JPS5952222B2 - Super free-cutting white copper alloy - Google Patents

Description

[Detailed Description of the Invention] This invention provides a method for severe cutting such as broach cutting.
This invention relates to a copper alloy that exhibits extremely good machinability, has high strength and excellent weather resistance, and has a preferred white color.

Conventionally, Pb has been used to manufacture parts such as the cylinder parts of cylinder locks for buildings and houses, as well as furniture and automobiles.
4/6 free-cutting brass containing 1.5-2% (wt%, hereinafter all % means wt%) is used.

This is because the above-mentioned member has a complicated shape.
Broach cutting, which is a severe cutting process, is necessary, and therefore, the only material that can withstand this severe cutting and has the specified mechanical strength is the 4/4 above.
This is because only 6 free-cutting brass is known.

On the other hand, the above-mentioned free-cutting brass has poor weather resistance and is extremely susceptible to discoloration.For this reason, and because white is preferred as a color tone, Ni plating is applied.

However, in this case, if the alloy layer formed between the Ni plating layer and the brass body is thick, the wear of the cutting tool during broaching becomes significant, shortening the life of the cutting tool, and causing premature wear of the cutting tool. This causes problems such as poor cutting quality, cracks on the cut end, and the occurrence of defective products due to peeling and peeling of the Ni plating layer. There was also a problem in that the peeled off exposed the bare surface of the brass body, and this exposed surface changed color, significantly impairing the appearance.

Moreover, in recent years there has been a tendency to avoid Ni plating from the standpoint of pollution prevention.

Therefore, from the above-mentioned viewpoint, the present inventors conducted research to solve various problems caused by the formation of a Ni plating layer, and as a result, they found that Mn: ~22%, Zn: 10~22%.
28%, A1: 0.1-3%, Ni: '0.2-10
%, Pb: 2-5.5%, Ca, Se, and Te
One or more of the following: 0.001-0.8%
A copper alloy containing 0.2 to 3% of one or two of Fe and CO as necessary, with the remainder consisting of Cu and unavoidable impurities, is one alloy itself. They found that it exhibits a preferred white color, exhibits good machinability even in severe cutting such as broaching, and has high strength and excellent weather resistance.

This invention was made based on the above knowledge, and the reason why the component composition range was limited as described above will be explained.

(a) Mn The Mn component has the effect of improving the strength of the alloy and making it white in color; however, if its content is less than 7%, the alloy becomes reddish, while if it exceeds 22%. If it is contained, a large amount of slag will be generated during melting, increasing the viscosity of the molten metal, and not only will melting become virtually impossible,
Since machinability also deteriorates significantly, its content was set at 7 to 22%.

(b) Zn If the Zn content is less than 10%, the alloy will take on a reddish tinge and the desired white tone cannot be secured, so it is necessary to contain 10% or more, but it is allowed to contain more than 28%. and,
Since toughness decreases and casting defects are likely to occur, the content is set at 10 to 28%.

(c) Ni The Ni component has the effect of improving the weather resistance of the alloy, but if its content is less than 0.2%, the desired effect of improving weather resistance cannot be obtained, while if it exceeds 10%, If it is included, the melting point of the alloy will rise and casting defects such as pores will be more likely to occur, so the content was set at 0.2 to 10%.

(d) AI For the Al component, the molten alloy is cleaned by deoxidizing action,
It also has the effect of improving the fluidity of the molten metal, but if its content is less than 0.1%, the desired deoxidizing effect and fluidity improving effect cannot be expected; on the other hand, if it is contained in excess of 3%. Since this causes a significant decrease in toughness and causes casting cracks, the content was set at 0.1 to 3%.

(e) 'pb The Pb component has the effect of significantly improving machinability and allowing severe cutting such as broach cutting to be performed well.
If the content is less than 2%, the desired effect cannot be obtained. On the other hand, if the content exceeds 5.5%, weight segregation will occur. %.

(f) Ca, Se, and 10 Normally, when the Pb content exceeds 2%, Pb causes weight segregation and it is impossible to obtain a sound ingot. The content of Pb contained was less than 2%.

However, in the alloy of the present invention, if the Pb content is less than 2%, the desired good machinability cannot be obtained as described above.

Therefore, in the alloy of this invention, Ca, Se, and Te are contained to make the crystal grains finer and p
The dispersion form of b was changed to intra-grain distribution so that it was finely dispersed so that weight segregation would not occur even when a large amount of 2 to 5.5% Pb was contained, and the machinability was further improved. It is something.

However, if the content is less than 0.001%, the desired effect described above cannot be obtained, and Pb in particular will cause weight segregation, while if the content exceeds 0.8%, dissolution will be impaired. Since it becomes difficult, the content should be set at 0.001 to 0.
It was set at 8%.

(g) Fe and C.

These components have the effect of refining crystal grains and improving the strength of the alloy, so they are included as necessary when these properties are particularly required, but if the content is 0.2 If it is less than %, the desired effect cannot be obtained in the above action,
On the other hand, if the content exceeds 3%, the toughness decreases and plastic processing becomes difficult, so the content should be reduced to 0.2 to 3%.
It was determined that

Next, the copper alloy of the present invention will be explained by examples and in comparison with comparative examples.

Example Molten metals having the compositions shown in Table 1 were prepared by a conventional melting method, and molten metals with a width of 150 mm and a length of 17 mm were prepared.
Cast into an ingot with dimensions of 0 mm x thickness 25 mm, and this ingot is 25 mm wide x 170 mm long.
Cut and divide into 5 square bars with dimensions of 25 mm in diameter and 15 mm diameter x 170 mm in length from these square bars
By cutting out the round bar of the present invention alloy test piece 1~
No. 22 and Comparative Alloy Test Specimens 1 to 9 were manufactured, respectively.

. Next, the resulting invention alloy test pieces 1 to 2
2 and comparative alloy test pieces 1 to 9, the mechanical strength was measured, and the surface properties, especially the color tone and the presence or absence of Pb weight segregation, were observed, and the presence or absence of surface discoloration after being left in the air for 1000 hours was examined. gender test, further 3mm in diameter
A machinability test was conducted to measure the wear amount of the broach blade after forming 210 small holes of φ×7 mm in depth.

These results are also shown in Table 1.

As shown in Table 1, the content of any one of the constituent components is outside the scope of this invention (see Table 1).
Comparative alloy test specimens 1 to 9 having the composition (marked) were inferior in at least one of the following properties: mechanical strength, color tone, PB weight distribution, weather resistance, and buwachi machinability. In contrast, all of the alloy test pieces 1 to 22 of the present invention had a clean white surface with no PB weight segregation or discoloration, and had good machinability even in edge cutting. It is clear that there is little wear and that it has high strength.

As mentioned above, the copper alloy of the present invention exhibits extremely good machinability against severe cutting such as broach cutting, has high strength and excellent weather resistance, and has a preferred white color. Because of its color tone, it has industrially useful properties, such as being suitable for manufacturing parts such as cylinder lock keys and building fittings that require complicated cutting.

Claims (1)

[Claims] 1 Mn near to 22%, Zn: 10 to 28%, Al: 0
, 1~3%, Ni: 0.2~10%, Pb: 2~
5.5%, Ca. One or more of Se and Te: 0, 0
An ultra-free-machining white copper alloy characterized by having a composition (the above weight %) containing 01 to 0.8% of Cu, and the remainder consisting of Cu and unavoidable impurities. 2 Mn near-22%, Zn: 10-28%, Al: 0
, 1-3%, Ni: 0.2-10%, Pb: 2-5.
5%, Ca. One or more of Se and Te: 0, 0
01 to 0.8%, further contains one or two of Fe and CO: 0.2 to 3%, and the remainder is Cu.
An ultra-free-machining white copper alloy characterized by having a composition (more than % by weight) consisting of unavoidable impurities.