized in that: The ion nitriding treatment comprises: Using an ion nitriding furnace to perform the ion nitriding treatment on the riser tube in a nitrogen environment; The ion nitriding furnace is evacuated to a target vacuum range, and the riser tube is powered on for ion bombardment. After the arc is broken, nitrogen is continuously introduced into the ion nitriding furnace, and the riser tube is treated within the nitriding temperature range and the nitriding time range. The ion nitriding furnace is then evacuated to a low vacuum, and the riser tube is removed from the furnace after cooling to a specified temperature.

7. The method for improving the wettability and service life of the riser tube surface according to claim 6, characterized in that: The target vacuum range is 100Pa-500Pa; And / or, the nitriding temperature ranges from 400°C to 800°C; And / or, the nitriding time ranges from 8h to 20h.

8. The method for improving the wettability of the melt on the surface of the riser tube and the service life according to claim 1, characterized in that: The vacuum high temperature diffusion comprises: The riser tube after ion nitriding treatment is placed in a vacuum furnace for high-temperature diffusion treatment, specifically including: raising the temperature in the vacuum furnace to a specified temperature range, maintaining the temperature within a target time range, and then cooling the vacuum furnace to room temperature.

9. The method for improving the wettability of the melt on the surface of the riser tube and the service life according to claim 8, characterized in that: The specified temperature range is 800°C-1200°C.

10. The method for improving the wettability of the melt on the surface of the riser tube and the service life according to claim 8, characterized in that: The target duration range is 2h-8h.

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