Forming process of lead-free free-cutting bismuth brass

Abstract

The invention discloses a forming process of lead-free free-cutting bismuth brass, which comprises the following steps of: 1, melting preset raw materials which comprise the following components in percentage by mass: 32-37% of Zn, 1.3-1.5% of Bi, 0.035-0.046% of Sb, 0.1-0.3% of Al, 0.03-0.04% of Fe, 0.06-0.09% of Sn and the balance of Cu, and enabling the distribution of Bi in a grain boundary to be in a relatively uniform particle shape under the cooperation of a refiner, heat treatment and the like, the alloy has good plasticity and mechanical properties, and the corrosion resistance of the alloy is improved.

Description

Technical Field

[0001] The invention relates to the technical field of materials, and in particular to a molding process of lead-free free-cutting bismuth brass. Background Art

[0002] Bismuth brass is widely used in bathroom and sanitary ware fields due to its excellent cutting performance, wear resistance and low cost. However, bismuth is prone to segregation in copper, which causes hot brittleness and cold brittleness in copper alloys, causing brittle fracture of copper alloys from metals with good plasticity. The common solution on the market is to combine bismuth with other elements to change the distribution of bismuth. At present, the effect cannot meet the demand and needs to be improved. Summary of the invention

[0003] To solve at least one of the above technical defects, the present invention provides the following technical solutions:

[0004] This application document discloses a molding process of lead-free free-cutting bismuth brass, comprising the following steps:

[0005] First, melt the predetermined raw materials, which include Zn32-37%, Bi1.3-1.5%, Sb0.035-0.046%, Al0.1-0.3%, Fe0.03-0.04%, Sn0.06-0.09%, and Cu balance by mass;

[0006] Second, the refined molten metal is cast into an ingot, and the ingot is heat treated at a temperature of 350-450°C.

[0007] Furthermore, in the melting process, a boron refiner and a rare earth refiner are used for refinement.

[0008] Furthermore, the amount of the boron refiner is 0.01-0.03% of the melt, and the rare earth refiner is composed of lanthanum and cerium in a mass ratio of 1:2 and the amount of the rare earth refiner is 0.05-0.07% of the melt.

[0009] Furthermore, in the melting process, copper raw materials are added to the furnace for melting, and zinc raw materials are added after the temperature is raised to 1030-1040°C. After the zinc is melted, Bi, Sb, Al, Fe, and Sn components are added, and then the molten metal is refined with a boron refiner and a rare earth refiner, and the refined molten metal is formed into ingots in a semi-continuous casting direction.

[0010] Furthermore, in the heat treatment process, the temperature is 410° C. and the time is 3-5 hours.

[0011] Furthermore, the raw material includes, by mass, 35% Zn, 1.4% Bi, 0.04% Sb, 0.2% Al, 0.035% Fe, 0.078% Sn, and the balance Cu.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1. The present invention adds Al and Sn to the components, and with the help of a refiner, Bi is distributed in a relatively uniform granular state at the grain boundary, so that the alloy has better plasticity and mechanical properties, and at the same time improves the corrosion resistance of the alloy.

[0014] 2. In the present invention, in the melting process, boron is combined with a rare earth refiner for refinement treatment, and a limited heat treatment process is combined to help improve the mechanical properties and the anti-dezincification corrosion performance. DETAILED DESCRIPTION

[0015] The present invention will be further described below in conjunction with specific embodiments.

[0016] Example 1

[0017] The forming process of lead-free free-cutting bismuth brass includes the following steps:

[0018] First, when the furnace temperature rises to 950°C, copper raw materials are added to the furnace for melting, and then the temperature is raised to 1035°C, other raw materials are added to the furnace in sequence according to a predetermined ratio for melting, and then deoxidation treatment is performed, and after deoxidation treatment, refinement treatment is performed, and boron and rare earth RE are used as refiners for refinement treatment. By mass, the amount of boron refiner is 0.01% of the melt, and the amount of rare earth refiner is 0.05% of the melt, with lanthanum and cerium composed of 1:2 by mass;

[0019] The raw materials include, by mass, 33% Zn, 1.3% Bi, 0.035% Sb, 0.1% Al, 0.03% Fe, 0.06% Sn, and the balance Cu.

[0020] Second, the refined molten metal is semi-continuously casted, the ingot is cut, and the cut ingot blocks are heat treated at a temperature of 350° C. for 5 hours.

[0021] Example 2

[0022] The forming process of lead-free free-cutting bismuth brass includes the following steps:

[0023] First, when the furnace temperature rises to 950°C, copper raw materials are added to the furnace for melting, and then the temperature is raised to 1040°C, other raw materials are added to the furnace in sequence according to a predetermined ratio for melting, and then deoxidation treatment is performed, and after deoxidation treatment, refinement treatment is performed, and boron and rare earth RE are used as refiners for refinement treatment. By mass, the amount of boron refiner is 0.02% of the melt, and the amount of rare earth refiner is 0.06% of the melt, with lanthanum and cerium composed of 1:2 by mass;

[0024] The raw materials include, by mass, 35% Zn, 1.4% Bi, 0.04% Sb, 0.2% Al, 0.035% Fe, 0.078% Sn, and the balance Cu.

[0025] Second, the refined molten metal is semi-continuously casted, the ingot is cut, and the cut ingot blocks are heat treated at a temperature of 410° C. for 3.5 hours.

[0026] Example 3

[0027] The forming process of lead-free free-cutting bismuth brass includes the following steps:

[0028] First, when the furnace temperature rises to 950°C, copper raw materials are added into the furnace for melting, and then the temperature is raised to 1030°C, other raw materials are added into the furnace in sequence according to a predetermined ratio for melting, and then deoxidation treatment is performed, and refinement treatment is performed after deoxidation treatment, and boron and rare earth RE are used as refiners for refinement treatment. In terms of mass, the amount of boron refiner is 0.03% of the melt, and the amount of rare earth refiner is 0.07% of the melt, and the mass ratio of lanthanum and cerium is 1:2;

[0029] The raw materials include, by mass, 36% Zn, 1.5% Bi, 0.045% Sb, 0.3% Al, 0.04% Fe, 0.09% Sn, and the balance Cu.

[0030] Second, the refined molten metal is semi-continuously casted, the ingot is cut, and the ingot blocks are heat treated at a temperature of 440°C for 3 hours.

[0031] Comparative Example 1

[0032] Compared with Example 3, this example does not contain Sn component.

[0033] Comparative Example 2

[0034] Compared with Example 3, no refining agent is used for refining treatment in this example.

[0035] The performance of the alloy prepared above was tested, wherein the corrosion solution was a 1% CuCl2 solution, as shown in Table 1:

[0036] Table 1

[0037] Corrosion depth μm Cutting size mm Example 1 330 1.2 Example 2 240 0.9 Example 3 310 1.2 Comparative Example 1 420 2.4 Comparative Example 2 560 3.3

[0038] According to the test, the theory of the above performance changes is as follows: Sn element increases the surface energy of grain boundaries, making Bi distributed in the grain boundaries in the form of particles, and the addition of Sn increases the impedance of bismuth brass, and Al reduces the corrosion current, which improves the corrosion resistance. The addition of Al helps the alloy maintain the appropriate strength to meet the application requirements, the addition of refiners helps to refine the a phase, the lath size becomes smaller, and the heat treatment temperature and Sn element make the distribution of Bi particles more uniform, and the cutting performance is improved.

[0039] The above are only preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A forming process for lead-free free-cutting bismuth brass, characterized in that: The following steps are involved: First, melt the predetermined raw materials, which include Zn 32-37%, Bi 1.3-1.5%, Sb 0.035-0.046%, Al 0.1-0.3%, Fe 0.03-0.04%, Sn 0.06-0.09%, and Cu balance by mass; Second, the refined molten metal is cast into an ingot, and the ingot is heat treated at a temperature of 350-450°C.

2. The forming process of lead-free free-cutting bismuth brass according to claim 1, characterized in that: In the melting process, boron refiners and rare earth refiners are used for refinement.

3. The forming process of lead-free free-cutting bismuth brass according to claim 2, characterized in that: The amount of the boron refiner is 0.01-0.03% of the melt, and the rare earth refiner is composed of lanthanum and cerium in a mass ratio of 1:2 and the amount of the rare earth refiner is 0.05-0.07% of the melt.

4. The forming process of lead-free free-cutting bismuth brass according to claim 2, characterized in that: In the melting process, copper raw materials are added into the furnace for melting, and zinc raw materials are added after the temperature is raised to 1030-1040°C. After the zinc is melted, Bi, Sb, Al, Fe, and Sn components are added, and then the molten metal is refined with a boron refiner and a rare earth refiner. The refined molten metal is formed into ingots in a semi-continuous casting direction.

5. The forming process of lead-free free-cutting bismuth brass according to claim 1, characterized in that: In the heat treatment process, the temperature is 410°C and the time is 3-5h.

6. The forming process of lead-free free-cutting bismuth brass according to claim 1, characterized in that: The raw materials include, by mass, 35% Zn, 1.4% Bi, 0.04% Sb, 0.2% Al, 0.035% Fe, 0.078% Sn, and the balance Cu.