JPS61113735A - Manufacture of copper or copper alloy casting - Google Patents

Abstract

PURPOSE:To manufacture a copper or copper alloy casting which is free from a surface defect, without causing a sudden rise of a cost of a raw material by executing the casting by using a copper or copper alloy molten metal in which Ca is a low content percentage. CONSTITUTION:A copper or copper alloy casting which is free from a surface defect is obtained economically by casting a copper or copper alloy molten metal of 0.0002-0.015wt% Ca content percentage, which has been obtained by forming a molten raw material by mainly electrolytic copper and adjusting a compounding quantity of a scrap, or bringing Ca to a removing treatment by using a filtrating method, etc. by a filter at the state of melting. The reason why said Ca content percentage has been limited is because it is necessary to use the electrolytic copper only in order to set it to <0.0002%, a sudden rise of a cost is caused, and if it exceeds 0.015%, the generation rate of the surface defect increases.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] □ The present invention relates to a method for producing copper or copper alloy castings free of surface defects.

[Conventional technology]

Copper is one of the most important nonferrous metal materials, and has higher electrical and thermal conductivity than other metal materials.
Excellent corrosion resistance. Due to its characteristics such as high plastic workability, it is widely used as wire rods, bars, plates, pipe materials, and various diameter casting materials. In addition, in order to enjoy these characteristics of copper while also exhibiting other required characteristics, copper alloys containing appropriate amounts of alloying elements such as zinc, tin, and aluminum are extremely useful.

By the way, copper is mainly produced from electrolytic copper ingots, but since there are limits to the reserves of copper-containing minerals, scraps such as waste wires, mainly waste wires, and high quality layers with low impurity content are also used as raw materials. Therefore, the amount of scrap added to electrolytic steel is adjusted according to the required properties.

[Problem that the invention seeks to solve]

As is well known, the purity of electrolytic steel is extremely high, so there is almost no effect of impurities, and the same is true for various copper alloys using electrolytic copper. However, since copper scrap contains various impurities, various defects caused by impurities appear in copper products and copper alloy products made with copper scrap in the melting stage.

The present invention seeks to provide a technique capable of eliminating such defects, particularly surface defects appearing in copper or copper alloy cast products and subsequently processed products.

[Means for solving problems]

The gist of the method for manufacturing copper or copper alloy castings according to the present invention is to use molten copper or copper alloy with a calcium content of 0.0002 to 0.015% by weight, and to eliminate surface defects caused by calcium. It has the following.

[Effect]

As mentioned above, copper or copper alloy casting products obtained by blending copper scrap in the melting stage and their processed products (rolled products, drawn products, extruded products, forged products, etc.) have more or less surface defects. Occur. Therefore, in order to establish measures to prevent such surface defects, we first conducted a component analysis of the defective parts. As a result, it was found that calcium or calcium-containing compounds were present in all defective areas, and that this was a major cause of defect occurrence. Also steel and copper alloy casting 1
When we investigated the existence form of calcium in cast products, we found that calcium was distributed almost uniformly throughout the cast product, and that when calcium was exposed on the surface of the cast product or the subsequent processed product, surface defects occurred. I knew that it would appear. Therefore, in order to prevent surface defects, it is necessary to suppress the amount of calcium at the melting stage to the lowest possible level, but for economic reasons it is not possible to not use scrap as well, and as a result, a certain amount of calcium must be contained. Contamination cannot be avoided. Therefore, we conducted an experiment to clarify the quantitative correlation between the calcium content in the molten metal and the surface defect occurrence rate. It has been confirmed that if the content is suppressed to .015% by weight or less, surface defects will not substantially occur.

For these reasons, the present invention stipulates that the calcium content in the molten metal must be limited to 0.015% by weight or less. However, in order to obtain copper or copper alloy molten metal with such a low calcium content, it is necessary to either reduce the proportion of scrap in high-purity electrolytic steel, or carry out efficient impurity removal during the melting process. The lower the calcium content by 1, the higher the price of the cast product will be.

In particular, when trying to reduce the calcium content to less than 0.0002% by weight, the raw material for smelting must be essentially electrolytic copper and the scrap content must be zero, or if a small amount of scrap is mixed, a highly Impurity removal treatment must be performed, and from a practical standpoint, versatility is significantly limited from a cost perspective. Moreover, the aim of the present invention is to eliminate surface defects.

From the point of view, surface defects can be sufficiently eliminated by reducing the amount of calcium to 0.0002% by weight, and reducing the amount of calcium further than this would simply increase the economic burden. Just do it. For these reasons, in the present invention, in order to satisfy both the prevention of surface defects and economic efficiency, the calcium content in the molten metal is set to 0.0005 to 0.
．． It was set in the range of 0.015% by weight.

Incidentally, FIG. 1 is a graph showing the relationship between the calcium content in molten copper, the incidence of surface defects (defects on the surface of the ingot and the surface of the extruded material), and the cost of raw materials. However, the relationship between calcium content and raw material cost was calculated based on the current standard prices shown in Table 1 below.

As is clear from Table 1 and Figure 1, when the calcium content in the molten metal exceeds 0.015% by weight, the incidence of surface defects tends to increase rapidly, and when the calcium content in the molten metal is reduced to 0.
．． It can be confirmed that when trying to reduce the weight to less than 0,002 weight, the raw material cost tends to rise sharply.

In addition, the method of obtaining molten metal with such calcium content is as follows.
As mentioned above, the raw material for smelting is mainly electrolytic copper and the amount of scrap is adjusted according to its calcium content, or calcium is removed by applying an appropriate calcium removal treatment (for example, filtration with a filter) at the smelting stage. A method for reducing the amount may be adopted.

〔Example〕

By using electrolytic steel and rotary steel as molten 9I raw materials, we melted a large number of phosphorus-deoxidized copper molten metals (Type 1 B: 10) with different calcium contents by changing the blending ratio of the two, and used each molten metal. Castings with a diameter of 200 mm were manufactured using a semi-continuous casting method, and the incidence of surface defects in each was investigated. Next, each casting was subjected to hot extrusion to a diameter of 10 mm without peeling, and the defect occurrence rate on the surface of the extruded material was investigated.

The results are shown in Table 2. According to general standards, the incidence of surface defects in both ingots and extrusions is
Judging from this standard, it is clear that the calcium content in the molten metal should be suppressed to 0.015% or less.

In addition, among the molten metal obtained above, one having a Ca content of o, oio% was passed through the molten metal, 30 parts by weight of zinc was added to 70 parts by weight of the molten metal, and after uniformly melting and mixing, 20% by semi-continuous casting method was used.
A free-cutting brass rod with a diameter of 0 mm was cast.

Next, do not peel the free-cutting brass rod (10
It was hot extruded to mmφ. The defect occurrence rate on the surface of the obtained hot extruded rod and ingot before hot extrusion was 0.
．． It was less than 0.01%.

(Tested 50 ingots and extrusions each) [Effects of the invention] The present invention is constructed as described above, but the key point is that by setting the calcium content in the molten copper or copper alloy within a specific range. In addition to dramatically reducing the incidence of defects on the surface of ingots without causing an extreme increase in raw material prices, it is also possible to virtually eliminate surface defects in products processed by extrusion, rolling, drawing, forging, etc. The quality of various copper or copper alloy products can be improved.

[Brief explanation of drawings]

FIG. 1 is a graph showing the influence of the Ca content in the phosphorus-deoxidized copper melt on the surface defect incidence of castings and subsequent extrusion products, as well as the influence on raw material cost. Corrected (voluntary) December 12, 1980 1. Indication of the case 1982 Patent Application No. 235718 2. Name of the invention Method for manufacturing copper or copper alloy castings 3. Person making the amendment Relationship: Patent applicant: 3-18 (119) Wakihama-cho, Chuo-ku, Kobe City; Representative: Fuyuhiko Maki, 4; Representative: Shinko Building, 2-3-7 Dojima, Kita-ku, Osaka City, Kobe Steel, Ltd., 530 Column 6 of “Detailed Description of the Invention” of the book, contents of amendment, / 7:
'-7～-'"l;' (1) Replace page 7 of the specification with pages 7-7'. (2) Insert pages 9-9 after page 9 of the specification It is sufficient to adopt a method of adjusting the amount of calcium, or a method of reducing the amount of calcium by applying an appropriate calcium removal treatment (for example, filtration method with a filter, etc.) at the melting stage. Another method for obtaining a molten alloy is to reduce the amount of calcium in the molten raw material. In this case, as will be shown in the examples below, the amount of calcium in the molten raw material should be suppressed to 5% or less. For example, the amount of calcium in the obtained molten metal can be kept within the above-mentioned preferred range. [Example] Using electrolytic copper and rotary copper as raw materials for melting, by changing the blending ratio of the two, a number of different calcium contents were prepared. A phosphorus-deoxidized copper molten metal (Type 1 B: 10 tons) was melted, and 200 mm diameter castings were manufactured using the half-speed #!i casting method using each molten metal, and the incidence of surface defects in each was investigated. Next, each casting was subjected to hot extrusion to IO+w-φ without peeling, and the defect occurrence rate on the surface of the extruded material was investigated.The results are shown in Table 2. According to the standards, the incidence of surface defects in both ingots and extrusions is r.
Judging from this standard, it is clear that the calcium content in the molten metal should be suppressed to 0.015% or less. Among the molten metals obtained above, one with a Cal content of 0.010% was selected, and 70 parts by weight of the molten metal was mixed with 30 parts of zinc and various molten raw materials with different calcium contents, and a large number of phosphates were added to the molten metal in a shaft furnace. Deoxidized copper #m (Type 1 B) was melted, the calcium content in each #molten metal was measured, and 20,000 φlets were manufactured using the '\I!fi continuous casting method using each molten metal. Then, each billet was subjected to hot extrusion up to 20 mm diameter without peeling, and the defect occurrence rate on the surface of the extruded material was investigated.The number of samples was The results are shown in Table 3. When the calcium content in the molten raw material is 5% or less, the calcium spherules that are finally mixed into the phosphorus-deoxidized copper molten metal are is 0.015% or less, and the defect occurrence rate on the extruded material surface is 0.05%.
(The above-mentioned general standard jti) The following is guaranteed. However, at the melting stage where the amount of calcium in the melting raw material exceeds 5%, the amount of calcium retained in phosphorus-deoxidized copper exceeds 0.015%, and the defect occurrence rate on the surface of the extruded material exceeds 0.05%. To do. That is, it can be seen that one means for achieving the object of the present invention is to suppress the calcium content in the molten raw material to 5% or less.

Claims (1)

[Claims] Production of copper or copper alloy castings free of surface defects, characterized in that a molten copper or copper alloy with a calcium content of 0.0002 to 0.015% by weight is used for casting steel or copper alloys. Method.