阅读说明：本技术 发动机活塞用高强耐热铸造铝硅合金 (High-strength heat-resistant cast aluminum-silicon alloy for engine piston ) 是由 张海涛 魏伟 郑强 于 2020-07-06 设计创作，主要内容包括：本发明公开了一种发动机活塞用铝硅合金材料,合金的组成元素的质量百分数含量为：Si 12.0～15.0％、Cu 2.0～4.5％、Mg 0.5～1.5％、Mn 0.2～0.5％、Ni 2.2～4.5％、Zr 0.1～0.6％,以及Al、附带的元素和杂质。微合金化附带元素为Er、Hf、Nb、Nd、Sc和Ti中的一种或多种,微合金化附带元素的添加总量满足0.1％≤(Er+Hf+Nb+Nd+Sc+Ti)wt％≤0.9％。铝硅合金中不可避免的杂质元素每种≤0.05wt％,总和≤0.15wt％。本发明合金的高温性能超过现用的ZL109合金,特别是350℃时的高温强度高达98MPa。(The invention discloses an aluminum-silicon alloy material for an engine piston, which comprises the following components in percentage by mass: 12.0 to 15.0% of Si, 2.0 to 4.5% of Cu, 0.5 to 1.5% of Mg, 0.2 to 0.5% of Mn, 2.2 to 4.5% of Ni, 0.1 to 0.6% of Zr, and Al, incidental elements and impurities. The microalloying incidental elements are one or more of Er, Hf, Nb, Nd, Sc and Ti, and the total addition amount of the microalloying incidental elements is more than or equal to 0.1 percent and less than or equal to 0.9 percent (Er + Hf + Nb + Nd + Sc + Ti) in percentage by weight. The inevitable impurity elements in the aluminum-silicon alloy are less than or equal to 0.05 wt% of each kind and less than or equal to 0.15 wt% of the total. The high-temperature performance of the alloy of the invention exceeds that of the prior ZL109 alloy, and particularly the high-temperature strength at 350 ℃ reaches 98 MPa.)

1. A high-strength heat-resistant aluminum-silicon alloy suitable for manufacturing engine pistons comprises the following basic components in percentage by mass: 12.0 to 15.0% of Si, 2.0 to 4.5% of Cu, 0.5 to 1.5% of Mg, 0.2 to 0.5% of Mn, 2.2 to 4.5% of Ni, 0.1 to 0.6% of Zr, and the balance of Al, incidental elements and inevitable impurities.

2. A high strength heat resistant aluminium silicon alloy suitable for engine piston manufacture according to claim 1, characterised in that the aluminium silicon alloy contains: 12.2 to 14.6% of Si, 2.0 to 4.2% of Cu, 0.5 to 1.3% of Mg, 0.2 to 0.4% of Mn, 2.2 to 4.5% of Ni, 0.15 to 0.6% of Zr, and the balance of Al, incidental elements and inevitable impurities.

3. The high-strength heat-resistant aluminum-silicon alloy suitable for manufacturing the engine piston as claimed in claim 2, wherein the aluminum-silicon alloy can be further added with micro-alloying accessory elements Er, Hf, Nb, Nd, Sc and Ti, and the addition amount of the single accessory element is 0.1-0.3%; whether a single incidental element is further added or 2 or more incidental elements are further added in a combined manner, the total amount of incidental elements added is 0.1% or more (Er + Hf + Nb + Nd + Sc + Ti) wt% or less and 0.9% or less.

4. An aluminium alloy suitable for use in the manufacture of sliding bearings according to claim 2, wherein the inevitable impurity elements are 0.05 wt% or less each and 0.15 wt% or less in total when the aluminium alloy is smelted to produce the aluminium alloy.

Technical Field

The invention belongs to the field of metal materials, and particularly relates to the technical field of aluminum-silicon alloy materials for engine pistons.

Background

At present, the high-strength diesel engine is developed towards high power and high load, and the performance of the aluminum piston which is used as an important reciprocating component of the internal combustion engine directly influences the performance and the reliability of the high-strength diesel engine.

With the development of high power density of an engine, the combustion pressure and working temperature borne by a piston are higher and higher, and higher requirements are put forward on the heat resistance of the aluminum-silicon alloy, such as high-temperature strength, linear expansion coefficient, volume stability and the like. The currently widely used ZL109Al-Si alloy material has poor high-temperature performance at 350 ℃ (which is not required by the existing national standards) and above, and the overall high-temperature strength, linear expansion coefficient and volume stability are not satisfactory.

In order to improve the high-temperature performance of the aluminum-silicon alloy, a great deal of research is carried out at home and abroad, so as to adjust and optimize the contents of Cu and Ni in the aluminum-silicon alloy, and add Zr, Ti, V, Co, rare earth elements and the like to improve the high-temperature performance of the alloy. U.S. patent document No. 5996471 discloses a piston aluminum alloy (Cu 2-5, Si 13-16, Mn0.2-1.3, Ni1.0-2.5, V0.05-0.2, P0.004-0.02) containing V Al-Si-Cu-Mg, which has good high-temperature strength and wear resistance, the tensile strength at 300 ℃ is not lower than 90MPa, and the yield strength is not lower than 70 MPa. Patent document CN101117679A discloses a high-performance aluminum-silicon piston alloy material, which comprises the following components: 12-13% of Si, 2.5-4% of Cu, 1.7-3% of Ni, 0.5-1.2% of Mg, 0.1-0.2% of Mn, 0.15-0.5% of V, 0.23-0.6% of Ti, 0.15-0.25% of Sigma Re0, less than or equal to 0.05% of Zn, less than or equal to 0.7% of Fe and the balance of Al. The tensile strength of the aluminum-silicon alloy at room temperature is not lower than 230MPa, the tensile strength of the aluminum-silicon alloy at 300 ℃ is not lower than 100MPa, and the tensile strength of the aluminum-silicon alloy at 360 ℃ is not lower than 80 MPa.

Although the high-temperature strength of the alloy is higher than that of the common Al-Si alloy, the high-temperature performance of the alloy at 250-300 ℃ is still lower, particularly the strength at 350 ℃. In order to further improve the high-temperature performance and wear resistance of piston materials, aluminum-based composite materials of ceramic particles or ceramic fiber reinforced aluminum-silicon alloys have been developed in recent years. Patent document CN1257299C discloses an aluminum-based composite material for manufacturing a piston, which is composed of a matrix alloy and a reinforcing phase, wherein the matrix alloy comprises silicon, copper, nickel, magnesium, titanium and aluminum elements, and is characterized in that the matrix alloy comprises the following components in percentage by mass: 9-16% of Si, 0.5-2.5% of Cu0.5-2.0% of Ni0.5-2.0%, 0.2-1.5% of Mg0.2-2.0% of Ti0.2-2.0% of Al in balance; the reinforced phase is Al generated by in-situ reaction₂O₃And TiC particles. The composite material has good performance, the room temperature strength is 240-300 Mpa, the high temperature strength at 300 ℃ is 120-140 Mpa, the high temperature strength is far greater than that of the conventional piston aluminum alloy (70-80 MPa), and meanwhile, the composite material piston has good volume stability.

Patent document CN108796316A discloses an in-situ TiB2 reinforced aluminum-silicon alloy piston material and a preparation method thereof. The material has good high-temperature strength and low linear expansionCoefficient of expansion. But TiB₂The density of the reinforcing phase 4.52g/cm3 is far greater than that of the molten aluminum, and the TiB of the aluminum alloy melt is greater than 0.2-0.5 micron₂The reinforcing particles will rapidly settle and aggregate in a short time, resulting in difficulty in mass production of such materials in production fields.

At present, cast aluminum-silicon alloy which is suitable for the existing equipment, can be produced in large scale and has the tensile strength of not less than 90MPa or higher at the temperature of more than 350 ℃ is lacked.

Disclosure of Invention

The invention firstly provides a high-strength heat-resistant cast aluminum-silicon alloy material, and for the aluminum-silicon alloy, a piston with an iron alloy insert ring and a salt core inner cooling oil duct design can be prepared by using a metal mold gravity casting technology.

In order to achieve the above object, the technical solution of the present invention is as follows: the invention provides a high-strength heat-resistant aluminum-silicon alloy material suitable for manufacturing an engine piston, which mainly comprises the following components in percentage by mass: 12.0 to 15.0% of Si, 2.0 to 4.5% of Cu, 0.5 to 1.5% of Mg, 0.2 to 0.5% of Mn, 2.2 to 4.5% of Ni, 0.1 to 0.6% of Zr, and Al, incidental elements and impurities.

The first preferred scheme of the invention is as follows: the aluminum-silicon alloy mainly comprises: 12.2 to 14.6% of Si, 2.0 to 4.2% of Cu, 0.5 to 1.3% of Mg, 0.2 to 0.4% of Mn, 2.2 to 4.5% of Ni, 0.15 to 0.6% of Zr, and Al, incidental elements and impurities.

The second preferred scheme of the invention is as follows: the aluminum-silicon alloy also contains at least one of micro-alloying accessory elements Er, Hf, Nb, Nd, Sc and Ti, wherein the single addition amount of the micro-alloying accessory elements is 0.1-0.3%, and the total addition amount of the micro-alloying elements is more than or equal to 0.1% (Er + Hf + Nb + Nd + Sc + Ti) wt% and less than or equal to 0.9%.

In a third preferred embodiment of the present invention, the inevitable impurity elements in the aluminum-silicon alloy are each equal to or less than 0.05 wt%, and the total is equal to or less than 0.15 wt%.

The principle of the design of the components of the aluminum alloy of the invention is explained in detail as follows:

12.0-15.0% of silicon (Si) ensures the aluminum-silicon alloyThe wear resistance, low linear expansion coefficient and high-temperature dimensional stability of the alloy are achieved, and agglomeration of primary crystal silicon in the conventional metal mold gravity casting technology can be avoided. The main functions of Cu (2.0-4.5%) are: at room temperature, after the aluminum-silicon alloy is subjected to aging treatment, Cu, Mg, Si and Al form Al with high complex thermal stability₅Cu₂Mg₈Si₆The multi-element nano-phase particles are precipitated and separated out, so that a precipitation strengthening effect is generated, and the room temperature strength of the aluminum-silicon alloy is obviously improved; under the high-temperature working condition, a small amount of Cu is dissolved in the Al matrix in a solid solution manner to generate a solid solution strengthening effect, the high-temperature strength of the aluminum-silicon alloy is improved, and part of Cu still uses Al₅Cu₂Mg₈Si₆The multi-phase particles exist in the form of particles, and contribute to the high-temperature strength of the aluminum-silicon alloy. The function of Mg is mainly to form a strengthening phase Al together with Cu, Si and the like₅Cu₂Mg₈Si₆(also possible to form S-Al)₂CuMg phase) for improving the room temperature strength and the fatigue performance of the alloy, and adjusting the density of the aluminum-silicon alloy, so that the Mg content is 0.50-1.50%, the Mg content is less than 0.5%, the quantity of formed Mg-containing strengthening phases is limited, the Mg-containing strengthening phases are not enough to obviously influence the room temperature performance of the aluminum alloy, and the Mg content is more than 1.5%, more skeleton-shaped Mg with lower stability can be formed in the aluminum alloy₂The Si phase is not beneficial to improving the high-temperature strength of the aluminum alloy and simultaneously reduces the fatigue property of the aluminum alloy.

Nickel forms Al primarily in aluminum alloys₃Ni and other heat-resistant phases improve the high-temperature strength of the aluminum alloy, the nickel content is less than 2.2 percent, the amount of the nickel-containing heat-resistant phases formed in the aluminum alloy matrix is small, the high-temperature performance of the aluminum alloy above 350 ℃ is difficult to support, and if the nickel content exceeds 4.5 percent, coarse nickel-containing heat-resistant phase particles are easy to form in the aluminum alloy, so that the high-temperature strengthening and fatigue performance of the aluminum alloy is deteriorated, and the preferred nickel content is 2.2-4.20 percent.

A small amount of Mn is used for neutralization modification, so that the flaky beta-Al in the aluminum-silicon alloy₅alpha-Al phase-to-skeletal FeSi₁₅(FeMn)₃Si₂And the toughness of the aluminum alloy is improved, and the fatigue performance is improved.

Zr in the Al-Si alloy isFormation of submicron or nanoscale Al in aluminum alloys₃The Zr precipitates and precipitates to form a phase, on one hand, the cast grain structure of the aluminum alloy is refined, and the refinement of primary crystal silicon and eutectic silicon is promoted, and on the other hand, coherent Al is precipitated in the solution treatment process₃The Zr nano particles can improve the room temperature and high temperature strength of the aluminum alloy, improve the creep resistance of the aluminum alloy, prevent the growth and coarsening of aluminum alloy grains under the high-temperature working state of the piston, and keep the high-temperature performance under the high-temperature working condition.

The micro-alloying incidental elements such as Er, Hf, Nb, Nd, Sc and Ti replace the nano-particle Al in the process of solution aging₃Zr atoms of the Zr phase forming more complex and stable multi-element Al₃And (Zr and M) (M represents Er, Hf, Nb, Nd, Sc and Ti) type nanometer precipitated phases further improve the high-temperature strength and the structure stability of the aluminum alloy and improve the creep resistance of the aluminum alloy.

Compared with the existing aluminum-silicon casting alloy, the aluminum-silicon alloy has the advantages that: by implementing the aluminum-silicon alloy, the cast aluminum-silicon alloy can obtain good room-temperature mechanical property and better high-temperature resistance, namely: by reasonably proportioning alloying elements Si, Cu, Ni, Mg, Zr, Mn, Er, Hf, Nb, Nd, Sc and Ti, the alloy of the invention can obtain the tensile strength of not less than 92MPa at 350 ℃, and the tensile strength of not less than 55MPa at 425 ℃, and can meet the requirement of a high-strength diesel engine on the high-temperature performance of a cast aluminum-silicon alloy piston.

Drawings

FIG. 1 shows an as-cast metallurgical structure of an aluminum-silicon alloy according to example 1 of the present invention.

FIG. 2 is a graph showing the engineering stress-strain curve of the Al-Si alloy at 350 ℃ in example 1 of the present invention.

FIG. 3 shows the metallographic structure of the aluminum-silicon alloy in the solid solution aged state in example 2 of the present invention.

FIG. 4 shows an electron microscopic structure of the aluminum-silicon alloy in the solid solution aged state in example 3 of the present invention.

Detailed Description

The present invention will be described in detail with reference to specific examples.

The preparation method comprises the following steps: the aluminum-silicon casting alloy with all components is subjected to the processes of smelting, casting, solid solution treatment, aging treatment and the like.

Example 1

Aluminum-silicon alloy components: 15.0% of Si, 4.5% of Cu, 1.2% of Mg, 0.2% of Mn, 3% of Ni, 0.3% of Zr, 0.2% of Ti, 0.5% of Hf, 0.2% of Sc, and the balance of Al and inevitable impurities.

And (3) microstructure: FIG. 1 shows the microstructure of the aluminum alloy piston material of this embodiment, in which the primary silicon particles are uniformly distributed and have a size generally in the range of 30-60 μm; the length of the needle-like heat-resistant phase is 60 to 150 μm.

Mechanical properties: the room temperature tensile strength is 320MPa, the elongation after fracture is about 2.0 percent, and the high temperature tensile strength at 350 ℃ and the elongation after fracture are respectively 98MPa and 2.9 percent (see figure 2)

Example 2

Aluminum-silicon alloy components: 13.5% of Si, 4.0% of Cu, 1.2% of Mg, 0.2% of Mn, 4% of Ni, 0.40% of Zr, 0.30% of Ti, 0.2% of Er, 0.3% of Nd, and the balance of Al and inevitable impurities.

And (3) microstructure: FIG. 3 shows the microstructure of the aluminum alloy piston material of the present example after solution aging. Compared with cast aluminum-silicon alloy, primary silicon is slightly thinned, corners are spheroidized, the needle-shaped heat-resistant phase is not obviously changed, and eutectic silicon is in a micro-granular shape due to redissolution and precipitation.

Mechanical properties: the room temperature tensile strength is 295MPa, the elongation after fracture is about 1.5 percent, and the high temperature tensile strength at 350 ℃ and the elongation after fracture are 93MPa and 2.1 percent respectively

Example 3

Aluminum-silicon alloy components: 13.5% of Si, 3.5% of Cu, 1.0% of Mg, 0.2% of Mn, 3.8% of Ni, 0.33% of Zr, 0.2% of Ti, 0.4% of Hf0, 0.3% of Nb, and the balance of Al and inevitable impurities.

And (3) microstructure: fig. 4 is a scanning electron microscope structure of the aluminum alloy piston material of the present embodiment. After high-temperature solution treatment, uniformly distributed spherical nanoscale Al₃Zr-type precipitates generally have a size of 50 nm.

Mechanical properties: the high-temperature tensile strength at 425 ℃ and the elongation after fracture are 59MPa and 27 percent respectively.

Obviously, the technical means disclosed in the present invention are not limited to the technical means disclosed in the above embodiments, and the above examples are only examples for clearly illustrating the invention, but not for limiting the embodiments, and all embodiments are not necessarily or not exhaustive. It will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the principles of the invention, and it is intended to cover all such changes and modifications as fall within the true spirit and scope of the invention.