JPS6254384B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to corrosion-resistant brass with excellent stress corrosion cracking resistance. Conventional brass is Zn30wt
%, the balance being Cu, and this brass is used for radiator tank materials, core plate materials, etc. On the other hand, in order to reduce the weight and cost of automobiles, the material for radiator tanks is changing from the traditional brass tanks to resin tanks. Unlike the case of a brass tank and core plate, the resin tank and core plate cannot be fixed by soldering, so a caulking method is used. There are two types of crimping methods: the indirect crimping method shown in FIG. 3 and the direct crimping method shown in FIG.
Mild steel is generally used for the caulking plate of the indirect caulking method shown in FIG. 3, but a direct caulking method that does not require such a special caulking plate is desirable from the viewpoint of ease of manufacture. However, if the direct caulking method were to be adopted, stress would remain in the caulked portion of the brass core plate material, and this residual stress would cause stress corrosion cracking to occur during use. In order to remove residual stress, strain relief annealing is generally performed, but it is practically impossible to perform this while fixed to a resin tank. Therefore, although indirect caulking has conventionally been used, there has been a desire for a brass material that can also be used for direct caulking. The present invention was made with the aim of meeting such demands, and the brass of the present invention has Zn20 to
35wt%, Zr0.005~0.05wt% and Ni or Fe0.005
It is a corrosion-resistant brass containing up to 0.3 wt% of Cu, with the remainder being substantially Cu. The Zn content is 20-35 wt%, more preferably 25-30 wt%. When the Zn content exceeds 35 wt%, formability and stress corrosion cracking resistance decrease. Moreover, if it is less than 20wt%, the strength will be low. The content of Zr is 0.005 to 0.05 wt%, more preferably 0.01 to 0.02 wt%. Zr content
If it is less than 0.005wt%, the effect of improving stress corrosion cracking resistance is poor, and if it exceeds 0.05wt%, it is undesirable because it increases the price and reduces workability. The Ni or Fe content is 0.005 to 0.3 wt%, more preferably 0.01 to 0.03 wt%. Ni or Fe
If the content is less than 0.005 wt%, excellent stress corrosion cracking resistance, which has a synergistic effect with the addition of Zr, cannot be obtained. If it exceeds 0.3 wt%, no improvement in stress corrosion cracking resistance commensurate with the addition can be expected, and on the contrary, workability will decrease. The following will be explained based on examples. The alloys of the present invention and comparative alloys shown in Table 1 were melted in a low-frequency groove electric furnace to form ingots with a thickness of 120 mm and approximately 500 kg. After melting, it was hot rolled at 800℃ to a thickness of 12mm. This sample was then cold-rolled to a thickness of 2 mm, continuously annealed at 780°C for 60 seconds, and then pickled, then rolled to 0.8 mm, annealed again at 700°C for 20 seconds, pickled, and tested. I got the material. The stress corrosion cracking resistance characteristics of the test materials were determined by the following two tests, A and B. In test A, the test material was actually formed into a core plate and caulked directly to a resin tank, and this test material was mixed with commercially available 28% ammonia water 1+
An aqueous solution having a volume ratio of 1 part water to 1 part water was placed in a container installed at the bottom, and the time required for cracking to occur after exposure to ammonia vapor was determined. In test B, 20
A part of the sample was immersed in Matson's solution with a bending stress of Kg/mm ² applied, and a tensile test was performed by pulling it up at regular intervals to create a strength-time curve, and in that curve, the time at which strength began to decrease was the time at which strength began to decrease. It was time. Table 1 shows the cracking time due to test A and the strength reduction start time due to test B, respectively, at time A and time B.
It was displayed as

[Table] The crystal grain size in Examples 1 to 6 was 2 to 7μ, Comparative Example 1 was 15μ, and Comparative Example 2 was 10μ. As seen in the examples, the corrosion-resistant brass of the present invention has improved stress corrosion cracking resistance by adding a small amount of Zr to conventional brass and further adding Ni or Fe. The reason why the stress corrosion cracking resistance of Example 6 is slightly inferior to that of other examples is because
This is because the Zn concentration is higher than the others. The alloy of the present invention can be used for radiator components such as tube materials, tank materials, and water inlets, by taking advantage of its excellent corrosion resistance and economic efficiency, in addition to radiator core plate materials that use the direct caulking method.
Switches, terminals, connectors, holders, clips, relays, etc. for electronic and electrical equipment such as wiring devices other than radiators that require corrosion resistance.
It can also be used for chips, sockets, etc. The alloy of the present invention can be easily melted, hot-rolled, cold-rolled, and subjected to intermediate heat treatment, and there is no problem in forming the alloy when it is packed into a radiator.

[Brief explanation of the drawing]

FIG. 1 is a front view of a typical automobile radiator, and FIG. 2 is a side view thereof. FIG. 3 shows the structure of the caulking portion between the resin tank and the core plate through the packing, taken along the line A-A in FIG. FIG. 4 shows a structure according to the present application in which the indirect crimping method shown in FIG. 3 is replaced with the direct crimping method. In the figure, 1 is a caulking plate, 2 is a core plate, 3 is a resin tank, 4 is an oil cooler, and 5 is packing.

Claims (1)

[Claims] 1 Zn20-35wt%, Zr0.005-0.05wt% and Ni
Or it contains Fe0.005~0.3wt% and the balance is substantially
Corrosion-resistant brass made of Cu. 2. Claim 1, which is directed to a core plate member for a heat exchanger that fixes a resin tank of an automobile engine cooling water heat exchanger by a direct caulking method.
Corrosion-resistant brass as described in section.