KR101216019B1 - Heat Treatment Method of Unleaded Brass Alloy - Google Patents

Abstract

The present invention relates to a heat treatment method of a lead-free brass alloy to improve the workability and corrosion resistance of the lead-free brass alloy containing no lead or containing a very small amount.
The present invention is a first step of full annealing lead-free brass alloy raw materials containing no lead content or 100% by weight of 0.005% to 0.2% by weight at 530 ± 30 ℃ temperature for 3 hours, and after the first step A second step of machining, and a third step of soft annealing for 1 hour at a temperature of 330 ± 30 ℃ after this second step.

Description

Heat Treatment Method of Unleaded Brass Alloy

The present invention relates to a heat treatment method of a lead-free brass alloy, and more particularly, a lead-free brass alloy to improve the workability, crack resistance, wear resistance and corrosion resistance of lead-free brass alloy containing no lead or a very small amount of lead It relates to a heat treatment method of.

In general, copper alloys are widely used in automobile parts, electronic parts, piping members (faucet brackets, valves, etc.), and should be excellent in machinability and corrosion resistance (de-zinc prevention) against aging.

As described above, it is known that the addition of lead is effective as a method for improving the machinability and corrosion resistance (preventing zinc) of the copper alloy.

When manufacturing copper alloy containing lead, since it contains lead which adversely affects the human body and the environment, the worker sucks the lead component in the metal vapor generated during melting and casting of the alloy, or mainly uses brass alloy. In the case of the piping member, there is always a risk that the lead component is eluted by the contact with drinking water and absorbed by the human body.

Therefore, when manufacturing a brass alloy (lead-free brass alloy) excluding lead that adversely affects the human body and the environment, the machinability becomes poor, and as a lead-free free-cutting copper alloy containing no lead or cadmium, for example, As disclosed in Japanese Patent Laid-Open No. 2000-119775, a copper alloy having a tensile strength of about 600 to 800 MPa has been proposed, but an additional element silicon (Si) improves the machinability (machinability) of the copper alloy, but Compared with the lead-containing brass alloy, because of the hardness, the cutting resistance is increased and the tool life is shortened.

In addition, in the case of lead-free brass alloy, because the workability is not good in itself, it was a level to manufacture the casting through the casting process. Therefore, there is a problem in that it is difficult to apply to products that need to be processed into various shapes such as pipe fitting products.

Furthermore, bismuth (Bi) or the like is added while varying the composition ratio of the brass alloy so as to replace lead or cadmium which may adversely affect the environment or human body, and to realize excellent mechanical properties by adding elements with improved machinability. However, since such bismuth is expensive and cracks occur due to brittleness during low temperature processing, when manufacturing a product from the brass alloy containing such bismuth, there is a problem in that the cost of the product is increased and the application is restricted.

Accordingly, the present invention has been made to solve the conventional problems as described above, the object of the present invention contains a very small amount of lead in a range that does not contain any harmful to the human body or the environment or does not adversely affect the human body or the environment. In the meantime, the present invention provides a heat treatment method of a lead-free brass alloy which is excellent in machinability, corrosion resistance and abrasion resistance, and improves time-lapse cracking without the addition of components for improving workability.

A solution for achieving the above object is the agent for the full annealing of lead-free brass alloy raw materials containing no lead content or 100% by weight of 0.005% to 0.2% by weight for 3 hours at a temperature of 530 ± 30 ℃ A first step, a second step of machining after this first step, and a third step of soft annealing for 1 hour at a temperature of 330 ± 30 ° C. after the second step are provided.
In another aspect, the present invention provides a first step of forging a lead-free brass alloy raw material in the absence of lead content in the total components or 0.005% to 0.2% by weight of 100% by weight, and after the first step 530 ± 30 Lead-free annealing comprising a second step of full annealing at 3 ° C. for 3 hours, a third step of machining after this second step, and a fourth step of soft annealing at 330 ± 30 ° C. for 1 hour after this third step. A method of heat treating brass alloy is provided.
Further, the raw material is naval brass, and the full annealing or soft annealing is treated in a nitrogen gas atmosphere.

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As such, the present invention can be used as an environmentally friendly material through the heat treatment method of lead-free brass alloy containing no lead or very small amount, and the machinability, abrasion resistance, homogeneity of tissue, crack resistance and corrosion resistance are particularly improved. By preventing the surface cracking and de-zinc corrosion over time, there is an effect that can be used suitably for pipe fittings for drinking water.

1 is a block diagram illustrating a manufacturing method according to a first embodiment of the present invention.
2 is a block diagram illustrating a manufacturing method according to a second embodiment of the present invention.
Figure 3 is a photograph showing the contrast between the structure of the lead-free brass alloy raw material and the case when not annealed.
Figure 4 is a result table showing the results of testing the pipe fitting test specimens when the heat treatment method according to the present invention and when not complete.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Lead-free brass alloy described in the present invention means a level containing no lead or a very small amount of lead.

The material used in the following embodiments of the present invention is naval brass.

[First Embodiment]

1 is a block diagram illustrating a manufacturing method according to a first embodiment of the present invention. As shown in the figure, a first step S1 of full annealing the lead-free brass alloy raw material, a second step S2 of machining after the first step S1, and this second After the step S2, a third step S3 of soft annealing is performed again.

The first step (S1) is subjected to full annealing of the raw material for 3 hours at a temperature of 530 ± 30 ℃. By performing full annealing in this way, the machinability of the raw material can be improved, and boundary cracks due to stress concentration can be removed.

In addition, the machining operation in the second step (S2) is, for example, the operation to the desired pipe fitting product.

In addition, the third step (S3) is subjected to soft annealing for 1 hour at a temperature of 330 ± 30 ℃.

Finally, soft annealing improves crack resistance, wear resistance and corrosion resistance by removing internal stresses of machined raw materials (pipe fitting products).

[Second Embodiment]

As a second embodiment of the present invention, as shown in FIG. 2, a first step P1 of forging a lead-free brass alloy raw material, and a second step of full annealing after the first step P1 (P2), a third step (P3) for machining after the second step, and a fourth step (P4) for soft annealing after the third step (P3).

In other words, the raw material (C46400) is subjected to the forging process first without undergoing a heat treatment process (annealing process), and after the forging process, the first full annealing for the forging product, and then machined for the forging product after the full annealing After the completion of processing, soft annealing is performed secondly to stabilize the structure of the forged product.

In addition, the second step (P2) of the full annealing, as in the first embodiment, by performing a full annealing of the forged product for 3 hours at a temperature of 530 ± 30 ℃ to improve the machinability and the external force during heating and forging of the metal Eliminate stresses and boundary cracks.

In addition, the fourth step (P4) is carried out for 1 hour at a temperature of 330 ± 30 ℃ to remove the stress concentration and residual stress by machining, thereby improving the crack prevention and wear resistance and corrosion resistance.

According to the heat treatment method according to the present invention, as a result of performing a full or soft annealing operation under the above-mentioned temperature and time conditions in a nitrogen gas atmosphere, cracking and de-zinc corrosion which may occur in metal structures after forging or machining, respectively. The phenomenon is prevented.

If the heat treatment is performed in a normal atmospheric atmosphere without heat treatment in a nitrogen gas atmosphere, corrosion may be caused by gas such as oxygen or ammonia, and surface hardening may occur due to the progress of corrosion of the surface of the tissue. The heat treatment in the gas atmosphere can prevent the occurrence of such corrosion.

3 is compared with the workpiece according to the heat treatment method of the present invention and the workpiece without heat treatment.

As shown in FIG. 3, the degree of corrosion of the raw material is much before the full annealing, but the degree of corrosion of the raw material is relatively low after the annealing.

In other words, as the corrosion progresses, the raw material structure is more divided, and the shape is less divided after the annealing than before the annealing, and according to the heat treatment method according to the present invention, the corrosion resistance of the raw material is improved. It can be.

FIG. 4 is a result table of six test pieces of pipe fittings 1,1-1, 2,2-1,3,3-1 for each treatment method, and a test piece 1 having a heat treatment method according to the present invention. -1,2-1,3-1, as shown in the enlarged photo, it can be seen that the cracks and corrosion does not appear over time compared to the specimens 1,2,3.

The test piece 1 and the test piece 1-1, the test piece 2 and 2-1, the test piece 3 and the test piece 3-1 are the same pipe products, respectively, and show the results of the tests with different heat treatment methods.

On the other hand, the heat treatment method according to the present invention contains a lead component of the lead (not 0.005 to 0.2% by weight in 100% by weight of the total composition ratio) of the lead-free brass alloy does not contain any lead, as well as the adverse effect on the human body and the environment. Even lead-free brass alloy (C46400 series) can improve the machinability and corrosion resistance.

While the invention has been described for the embodiments of the invention based on the accompanying drawings for convenience, various modifications and variations are possible within the scope of the technical idea of the present invention, such variations and modifications are claims of the present invention Inclusion within is self-evident.

S1, P1: first stage
S2, P2: second stage
S3, P3: Third Step
P4: Fourth Step

Claims (7)

A first step of full annealing of lead-free brass alloy material having no lead content or 100% by weight of 0.005% to 0.2% by weight at 530 ± 30 ° C. for 3 hours,
After the first step, the second step of machining,
And a third step of soft annealing at a temperature of 330 ± 30 ° C. for one hour after the second step.
A first step of forging a lead-free brass alloy raw material having no lead content in the total ingredients or 0.005% to 0.2% by weight in 100% by weight;
A second step of full annealing at 530 ± 30 ° C. for 3 hours after the first step,
After the second step, the third step of machining,
And a fourth step of soft annealing at a temperature of 330 ± 30 ° C. for one hour after the third step.
The method according to claim 1 or 2,
The raw material is a heat treatment method of lead-free brass alloy, characterized in that the naval brass.
delete delete The method according to claim 1 or 2,
The full annealing or soft annealing is heat treatment method of the lead-free brass alloy, characterized in that in the nitrogen gas atmosphere.
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