Heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy and preparation method and application thereof
阅读说明：本技术 一种耐热耐磨Al-Si-Cu-Ni铝合金及制备方法与应用 (Heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy and preparation method and application thereof ) 是由 刘玉林 毕常兰 徐宏 于 2020-07-08 设计创作，主要内容包括：一种耐热耐磨Al-Si-Cu-Ni铝合金及制备方法与应用,属于铸造铝合金领域。该耐热耐磨Al-Si-Cu-Ni铝合金,包括按质量百分数计的如下元素：Si为11.5～22％,Cu为5.0～7.0％,Ni为3.5-5.0％,Mg为0.8-1.5％,Mn为0.4-0.8％,Fe为0.8-1.2％,Zr为0.08-0.25％,Ti为0.08-0.25％,V为0.08-0.25％,Sr为0.1-0.5％,余量为Al和杂质,其中杂质总含量不大于0.3％。其制备方法为：将原料熔炼后,加入Sr的原料进行变质处理,上下加压浇铸得到耐热耐磨Al-Si-Cu-Ni铝合金。该耐热耐磨Al-Si-Cu-Ni铝合金具有质量轻、铸造性能好、耐磨性好、热膨胀系数小,耐热,并且力学性能高的优点。(A heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy, a preparation method and application thereof belong to the field of cast aluminum alloys. The heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy comprises the following elements in percentage by mass: 11.5-22% of Si, 5.0-7.0% of Cu, 3.5-5.0% of Ni, 0.8-1.5% of Mg, 0.4-0.8% of Mn, 0.8-1.2% of Fe, 0.08-0.25% of Zr, 0.08-0.25% of Ti, 0.08-0.25% of V, 0.1-0.5% of Sr and the balance of Al and impurities, wherein the total content of the impurities is not more than 0.3%. The preparation method comprises the following steps: after the raw materials are smelted, Sr raw materials are added for modification treatment, and the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy is obtained by up-down pressure casting. The heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy has the advantages of light weight, good casting performance, good wear resistance, small thermal expansion coefficient, heat resistance and high mechanical property.)
1. The heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy is characterized by comprising the following elements in percentage by mass: 11.5-22% of Si, 5.0-7.0% of Cu, 3.5-5.0% of Ni, 0.8-1.5% of Mg, 0.4-0.8% of Mn, 0.8-1.2% of Fe, 0.08-0.25% of Zr, 0.08-0.25% of Ti, 0.08-0.25% of V, 0.1-0.5% of Sr and the balance of Al and impurities, wherein the total content of the impurities is not more than 0.3%.
2. The heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy as recited in claim 1, wherein the as-cast room temperature tensile strength of the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy is 241-315MPa, and the elongation thereof is 0.9-2.6%; the 350 ℃ instantaneous tensile strength is 121-172MPa, and the elongation is 4.3-7.9%.
3. The heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy according to claim 1, wherein the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy is a low-silicon heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy, and comprises the following elements in percentage by mass: 11.5-14.0% of Si, 5.0-7.0% of Cu, 3.5-5.0% of Ni, 0.8-1.5% of Mg, 0.4-0.8% of Mn, 0.8-1.2% of Fe, 0.08-0.25% of Zr, 0.08-0.25% of Ti, 0.08-0.25% of V, 0.1-0.5% of Sr and the balance of Al and impurities, wherein the total content of the impurities is not more than 0.5%;
the low-silicon heat-resistant wear-resistant Al-Si-Cu-Ni aluminum alloy has the as-cast room-temperature tensile strength of 271-315MPa and the elongation of 1.8-2.6 percent; the 350 ℃ instantaneous tensile strength is 157-172MPa, and the elongation is 5.8-7.9%.
4. The heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy according to claim 1, wherein the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy is a high-silicon heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy, and comprises the following elements in percentage by mass: 16.0-22.0% of Si, 5.0-7.0% of Cu, 3.5-5.0% of Ni, 0.8-1.5% of Mg, 0.4-0.8% of Mn, 0.8-1.2% of Fe, 0.08-0.25% of Zr, 0.08-0.25% of Ti, 0.08-0.25% of V, 0.1-0.5% of Sr and the balance of Al and impurities, wherein the total content of the impurities is not more than 0.5%;
the high-silicon heat-resistant wear-resistant Al-Si-Cu-Ni aluminum alloy has the as-cast room-temperature tensile strength of 241-; the 350 ℃ instantaneous tensile strength is 121-138MPa, and the elongation is 4.3-5.7%.
5. The method for preparing the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy according to any one of claims 1 to 4, comprising the steps of:
step 1: preparing raw materials according to the element proportion contained in the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy;
step 2: heating and melting Al raw materials to obtain an aluminum melt; adding other raw materials except Mg and Sr into the aluminum melt, adding the Mg raw material after the raw materials are melted, and stirring uniformly after the Mg raw material is completely melted to obtain an alloy melt; in the whole process, controlling the temperature of the alloy melt to be 680-800 ℃;
and step 3: adding a refining agent into the alloy melt for refining, then adding a Sr raw material Al-10Sr as a modifier for modification, and obtaining the modified alloy melt;
and 4, step 4: degassing the modified alloy melt, slagging off, standing at 680-760 ℃ for 30-60min to obtain a metal liquid, and casting to obtain a heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy casting.
6. The method for preparing the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy according to claim 5, wherein in the step 1, Si is taken as a raw material of metallic silicon and/or an aluminum-silicon intermediate alloy; the raw material of Cu is an aluminum-copper intermediate alloy and/or a copper additive; the material of Ni is an aluminum-nickel intermediate alloy and/or a nickel additive, the material of Mg is an industrial pure magnesium ingot, the material of Mn is an aluminum-manganese intermediate alloy and/or a manganese additive, the material of Fe is an aluminum-iron intermediate alloy and/or an iron additive, the material of Zr is an aluminum-zirconium intermediate alloy, the material of Ti is an aluminum-titanium intermediate alloy and/or a titanium additive, the material of V is an aluminum-vanadium intermediate alloy, and the material of Al is one or more of an aluminum ingot, a remelted aluminum ingot or a cast aluminum alloy ingot.
7. The method for preparing the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy according to claim 5, wherein in the step 3, the refining agent is a refining agent capable of refining the alloy melt, and the adding mass of the refining agent is 0.2-0.8% of the total mass of the alloy melt;
in the step 3, the raw material Al-10Sr of Sr is added, wherein the mass of the residual amount of Sr in the alloy melt after modification is 0.1-0.5%;
when the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy contains more than or equal to 12.8 percent of Si, the modifier Al-10Sr is matched with the Al-3P modifier for modification treatment, and the adding mass of P is 0.005-0.008 percent of the residual amount of P in the modified alloy melt.
8. The method for preparing the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy according to claim 5, wherein in the step 4, the following pressure casting process is adopted for casting, specifically:
the method comprises the following steps: according to the shape of a workpiece needing to be cast by the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy, a casting die is designed to be composed of a side die, an upper die and a lower die; the side die is a fixed die, the upper die and the lower die are movable dies, and after the movable dies and the fixed die are assembled, the metal liquid is poured into a casting cavity;
step two: when the metal liquid is poured into the whole casting cavity, the pouring gate is blocked;
step three: and respectively applying pressure from the upper die and the lower die to press the metal liquid in the casting cavity, keeping the pressure for 60-300s according to the size of the casting after the pressure reaches 25-100MPa, and releasing the pressure after the metal liquid is completely solidified, removing the die to obtain the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy casting.
9. The preparation method of the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy as claimed in claim 5, wherein in the step 4, after casting, the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy casting is placed at 170-210 ℃ for heat preservation for 6-8 h to obtain the final heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy casting.
10. The use of the heat and wear resistant Al-Si-Cu-Ni aluminum alloy of claim 3 or 4, wherein a low-silicon heat and wear resistant Al-Si-Cu-Ni aluminum alloy is used in an engine piston; the high-silicon heat-resistant wear-resistant Al-Si-Cu-Ni aluminum alloy is applied to an automobile brake disc.
Technical Field
The invention relates to a heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy, a preparation method and application thereof, and belongs to the field of cast aluminum alloys.
Background
The aluminum alloy has the characteristics of small density, high specific strength and specific stiffness, good corrosion resistance, excellent electric and thermal conductivity, easiness in recovery, good low-temperature performance and the like, is widely applied to automobile manufacturing, plays an important role in realizing the light weight of automobiles, and has obvious advantages in realizing weight reduction, improving the fuel utilization rate and increasing the output power. In aluminum alloys for automobiles, the cast aluminum alloy accounts for up to 80%. The cast aluminum alloy has good fluidity and mold filling capability and moderate mechanical property, and can be widely used for replacing cast iron materials to manufacture structural members of engine parts, cylinder covers, wheels, bumpers and the like, and more engine pistons are manufactured by using the aluminum alloy. In an engine, the working condition of a piston is the worst, the instantaneous temperature of high-temperature gas in a combustion chamber can reach 2000 ℃, the highest working temperature of the top of the piston exceeds 400 ℃, and the piston also bears 10-15MPa of gas pressure. Meanwhile, the piston has a complex structure and needs to move at a high speed, so the material has to be light in weight, good in casting formability and wear resistance and small in thermal expansion coefficient. The eutectic Al-Si series cast aluminum alloy has small thermal expansion coefficient and good wear resistance, and is an ideal piston material. At present, various relatively formed piston alloys are developed, such as ZL117 in China, A390 in the United states, M142 and M174 in Germany, and the like, which are Al-Si-Cu series multi-element casting eutectic alloys.
With the increase of the power density of the engine, the combustion pressure and the working temperature borne by the piston are higher and higher, and the requirement on the heat resistance of the prepared material is higher and higher. Increasing the proportion of the refractory phase in the alloy is an effective way to increase the use temperature of the alloy. Adding Ni element to Al-Si-Cu alloy to form-Al3CuNi phase and gamma-Al7Cu4Ni phase, adding Mg element to form Al4CuMg5Si4(W phase) and Al5Mg8Si6Cu2(Q phase), adding Fe element to form Al9A (FeNi) phase, adding Mn element to form alpha-Al15(Mn,Fe)3Si2These phases are heat-resistant phases and have a remarkable effect of improving heat resistance. With the application of aluminum alloy on brake discs, higher requirements are put forward on wear resistance. Increasing the Si content in the alloy is an effective way to improve the wear resistance. However, the addition of these elements at the same time makes the alloy system very complicated, and if the content of these elements is high, the phases formed are very coarse, which adversely affects the mechanical properties of the alloy. The coarse intermetallic compound phases are effectively refined, and the method is greatly helpful for developing high-strength high-heat-resistance alloys.
The Si content of the alloy is improved, so that the primary silicon phase is distributed in the alloy matrix, and the wear resistance of the alloy is greatly improved. However, if the primary silicon phase is too coarse and is biased and unevenly distributed, the mechanical properties of the alloy are seriously impaired. Therefore, how to refine and uniformly distribute the primary silicon phase is the key point for developing the high-silicon heat-resistant and wear-resistant alloy.
The high-pressure solidification is beneficial to improving the feeding capacity of the interdendritic alloy liquid, reducing shrinkage cavities and shrinkage porosity of the casting and improving the density, thereby effectively improving the performance of the casting. When the external pressure is increased, the supercooling degree of the metal liquid can be increased, so that the number of the spontaneous nucleation cores is increased, the crystal grains are refined, the phases of primary crystal silicon and intermetallic compounds are refined, the casting quality is improved, and the mechanical property is improved. The high pressure solidification process commonly used at present is liquid die forging. However, the process is complex and the equipment is huge, so that the production cost of the casting is high, and the application of the process is limited.
Disclosure of Invention
In order to further improve the heat resistance of the alloy and not influence the mechanical properties of the aluminum alloy, the invention provides the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy, and the preparation method and the application thereof. The heat-resistant wear-resistant Al-Si-Cu-Ni aluminum alloy can be applied to automobile parts with special requirements on wear resistance and heat resistance, and the low-silicon heat-resistant wear-resistant Al-Si-Cu-Ni aluminum alloy is suitable for engine pistons according to different silicon contents; the high-silicon heat-resistant wear-resistant Al-Si-Cu-Ni aluminum alloy is suitable for automobile brake discs.
The invention is realized by adopting the following technical scheme:
the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy comprises the following elements in percentage by mass: 11.5-22% of Si, 5.0-7.0% of Cu, 3.5-5.0% of Ni, 0.8-1.5% of Mg, 0.4-0.8% of Mn, 0.8-1.2% of Fe, 0.08-0.25% of Zr, 0.08-0.25% of Ti, 0.08-0.25% of V, 0.1-0.5% of Sr and the balance of Al and impurities, wherein the total content of the impurities is not more than 0.3%.
The heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy has the as-cast (F state) room temperature tensile strength of 241-315MPa and the elongation of 0.9-2.6 percent; the 350 ℃ instantaneous tensile strength is 121-172MPa, and the elongation is 4.3-7.9%.
According to the content of Si, the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy is more preferably as follows:
a low-silicon heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy comprises the following elements in percentage by mass: 11.5-14.0% of Si, 5.0-7.0% of Cu, 3.5-5.0% of Ni, 0.8-1.5% of Mg, 0.4-0.8% of Mn, 0.8-1.2% of Fe, 0.08-0.25% of Zr, 0.08-0.25% of Ti, 0.08-0.25% of V, 0.1-0.5% of Sr and the balance of Al and impurities, wherein the total content of the impurities is not more than 0.5%.
The low-silicon heat-resistant wear-resistant Al-Si-Cu-Ni aluminum alloy has the as-cast (F state) room-temperature tensile strength of 271-315MPa and the elongation of 1.8-2.6 percent; the 350 ℃ instantaneous tensile strength is 157-172MPa, and the elongation is 5.8-7.9%.
More preferably:
a high-silicon heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy comprises the following elements in percentage by mass: 16.0-22.0% of Si, 5.0-7.0% of Cu, 3.5-5.0% of Ni, 0.8-1.5% of Mg, 0.4-0.8% of Mn, 0.8-1.2% of Fe, 0.08-0.25% of Zr, 0.08-0.25% of Ti, 0.08-0.25% of V, 0.1-0.5% of Sr and the balance of Al and impurities, wherein the total content of the impurities is not more than 0.5%.
The high-silicon heat-resistant wear-resistant Al-Si-Cu-Ni aluminum alloy has the as-cast (F state) room-temperature tensile strength of 241-264MPa and the elongation of 0.9-1.9 percent; the 350 ℃ instantaneous tensile strength is 121-138MPa, and the elongation is 4.3-5.7%.
The invention relates to a preparation method of a heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy, which comprises the following steps:
step 1: preparing raw materials according to the element proportion contained in the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy;
step 2: heating and melting Al raw materials to obtain an aluminum melt; adding other raw materials except Mg and Sr into the aluminum melt, adding the Mg raw material after the raw materials are melted, and stirring uniformly after the Mg raw material is completely melted to obtain an alloy melt; in the whole process, controlling the temperature of the alloy melt to be 680-800 ℃;
and step 3: adding a refining agent into the alloy melt for refining, then adding a Sr raw material Al-10Sr as a modifier for modification, and obtaining the modified alloy melt;
and 4, step 4: degassing the modified alloy melt, slagging off, standing at 680-760 ℃ for 30-60min to obtain a metal liquid, and casting to obtain a heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy casting;
in the step 1, the raw material of Si is metal silicon and/or aluminum-silicon intermediate alloy; the raw material of Cu is an aluminum-copper intermediate alloy and/or a copper additive; the material of Ni is an aluminum-nickel intermediate alloy and/or a nickel additive, Mg selects an industrial pure magnesium ingot, the material of Mn is an aluminum-manganese intermediate alloy and/or a manganese additive, the material of Fe is an aluminum-iron intermediate alloy and/or an iron additive, the material of Zr is an aluminum-zirconium intermediate alloy, the material of Ti is an aluminum-titanium intermediate alloy and/or a titanium additive, the material of V is an aluminum-vanadium intermediate alloy, and the material of Al selects one or more of an aluminum ingot, a remelted aluminum ingot or a cast aluminum alloy ingot.
In the step 3, the refining agent is a refining agent which has a refining effect on the alloy melt, such as an RJ-1 refining agent, and the adding mass of the refining agent is 0.2-0.8% of the total mass of the alloy melt.
In the step 3, the raw material Al-10Sr of Sr is added, wherein the mass of the added Sr is 0.1-0.5 percent of the residual amount of Sr in the alloy melt after modification.
In the step 3, when the content of Si in the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy is more than or equal to 12.8 percent, the alterant Al-10Sr needs to be matched with an Al-3P alterant for alteration treatment, and the adding mass of P is 0.005-0.008 percent of the residual amount of P in the altered alloy melt.
In the step 4, the following pressure casting process is adopted for casting, and specifically:
the method comprises the following steps: according to the shape of a workpiece needing to be cast by the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy, a casting die is designed to be composed of a side die, an upper die and a lower die; the side die is a fixed die, the upper die and the lower die are movable dies, and after the movable dies and the fixed die are assembled, the metal liquid is poured into a casting cavity;
in the first step, the casting cavity is determined according to the structural characteristics of the piston and the brake disc.
Step two: when the metal liquid is poured into the whole casting cavity, the pouring gate is blocked;
step three: and respectively applying pressure from the upper die and the lower die to press the metal liquid in the casting cavity, keeping the pressure for 60-300s according to the size of the casting after the pressure reaches 25-100MPa, and releasing the pressure after the metal liquid is completely solidified, removing the die to obtain the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy casting.
In the step 4, after casting, the heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy casting can be placed at the temperature of 170-210 ℃ for heat preservation for 6-8 hours to obtain the final heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy casting.
In the step 4, degassing is performed by introducing argon or nitrogen into the alloy melt after modification by using a degassing machine, wherein the flow of the argon or the nitrogen is 0.2-0.3 m3/h。
The application of the low-silicon heat-resistant wear-resistant Al-Si-Cu-Ni aluminum alloy is applied to engine parts, in particular to engine pistons;
the invention relates to application of high-silicon heat-resistant wear-resistant Al-Si-Cu-Ni aluminum alloy in an automobile brake disc.
The heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy, the preparation method and the application have the beneficial effects that:
the invention adopts the addition of a large amount of Sr, wherein the Sr is All5(MnFe)3Si2And the effective alterant of the intermetallic compound phase can greatly refine the intermetallic compound phase. In the casting process, the pressure is applied to the molten aluminum, so that the molten aluminum is solidified under higher pressure, intermetallic compound phases and primary silicon are greatly refined, and the intermetallic compound phases and the primary silicon are distributed more uniformly. The invention breaks through the restriction of the quantity of alloy elements and the content of each alloy element by two key technologies of Sr modification and aluminum water solidification under pressure, obtains an alloy with multiple alloy elements and high alloy element content, increases the quantity of high-temperature strengthening phases, reduces the size, greatly improves the high-temperature performance of the alloy and further improves the service temperature of the piston alloy.
Drawings
FIG. 1 is a metallographic structure of a low-silicon heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy casting prepared in example 1 of the present invention;
FIG. 2 is a metallographic structure diagram of an Al-Si-Cu-Ni aluminum alloy casting prepared in comparative example 1.
FIG. 3 is a metallographic structure of a low-silicon heat-resistant and wear-resistant Al-Si-Cu-Ni aluminum alloy casting prepared in example 3 of the present invention;
FIG. 4 is a metallographic structure diagram of an Al-Si-Cu-Ni aluminum alloy casting prepared in comparative example 2.
Detailed Description
The present invention will be described in further detail with reference to examples.
In the description of the present invention, it is to be noted that those who do not specify specific conditions in the examples are performed according to conventional conditions or conditions recommended by manufacturers; the reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially. In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below; the embodiment of the invention provides a die-casting aluminum alloy material, and the die-casting aluminum alloy material and a preparation method thereof are explained in detail through the following specific embodiment; each example was prepared with 100kg of alloy.
The remelting aluminum ingot selected in the embodiment of the invention is Al99.70 in the national standard GB/T1196-2008 remelting aluminum ingot, and the aluminum content is not less than 99.70 wt%; or scrap remelting aluminum ingots; when adding Fe element, selecting Al-10Fe intermediate alloy or 75Fe agent (aluminum alloy additive with 75% of Fe mass percent); when Mn element is added, Al-10Mn intermediate alloy or 75Mn agent (aluminum alloy additive with Mn content of 75 percent in mass percent) is selected; when adding Si element, selecting Al-30Si intermediate alloy; when Mg element is added, metal magnesium is selected; when Zn element is added, metal zinc is selected; when adding Cu element, selecting Al-50Cu intermediate alloy; when adding Ti element, selecting Al-10Ti intermediate alloy or 75Ti agent (aluminum alloy additive with Ti content of 75%); when adding Ni element, selecting Al-20Ni intermediate alloy; when Zr element is added, Al-10Zr intermediate alloy is selected, and when V element is added, Al-10V intermediate alloy is selected. The pre-alloyed cast aluminum alloy ingot commonly used in the casting industry, such as the aluminum ingot in the national standard GB/T8733-2016 cast aluminum alloy ingot, can also be used for adjusting the alloy components on the basis to achieve the component target.
In the degassing in the embodiment of the invention, argon is introduced into the added aluminum water by using a degassing machine, and the flow of the argon is 0.2-0.3 m3/h。
In the embodiment of the invention, the residual amount of Sr in the alloy is 0.1-0.5% due to the addition of the alterant.