JPS6013417B2 - Free-cutting white Cu alloy with excellent hot workability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a white Cu alloy that has excellent weather resistance and machinability, and can be subjected to not only cold working but also hot working in a good Z state. It is.

Conventionally, for manufacturing high-quality male keys for houses and furniture, for example, white is preferred as a color tone and the shape is relatively complex, so Cu-10%Ni-226%Zn-0 was used.
．． Free-cutting nickel silver with a typical composition of 5% Pb and Ni:1
6.5-19.5%, Cu: 61-67%, Pb: 0.
Composition consisting of 8-1.8%, Zn: remainder (more than % by weight,
Free-cutting nickel silver (JIS/PbN) plate materials and solid wood materials having a high percentage (all percentages below mean weight percentages) were used.

It is generally known that in Cu alloys, a Q-phase structure has excellent cold workability, while an 8-phase structure has excellent hot workability; however, the above-mentioned nickel silver has a Q-phase structure at room temperature. death,
Moreover, even when heated to high temperatures, the Q phase is stable and there is almost no formation of 8 phases, resulting in extremely poor hot workability.
b melts, which easily cracks due to tensile stress and causes cracks.Therefore, these nickel silver plates are manufactured exclusively through the repeated processes of inter-line rolling and competitive anchor treatment. Because it is produced by hot rolling, the thermal efficiency and productivity are inevitably poorer than in the case of hot rolling, and the cold rolling conditions are severe because the Pb it contains causes weight segregation. Furthermore, it is extremely difficult to prevent the occurrence of rolling cracks even if very strict condition control is carried out.On the other hand, these nickel silver pine materials cannot be subjected to hot extrusion processing as mentioned above. Industrially, it had to be manufactured by continuous casting, and there were problems in terms of strength.

Therefore, at present, when manufacturing furniture fittings and keys as mentioned above, the color is yellow, but it can withstand harsh cutting and
Fq-containing 4/8-cut cut steel material with a specified mechanical strength is used, and after cutting it into a specified shape, the surface is plated with Ni or Cr to make it white. A method is being taken to do so.

However, in the products obtained as a result, the plating peels off during use and the yellow steel surface appears, which seriously impairs the appearance.In addition, in recent years, from the viewpoint of pollution prevention, It is in the mirror direction to avoid Ni and Cr plating. From the above-mentioned viewpoints, the present inventors have developed an alloy that does not require Ni and Cr plating, has a white color, has excellent tear resistance and machinability, and has further excellent hot workability. In order to obtain a material that has both hardness and cold workability (research results show that Mn: 7 to 12%, Zn: 1
5-30%, Nail: 0.1-2.5%, Nj: 0.2-8.5%, Pb: 0.2-2.5%, B and one of the rare elements or Type 2: 0.00
5 to 0.8%, Cu and unavoidable impurities: The rest: The L alloy itself has a white color, and has excellent film resistance and mountain resistance, and it also has a It has a Q-phase structure, so it has excellent cold workability, and at high temperatures, a large amount of B phase is formed, and the inclusion of B and two rare elements makes the crystal grains finer. Because it is finely distributed within the crystal grains, for example, even if tensile stress is applied during hot rolling, there is no cracking caused by molten Pb, which improves hot workability. We obtained the knowledge that 2 is an excellent product.

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

{a-Mn
The 3Mn component has the effect of improving the strength of the alloy, making it white in color, expanding the 8-phase castle at high temperatures, and promoting the formation of 8 phases during high-temperature heating. If the content is less than 22%, the desired effect cannot be obtained, while if the content exceeds 22%, 8 phases will remain even at room temperature and cold workability will deteriorate. The amount was determined to be 7-12%. [b} Z
n The Zn component has the effect of improving the strength and hot workability4 of the alloy, but if its content is less than 15%, the desired strength and hot workability improvement effects cannot be obtained; If the content exceeds this amount, the elongation at room temperature will decrease and cracks will occur during cold working, so the content was set at 15 to 30%.

(c) In addition to its deoxidizing effect, the NAI component has the effect of improving the melting and castability of the alloy, but if its content is less than 0.1%, the desired effect will not be obtained. On the other hand, if the content exceeds 2.5%, the elongation of the alloy will decrease and the alloy will form arms, so the content was set at 0.1 to 2.5%.

Wind The NiNi component has the effect of significantly improving the weather resistance of the alloy, but if its content is less than 0.2%, the desired excellent weather resistance cannot be secured;
Since hot workability deteriorates if the content exceeds 0.2% to 8.5%.

{e'Pb The Pb component has the effect of significantly improving the machinability of the alloy, but if the content is less than 0.2%, the desired machinability cannot be obtained; If the content exceeds 0.05%, weight segregation will occur during casting, which will cause cracks to occur, especially during hot working.
It was set at 2 to 2.5%.

'f} 8 and rare elements In these components, the crystal grains are made fine as described above, and Pb is distributed finely and granularly within the crystal grains, thereby completely eliminating the occurrence of cracking during hot working. However, if the content is less than 0.005%, the desired effect cannot be obtained, while if the content exceeds 0.8%, not only will the dissolution operation become difficult, Since castability also deteriorates, the content should be reduced to 0.005 to 0.
It was set at 8%.

Further, the Cu alloy of the present invention contains Co, Fe, and Sn.
When one or more of these components are contained in a total amount of 3% or less, the strength of the alloy is significantly improved without any loss in the properties of the alloy itself.

Next, the Cu alloy of the present invention will be explained using examples.

Example Molten metals having the compositions shown in Table 1 were prepared using the usual melting method, cast, and surface-milled to obtain a piece with dimensions of 100 mm width x 15 mm length x 20 mm thickness. Cu alloys 1 to 18 of the present invention and conventional nickel silver 1 and 2 were manufactured by preparing slabs having the following properties.

The resulting Cu alloys 1 to 18 of the present invention and conventional nickel silver 1
, 2 were all white in color and had the tensile strength and elongation shown in Table 1 in the cast state.

Next, the above-mentioned Cu alloys 1 to 18 of the present invention and nickel silver 1
, 2 slabs were hot rolled at a temperature of 750 to 80,000, and the hot workability was evaluated by measuring the maximum working rate at which cracks occur in one pass of rolling. The workability was evaluated by cold rolling two ribs per pass and measuring the total working rate until cracking occurred.

Claims (1)

[Claims] 1 Mn: 7-22%, Zn: 15-30%, Al: 0.1-2.5%, Ni: 0.2-8.5%, Pb: 0.2-2 .5%, one or two of B and rare earth elements: 0.00
A free-cutting white Cu alloy with excellent hot workability, characterized by having a composition consisting of: 5 to 0.8%, Cu and unavoidable impurities: (or more weight %).