JP3467711B2 - Copper based alloy casting method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper-based alloy and a method for casting the same, and more particularly, to a copper-based alloy used for electric / electronic parts such as a lead frame. It relates to a casting method. 2. Description of the Related Art Copper-based alloys have excellent electrical conductivity, heat resistance, corrosion resistance, and cost performance in addition to their high strength, elasticity, and hardness. -Widely used for electronic components. Further, a copper-based alloy in which various properties are improved by further using iron as a first additive element and further adding a trace additive element has been proposed. Conventionally, in order to produce a wrought copper-based alloy,
Ingots with large cross-sectional areas are manufactured by semi-continuous casting or continuous casting, and this is subjected to hot working such as hot pressing, cold pressing, heat treatment, etc. to produce a sheet material (coil) having a desired thickness. Was. [0004] However, defects such as surface cracks occur on the surface of the ingot in the casting stage, and these defects remain as serious defects in the final sheet material (coil), which causes a reduction in yield. [0005] Here, surface cracks are cracks that occur in parallel with the casting direction of the ingot, and are roughly classified into vertical cracks that occur near the center of the surface and corner cracks that occur near the corners according to the location of the cracks. . These cracks vary in length from fine cracks having a total length of about several mm to cracks exceeding 150 mm. [0006] The frequency of occurrence of cracks is greatly affected by the contained components, and in particular, alloys containing iron are easily cracked. The above cracks are caused by the inclusion of iron, so that the thickness of the solidified shell formed in the mold is likely to be uneven, and the segregation of iron is likely to occur at the grain boundaries, resulting from solidification shrinkage and heat shrinkage It is considered that surface cracks occur due to tensile stress. At present, as measures for preventing the above-mentioned cracks, the cooling conditions in the mold, the shape of the mold, the casting speed, the physical properties of the powder, and the cooling of the direct cooling zone immediately below the mold, uniformization, and the like have been taken. However, there are many unclear points in the correlation between the respective conditions, and it has been difficult to obtain a sound ingot without defects such as surface cracks by control and management in the current production line. [0008] The present invention solves the above-mentioned problems of the prior art, and shows no defects such as surface cracks and blowholes of the ingot, A method of casting a copper-based alloy that excels in bending workability and plating reliability as a rolled material, and that can efficiently produce ingots by vertical continuous casting, and that contributes to cost reduction with high quality as a rolled copper-based alloy. Is proposed. The present invention has been made as a result of intensive studies to solve the above-mentioned conventional problems. As a result, by controlling the surface temperature of the ingot in the casting and cooling processes, it is possible to prevent surface cracks. An object of the present invention is to provide a method for casting a copper-based alloy capable of efficiently producing a large ingot of a cross-sectional area of a sound copper-based alloy having no defect. That is, the first invention is characterized in that iron is contained in an amount of 0.01 to 3 wt%.
Or further selected from phosphorus, nickel, cobalt, tin, zinc, magnesium, zirconium, chromium, silicon, titanium, manganese, aluminum, and silver
A copper-based alloy containing 0.01 to 5% by weight of a total of two or more kinds, and a balance substantially consisting of copper; the second invention contains 0.01 to 3% by weight of iron; Or even phosphorus, nickel, cobalt, tin, zinc,
Magnesium, zirconium, chromium, silicon, titanium,
Continuously casting, via a mold, a molten metal of a copper-based alloy containing 0.01 to 5% by weight in total of one or more selected from manganese, aluminum, and silver, with the balance being substantially copper・ When cooling, set the surface temperature of the ingot immediately below the mold to 7
80-920 ° C., the ingot immediately below the cooling zone for continuously cooling the ingot discharged from the mold is heated to a surface temperature of 700-75.
An object of the present invention is to provide a method for casting a copper-based alloy, which is controlled at 0 ° C. Hereinafter, the method for casting a copper-based alloy according to the present invention will be described in detail. First, the composition range of the copper-based alloy in the method of the present invention will be described. (1) Regarding iron: Iron is an essential element for forming a simple substance of iron or an iron-phosphorus compound in a copper matrix to strengthen precipitation strengthening and dispersion strengthening. Iron content is% by weight
If less than 0.01, the above effect is not sufficient, while 3%
If the temperature exceeds the above range, coarse precipitates precipitate in the solidification process and remain after the subsequent heat treatment, so that bending workability and plating reliability are adversely affected. Therefore, the iron content is in the range of 0.01 to 3% by weight. (2) Phosphorus, nickel, cobalt, tin, zinc, magnesium, zirconium, chromium, silicon, titanium, manganese, aluminum, and silver: these elements form solid compounds or precipitates in a copper matrix to form compounds This has the effect of improving strength and elasticity, and has the effect of preventing crystal grain coarsening. In particular, phosphorus acts as a deoxidizing agent for molten metal, and forms a compound with iron to be dispersed and precipitated, thereby improving thermal (electric) conductivity, and further improving strength and elasticity. However, if the content of phosphorus is less than 0.01% by weight, the deoxidizing effect in the molten metal is insufficient, while if it exceeds 0.3%, thermal (electric) conductivity is reduced even in the presence of iron, and It also has an adverse effect on hot workability. Therefore, the content of phosphorus is 0.1.
The range of 01 to 0.3% by weight is preferred. Further, nickel, cobalt, magnesium and the like form a compound with phosphorus, and have strength, elasticity and heat (electricity) conductivity, titanium, zirconium, silicon and chromium have heat resistance, and zinc and manganese have solder heat resistance. Improve the releasability. The total amount of these additional elements is 0.01% by weight.
If it is less than 5% by weight, on the other hand, if it exceeds 5% by weight, the thermal (electrical) conductivity and workability are significantly reduced.
To 5% by weight. Next, the surface temperature of the ingot immediately below the mold is:
If the temperature is lower than 780 ° C., the cooling in the mold is too strong, and rapid solidification shrinkage causes cracking. Further, gas is more easily trapped, which causes blowholes. On the other hand, 920
If the temperature exceeds ℃, the solidified layer is not thick enough to withstand the tensile stress generated by solidification shrinkage or heat shrinkage in the mold, and surface cracks occur. Therefore, the surface temperature of the ingot immediately below the mold was set in the range of 780 to 920 ° C. The surface temperature of the ingot immediately below a cooling zone (hereinafter, simply referred to as a direct cooling zone) for continuously and directly cooling the ingot discharged from the mold is in the range of 700 to 750 ° C.
This is because if the temperature is less than 700 ° C., the cooling capacity per unit time in the direct cooling zone is too large, and surface cracks occur due to stress caused by solidification shrinkage and heat shrinkage accompanying solidification of the unsolidified portion,
On the other hand, when the temperature exceeds 750 ° C., unsolidified remains in a region directly below the cooling zone, and as a result, cracks occur on the surface of the ingot due to the static pressure of the molten metal. Further, the precipitates are further coarsened and agglomerated, and remain even after the subsequent heat treatment, which adversely affects bending workability. As described above, by defining the surface temperature of the ingot immediately below the mold and directly below the cooling zone, a sound ingot without surface cracks can be obtained. Next, an embodiment of the present invention will be described with reference to the drawings. EXAMPLES Example 1 Iron: 0.20%, Nickel: 0.15%, Tin:
0.07%, phosphorus: 0.06%, the balance being copper and a copper-based alloy consisting of unavoidable impurities dissolved in a reducing atmosphere,
Under a condition shown below, the resultant was cast into a copper mold having a cross section of 186 mm × 484 mm, and continuously cast. FIG. 1 is an explanatory view showing an embodiment of a casting method according to the present invention. First, a molten copper-base alloy melted in a melting furnace (high-frequency induction furnace) is introduced into a turn dish, and a hot water supply nozzle is provided. 1 and is introduced into a copper mold 2 and is indirectly cooled in the mold 2 by a cooling structure 3 provided in contact with the outer wall of the mold 2. The temperature of the molten metal is changed by controlling the melting furnace, and the cooling ability of the molten metal in the mold 2 is determined by the contact position and contact area of the cooling structure 3 on the outer wall of the mold 2 and the inside of the cooling structure 3. It can be changed by controlling the amount of flowing water and the water temperature. Next, the molten metal in the mold 2 is cooled by the cooling structure 3 via the mold 2 to form a solidified interface 9 between the solidified slab and the molten metal. The ingot (ingot) 8 in the mold 2 is drawn out of the mold 2 by the hydraulic syringe 5, and the drawn ingot 8 is directly cooled by the cooling water 7 jetted from the spray nozzle 6. The casting speed can be changed as appropriate by controlling the oil amount of the hydraulic cylinder 5, and the water amount in the direct cooling zone is
Can be changed by changing the number of nozzles or the nozzle diameter. In this embodiment, the ingot surface temperatures were measured at a point a of the ingot surface temperature immediately below the copper mold 2 and at a point b of the ingot surface temperature immediately below the cooling zone using a radiation thermometer. . Further, with respect to the obtained ingot, the surface of the ingot was visually observed, and those having no defects due to surface cracks were evaluated as ○, and those having defects were evaluated as x. The blowhole in the ingot was cut in the width direction at a position of 100 mm in the length direction from the bottom and the sprue of the ingot, respectively. Those with defects were evaluated as x marks. The bending workability was determined by repeating cold rolling and heat treatment of the ingot to obtain a wrought material having a thickness of 0.25 mm.
0 ° W bending test (JIS H 3110, R = 0.2
(The rolling direction and the direction perpendicular to the rolling direction), and those having a good mountain surface at the center were evaluated as ○, and those having wrinkles and cracks were evaluated as x. Table 1 shows the above results. [Table 1] As can be seen from the results shown in Table 1, the ingot obtained by the casting method according to the present invention has no surface cracks and no defects of blow holes, and the wrought material has excellent bending workability. It is a lump. On the other hand, in Comparative Example No. 2 in which the surface temperature at the fixed point a on the ingot surface temperature side immediately below the mold 2 was high. In Comparative Example No. 2 where a surface crack was observed and the ingot surface temperature at the measurement point a was low. In Comparative Example No. 3 where blowholes were found at the surface cracks but the ingot surface temperature at the measurement points a and b was high. It can be seen that No. 4 had cracks and had poor bending workability. Example 2 Iron: 1.00%, nickel: 0.15%, tin:
A copper-based alloy containing 1.00% and phosphorus: 0.06%, with the balance being copper and unavoidable impurities, is melted in a reducing atmosphere to form a copper mold having a section of 186 mm x 484 mm under the following conditions. It was cast and continuously cast in the same manner as in Example 1 above. Further, the obtained ingot was evaluated in the same manner as in Example 1. Table 2 shows the above results. [Table 2] As can be seen from the results shown in Table 2, the ingot obtained by the casting method according to the present invention has no surface cracks and no defects of blowholes, and the wrought material is an ingot excellent in bending workability. It is. On the other hand, in Comparative Example No. 2 in which the ingot surface temperature was high at the ingot surface measurement point a immediately below the mold 2. Comparative Example No. 2 had a surface crack and had a high ingot surface temperature at measurement points a and b. 3 has cracks and poor bending workability. In Comparative Example No., the surface temperature at the measurement point a was low and the ingot surface temperature at the side fixed point b was high. It can be seen that No. 4 has surface cracks and blowholes and has poor bending workability. As described above, according to the method for casting a copper-based alloy according to the present invention, no defects such as surface cracks and blowholes are observed in the obtained ingot. The wrought material has excellent bending workability and plating reliability. Further, according to the present invention, an ingot can be efficiently produced by continuous casting, and it is extremely large that it contributes to improving the quality of wrought copper-based alloy and reducing the cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing one embodiment of a casting method according to the present invention. [Description of Signs] 1-Hot water supply nozzle 2-Copper mold 3-Cooling structure 4-Shilling head 5-Hydraulic cylinder 6-Spray nozzle 7-Cooling water 8-Ingot 9-Solidification interface a-Immediately below the mold Ingot surface temperature measurement point b-ingot surface temperature measurement point immediately below the direct cooling zone

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Akira Sugawara 1-8-2 Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd. (56) References JP-A-4-231445 (JP, A) JP-A-6 JP-A-145847 (JP, A) JP-A-1-139736 (JP, A) JP-A-1-212732 (JP, A) JP-A-2-221344 (JP, A) JP-A-3-75325 (JP, A) JP-A-61-257443 (JP, A) JP-A-62-93325 (JP, A) JP-A-62-9630 (JP, A) JP-A-62-99429 (JP, A) JP-A-62-99429 164843 (JP, A) JP-A-62-185842 (JP, A) JP-A-62-267456 (JP, A) JP-A-63-266053 (JP, A) JP-A-63-266605 (JP, A) JP-A-57-62845 (JP, A) JP-A-6-262323 (JP, A) JP-A-54-117323 (JP, A) Open flat 3-193253 (JP, A) JP flat 6-246411 (JP, A) (58 ) investigated the field (Int.Cl. ^7, DB name) B22D 11/00 B22D 11/22 C22C 9/00 H01L 23/50

Claims (1)

(57) [Claims 1] Iron 0.01 to 3% by weight, Phosphorus 0.01 to
Containing 0.3% by weight, forming an iron-phosphorus compound and uniformly dispersing and depositing the same; and among nickel, cobalt, tin, zinc, magnesium, zirconium, chromium, silicon, titanium, manganese, aluminum and silver When continuously casting and cooling a molten metal of a copper base alloy containing at least one or more selected metals in a total amount of 0.01 to 5% by weight, with the balance being substantially copper, through the mold, the surface of the ingot immediately below the mold The temperature is 780 ° C to 920 ° C, and the surface temperature of the ingot immediately below the cooling zone for continuously cooling the ingot discharged from the mold is 700 ° C to
A method for casting a copper-based alloy, wherein the temperature is controlled to 750 ° C.