Magnesium alloy steering knuckle and extrusion casting method thereof

Abstract

The invention relates to a magnesium alloy steering knuckle and an extrusion casting method thereof. The magnesium alloy steering knuckle is composed of the following raw materials of, by weight, 8-10% of Zn, 0.5-2.0% of Al, 1.2-3% of strengthening alloy elements and the balance Mg. The method comprises the following steps: preparing a magnesium alloy material in percentage by weight, and melting and refining the magnesium alloy material in a smelting furnace; magnesium liquid is injected into the material cup through a centrifugal pump, the magnesium liquid is pressed into the steering knuckle mold through an extrusion punch, the magnesium alloy is solidified through pressurization, and a magnesium alloy extrusion casting steering knuckle casting is obtained; and solid solution and aging treatment are conducted on the casting obtained after sand blasting, and the high-strength plastic magnesium alloy extrusion casting steering knuckle is obtained. The problems that an existing magnesium alloy casting process is single and cannot be applied to the field of structural parts such as a chassis with large bearing capacity are solved; and compared with an aluminum alloy steering knuckle, the weight is reduced by 28.1% while the product performance is met, and the large light weight effect is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of casting and relates to a magnesium alloy steering knuckle and an extrusion casting method thereof. Background Art

[0002] Lightweighting is an important way to reduce carbon in the automotive industry and has become a major trend in the current development of automobiles. Experiments have shown that for fuel vehicles, if the weight of the entire vehicle is reduced by 10%, the fuel efficiency can be increased by 6%-8%. For every 100 kg reduction in the curb weight of the vehicle, the fuel consumption per 100 kilometers can be reduced by 0.3-0.6 liters. For a 1% reduction in the weight of the vehicle, the fuel consumption can be reduced by 0.7%. For electric vehicles, the total cruising range can be increased by 10km for every 100kg reduction in the weight of the vehicle. According to the "Energy-Saving and New Energy Vehicle Technology Route 2.0" released by the my country Society of Automotive Engineering, by 2025, the lightweight level of fuel vehicles in my country will be increased by 10% compared with 20 years, and the lightweight level of new energy vehicles will be increased by 15% compared with 20 years. Therefore, domestic and foreign researchers have carried out a large number of studies on lightweighting of automobiles. As the lightest structural metal material, magnesium alloy has the characteristics of low density, high strength, good rigidity, good die-casting performance, noise reduction, good electromagnetic shielding and shock absorption, and recyclability, which can achieve the ultimate lightweighting of automotive products.

[0003] At present, magnesium alloy materials have been used in the field of automotive interior parts such as steering wheels and dashboard beams through high-pressure casting. However, the fast filling speed of the high-pressure casting process often leads to problems such as air entrainment in the castings, making it impossible to perform heat treatment, resulting in low strength and plasticity of the products, making it difficult to apply them to body and chassis structural parts that bear large dynamic loads and fatigue loads. Squeeze casting, also known as liquid die forging, is an emerging metal forming process that has both casting characteristics and is similar to die forging. It uses the easy flow and forging technology during metal casting solidification to cause plastic deformation of the solidified hard shell, so that the metal crystallizes and solidifies under pressure and forcibly eliminates shrinkage cavities and shrinkage formed by solidification shrinkage, so as to obtain liquid die forging parts without casting defects. Products prepared by the squeeze casting process have dense structure, high strength and plasticity, and can undergo subsequent heat treatment processes. However, there is no mature magnesium alloy squeeze casting process. Therefore, this application uses the chassis structural component steering knuckle as the carrier, adopts high-strength plastic magnesium alloy material, and realizes the development of magnesium alloy chassis steering knuckle through extrusion casting process. While meeting product performance, it achieves product lightweighting, broadens the application of magnesium alloy materials in the automotive field, and promotes the development of lightweight automobiles.

[0004] Patent document CN106917014A proposes a car aluminum alloy steering knuckle and its extrusion casting method. Compared with traditional low-pressure and gravity steering knuckles, the internal defects of the extrusion casting steering knuckle are significantly reduced, and the comprehensive performance is significantly improved. This application is aimed at magnesium alloy steering knuckles, which can achieve a weight reduction of 28.1% while meeting product performance, broaden the application field of magnesium alloys, and solve the problem that magnesium alloys are difficult to apply in chassis structural parts.

[0005] Patent document CN114318327A discloses a method for preparing a magnesium alloy steering knuckle with an anti-galvanic corrosion structure. The method includes the steps of pre-setting powder, preparing a coating layer and electrophoresis treatment. By reducing the potential difference of the contact surface of the steering knuckle, the occurrence of galvanic corrosion can be effectively reduced. The method is simple and easy to implement, can improve the corrosion resistance of the magnesium alloy steering knuckle, and has good application prospects. This application is mainly a structural magnesium alloy steering knuckle extrusion casting process, which is different from the development content of the above patent document, and the process flow method is also different.

[0006] Patent document CN108251714A discloses a high-strength and tough aluminum alloy for extrusion casting and its extrusion casting method. This patent aims to improve and develop the existing aluminum alloy for extrusion casting and the extrusion casting method, so as to improve the strength and plasticity of aluminum alloy automobile parts, meet the development needs of automobile lightweight as the starting point, and optimize the extrusion casting process and heat treatment process of aluminum alloy. Compared with the above patent documents, this application is to expand the application field of magnesium alloys and achieve a leap from interior decoration parts to chassis structural parts. It creatively starts from the whole process of materials, extrusion casting process and heat treatment, and conducts research on magnesium alloy extrusion steering knuckles. While meeting product performance, it achieves a weight reduction of 28.1%, which helps the application of magnesium alloys.

[0007] The above patent documents have low relevance to the present application. Summary of the invention

[0008] The technical problem to be solved by the present invention is to overcome the above-mentioned problems existing in the prior art and provide a magnesium alloy steering knuckle and an extrusion casting method thereof.

[0009] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0010] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0011] The present invention relates to a magnesium alloy steering knuckle and an extrusion casting method thereof. First, the magnesium alloy material is prepared according to weight percentage and placed in a smelting furnace for melting and refining. Then, the magnesium liquid is injected into a material cup through a centrifugal pump, and the magnesium liquid is pressed into the steering knuckle mold through an extrusion punch, and the magnesium alloy is solidified by increasing pressure to obtain a magnesium alloy extrusion casting steering knuckle casting. Subsequently, the casting after sandblasting is subjected to solid solution and aging treatment to obtain a high-strength and plastic magnesium alloy extrusion casting steering knuckle.

[0012] A magnesium alloy steering knuckle for a car is made of high-strength magnesium alloy material, which consists of the following raw materials by weight percentage: Zn: 8-10%, Al: 0.5-2.0% and strengthening alloy elements: 1.2-3%, and the rest is Mg.

[0013] The specific steps of the above-mentioned magnesium alloy extrusion casting steering knuckle are as follows:

[0014] S1. Preheating the magnesium ingot and the alloy ingot;

[0015] S2. The preheated magnesium ingot and alloy ingot are placed in a smelting furnace for melting to obtain a magnesium alloy melt;

[0016] S3. The magnesium alloy melt is subjected to refining treatment;

[0017] S4. The refined magnesium alloy melt is quantitatively injected into the material cup of the squeeze casting machine for extrusion casting of the magnesium alloy steering knuckle to obtain a magnesium alloy extrusion casting steering knuckle sample;

[0018] S5. The above-mentioned magnesium alloy extrusion casting steering knuckle sample is subjected to gating system processing and sandblasting to obtain a magnesium alloy steering knuckle to gate sample;

[0019] S6. Perform solution treatment and aging treatment on the above-mentioned de-sprued sample to obtain a magnesium alloy extruded steering knuckle sample.

[0020] In the magnesium alloy high-strength alloy, the strengthening alloy element is one or more of elements such as Mn, Sn, and Y.

[0021] In step S1, the magnesium ingot and the alloy ingot need to be dried in an oven at 100-120° C. for 0.5-1 hour.

[0022] In the step S2, the magnesium alloy smelting furnace is a double-chamber furnace, and the preheated alloy ingot is placed in the melting chamber of the magnesium alloy smelting furnace at a smelting temperature of 700-730°C.

[0023] In the step S3, the magnesium alloy melt is refined in a magnesium alloy melting chamber using argon gas, which can ensure uniform distribution of alloy elements on the one hand and play a refining role on the other hand.

[0024] In the step S4, the refined melt is pumped into a pouring chamber through a liquid transfer pump, and the temperature of the pouring chamber is 670-700°C.

[0025] In the step S4, the squeeze casting machine cup is heated to 100-200° C. by flame in advance.

[0026] In the step S5, before the magnesium alloy liquid is pumped into the material cup of the extrusion casting machine, argon gas is first introduced into the material cup for 10-20 seconds to reduce oxidation of the magnesium alloy liquid in the material cup.

[0027] In the step S4, the extruder used is a 1000-ton extrusion casting machine.

[0028] In the step S4, the steering knuckle mold is fixed on the mold frame of the 1000-ton extrusion casting machine, and the mold cavity is heated by an oil-type mold temperature controller, wherein the dynamic mold heating temperature is 210-230°C, and the static mold heating temperature is 200-220°C.

[0029] In the step S4, before pouring, a layer of water-based release agent is evenly sprayed on the surface of the mold, and the spraying time is 5-15s.

[0030] In the step S4, the mold is vacuumed after the mold is closed, and the vacuuming time is 5-10s.

[0031] In step S4, the punch speed is -0.2-1 m / s, the extrusion pressure is 200-250 MPa, and the injection time is 80-100 s.

[0032] In the step S5, the magnesium alloy steering knuckle casting system, the slag bag and the exhaust corrugated plate are removed, and then sandblasting is performed.

[0033] In step S6, the solution treatment process is 320-360° C. for 18-24 h, the quenching temperature is 80-95° C., and the aging process is 50-70° C. for 15-20 h and 160-180° C. for 1-2 h.

[0034] A magnesium alloy steering knuckle is prepared by the method as described above.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention proposes a magnesium alloy steering knuckle and an extrusion casting method thereof. By adopting high-strength and plastic magnesium alloy materials, extrusion casting technology and advanced heat treatment technology, the product development of magnesium alloy extruded steering knuckle is realized. While meeting product performance requirements, a weight reduction of 28.1% is achieved, realizing the first development of a magnesium alloy chassis steering knuckle.

[0037] The present invention solves the problem that the current magnesium alloy casting process is single and cannot be applied in the field of structural parts such as chassis with large load-bearing capacity; compared with aluminum alloy steering knuckles, the present invention achieves a weight reduction of 28.1% while meeting product performance, and has a greater lightweight effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention will be further described below in conjunction with the accompanying drawings:

[0039] Figure 1 It is the internal quality diagram of each position of magnesium alloy steering knuckle;

[0040] Figure 2 This is a flow chart of the magnesium alloy steering knuckle extrusion casting method of the present invention. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the implementation of the present invention clearer, the technical scheme in the embodiment of the present invention will be described in more detail below in conjunction with the drawings in the embodiment of the present invention. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of the present invention, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limitations on the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The embodiments of the present invention are described in detail below in conjunction with the drawings.

[0042] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present invention.

[0043] The present invention is described in detail below in conjunction with the accompanying drawings:

[0044] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes the mutual combination of the specific implementation modes.

[0045] Embodiment 1:

[0046] A magnesium alloy steering knuckle for a car is characterized in that it adopts a high-strength magnesium alloy material, and its components are composed of the following raw materials by weight percentage: Zn: 8%, Al: 2.0% and strengthening alloy elements: 2%, and the rest is Mg.

[0047] The above-mentioned magnesium alloy steering knuckle extrusion casting method comprises the following steps:

[0048] 1. Preheat the magnesium ingot and the alloy ingot at 110° C. for 0.75 h. Then place the preheated magnesium ingot and the alloy ingot in the melting chamber of the magnesium alloy melting furnace for melting at a melting temperature of 720° C. to obtain a magnesium alloy melt and use argon gas for refining in the magnesium alloy melting chamber.

[0049] 2. The pouring chamber temperature is set to 680°C, the material cup is preheated to 100°C, the dynamic mold temperature is set to 210°C, the static mold temperature is set to 220°C, the release agent is sprayed for 10s, and the vacuum is drawn for 5s.

[0050] 3. The extrusion process parameters of the 1000T extrusion unit are set as punch speed 0.5m / s, extrusion pressure 230MPa, and injection time 90s.

[0051] 4. The samples without gating system and sandblasting were subjected to solution treatment at 330℃ for 20h and quenching at 90℃. Then, they were aged at 60℃ for 17h and 170℃ for 1.5h.

[0052] The magnesium alloy steering knuckle obtained in this embodiment was subjected to X-ray flaw detection: the X-ray flaw detection results are as follows: Figure 1 As shown, the internal quality is good and meets the requirements of actual production and use. The body is sampled for mechanical property testing, with tensile strength ≥284MPa, yield strength ≥226MPa, and elongation ≥7.6%. Compared with aluminum alloy steering knuckle, magnesium alloy steering knuckle is 28.1% lighter.

[0053] Embodiment 2:

[0054] A magnesium alloy steering knuckle for a car is characterized in that it adopts a high-strength magnesium alloy material, and its components are composed of the following raw materials by weight percentage: Zn: 9%, Al: 0.5% and strengthening alloy elements: 1.2%, and the rest is Mg.

[0055] The above-mentioned magnesium alloy steering knuckle extrusion casting method comprises the following steps:

[0056] 1. Preheat the magnesium ingot and the alloy ingot at 100°C for 1 hour. Then place the preheated magnesium ingot and the alloy ingot in the melting chamber of the magnesium alloy melting furnace for melting at a melting temperature of 700°C to obtain a magnesium alloy melt and use argon gas for refining in the magnesium alloy melting chamber.

[0057] 2. The pouring chamber temperature is set to 700°C, the material cup is preheated to 150°C, the dynamic mold temperature is set to 220°C, the static mold temperature is set to 210°C, the release agent is sprayed for 5s, and the vacuum is drawn for 10s.

[0058] 3. The extrusion process parameters of the 1000T extrusion unit are set as punch speed 0.2m / s, extrusion pressure 200MPa, and injection time 80s.

[0059] 4. The samples without gating system and sandblasting were subjected to solution treatment at 320℃ for 24h and quenching at 80℃. Then, they were aged at 50℃ for 20h and 160℃ for 2h.

[0060] The magnesium alloy steering knuckle obtained in this embodiment was subjected to X-ray flaw detection: the X-ray flaw detection results are as follows: Figure 1 As shown, the internal quality is good and meets the requirements of actual production and use. The body samples were taken for mechanical property testing, with tensile strength ≥282MPa, yield strength ≥221MPa, and elongation ≥8.3%. Compared with aluminum alloy steering knuckle, magnesium alloy steering knuckle is 28.1% lighter.

[0061] Embodiment three:

[0062] A magnesium alloy steering knuckle for a car is characterized in that it adopts a high-strength magnesium alloy material, and its components are composed of the following raw materials by weight percentage: Zn: 10%, Al: 1.0% and strengthening alloy elements: 3%, and the rest is Mg.

[0063] The above-mentioned magnesium alloy steering knuckle extrusion casting method comprises the following steps:

[0064] 1. Preheat the magnesium ingot and the alloy ingot at 120°C for 0.5h. Then place the preheated magnesium ingot and the alloy ingot in the melting chamber of the magnesium alloy melting furnace for melting at a melting temperature of 730°C to obtain a magnesium alloy melt and use argon gas for refining in the magnesium alloy melting chamber.

[0065] 2. The pouring chamber temperature is set to 670°C, the material cup is preheated to 200°C, the dynamic mold temperature is set to 230°C, the static mold temperature is set to 200°C, the release agent is sprayed for 15 seconds, and the vacuum is drawn for 7 seconds.

[0066] 3. The extrusion process parameters of the 1000T extrusion unit are set as punch speed 1m / s, extrusion pressure 250MPa, and injection time 100s.

[0067] 4. The samples without gating system and sandblasting were subjected to solution treatment at 360℃ for 15h and quenching at 95℃. Then, they were aged at 70℃ for 15h and 180℃ for 1h.

[0068] The magnesium alloy steering knuckle obtained in this embodiment was subjected to X-ray flaw detection: the X-ray flaw detection results are as follows: Figure 1 As shown, the internal quality is good and meets the requirements of actual production and use. The body samples were taken for mechanical property testing, with tensile strength ≥303MPa, yield strength ≥230MPa, and elongation ≥6.5%. Compared with aluminum alloy steering knuckle, magnesium alloy steering knuckle is 28.1% lighter.

[0069] Embodiment 4:

[0070] A magnesium alloy steering knuckle adopts a high-strength magnesium alloy material, and its components are composed of the following raw materials by weight percentage: Zn: 8-10%, Al: 0.5-2.0% and strengthening alloy elements:

[0071] 1.2-3%, the rest is Mg.

[0072] The above magnesium alloy steering knuckle is prepared by the following method, see Figure 2 :

[0073] S1. Preheating the magnesium ingot and the alloy ingot;

[0074] S2. The preheated magnesium ingot and alloy ingot are placed in a smelting furnace for melting to obtain a magnesium alloy melt;

[0075] S3. The magnesium alloy melt is subjected to refining treatment;

[0076] S4. The refined magnesium alloy melt is quantitatively injected into the material cup of the squeeze casting machine for extrusion casting of the magnesium alloy steering knuckle to obtain a magnesium alloy extrusion casting steering knuckle sample;

[0077] S5. The above-mentioned magnesium alloy extrusion casting steering knuckle sample is subjected to gating system processing and sandblasting to obtain a magnesium alloy steering knuckle to gate sample;

[0078] S6. Perform solution treatment and aging treatment on the above-mentioned de-sprued sample to obtain a magnesium alloy extruded steering knuckle sample.

[0079] The magnesium alloy steering knuckle for a car is made of a high-strength magnesium alloy material, and its specific components are composed of the following raw materials by weight percentage: Zn: 8%, Al: 2.0% and strengthening alloy elements: 2%, and the rest is Mg.

[0080] The extrusion casting method of the magnesium alloy steering knuckle used in the above-mentioned magnesium alloy steering knuckle for a passenger car may be specifically performed in the following steps:

[0081] 1. Preheat the magnesium ingot and the alloy ingot at 110° C. for 0.75 h. Then place the preheated magnesium ingot and the alloy ingot in the melting chamber of the magnesium alloy melting furnace for melting at a melting temperature of 720° C. to obtain a magnesium alloy melt and use argon gas for refining in the magnesium alloy melting chamber.

[0082] 2. The pouring chamber temperature is set to 680°C, the material cup is preheated to 100°C, the dynamic mold temperature is set to 210°C, the static mold temperature is set to 220°C, the release agent is sprayed for 10s, and the vacuum is drawn for 5s.

[0083] 3. The extrusion process parameters of the 1000T extrusion unit are set as punch speed 0.5m / s, extrusion pressure 230MPa, and injection time 90s.

[0084] 4. The samples without gating system and sandblasting were subjected to solution treatment at 330℃ for 20h and quenching at 90℃. Then, they were aged at 60℃ for 17h and 170℃ for 1.5h.

[0085] The magnesium alloy steering knuckle obtained in this embodiment was subjected to X-ray flaw detection: the X-ray flaw detection results are as follows: Figure 1 As shown, the internal quality is good and meets the requirements of actual production and use. The body is sampled for mechanical property testing, with tensile strength ≥284MPa, yield strength ≥226MPa, and elongation ≥7.6%. Compared with aluminum alloy steering knuckle, magnesium alloy steering knuckle is 28.1% lighter.

[0086] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

[0087] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

Claims

1. A magnesium alloy steering knuckle, characterized in that: High-strength magnesium alloy material is used, and its components are composed of the following raw materials by weight percentage: Composition: Zn: 8-10%, Al: 0.5-2.0% and strengthening alloy elements: 1.2-3%, the rest is Mg.

2. A magnesium alloy steering knuckle extrusion casting method, characterized in that: S1. Preheating the magnesium ingot and the alloy ingot; S2. The preheated magnesium ingot and alloy ingot are placed in a smelting furnace for melting to obtain a magnesium alloy melt; S3. The magnesium alloy melt is subjected to refining treatment; S4. The refined magnesium alloy melt is quantitatively injected into the material cup of the squeeze casting machine for extrusion casting of the magnesium alloy steering knuckle to obtain a magnesium alloy extrusion casting steering knuckle sample; S5. The above-mentioned magnesium alloy extrusion casting steering knuckle sample is subjected to gating system processing and sandblasting to obtain a magnesium alloy steering knuckle to gate sample; S6. Perform solution treatment and aging treatment on the above-mentioned de-sprued sample to obtain a magnesium alloy extruded steering knuckle sample.

3. A magnesium alloy steering knuckle extrusion casting method according to claim 2, characterized in that: In the high-strength magnesium alloy, the strengthening alloy element is one or more of Mn, Sn and Y elements.

4. A magnesium alloy steering knuckle extrusion casting method according to claim 2, characterized in that: In the step S4, the refined melt is pumped into a pouring chamber through a liquid transfer pump, and the temperature of the pouring chamber is 670-700°C; In step S4, the squeeze casting machine cup is heated to 100-200° C. by flame in advance.

5. The method for extrusion casting of a magnesium alloy steering knuckle according to claim 2, characterized in that: In the step S4, the steering knuckle mold is fixed on the mold frame of the 1000-ton extrusion casting machine, and the mold cavity is heated by an oil-type mold temperature controller, wherein the dynamic mold heating temperature is 210-230°C, and the static mold heating temperature is 200-220°C.

6. A magnesium alloy steering knuckle extrusion casting method according to claim 2, characterized in that: In the step S4, before pouring, a layer of water-based release agent is evenly sprayed on the surface of the mold, and the spraying time is 5-15s.

7. A magnesium alloy steering knuckle extrusion casting method according to claim 2, characterized in that: In the step S4, the mold is vacuumed after the mold is closed, and the vacuuming time is 5-10s; In step S4, the punch speed is 0.2-1 m / s, the extrusion pressure is 200-250 MPa, and the injection time is 80-100 s.

8. The method for extrusion casting of a magnesium alloy steering knuckle according to claim 2, characterized in that: In the step S5, before the magnesium alloy liquid is pumped into the material cup of the extrusion casting machine, argon gas is first introduced into the material cup for 10-20 seconds to reduce oxidation of the magnesium alloy liquid in the material cup.

9. The method for extrusion casting of a magnesium alloy steering knuckle according to claim 2, characterized in that: In step S6, the solution treatment process is 320-360° C. for 18-24 h, the quenching temperature is 80-95° C., and the aging process is 50-70° C. for 15-20 h and 160-180° C. for 1-2 h.

10. A magnesium alloy steering knuckle, characterized in that: The method is prepared by any one of claims 2 to 9.

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