JPS61154788A - Soft solder for steel or copper and copper alloy and its production - Google Patents

Abstract

PURPOSE:To provide an improvement in tensile strength, etc. by adding prescribed % of bismuth to a ternary eutectic compsn. consisting of specific weight % of tin, zinc and cadmium. CONSTITUTION:The soft solder is composed by adding 0.05-1.5% bismuth to the ternary eutectic compsn. consisting of 55-59% tin, 17-19% zinc and 24-26% cadmium. The flux soln. mixture composed of 5-20% tin chloride and 80-95% zinc chloride is charged to the melt of the alloy consisting of the above-mentioned compsn. at about 0.2% the weight of the molten alloy and is stirred. The surface of the molten four-components alloy contg. bismuth is coated with the flux mixture melt by the above-mentioned method, by which the soft solder is obtd. The soft solder has the improved tensile strength while maintaining the elongation rate when the bismuth is added thereto. Since the surface of the molten metal is coated with the flux mixture melt in the stage of production. the crystal grains are fined and the loss of the soft solder is decreased.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a flexible steel, copper, or copper alloy material, which is particularly suitable for welding a rail bond made of copper or brass to a rail, and a method for manufacturing the same. It is.

<Prior art> As a conventional technology regarding this type of soft metal, for example, as shown in Japanese Patent Publication No. 31-862, tin 55
~59% by weight, zinc 17-19% by weight, cadmium 24%
~26% by weight ternary eutectic alloy. This alloy has a low melting point (155-160℃) and a tensile strength of 10-10.5
It has characteristics such as kM diameter of 1 and elongation rate of 40 to 46%, and is a suitable soft material for welding rail pounds to rails, so it is widely used in Japan's electric railways. The above publication states that when this alloy is cast, it is coated with a solvent melt containing 95 to 98% by weight of zinc chloride anthene and 2 to 5% by weight of chlorophyll to deoxidize and prevent oxidation. It is disclosed what can be done.

In addition, the above-mentioned 7Lux was unable to float and remove the oxidation products caused by reoxidation inside the molten metal.
In order to improve this point, Japanese Patent Publication No. 4B-6341 discloses that 0.2% by weight of red phosphorus is mixed into the molten metal to deoxidize the inside and outside of the molten metal and prevent oxidation. It is disclosed that a residual content of 0.003 to 0.006% by weight of phosphorus can be used to exhibit a deoxidizing effect during remelting during on-site welding.

<Problems to be solved by the invention> The above-mentioned soft ternary eutectic alloy causes a diffusion phenomenon at the soldering interface, so it is easy to bond rail brass terminals, etc.
Since low-temperature welding is possible at temperatures below 'C, it does not alter the quality of the rail, it does not deteriorate the mild steel strands of the rail bond itself, and it has sufficient strength against shearing caused by passing trains.
The growth rate was also excessive, and there was little risk of the rail bond falling off.

However, in recent years, as trains have become heavier, the number of connected trains has increased, and speeds have increased in addition to overcrowded train schedules, the shock vibrations borne by rail bonds have tended to increase further than before. There is also a demand for higher strength than conventional products. However, the above ternary eutectic alloy, which does not suffer from twisting, has an IR of 10.5 kg/aIR2.
It was extremely difficult to achieve such a high tensile strength.

One of the purposes of this invention was to improve and devise a flexible product so that it can meet the desired demands while maintaining its excellent characteristics, in view of the actual situation of the savior.

In addition, when examined from the viewpoint of a deoxidizing agent, the use of zinc chloride ammonium, red phosphorus, or phosphorus tin has a considerable effect of 1q
However, red phosphorus, which is used as a reaction accelerator with air, increases the surface tension of the molten alloy, and considering the fluidity of the molten alloy, it could only be added in small amounts. Furthermore, in the case of phosphorus tin, which starts to decompose at 480'C, in the case of a molten alloy at 600°C, the oxidation products due to reoxidation cannot be sufficiently floated away, and the loss due to oxidation was as large as about 8%. In the case of zinc ammonium chloride, the melting point of the eutectic salt is 177°C, which is close to that of the soft eutectic salt.
Although it promotes the flow of solder during welding, when used in a high-temperature furnace for the purpose of melting and fusing heavy metals such as tin, zinc, and cadmium, the molten zinc-ammonium chloride boils and generates nitrogen.
When H4Cλ exceeds 60%, the melt directly turns into steam and vapor containing a large amount of ammonium chloride is volatilized, so care must be taken in terms of health and safety. In this way, there was still room for improvement in terms of advantages and disadvantages. Therefore, another object of the present invention is to provide a new and improved method for producing soft foam that also includes a deoxidizing agent.

<Means for Solving the Problems> In general, alloys containing bismuth have a lower melting point, but the conventional wisdom is that they become brittle and have reduced tensile strength. But tin, zinc.

When we added bismuth in various proportions to a ternary eutectic composition made of cadmium, we found that, contrary to popular belief, it was possible to easily adjust the elongation rate and also adjust the tensile strength. I understand. The first invention of the present invention was completed based on this knowledge, and has a ternary eutectic composition of 55 to 59% by weight of tin, 17 to 19% by weight of zinc, and 24 to 26% by weight of cadmium. In contrast, that 0.
Adding bismuth amounting to 0.05-1.5% by weight,
This is its characteristic.

The reason why the amount of bismuth added is specified as 0.05 to 1.5% by weight is that for bismuth to substantially function as a material for improving the strength of the flexible material and adjusting the elongation rate, the amount added must be 0.05% by weight or less. This is not possible, and the reason why the upper limit was set as i, sii% is that past results have shown that the suitable growth rate for rail bonds is in the range of 22 to 26%. Although the multi-component eutectic system can improve tensile strength by adding up to 3% of bismuth,
This is because if it exceeds 1.5%, the elongation rate will deviate from the above-mentioned preferred elongation rate range and will decrease significantly.

To give an example, for a ternary eutectic composition of 57% by weight of tin, 18% by weight of zinc, and 25% by weight of cadmium, 0.05% of
Table 1 shows the properties of the soft foam prepared by adding up to 1.5% by weight of bismuth.

Table 1 On the other hand, Table 2 shows the case where bismuth is not added.

Table 2 Also, when 1.5% by weight or more of bismuth is added, as shown in Table 3, the elongation rate decreases significantly, which is unsuitable.

Table 3 Next, to explain the second invention of this invention, a method for manufacturing a soft metal, zinc chloride is generally a typical solvent for brazing and melting operations, but in the method of this invention, tin is used as a solvent. The surface of the molten metal, which consists of four components, approximately 57% by weight and the others being zinc, bismuth, and cadmium, is coated with 5 to 20% by weight.
It is characterized in that it is coated with a mixed solvent melt of tin chloride and zinc chloride in an amount of 80 to 95% by weight, and then melted and cast.

The melting point and boiling point of zinc chloride and tin chloride are 365, respectively.
C and 732 C, and 247 C and 623 C, this mixed solvent melt is suitable for furnace temperatures of 550 to 600 C. Both are corrosive solvents, and have superior surface activity and coating properties on their own compared to other corrosive solvents, and can dissolve and remove refractory oxides unique to alloys. In addition to deoxidizing, zinc chloride is effective for crystal refinement, which eliminates local differences in properties and directionality and makes the whole uniform. On the other hand, tin chloride has a degassing effect rather than a deoxidizing effect, promotes the formation of bubbles, and prevents the formation of pores.

The interfacial tension between zinc chloride and tin chloride is shown in FIG. 1, and zinc chloride has a property of having a positive temperature coefficient due to its structural specificity. Therefore, the mixed solvent melt of zinc chloride and tin chloride has good fluidity at the melt flow temperature, and the melt of the melt and the solvent in which the oxide is dissolved can be easily replaced within the narrow mold gap. Further, after the melting operation is completed, the remaining solvent adheres to the inner wall of the crucible and does not need to be removed.

In the method of this invention, the reason why tin chloride is specified as 5 to 20% by weight and zinc chloride is specified as 80 to 95% by weight is that, as shown in Table 4, the loss of soft particles is small.

Table 4 <Effects of the Invention> The soft solder according to the present invention has a tensile strength of 10.5 kmMIII while maintaining a suitable elongation rate as a soft solder for rail bonding.
Since the number can be set to 12 or more, it is possible to respond well to increasingly severe usage conditions.

In addition, in the method for manufacturing a soft metal according to the present invention, since the surface of the molten metal is coated with the mixed solvent melt as described above, it is possible to suppress the formation of an oxide film peculiar to molten metal and alloys.
The mixed solvent has a lower melting point and higher boiling point than the molten alloy and has good fluidity; 2) it does not attack the molten alloy and causes less loss of soft particles; 3) the molten alloy has excellent gas absorption ability and is suitable for castings. It does not produce defects such as pores that occur in the final condensation part of castings, and contributes to the refinement of crystal grains in castings.

It's extremely good.

<Example> Tin 57% by weight, zinc 18% by weight, bismuth 0.05-1
．． 152 g of 5% by weight three components are heated and fused at 550-600°C, and 25% by weight of preheated cadmium (
50q) were mixed and fused. During this mixing fusion, tin chloride 5
A mixed solvent consisting of ~10% zinc chloride and 90-95% by weight of zinc chloride is poured into the molten metal in an amount of 0.2% of the amount of the molten alloy, and thoroughly stirred to suppress the progress of oxidation and to inhibit the volatilization reaction. The oxygen contained in the molten alloy was removed.

The molten alloy thus molten is poured into a metal mold preheated to approximately 100°C, slowly cooled, and molded into a predetermined soft mold 19.
6.9C7 was obtained. The loss was about 2.5%.

The performance of this flexible material is as shown in the table below.Compared to conventional products, the tensile strength is approximately 12%, and the shear strength is approximately 12%.

[Brief explanation of the drawing]

The figure shows how the interfacial tension of tin and tin chloride and tin and zinc chloride change with respect to temperature changes.

Claims (1)

[Claims] 1. For a ternary eutectic composition of 55-59% by weight of tin, 17-19% by weight of zinc, and 24-26% by weight of cadmium,
Soft solder for steel, copper, and copper alloys, which is made by adding bismuth in an amount of 0.05 to 1.5% by weight. 2. The surface of the molten metal, which is composed of four components with approximately 57% by weight of tin and the others being zinc, bismuth, and cadmium, is
A method for producing soft solder for steel, copper, or copper alloys, which comprises coating with a mixed solvent melt of tin chloride in an amount of 80 to 95% by weight and zinc chloride, and then melting and casting.