JP3625963B2 - Stainless steel welded brazing material and stainless steel wire mesh for paper making using this brazing material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a brazing material for welding a stainless molded body, and more particularly to a stainless steel mesh for papermaking welded using this brazing material.
[0002]
[Prior art]
In order to improve the corrosion resistance and strength of the brazing filler metal itself, it is necessary to increase the gold content, and most of the gold content is as high as 70% or more. Met. In the environment where brazing material is used, nickel has been added to improve the corrosion resistance to chlorides, and chromium has been added to improve the corrosion resistance to sulfides. There was no change in the content ratio of being 70% or more and being mainly gold. This is the so-called gold wax. Theoretically, when the gold content is 18 carats (75%) or more, corrosion of the brazing material itself can be prevented.
However, in order to increase the content of gold, there has been a serious problem that the base material to be welded of the welded portion corrodes more rapidly due to the difference in ionization tendency. If the base material to be welded is corroded, the strength of the welded portion will eventually decrease, causing a problem that the welded portion is cut or dropped. Therefore, even if only the brazing material remains uncorroded, joining the objects has no meaning for the intended welding. There is also a cost problem.
In addition to gold brazing, silver brazing was sometimes used. However, in the environment where stainless steel products are used, silver brazing has a disadvantage that the brazing material corrodes immediately, which is problematic in practice. It was.
[0003]
By the way, in the field of papermaking, a stainless wire mesh welded endlessly to a dandy roll or a mesh of a circular mesh cylinder is often used.
In the papermaking process, many chemicals are used to improve the quality of paper. Therefore, the raw materials contain additives such as chloride bleaching materials, oxidant residues, and aluminum sulfate.
In addition, paper factories are often built along the sea for the convenience of carrying in raw materials and carrying out paper, and there are many cases where seawater is mixed in the groundwater used.
In this way, stainless steel mesh used in paper mills is used in an environment where metals are very susceptible to corrosion. Is big.
When the welded portion breaks, it is of course impossible to use it, which increases the number of service life, which is a serious problem, and the development of a brazing material that does not cause corrosion of the welded portion has been strongly desired.
[0004]
[Problems to be solved by the invention]
In view of the above-mentioned problems of the prior art, the present invention provides a brazing material improved in corrosion resistance of a welded portion and having good performance such as workability and a stainless steel mesh for papermaking welded by this brazing material. The purpose is to provide.
[0005]
[Means for solving problems]
The present invention
"1. Stainless steel consisting of 20-40 wt% gold, 15-30 wt% silver, 15-30 wt% copper, 2-6 wt% nickel and 0-4 wt% chromium. Brazing material for welding compacts.
2. 2. The brazing material for welding a stainless molded body according to item 1, wherein the stainless molded body is a stainless steel mesh for papermaking.
3. For the papermaking in which the brazing material described in item 1 is placed by being sandwiched between the ends of the stainless steel wire mesh for papermaking, and then heated to melt the brazing material and weld the end of the wire mesh to make it endless. Stainless steel wire mesh. "
About.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The present inventor has found that the welded portion welded with the conventional brazing material has a large difference in ionization tendency between the brazing material and the base material to be welded, so that electrolytic corrosion occurs between the brazing material and the base material. The present invention was completed by elucidating that the corrosion proceeded rapidly.
That is, when the base material to be welded is stainless steel and the brazing material is gold brazing as in the prior art, the base material to be welded is an electrically base metal having a higher ionization tendency than the brazing material, and the brazing material is the base material. It is a noble metal that is electrically noble and has a lower ionization tendency than stainless steel. Therefore, electrolytic corrosion occurred due to the potential difference, and the corrosion of the base stainless steel was progressing.
In particular, when chloride or seawater is mixed, naturally, the corrosion of the base material of the welded portion is significantly accelerated.
Therefore, in order to achieve the above object, first, it is necessary to reduce the potential difference between the brazing material and stainless steel as much as possible.
[0007]
In order to reduce the potential difference between the stainless steel and the brazing material, it is necessary to lower the potential of the brazing material. To lower the potential, it is necessary to reduce the gold content of the brazing material.
As a result of earnest research, the present inventor has to make the content of gold, which has been conventionally contained 70% or more for preventing corrosion of the brazing filler metal itself, to be 20 to 40% in order to reduce the potential difference. I clarified that it was not. If the gold content is less than 20%, the corrosion resistance of the brazing filler metal itself is not sufficient, and corrosion due to the brazing filler metal environment occurs during use. Electric corrosion occurs on stainless steel.
When the gold content is 20 to 40%, the potential of the brazing material is almost the same as that of stainless steel, and no electrolytic corrosion occurs.
In addition, since the gold content is low, there is a secondary effect that the brazing material can be manufactured at a low price.
[0008]
By the way, since the gold content is reduced, other materials must be blended in the brazing material instead of gold. In the present invention, 15 to 30% by weight of silver and 15 to 30% by weight of copper are used. %. Other metals such as palladium and indium are not considered for reducing the potential. However, they cannot be used because they are difficult to segregate or alloy.
Since the melting point of silver is low, if the silver content is increased, the brazing material is easily dissolved, the flow is good, and the workability is improved. However, if the amount is too large, the flowability becomes too large and the flow does not stop at the welded portion, so that the workability deteriorates.
Therefore, copper having a melting point higher than that of silver is contained to control the flow of the brazing material. If the copper content is 30% or more, the flowability is poor and workability is poor, and if it is less than 15%, the flowability is too high. Workability is improved when silver is in the range of 15 to 30% by weight and copper is in the range of 15 to 30% by weight.
[0009]
Furthermore, in the present invention, 2 to 6% of nickel is contained in order to improve the corrosion resistance of the brazing material itself to chloride, and 0 to 4% of chromium is contained in order to improve the corrosion resistance to sulfide.
If the nickel content is less than 2%, nickel segregation at the interface between the solder brazing and the stainless steel is small, but the strength and corrosion resistance are not sufficient, and if it is more than 6%, the melting point becomes high and the workability becomes poor.
Chromium does not necessarily have to be contained, but if it is contained, there is an advantage that the corrosion resistance against sulfides is improved. However, when the content is more than 4%, the melting point becomes high and the workability deteriorates.
[0010]
In this way, the corrosion resistance against chlorides and sulfides has been improved, so the welding of stainless steel mesh for papermaking used in situations where chlorides and sulfides are present in the papermaking raw material and the metal is very susceptible to corrosion. It is particularly suitable for.
In addition, the stainless steel mesh for papermaking must be formed so that there is no difference between the welded portion and the normal portion in order not to generate the mark of the welded portion on the paper.
Therefore, we cut the parallels along the ends of both ends of the stainless steel wire mesh for papermaking to about half the diameter and butt them together, and after placing the brazing material in the form of a narrow plate between the butt, brazing It is desirable to melt and weld the material.
This is because, when welding is performed in this way, the welded portion is formed in almost the same state as the normal portion, and the welded portion becomes one latitude line.
[0011]
【Example】
Embodiments of the present invention will be described based on examples.
Example 1
The alloy was melted at a ratio of 35% gold, 40% silver, 21% copper, and 4% nickel.
Example 2
The alloy was melted at a ratio of 35% gold, 40% silver, 17% copper, 5% nickel, and 3% chromium.
Both examples were manufactured by a method of containing nickel and chromium based on an alloy of gold, silver and copper. In this way, there is an advantage that electrolytic corrosion is prevented and welding workability is improved.
[0012]
Comparative Example An alloy was melted at a ratio of 82% gold and 18% nickel.
The comparative test was a sample prepared by welding the ends of a 45 mesh stainless steel wire mesh that was plain woven using a stainless steel meridian having a wire diameter of 0.254 mm and a latitude line having a wire diameter of 0.254 mm with the brazing material of the example and the comparative example. Were put into a 1: 1 mixed acid of 0.1% by weight hydrochloric acid and 0.05% by weight sulfuric acid prepared for the test, and the time until the weld fractured was compared.
[0013]
FIG. 1 is a cross-sectional view of a welded portion for explaining a welding method.
An end 4 of a stainless wire mesh woven with meridians 2 and latitudes 3 is abutted, and a plate-like brazing material 1 is disposed therebetween. The latitude line 5 along the end 4 at both ends is cut to about half the wire diameter. When the plate-like brazing material 1 is melted and welded in this way, the latitude lines 5 along the end portions 4 at both ends are integrated into one line, which is formed in substantially the same manner as the normal portion. Therefore, no mark is generated on the paper. Of course, there is no problem even if the meridian and the parallel are reversed.
The test results were 27 days for the example, 30 days for the example 2, and 5 days for the comparative example.
As is clear from the comparative test, the welded portion welded using the brazing filler metal of the present invention has improved corrosion resistance at each stage as compared with the prior art. Therefore, the life of the stainless steel wire mesh is extended.
[0014]
【The invention's effect】
As described above, the brazing filler metal of the present invention has a small gold content and a small potential difference from stainless steel, so that the corrosion resistance of the welded portion is good, and it can be manufactured at low cost and the cost is reduced.
Further, not only gold but also nickel is low, and since silver is contained, the melting point becomes low, the flowability of the brazing material is good, the workability is good, and the welding work time is shortened.
Also, because of its low melting point, it can be welded at a lower temperature than before, so it can use a low-temperature flux that does not vitrify by heat, but can prevent vitrification by high heat, and further after welding It is possible to perform the linear shape with hot water instead of hot water, and there is an effect that the cleaning property and safety are improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a welded portion for explaining a welding method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Plate-like brazing material 2 Meridian line 3 Parallel line 4 Edge part 5 Parallel line along edge part

Claims (3)

Stainless steel body weld consisting of 20-40 wt% gold, 15-30 wt% silver, 15-30 wt% copper, 2-6 wt% nickel, and 0-4 wt% chromium. Brazing material. The brazing material for welding a stainless molded body according to claim 1, wherein the stainless molded body is a stainless steel mesh for papermaking. A papermaking machine in which the brazing material according to claim 1 is placed by being sandwiched between the ends of the stainless steel wire mesh for papermaking, and then heated to melt the brazing material and weld the end portions of the metal mesh to make endlessness. Stainless steel wire mesh.

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