JPH02170954A - Production of copper alloy having good bendability - Google Patents

Abstract

PURPOSE:To produce low-zinc-content brass having good bendability by controlling the working rate of cold rolling in a copper alloy having specific compsn. and its grains at the time of annealing. CONSTITUTION:A copper alloy material contg., by weight, 1.5 to <25% Zn and the balance Cu with inevitable impurities is cold-rolled at >=35% working rate. After that, the material is annealed so that the average grains are regulated to 10 to 35mum as well as the ratio of the maximum grains to the minimum grains is regulated to <=2. The material is furthermore cold-rolled at >=35% working rate and is thereafter annealed so that the average are regulated to 2 to <10mum. After that, the material is cold-rolled and is thereafter suitably subjected to strain relieving annealing. As the result, low-brass having excellent bendability is produced, which is suitable for the production of the alloy having high strength and excellent bendability and corresponding to the need for the miniaturization of electrical and electronic parts.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a manufacturing method for modifying the bending workability of red copper.

[Prior Art] Red copper is a copper alloy with a beautiful luster and excellent malleability, drawability, and corrosion resistance, and has traditionally been used for construction, jewelry, cosmetic cases, and the like. Furthermore, after final rolling, strain relief annealing is performed to improve spring strength, and this alloy is used as a spring copper alloy for connectors and terminals. on the other hand,
In recent years, the demand for miniaturization of electrical and electronic components has become stronger, and in order to meet this demand, bending processes that are more severe than before have become necessary. At the same time, high 1B reliability is also required for parts, and to meet this requirement, it is necessary to
There is a need for a material that has good bending properties and is difficult to break at L.

[Problem to be solved by the invention] In order to improve bending workability to meet these demands using conventional red copper, it is necessary to reduce the strength and increase elongation.
The only option was to make design changes such as increasing the bending radius. However, if the strength of the material is reduced, the strength of the part will also be reduced, so it will not be possible to make the material thinner or the part smaller, and the quality of the product will be lowered. Furthermore, the method of increasing the bending radius imposes constraints on component design, making it impossible to miniaturize the product.

For this reason, there is currently a strong need for a method to improve bending workability while maintaining the excellent properties of conventional red copper.

[Means for Solving the Problems] The present invention was made in view of the above points, and therefore provides a method for producing a material that improves the bending workability of conventional red copper and is suitable mainly as a material for electrical and electronic parts. This is what I am trying to do.

That is, the present invention provides Znl, 5% by weight or more and less than 25% by weight - 5, or further as a subcomponent PsSnsSi
SN is M g % T t SCr SZ r
s A A copper alloy material containing 0.001 to 5 vL% of 18 or two or more of 11Fe, Pb, Mn, and Co, with the balance being Cu and unavoidable impurities, is cold rolled at a working degree of 35% or more. After the process, the average grain size is 10-35 μm.
Moreover, the maximum crystal grain (Xmax) and the minimum crystal grain (X-r
. ) is annealed so that the ratio (Xmax / This is a method for producing a copper alloy with good bending workability, which is characterized by cold rolling and then appropriately strain relief annealing.

It is well known that red copper, which is composed of Cu-Zn components, is a copper alloy with excellent malleability, drawability, and corrosion resistance. In the present invention, the reason why the Zn content is 1.5% by weight or more and less than 25% by weight is to improve the strength.
If it is less than 1.512%, the strength required for red copper cannot be obtained, and if it is more than 25% by weight, the workability and stress corrosion cracking resistance required for red copper deteriorate. Further, in the second invention, PlS n SS as a subcomponent
+ −, M g SN i% T t s Cr %
Z r sAl, Fe, Pb, Mn5Co 0.001
The reason for adding ~5% by weight is to improve the strength and further refine the crystal grains to improve bending workability, but if the melon is less than 0.0011 fik%, there is no effect, and 5% by weight is added. If this value is exceeded, workability and soldering properties will deteriorate.

There are 35 reasons why the degree of workability in cold rolling is set to 3506 or more, and this is because when the grains become mixed, the bending workability deteriorates.

The average grain size in the first annealing is 10 to 35μ.
m, and the largest crystal grain (X□1) and the smallest crystal grain (X, +
The reason why annealing is performed so that the ratio (X□, /X, .) of This is because the roughness of the steel becomes coarse, the strength decreases, and mixed grains are generated in the next annealing, resulting in poor quality. The reason why X□K/X a l n is set to 2 or less is that if it exceeds 2, a mixed grain structure will result, and the bendability will be significantly deteriorated. In addition, it is possible to make it 2 or less by examining the annealing temperature and the working degree of cold rolling before annealing.

The reason why the average crystal grain in the final annealing is set to 2 .mu.m or more and less than 10 .mu.l is that if it is less than 2 .mu.m, mixed grains tend to form, and end recrystallized portions remain, which significantly deteriorates the bendability. The reason why it is set to be less than 10 μl is that even if it is 10 μl or more, the bending workability deteriorates and the surface becomes rough and crystallized.

After final annealing, cold rolling is performed to obtain the required strength, and appropriate annealing is performed to improve bending workability and spring properties.

[Example 1 Ingot (30 mn + X G
.

■X 9 ; 2 kg) was melted and cast in the air, skinned and hot rolled to a thickness of 8 μm. This material was skinned and cold-rolled, then annealed and rolled repeatedly, and finally strain-relief annealed to obtain a plate with a thickness of 0.3 mm. The tensile strength, elongation, hardness, and bendability of these materials were investigated.

Tensile strength and elongation were measured by taking a JI No. 85 tensile test piece in a direction parallel to the rolling direction and performing a tensile test.

The hardness was measured by Vickers hardness from the material surface.

Bendability is according to CES MOOO2, inner bending radius 0
．． A 3 mm (-plate thickness) W bending test was conducted, and the appearance was evaluated by observing the appearance. Rating: A; Very good; B;
Good, C: Slightly rough skin, D: Severely rough skin, E: Cracking occurred, F
; The crack is penetrating, and the bending direction is the bending axis perpendicular to the rolling direction (Good Way), parallel direction (1 eadνa
It was investigated in two directions: y).

Table 1 shows the average grain size after annealing (two-time annealing) before strain relief annealing at a thickness of 0.3cm, and the average grain size after the previous cold rolling (
The ratio of the average crystal grain to the maximum crystal grain (X□1) to the minimum crystal grain (X, 1.) after the previous annealing (first-pass annealing) ,,,/X-1゜),
Then, the working degree of the previous cold rolling (first cold rolling) was described. The example in Table 1 is an example in which cold rolling was performed at a workability of 40% after annealing twice, and then strain relief annealing was performed.

In Table 1, No, 1, No, 2 are red copper type 2, red copper 3Fr
! It can be seen that the manufacturing method of the present invention has good bendability. In addition, No. 3 to No. 9 are red copper 2FI and red copper 3 types with additional elements added,
It can be seen that the strength is improved compared to red copper type 2 and red copper 38, and the bendability is also good. No, 10 ~ No, 15
is a comparative example.

For No. IO, the degree of hardening in the first cold rolling is low, and therefore (X, , , /X, 1.) is large, resulting in a mixed grain structure, and the bendability is not very good. No. 11 is an example in which the crystal grains were large and mixed grains during the first annealing.
Even if the average crystal grain is 4 μm during the second baking process, the bendability is not good because of the mixed grain structure. No. 12 has a low workability in the second cold rolling, and even if the average grain size in the second round annealing is 4 μl, it becomes a mixed grain structure and has poor bendability.

No. 13 has coarse grains during second annealing, so
The surface becomes rough when bent, and the bendability is not very good. N
o, I4 is an example in which cold rolling was performed without performing IEI annealing twice, but the average crystal grain at the first mouth annealing was 20μ
It is l. In other words, final place 1i! (In other examples, the crystal grains are as large as 20 μm during two-time annealing), and after the final annealing, the crystal grains are as large as 20 μm.
This is an example of cold rolling with a working degree of 696, and because the working degree is high, the strength is considerably high, but the bendability is very poor. N
No. 15 is an example in which the crystal grains are made fine after the first annealing, but since the crystal grains are fine and not uniform, even if the grains are made fine to 4μ in the second annealing, mixed grains will not be produced. Since it is a tissue, its bendability is poor.

These examples show that the manufacturing method of the present invention improves bendability, especially B
It can be seen that the bendability in the ad way direction (the bending axis is in the rolling direction in the grain direction) is quite good.

That is, by the method of the present invention, red copper with improved bending workability can be produced, and an alloy with high strength and excellent bending workability can be produced that can sufficiently meet the needs for miniaturization of electrical and electronic parts. This is the best method.

[Effects of the Invention] By the manufacturing method of the present invention, that is, by controlling the workability of cold rolling and the crystal grains during annealing, red copper having good bending workability can be manufactured. That is,
The alloy composition and manufacturing process of the present invention make it possible to manufacture red copper with good bendability.
The manufacturing process before the first cold rolling is not particularly specified.

Since the red bronze manufactured by the manufacturing method of the present invention has better bending workability than conventional brass, bending of spring parts and the like can be made more severe and the parts can be made smaller.

Claims (1)

[Claims] (1) 35% copper alloy material containing 1.5% by weight or more and less than 25% by weight of Zn, and the balance consisting of Cu and unavoidable impurities.
After cold rolling with a working degree of above, the average grain size is 10
~35 μm and the ratio of the largest crystal grain (X_m_a_x) to the smallest crystal grain (X_m_i_n) (X_m_a_x/X
_m_i_n) is 2 or less, then cold rolling is performed with a workability of 35% or more, annealing is performed so that the average grain size is 2 μm or more and less than 10 μm, and then cold rolling is performed so that the average grain size is 2 μm or more and less than 10 μm. A method for producing a copper alloy with good bending workability, which comprises rolling and then appropriately strain-relieving annealing. (2) Contains 1.5% by weight or more and less than 25% by weight of Zn, and further contains P, Sn, Si, Ni, Mg, Ti,
1 from Cr, Zr, Al, Fe, Pb, Mn, Co
After cold rolling a copper alloy material containing 0.001 to 5 wt% of one or more species and the remainder Cu and unavoidable impurities at a workability of 35% or more, the material has an average crystal grain size of 10 to 35 μm. The largest crystal grain (X_m_a_x) and the smallest crystal grain (X_m_i_
Annealing is performed so that the ratio (X_m_a_x/X_m_i_n) of n) is 2 or less, and then cold rolling is performed at a workability of 35% or more, and the average grain size is 2 μm or more.10
After annealing to less than μm, cold rolling is performed,
A method for producing a copper alloy with good bending workability, the method comprising appropriately performing strain relief annealing thereafter.