JPH0638997B2 - Brazing ribbon for brazing - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a brazing ribbon for brazing, in particular, a brazing ribbon made of a Ni—Cr—B alloy for joining stainless steel.

(Prior Art) Conventionally, welding methods for stainless steel include arc welding,
There is brazing welding, but the former is mainly used. However, brazing welding is an industrial field that will greatly develop in the future because it can perform simpler and more precise welding than arc welding and has high mass productivity.

As the brazing material used for this brazing, a B-Ni powder hardened with a binder to form a thin plate has been used. However, recently, Japanese Patent Publication Nos. 57-36075 and 58
Ni-based amorphous alloy ribbons by the melt quenching method disclosed in No. -15234 have come to be used.

Similar brazing alloys are available from the Japan Institute of Metals
Vol. 49, No. 4, 1985, pp. 285-290 6 Ni-15.7 Cr-2.8
B-Fe based braze alloys are disclosed as microcrystalline.

(Problems to be Solved by the Invention) However, in the former brazing material hardened with a binder, the unsublimated binder at the time of joining is apt to form voids, which causes a brazing defect. In addition, since the binder is not used in the latter amorphous or microcrystalline brazing filler metal, void formation due to it is not seen, and although the joint strength increases considerably, when stainless steel is joined, the corrosion resistance of the joint is It was not as good as or better than that of the base material stainless steel, and when used in a corrosive environment, there was a drawback that the joint was eluted and fragmented.

Thus, an object of the present invention is to provide a brazing ribbon having excellent corrosion resistance at the joint, especially when joining stainless steel, Ni-base alloy, and high alloy steel containing a large amount of Ni, Mo, Co, W and the like. Is to provide.

(Means for Solving Problems) In order to achieve the above-mentioned objects, the present inventors have conducted research on a brazing ribbon for stainless steel joining by a molten metal ultra-quenching method, and as a result, obtained the following findings, The present invention has been completed.

(1) When an appropriate amount of an element such as B or Cr is added, a brazing ribbon for joining stainless steel, which is excellent in strength and corrosion resistance, can be obtained even if it is not a Ni-based alloy but an inexpensive Fe-based alloy.

(2) The amount of B and Cr, especially the amount of B, has a great influence on the corrosion resistance of the joint. By adding B: 2.5 wt% or less and Cr: 10 wt% or more, the joint corrosion resistance higher than the base material can be obtained. . In this respect, it has been conventionally considered that the addition of a large amount of B (eg, more than 2.5% by weight) becomes amorphous and is essential for improving strength and toughness.

(3) As described above, in such Ni-based and Fe-based alloys,
It was thought that a tough ribbon as an amorphous material could be obtained only by adding about 15 to 20 atomic% of elements such as B, Si, P, and C by the molten metal quenching method. : 2.0 to 2.5% by weight (10 to 12.3 atomic%) is amorphous or a mixture of amorphous and crystalline and has sufficient toughness as a brazing material ribbon. Also,
B: 1 to 2 wt% (5.2 to 10 atom%) becomes fine crystalline, but a brazing ribbon having sufficient toughness can be obtained because the amount of B, which is an embrittlement element, is reduced.

(4) By using such a ribbon and brazing stainless steel, especially by welding the circumference of a stainless steel pipe, welding that is simpler, more precise, and more productive than conventional arc welding is possible. Becomes

Thus, the gist of the present invention is, in weight%, Si: 1.5% or less, Mn: 1.0% or less, Cr: 10-40%, Ni: 50% or less, B: 1.0-2.5%, and further required. Depending on Co: 20% or less and / or Mo: 20
% Or less, and the balance consisting essentially of Fe, which is a brazing ribbon for brazing.

Here, the brazing ribbon is generally amorphous, but it may be fine crystalline without being rapidly cooled.
It suffices that the above compositional alloy is obtained as a homogenous body, and therefore, it may have a mixed structure of amorphous substance and fine crystalline substance.

Further, the object of brazing using the brazing ribbon according to the present invention is typically stainless steel.
Base alloys as well as high alloy steels containing a large amount of Ni, Mo, Co, W and the like are included.

(Operation) Next, the reason why the alloy composition of the brazing ribbon according to the present invention is limited as described above will be described.

Si: It is advisable to add Si to increase the strength of the joint, improve corrosion resistance, and lower the melting point of the alloy, but it was made 1.5% by weight or less because it causes embrittlement of the brazing ribbon. Preferably,
It is 1.0% by weight or less.

Mn: Mn may be added as a substitute for expensive Ni or the like, but the corrosion resistance is deteriorated, so the content is set to 5% by weight or less.

Cr: Add 10 wt% or more to improve the corrosion resistance of the joint,
On the other hand, since the melting point of the alloy increases and the σ phase precipitates at the joint and causes embrittlement, the content is set to 40% by weight or less. Preferably 15-35
% By weight.

Ni: It is preferable to add Ni in order to improve the corrosion resistance of the joint and to lower the melting point of the alloy. Particularly, for joining austenitic stainless steel, 5% by weight or more is necessary to prevent the joining portion from being ferrite. Most of Ni is Ni
However, since Ni is expensive and the joint strength and corrosion resistance do not change even if a large amount is added, the amount of Ni is set to 50% by weight or less. It is preferably 5 to 30% by weight.

B: 1% by weight for lowering the melting point of the alloy and improving the fluidity of the molten braze
Although it is added above, the corrosion resistance of the joint is deteriorated, so the content is set to 2.5% by weight or less. It is preferably 1.6 to 2.3% by weight.

Co and Mo: These are optional additives, and at least one of them is preferably added in order to improve the corrosion resistance and high temperature strength of the joint. However, the cost of each of them is elemental, so that each is limited to 20% by weight or less.

In the case of Mo, there is a strong tendency to increase the melting point of the alloy. Therefore, it is preferable to add Mo in an amount of 10% by weight or less.

In addition, impurities such as C and P will result in deterioration of the corrosion resistance of the joint if it is contained in a too large amount.
It is preferable to limit it to the weight% or less.

Next, the molten metal ultra-rapid cooling method, which is a typical method for manufacturing a thin ribbon for brazing according to the present invention, will be described.

FIG. 1 is a schematic explanatory view of the concept of the molten metal super-quenching method, which is a method called a single roll method in the illustrated example, in which a molten metal flow is appropriately supplied from a holding container to a roll through an injection nozzle. It is then cooled rapidly on rolls. At this time, the roll is rotated at a high speed and is rapidly cooled from the inside, so that ultra-rapid cooling is possible.

For example, when cooling the molten alloy having the above composition,
It is cooled and solidified at a cooling rate of 10 ⁴ ° C / sec or more, and 20 to 10
A thin strip with a thickness of 0 μm is used.

Thus, a ribbon of amorphous or fine crystalline or a mixture thereof is obtained. These ribbons have almost no surface oxidation and are useful for brazing as they are, but since they have sufficient toughness, they may be used for brazing after cutting and pressing into a complicated shape.

When stainless steel is liquid phase diffusion bonded using the ribbon of the present invention, the ribbon is inserted as an insert material between the joining materials, and when the insert material is melted, it is mutually diffused with the joining material, and then, , The insert material disappears by isothermal solidification, and a joint of the same quality as the joining material is obtained.

In this joining method, the insert material has a lower melting point than the joining material, and the joining temperature is higher than the melting temperature of the insert material and lower than the melting temperature of the joining material. The bonding atmosphere is a protective atmosphere such as an inert gas.

Thus, according to the invention, not only stainless steel,
Excellent brazing of Ni-based alloys and even high alloy steels.

The term "stainless steel" as used herein generally refers to steel containing Cr: 12% by weight or more, but brazing of heat-resistant alloys of Ni-based or Fe-based even if the amount of Cr is less than that Even if the ribbon according to the present invention is used for the purpose, sufficient joint strength and corrosion resistance can be obtained.

Next, the present invention will be further described with reference to examples.

Example 1 FIG. 2 is a schematic cross section of a diffusion bonding apparatus used in this example.

The joining base materials 1 and 2 are respectively supported by the vertical pressing jigs 3 and 4, and the hydraulic cylinder 10 is supported via the vertical pressing rams 5 and 6.
Is pressurized by. Reference numeral 7 is a fixed base, 8 is a load cell, and 9 is a high frequency heating coil. These are entirely surrounded by the outer wall 11 and form a protective atmosphere inside.

When performing brazing with such a device, first, the welding base material
Insert the brazing ribbon 10 as an insert material between 1 and 2,
Brazing is performed by forming a protective atmosphere in the outer wall 11 with a certain Ar gas or the like, and then press-bonding both joining materials by the action of the upper and lower pressurizing rams 5 and 6 in a high temperature state.

Ten kinds of molten alloys having the composition shown in Fig. 1 were sprayed on the surface of a steel roll having a diameter of 300 mm rotating at 3000 rpm as shown in Fig. 1 using a rectangular nozzle with an opening of 0.5 x 14 mm. A thin strip having a width of 14 mm and a thickness of 35 μm was produced. These were a mixed structure of amorphous and fine crystalline. After cutting these ribbons to a size of 14 mm × 14 mm,
12mm × 14mm × 60mm SUS304 square bar is sandwiched between 14mm × 14mm end faces and a load of 1Kgf / mm ² is applied.
The ribbon was melted and joined by heating at 50 ° C. for 5 minutes.
Table 2 shows the composition of SUS304 as the test material. As a comparative example, JIS standard BNi-1A Ni-based powder sheet wax was used and joined in the same manner.

Then, in order to measure the bonding strength, the bonded square bar was formed into a shape of JIS Z 2201 by cutting, and a tensile test was performed.

Corrosion resistance of the joint is more
3mm (t) x 10mm (w) x 40mm (l) and 2mm (t) x 11mm diameter test pieces were processed and subjected to sulfuric acid and sulfuric acid steel corrosion test of stainless steel (JIS G 0575. Hereinafter referred to as "Strauss test". ) And pitting potential measurement.

The test piece of the Strauss test was wet-finished No. 600 emery paper polished, U-bend bending was performed after the test, and the presence or absence of cracks was determined using a microscope.

The pitting potential was measured by a potentiodynamic method with a sweep rate of 20 mV / min in 0.01 molar NaCl aqueous solution, 60 ° C., under Ar deaeration. The n number was 3.

The above results are shown together.

Alloys A to D are specifically for investigating the influence of the amount of B, but the alloy A containing 0.85 wt% B, which is a comparative material, has a high melting point, does not melt, and cannot be joined. In the D alloy containing 3 wt% B, which is the material, the joint strength,
It can be seen that the elongation is high but the corrosion resistance is poor. As compared with these, it is understood that the B and C alloys according to the present invention have excellent mechanical properties and corrosion resistance of the joint.

The E to I alloys were examined especially for the influence of the amount of Cr, and the mechanical properties of these alloys are excellent. However, it can be seen that the E alloy, which is a comparative material having a low Cr content, is inferior in corrosion resistance, while the alloys F to I, which are alloys according to the present invention, have no problem in corrosion resistance.

The J alloy has almost the same composition as a commercially available amorphous alloy brazing ribbon. The alloy according to the present invention has excellent mechanical properties and corrosion resistance without any problem, but it is clear that the J alloy, which is a comparative material, has a problem with corrosion resistance.

It is also clear that the alloy of the present invention is superior in both mechanical properties and corrosion resistance to the conventional BNi-1A-based powder sheet brazing material.

As described above, by brazing and joining stainless steel using the brazing ribbon according to the present invention, excellent mechanical properties and corrosion resistance of the joint can be obtained.

Example 2 The molten metal of the G alloy composition of Example 1 was sprayed from a rectangular nozzle having an opening of 0.6 × 20 mm onto a steel roll surface having a diameter of 300 mm rotating at 2500 rpm, and a brazing material having a width of 20 mm and a thickness of 30 μm was used. A band was made. These were a mixed structure of amorphous and fine crystalline.

As shown in Fig. 2, using a diffusion welding device, a pipe made of SUS304 stainless steel and having a diameter of 25.4 mm x thickness of 1.0 mm x length of 100 was joined using the brazing ribbon obtained as described above as an insert material. It was inserted into the surface and bonded in an argon atmosphere at a bonding temperature of 1250 ° C., a bonding time of 200 seconds, and a pressure of 1 Kgf / mm ² . Four plate-like tensile test pieces and corrosion resistance test pieces were sampled from this joint.

Even if the brazing strip of the present invention was applied to pipe joining, there was no problem, and the joining strength at the base metal level was obtained. Further, the corrosion resistance was evaluated under the same conditions as in Example 1. As is clear from Table 4 which summarizes the results, according to the present invention, good corrosion resistance was confirmed.

(Effects of the Invention) As described in detail above, the present invention can improve the corrosion resistance by significantly reducing the amount of boron added, which was conventionally considered to be absolutely necessary. Is not made amorphous and may contain a part of fine crystalline, so that it is practically easy to carry out, and its profit is great.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of the concept of a method for manufacturing a ribbon according to the present invention, and FIG. 2 is a schematic sectional view of a brazing device used in the present invention. 1, 2: Joining base material, 3, 4: Vertical pressing jig 5, 6: Vertical pressing unevenness, 7: Fixing stand 8: Load cell, 9: High frequency heating coil 10: Hydraulic cylinder, 11: Outer wall

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yoshio Tarutani 1-3-3 Nishi-Nagasumotodori, Amagasaki City, Hyogo Prefecture Sumitomo Metal Industries, Ltd. Central Research Laboratory (72) Inventor Kenji Kitano 5 Kitahama, Higashi-ku, Osaka-shi, Osaka 15-chome Sumitomo Metal Industries, Ltd.

Claims (2)

[Claims] 1. A composition comprising, by weight, Si: 1.5% or less, Mn: 1.0% or less, Cr: 10-40%, Ni: 50% or less, B: 1.0-2.5%, and the balance substantially Fe. A brazing ribbon for brazing. 2. By weight%, Si: 1.5% or less, Mn: 1.0% or less, Cr: 10-40%, Ni: 50% or less, Co: 20% or less and / or Mo: 20% or less, B: A brazing ribbon for brazing, having a composition of 1.0 to 2.5% and the balance essentially Fe.