High-strength die-casting cylinder aluminum alloy material and preparation method thereof

Abstract

The invention relates to a high-strength die-casting cylinder aluminum alloy material and a preparation method thereof.The preparation method comprises the steps that pure aluminum, crystalline silicon, Al-Cu intermediate alloy, Al-Mn intermediate alloy, pure magnesium, pure zinc, Al-Sr intermediate alloy, Al-Zr intermediate alloy and Al-Ti intermediate alloy are weighed according to the stoichiometric ratio and smelted at the temperature of 700-750 DEG C; the melt is transferred into a preheated transfer ladle, degassing refining treatment is conducted in the Ar gas atmosphere, and gas and included slag in the melt are removed; transferring the melt into a machine edge heat preservation furnace which is heated in advance; the aluminum alloy melt is injected into a material cup of a die-casting machine according to the metered weight, and cylinder die casting is conducted; and the die-casting aluminum alloy cylinder body blank is subjected to machining and performance testing, and a die-casting aluminum alloy cylinder body finished product is obtained after the testing is passed. According to the method, a novel high-strength die-casting aluminum alloy material is developed, so that the performance of a die-casting aluminum alloy cylinder body product body is improved, and the tensile strength is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of automobiles, and in particular relates to a high-strength die-casting cylinder body aluminum alloy material and a preparation method thereof. Background Art

[0002] Currently, passenger car gasoline engine cylinder blocks are divided into cast iron and cast aluminum. Among them, cast iron cylinder blocks have the advantages of low cost, high strength, good wear resistance and high temperature resistance. Therefore, lightweighting has become a major development trend in the current automotive field. However, the cast iron cylinder block is heavy, which will increase the overall weight of the vehicle and increase fuel consumption. As a result, cast aluminum cylinder blocks have been rapidly developed. Cast aluminum cylinder blocks can effectively reduce the weight of the engine, help improve fuel economy and improve vehicle operability.

[0003] At present, cast aluminum cylinder blocks are mainly divided into low-pressure cast aluminum cylinder blocks and high-pressure cast aluminum cylinder blocks. Among them, high-pressure cast aluminum cylinder blocks have been widely used due to their faster production cycle and higher degree of automation. At present, the material of die-cast aluminum cylinder blocks is mainly AlSi9Cu3 alloy, but with the increase in engine displacement, the performance requirements for engine cylinder blocks are gradually increasing, and conventional aluminum alloy die-cast cylinder block materials cannot meet product performance requirements. Therefore, it is urgent to develop a high-strength die-cast aluminum alloy cylinder block material to improve the performance of the die-cast aluminum alloy cylinder block product so that it can meet the product design target requirements. Summary of the invention

[0004] The purpose of the present invention is to provide a new type of high-strength die-cast aluminum alloy material to solve the problem of low body performance of existing die-cast aluminum alloy cylinder products.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A high-strength die-cast cylinder aluminum alloy material, wherein the components are calculated by mass percentage as follows: silicon 9-11%, copper 2.5-3.5%, manganese 0.35-0.55%, magnesium 0.35-0.50, strontium 0.04-0.06, iron ≤0.9%, zinc 0.7-0.9%, titanium 0.1-0.2%, zirconium 0.05-0.2%, and the balance is aluminum and impurity elements; wherein the total content of all impurity elements is ≤0.3%, the Fe / Mn ratio is limited to ≤2, and the unavoidable inclusions include at least one selected from copper, magnesium, zinc, phosphorus and chromium.

[0007] A method for preparing a high-strength die-casting cylinder aluminum alloy material comprises the following steps:

[0008] S1. Weigh pure aluminum, crystalline silicon, Al-Cu master alloy, Al-Mn master alloy, pure magnesium, pure zinc, Al-Sr master alloy, Al-Zr master alloy, and Al-Ti master alloy according to the stoichiometric ratio, and perform smelting treatment in a smelting furnace at 700-750° C.;

[0009] S2, transferring the melt to a preheated transfer bag, and performing a degassing and refining treatment under an Ar gas atmosphere to remove gas and slag in the melt;

[0010] S3, then transferring the melt to a pre-heated machine-side quantitative heat preservation furnace; preheating the mold by an oil / water mold temperature controller;

[0011] S4, spraying the mold, injecting the aluminum alloy melt into the material cup of the die-casting machine according to the measured weight, and die-casting it into the mold, performing cylinder die-casting to obtain a casting blank;

[0012] S5. Processing and performance testing the die-cast aluminum alloy cylinder block blank, and obtaining a die-cast aluminum alloy cylinder block finished product after passing the test; cleaning the flash and runner of the casting blank, and machining the cleaned casting blank to obtain a product.

[0013] Furthermore, in step S1, the pure aluminum and crystalline silicon are added into the smelting furnace in advance, and after they are completely melted, Al-Cu master alloy, Al-Mn master alloy, pure magnesium, pure Zn, Al-Zr master alloy, and Al-Ti master alloy are added according to the metered proportion; and Al-Sr master alloy is added after melting.

[0014] Furthermore, in step S2, the transfer bag is preheated to a temperature of 750-780°C.

[0015] Furthermore, in step S2, Ar degassing and refining treatment is performed for 10-30 minutes, and a density index test is performed after the treatment, and the density index is <1%.

[0016] Furthermore, in step S3, the temperature of the machine-side insulation furnace is set to 640-680°C.

[0017] Furthermore, in step S4, the die-casting process parameters include: pouring temperature: 640-680°C, mold temperature: 80-150°C, low speed: 0.1-0.5 m / s, high speed: 4-6 m / s.

[0018] Furthermore, in step S4, the injection process is vacuumed, and the vacuum degree of the cavity is ≤100 mbar.

[0019] Furthermore, in step S5, the sampling position of the die-cast aluminum alloy cylinder product body is the crankshaft hole, and its yield strength is 159-180 MPa, the tensile strength is 235-261 MPa, and the elongation is 1.0-1.6%.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention aims at the current die-cast aluminum alloy cylinder products and develops a new type of high-strength die-cast aluminum alloy material to improve the performance of the die-cast aluminum alloy cylinder product body so that it meets the product performance requirements. Compared with the traditional AlSi9Cu3 alloy die-cast cylinder product, the body tensile strength at the crankshaft hole position is increased by 15-27%. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 A flow chart of the steps of the method for preparing the high-strength die-casting cylinder aluminum alloy material of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with embodiments:

[0025] The high-strength die-casting cylinder aluminum alloy material of the present invention comprises the following components by mass percentage: silicon 9-11%, copper 2.5-3.5%, manganese 0.35-0.55%, magnesium 0.35-0.50, strontium 0.04-0.06, iron ≤0.9%, zinc 0.7-0.9%, titanium 0.1-0.2%, zirconium 0.05-0.2%, and the remainder is aluminum and impurity elements. The total content of all impurity elements is ≤0.3%, the Fe / Mn ratio is limited to ≤2, and the unavoidable inclusions include at least one selected from copper, magnesium, zinc, phosphorus and chromium.

[0026] The method for preparing a high-strength die-casting cylinder aluminum alloy material of the present invention comprises the following steps:

[0027] S1. Pure aluminum, crystalline silicon, Al-Cu master alloy, Al-Mn master alloy, pure magnesium, pure zinc, Al-Sr master alloy, Al-Zr master alloy and Al-Ti master alloy are weighed according to the stoichiometric ratio and smelted in a smelting furnace at 700-750°C.

[0028] S2. The melt is transferred to a preheated transfer bag and subjected to a degassing and refining treatment in an Ar gas atmosphere to remove gas and slag inclusions in the melt.

[0029] S3, then the melt is transferred to a pre-heated machine-side quantitative heat preservation furnace, and the mold is preheated by an oil / water mold temperature controller.

[0030] S4, spraying the mold, injecting the above aluminum alloy melt into the material cup of the die-casting machine according to the measured weight, and die-casting it into the mold, performing cylinder die-casting to obtain a casting blank.

[0031] S5. Processing and performance testing the die-cast aluminum alloy cylinder block blank, and obtaining a die-cast aluminum alloy cylinder block finished product after passing the test. Cleaning the casting blank from flash and runner, and machining the cleaned casting blank to obtain a product.

[0032] In step S1, the pure aluminum and crystalline silicon are added into a smelting furnace in advance, and after they are completely melted, Al-Cu master alloy, Al-Mn master alloy, pure magnesium, pure Zn, Al-Zr master alloy, and Al-Ti master alloy are added according to the metered proportion; after they are melted, Al-Sr master alloy is added.

[0033] In step S2, the transfer bag is preheated to a temperature of 750-780°C.

[0034] In step S2, Ar degassing and refining treatment is performed for 10-30 minutes. After the treatment, a density index test is performed, and the density index is <1%.

[0035] In step S3, the temperature of the machine-side insulation furnace is set to 640-680°C.

[0036] In step S4, the die-casting process parameters include: pouring temperature: 640-680°C, mold temperature: 80-150°C, low speed: 0.1-0.5m / s, high speed: 4-6m / s.

[0037] In step S4, the injection process will be vacuumed, and the vacuum degree of the cavity is ≤100mbar.

[0038] In step S5, the sampling position of the die-cast aluminum alloy cylinder product body is the crankshaft hole, and its yield strength is 159-180MPa, the tensile strength is 235-261MPa, and the elongation is 1.0-1.6%. Compared with the traditional aluminum alloy die-cast cylinder material, the tensile strength is increased by 15-27%.

[0039] Example 1

[0040] The ingredients are prepared according to the following mass percentages: 9% silicon, 3.5% copper, 0.55% manganese, 0.50% magnesium, 0.06% strontium, 0.87% iron, 0.9% zinc, 0.2% titanium, 0.05% zirconium, and the balance is aluminum.

[0041] Preparation method:

[0042] 1. Weigh pure aluminum, crystalline silicon, Al-Cu master alloy, Al-Mn master alloy, pure magnesium, pure zinc, Al-Sr master alloy, Al-Zr master alloy and Al-Ti master alloy according to the stoichiometric ratio, and perform smelting treatment at 750°C.

[0043] 2. The melt was transferred to a transfer bag preheated at 750°C and subjected to a degassing and refining treatment for 30 minutes in an Ar gas atmosphere to remove gas and slag in the melt.

[0044] 3. The melt is then transferred to a machine-side holding furnace at 650°C.

[0045] 4. Pour the above aluminum alloy melt into the material cup of the die-casting machine according to the measured weight, and perform cylinder die-casting, wherein the pouring temperature is 650°C, the mold temperature is 150°C, the low speed is 0.5m / s, and the high speed is 4m / s.

[0046] 5. Take samples from the crankshaft hole position and conduct mechanical property tests.

[0047] Example 2

[0048] The ingredients are prepared according to the following mass percentages: 11% silicon, 2.5% copper, 0.35% manganese, 0.35% magnesium, 0.04% strontium, 0.86% iron, 0.7% zinc, 0.1% titanium, 0.2% zirconium, and the balance is aluminum.

[0049] Preparation method:

[0050] 1. Weigh pure aluminum, crystalline silicon, Al-Cu master alloy, Al-Mn master alloy, pure magnesium, pure zinc, Al-Sr master alloy, Al-Zr master alloy and Al-Ti master alloy according to the stoichiometric ratio, and perform smelting treatment at 700°C.

[0051] 2. The melt was transferred to a transfer bag preheated at 780°C and subjected to a degassing and refining treatment for 10 minutes in an Ar atmosphere to remove gas and slag in the melt.

[0052] 3. The melt is then transferred to a machine-side holding furnace at 680°C.

[0053] 4. Pour the above aluminum alloy melt into the material cup of the die-casting machine according to the measured weight, and perform cylinder die-casting, wherein the pouring temperature is 680°C, the mold temperature is 80°C, the low speed is 0.2m / s, and the high speed is 6m / s.

[0054] 5. Take samples from the crankshaft hole position and conduct mechanical property tests.

[0055] Example 3

[0056] The ingredients are prepared according to the following mass percentages: 10% silicon, 3% copper, 0.45% manganese, 0.45% magnesium, 0.05% strontium, 0.79% iron, 0.8% zinc, 0.15% titanium, 0.1% zirconium, and the balance is aluminum.

[0057] Preparation method:

[0058] 1. Weigh pure aluminum, crystalline silicon, Al-Cu master alloy, Al-Mn master alloy, pure magnesium, pure zinc, Al-Sr master alloy, Al-Zr master alloy and Al-Ti master alloy according to the stoichiometric ratio, and perform smelting treatment at 720°C.

[0059] 2. The melt was transferred to a transfer bag preheated at 760°C and subjected to a degassing and refining treatment for 20 minutes in an Ar gas atmosphere to remove gas and slag in the melt.

[0060] 3. The melt is then transferred to a machine-side holding furnace at 670°C.

[0061] 4. Pour the above aluminum alloy melt into the material cup of the die-casting machine according to the measured weight, and perform cylinder die-casting, wherein the pouring temperature is 670°C, the mold temperature is 120°C, the low speed is 0.3m / s, and the high speed is 5m / s.

[0062] 5. Take samples from the crankshaft hole position and conduct mechanical property tests.

[0063] Comparative Example 1

[0064] AlSi9Cu3 alloy was prepared according to the following method.

[0065] Preparation method:

[0066] 1. Weigh pure aluminum, crystalline silicon, Al-Cu master alloy, Al-Mn master alloy, pure magnesium, pure zinc, Al-Sr master alloy, Al-Zr master alloy and Al-Ti master alloy according to the stoichiometric ratio, and perform smelting treatment at 720°C.

[0067] 2. The melt was transferred to a transfer bag preheated at 760°C and subjected to a degassing and refining treatment for 20 minutes in an Ar gas atmosphere to remove gas and slag in the melt.

[0068] 3. The melt is then transferred to a machine-side holding furnace at 670°C.

[0069] 4. Pour the above aluminum alloy melt into the material cup of the die-casting machine according to the measured weight, and perform cylinder die-casting, wherein the pouring temperature is 670°C, the mold temperature is 120°C, the low speed is 0.3m / s, and the high speed is 5m / s.

[0070] 5. Take samples from the crankshaft hole position and conduct mechanical property tests.

[0071] Comparative Example 2

[0072] AlSi9Cu3 alloy was prepared according to the following method.

[0073] Preparation method:

[0074] 1. Weigh pure aluminum, crystalline silicon, Al-Cu master alloy, Al-Mn master alloy, pure magnesium, pure zinc, Al-Sr master alloy, Al-Zr master alloy and Al-Ti master alloy according to the stoichiometric ratio, and perform smelting treatment at 700°C.

[0075] 2. The melt was transferred to a transfer bag preheated at 780°C and subjected to a degassing and refining treatment for 10 minutes in an Ar atmosphere to remove gas and slag in the melt.

[0076] 3. The melt is then transferred to a machine-side holding furnace at 680°C.

[0077] 4. Pour the above aluminum alloy melt into the material cup of the die-casting machine according to the measured weight, and perform cylinder die-casting, wherein the pouring temperature is 680°C, the mold temperature is 80°C, the low speed is 0.2m / s, and the high speed is 6m / s.

[0078] 5. Take samples from the crankshaft hole position and conduct mechanical property tests.

[0079] The mechanical properties of Examples 1-3 and Comparative Example 1 are shown in the following table:

[0080] Table 1

[0081] Yield strength / MPa Tensile strength / MPa Elongation / % Example 1 159 252 1.6 Example 2 178 248 1.4 Example 3 180 261 1.2 Comparative Example 1 118 205 1.2 Comparative Example 2 126 195 1.0

[0082] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A high-strength die-casting cylinder aluminum alloy material, characterized by: The components are calculated by mass percentage as follows: silicon 9-11%, copper 2.5-3.5%, manganese 0.35-0.55%, magnesium 0.35-0.50, strontium 0.04-0.06, iron ≤0.9%, zinc 0.7-0.9%, titanium 0.1-0.2%, zirconium 0.05-0.2%, and the balance is aluminum and impurity elements; wherein the total content of all impurity elements is ≤0.3%, the Fe / Mn ratio is limited to ≤2, and the unavoidable inclusions include at least one selected from copper, magnesium, zinc, phosphorus and chromium.

2. A method for preparing a high-strength die-casting cylinder aluminum alloy material, characterized in that: The following steps are involved: S1. Weigh pure aluminum, crystalline silicon, Al-Cu master alloy, Al-Mn master alloy, pure magnesium, pure zinc, Al-Sr master alloy, Al-Zr master alloy, and Al-Ti master alloy according to the stoichiometric ratio, and perform smelting treatment in a smelting furnace at 700-750° C.; S2, transferring the melt to a preheated transfer bag, and performing a degassing and refining treatment under an Ar gas atmosphere to remove gas and slag inclusions in the melt; S3, then transferring the melt to a pre-heated machine-side quantitative heat preservation furnace; preheating the mold by an oil / water mold temperature controller; S4, spraying the mold, injecting the aluminum alloy melt into the material cup of the die-casting machine according to the measured weight, and die-casting it into the mold, performing cylinder die-casting to obtain a casting blank; S5. Processing and performance testing the die-cast aluminum alloy cylinder block blank, and obtaining a die-cast aluminum alloy cylinder block finished product after passing the test; cleaning the flash and runner of the casting blank, and machining the cleaned casting blank to obtain a product.

3. The method for preparing a high-strength die-casting cylinder aluminum alloy material according to claim 2, characterized in that: In step S1, the pure aluminum and crystalline silicon are added into a smelting furnace in advance, and after they are completely melted, Al-Cu master alloy, Al-Mn master alloy, pure magnesium, pure zinc, Al-Zr master alloy, and Al-Ti master alloy are added according to the metering ratio; after they are melted, Al-Sr master alloy is added.

4. The method for preparing a high-strength die-casting cylinder aluminum alloy material according to claim 2, characterized in that: In step S2, the transfer bag is preheated to a temperature of 750-780°C.

5. The method for preparing a high-strength die-casting cylinder aluminum alloy material according to claim 2, characterized in that: In step S2, Ar degassing and refining treatment is performed for 10-30 minutes. After the treatment, a density index test is performed, and the density index is <1%.

6. The method for preparing a high-strength die-casting cylinder aluminum alloy material according to claim 2, characterized in that: In step S3, the temperature of the machine-side insulation furnace is set to 640-680°C.

7. The method for preparing a high-strength die-casting cylinder aluminum alloy material according to claim 2, characterized in that: In step S4, the die-casting process parameters include: pouring temperature: 640-680°C, mold temperature: 80-150°C, low speed: 0.1-0.5m / s, high speed: 4-6m / s.

8. The method for preparing a high-strength die-casting cylinder aluminum alloy material according to claim 2, characterized in that: In step S4, the injection process will be vacuumed, and the vacuum degree of the cavity is ≤100mbar.

9. The method for preparing a high-strength die-casting cylinder aluminum alloy material according to claim 2, characterized in that: In step S5, the sampling position of the die-cast aluminum alloy cylinder product body is the crankshaft hole, and its yield strength is 159-180 MPa, the tensile strength is 235-261 MPa, and the elongation is 1.0-1.6%.

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