CN109295404B

CN109295404B - Wear-resistant brass alloy based on phase change control of silicon-manganese compound

Info

Publication number: CN109295404B
Application number: CN201811015948.9A
Authority: CN
Inventors: 王世民; 吴明英; 戴娇燕; 杨标
Original assignee: Ningbo Zycalloy Co ltd
Current assignee: Ningbo Zycalloy Co ltd
Priority date: 2018-09-01
Filing date: 2018-09-01
Publication date: 2020-11-03
Anticipated expiration: 2038-09-01
Also published as: CN109295404A

Abstract

The invention discloses a wear-resistant brass alloy, wherein the elements of the brass alloy comprise Cu, Mn, Si, Zn and Pb, and the microstructure of the high-strength high-wear-resistant silicon brass alloy comprises an alpha phase, a beta phase and manganese-silicon intermetallic compounds such as Mn3Si, MnSi, Mn5Si3 and the like. The invention provides wear-resistant brass based on phase change control of a silicon-manganese compound, which improves the wear resistance of an alloy by controlling each phase of the alloy and solves the problems of poor friction and wear resistance and difficult tissue control of the alloy in the prior art.

Description

Wear-resistant brass alloy based on phase change control of silicon-manganese compound

Technical Field

The invention relates to a wear-resistant brass alloy based on phase change control of a silicon-manganese compound, and belongs to the technical field of brass alloys.

Background

The wear-resistant copper alloy has wide application in the fields of engineering machinery, automobile engines, turbochargers, gearboxes and the like. For example, the floating bearing and the thrust plate are core components in the turbocharger, when the turbocharger works normally, the rotating speed of the bearing is more than 6-12 ten thousand revolutions per minute, the requirements on the wear resistance and the stability of the material are strict, and the friction pair composed of copper steel can form a good oil film under the working condition, so the floating bearing and the thrust plate of the turbocharger are made of copper alloy materials widely. Silicomanganese brass is among the most common wear resistant copper alloys.

With the upgrade of products, higher and higher requirements are put on the performance of wear-resistant copper alloys. The elastic modulus of the silicomanganese compound is more than 600, the silicomanganese compound forms a friction pair with other materials, the deformation is small when the silicomanganese compound bears compressive stress, and the silicomanganese compound plays a supporting role, so the silicomanganese compound is a main strengthening phase and a wear-resistant phase in the silicomanganese brass.

A great deal of research has been devoted to the improvement of wear resistance of silicomanganese brass, and much research has focused on improving wear resistance by adding alloying elements, for example, Toyota auto-mobiles (Chinese patent application No. CN200480037582.5) invented a wear-resistant copper alloy comprising, by weight, 4.7-22.0% of nickel, 0.5-5.0% of silicon, 2.7-22.0% of iron, 1.0-15.0% of chromium, 0.01-2.00% of cobalt, 2.7-22.0% of one or more of tantalum, titanium, zirconium and hafnium. An obvious disadvantage of this approach is that the toughness of the material is compromised while strength and wear resistance are improved.

Disclosure of Invention

The invention aims to provide a wear-resistant brass alloy based on phase change control of a silicon-manganese compound, aiming at overcoming the defects in the prior art, the existence form of each phase is controlled by controlling the phase change, the wear-resistant performance of the alloy is improved, and meanwhile, the wear-resistant brass alloy has good toughness.

The above object of the present invention is achieved by the following technical solutions: a wear resistant brass alloy based on phase change control of silicon manganese compounds, the elements of the wear resistant brass alloy comprising copper, manganese, silicon, zinc, lead, characterized in that: the microstructure of the wear-resistant brass alloy comprises an alpha phase, a beta phase and 4 silicon-manganese compounds. The 4 silicon-manganese compounds are respectively: face centered cubic beta-Mn₃Si、α-Mn₃Si, Mn of hexagonal structure₅Si₃And simple cubic MnSi phases. In the wear-resistant brass alloy, the sum of silicon and manganese compounds accounts for 3.1-6% of the alloy by mass percent. Wherein, the proportion of the 4 silicon-manganese compounds in the total silicon-manganese compounds is respectively as follows: face centered cubic beta-Mn₃Si 20-50%, alpha-Mn₃Si is less than 3 percent; mn of hexagonal structure₅Si₃10-40% of simple cubic MnSi, and 15-40% of simple cubic MnSi.

After adopting above-mentioned scheme, have following advantage: the wear-resistant brass alloy can form 4 different strengthening phases without additionally adding alloy elements, and the wear resistance of the alloy is improved.

beta-Mn in Brass₃Si is in a face-centered cubic structure, the alpha phase of the brass matrix is also in the face-centered cubic structure, and the lattice constants of the two are relatively close, so that the beta-Mn is₃There is a semi-coherent orientation relationship between Si and the alpha phase matrix. This orientation relationship results in β -Mn₃The Si phase can greatly improve the strength and the wear resistance of the silicomanganese brass, and meanwhile, the beta-Mn phase₃The Si has strong binding force with the matrix and is not easy to fall off from the matrix, thereby scratching the surface of the part. The brass of the invention is subjected to phase change control to enable alpha-Mn₃Si is converted into beta-Mn by high-temperature heat treatment₃Si, thereby improving the toughness and the wear resistance of the manganese silicon brass. Thus, beta-Mn in the brass alloy₃The mass percent of Si is controlled to be 20-50%, preferably 28-42%, and more preferably 33-40%. Preferred alpha-Mn₃Conversion of Si to beta-Mn₃Phase transition controlled heat treatment temperature of SiAt 600 ℃ and 800 ℃, the preferred diameter is 2-10 um.

Mn in Brass₅Si₃The phase is a hexagonal structure, and the appearance of the phase is a long rod with a hexagonal section. Mn₅Si₃Has lower forming energy than other silicomanganese compounds, and preferentially forms Mn within a certain range of specific Mn and Si components₅Si₃Phase and easily grow up. Mn₅Si₃Coarse Mn not having a definite orientation relation with the matrix₅Si₃The reinforcing effect of the phases is limited, and the phases are easy to fall off from the matrix and scratch parts.

The primary driver of phase change (e.g., precipitation) is the reduction of gibbs free energy in the system. Mn₅Si₃The Gibbs free energy formed decreases significantly with increasing temperature, so that at high temperatures, Mn₅Si₃The formed Gibbs has low free energy, and fine and dispersed Mn is separated out₅Si₃And the toughness and the wear resistance of the manganese silicon brass can be greatly improved. Thus, Mn in the brass alloy₅Si₃The mass percentage of (B) is controlled to 10-40%, preferably 15-30%, more preferably 18-25%. Preferred fine Mn₅Si₃The heat treatment temperature for phase transformation control of phase precipitation is 650-850 ℃, and the preferred diameter is 3-20 um.

The MnSi phase in the brass is stable in the high-temperature liquid. In the solidification process, coarse primary MnSi is firstly separated out, and when the temperature is continuously reduced, eutectic reaction is carried out to generate fine MnSi and Mn₅Si₃A eutectic phase. MnSi is a simple cubic structure, is closest to the lattice constant of a copper matrix, is more likely to form a coherent or semi-coherent interface, has strong capability of improving the wear resistance of the alloy, and is an ideal strengthening and toughening phase for fine eutectic MnSi. The nascent MnSi phase can be refined by an electromagnetic stirring technology, and the ideal size and content can be obtained by combining a high-temperature heat treatment process. Therefore, the mass percentage of MnSi in the brass alloy is controlled to 15 to 40%, preferably 20 to 35%, more preferably 25 to 32%. The preferred eutectic MnSi heat treatment temperature is 550-700 deg.C, with a preferred diameter of 1-5 um.

Preferably, the wear-resistant brass alloy based on the phase change control of the silicomanganese compound further comprises one or more components selected from iron, nickel, aluminium, the total content of said components being less than 4% by weight.

The iron element is a particle of heterogeneous nucleation of the silicomanganese phase. The supercooling degree required by the homogeneous nucleation of the silicomanganese phase is large, the nucleation process is long, the number of the nucleation is small, and the size of the silicomanganese phase after the nucleation is large is unfavorable for the wear resistance of the alloy. A small amount of iron element is added, and the melting point of the iron element is higher than that of all silicomanganese phases, so that the iron element can be used as a mass point of heterogeneous nucleation of the silicomanganese phases, the nucleation supercooling degree is reduced, the nucleation quantity is greatly increased, and the silicomanganese phases are refined. Therefore, the content of the iron element is 0.01 to 0.5% by mass, preferably 0.05 to 0.4% by mass, and more preferably 0.1 to 0.25% by mass.

The nickel and the aluminum have higher solid solubility in the alloy, are easy to occupy gaps in a beta phase and an alpha phase, hinder solid solution of a silicon-manganese phase in a matrix, promote precipitation of the silicon-manganese phase and improve the wear resistance of the alloy. The weight percentage of nickel and aluminium is therefore between 0.1 and 4.0%, preferably between 0.2 and 1.8%, more preferably between 0.3 and 1.0%.

Compared with the prior art, the wear-resistant brass alloy based on the phase change control of the silicon-manganese compound has the following advantages: by phase change control, the dispersed fine and well-proportioned face-centered cubic beta-Mn₃Si, Mn of hexagonal structure₅Si₃Simple cubic MnSi phase Mn₅Si₃The phase is uniformly distributed in the material matrix, and the alloy has higher strength, toughness and better frictional wear performance without depending on the addition of alloy elements, thereby meeting the requirements of manufacturing wear-resistant parts.

In addition, the application also discloses a preparation method of the wear-resistant brass alloy based on the phase change control of the silicon-manganese compound, which comprises the following steps: preparing materials, smelting, casting, extruding, carrying out high-temperature heat treatment, carrying out low-temperature heat treatment and cold stretching to obtain the wear-resistant brass alloy;

the high-temperature heat treatment comprises the following steps: carrying out high-temperature heat treatment on the silicomanganese brass blank in a heat treatment furnace, and satisfying the following formula:

0.5≤x≤6

870-42x≤y≤870-31x

in the formula, x on the left and right sides is substituted for the same value, x represents the annealing time in hours, and y represents the annealing temperature in ℃.

After the method is adopted, the following advantages are achieved: through high-temperature heat treatment under different conditions, the silicomanganese compounds in the extrusion blank are re-dissolved into the alloy matrix to different degrees, and 4 silicomanganese compounds with different components and different proportions are precipitated in the subsequent low-temperature heat treatment process. 4 different silicon-manganese compounds act together to improve the wear resistance of the alloy.

Drawings

FIG. 1 is a microstructure and morphology diagram of wear-resistant brass alloy based on phase change control of silicon-manganese compound

Detailed Description

The technical solutions of the present invention will be further described with reference to specific examples, but the present invention is not limited to these examples.

Table 1 shows a comparison between the examples of the present invention and comparative examples.

TABLE 1

In conclusion, the microstructure of the silicon-manganese brass comprises alpha phase, beta phase and face-centered cubic beta-Mn through phase change control₃Si,α-Mn₃Si, Mn of hexagonal structure₅Si₃Simple cubic MnSi phase. Based on the mass percentage, the microstructure of the wear-resistant brass alloy contains face-centered cubic beta-Mn₃Si 20-50%, alpha-Mn₃Si is less than 3 percent; mn of hexagonal structure₅Si₃10-40% of simple cubic MnSi, and 15-40% of simple cubic MnSi. The total weight percentage of the silicon-manganese compound in the alloy is 3.1-6%. The alloy does not depend on addition of alloy elements, so that the alloy has higher strength, toughness and better frictional wear performance, and meets the requirements of manufacturing wear-resistant parts.

Claims

1. A wear resistant brass alloy based on phase change control of silicon manganese compounds, the elements of the wear resistant brass alloy comprising copper, manganese, silicon, zinc, lead, characterized in that: the microstructure of the wear-resistant brass alloy comprises an alpha phase, a beta phase and 4 silicon-manganese compounds; the 4 silicon-manganese compounds are respectively: face centered cubic beta-MnSi, alpha-MnSi, hexagonal MnSi and simple cubic MnSi phases; in the wear-resistant brass alloy, the sum of silicon and manganese compounds accounts for 3.1-6% of the alloy by mass percent; wherein, the proportion of the 4 silicon-manganese compounds in the total silicon-manganese compounds is respectively as follows: the face centered cubic beta-MnSi accounts for 20-50%, and the alpha-MnSi is less than 3%; 10-40% of MnSi with a hexagonal structure and 15-40% of MnSi with a simple cube, and the preparation method of the wear-resistant brass alloy based on the phase change control of the silicon-manganese compound comprises the following steps: preparing materials, smelting, casting, extruding, carrying out high-temperature heat treatment, carrying out low-temperature heat treatment and cold stretching to obtain the wear-resistant brass alloy; the high-temperature heat treatment comprises the following steps: carrying out high-temperature heat treatment on the silicomanganese brass blank in a heat treatment furnace, and satisfying the following formula: x is more than or equal to 0.5 and less than or equal to 6, y is more than or equal to 870-42x and less than or equal to 870-31x, x on the left and the right is substituted for the same value, x represents annealing time and is expressed in hours, y represents annealing temperature and is expressed in ℃.

2. The wear-resistant brass alloy of claim 1, further comprising one or more elements selected from the group consisting of iron, nickel, aluminum, and rare earths, wherein the total content of the one or more elements selected from the group consisting of iron, nickel, aluminum, and rare earths is less than 4% by weight.