JPS63268592A - Ferrite welding material - Google Patents

Abstract

PURPOSE:To improve oxidizing resistance and workability as well as to better weldability between dissimilar stainless steel materials by specifying the structure of a ferrite welding material. CONSTITUTION:A ferrite welding material contains 0.03% C, <=1.00% Si, <=1.00% Mn, 16.0-21.0% Cr, 0.30-0.80% Nb, 0.30-0.80% Cu and <=0.025% N and the balance Fe. An oxidizing resistance and workability can be increased with said composition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to ferritic welding materials used for welding stainless steel.

[Prior art] Many austenitic welding materials (welding rods) conventionally used for welding stainless steel have been announced. However, as a ferritic welding material, J15Z3321
(Y410.Y430) is the only standard. Y
410 is carbon: 0.12% by weight or less (hereinafter, % is 11%)
%), silicon di 0.50% or less, manganese 20.6
% or less, phosphorus 20.03% or less, sulfur: 0.03% or less, nickel = 0.6% or less, chromium: 11.5-13.
5%, molybdenum: 0.60% or less, balance iron. In addition, Y430 has carbon: 0.10% or less, silicon: 0
．． 50% or less, manganese 20.6% or less,
Mi, 03% or less, sulfur: 0.03% or less, nickel 2
0.6% or less, chromium: 15.5-1"t', o%,
The balance consists of iron.

In addition, as a commercially available ferritic welding material, YT434NB (carbon: 0.07
%, silicon: 0.35%, manganese: 0.64%, oxide: 17.7%, molybdenum: 0.90%, niobium: 0.
91%, balance iron) is known.

Furthermore, when welding dissimilar metals, such as welding ferritic and austenitic stainless steels, JIS Z3
321 (Y2O2) is often used.

This Y2O2 is carbon: 0.12% or less, silicon = 0.6%
0% or less, manganese = 1.0-2.5%, phosphorus: 0.0
3% or less, sulfur: 0.03% or less, nickel: 12.0
~14.0%, chromium: 23.0~25.0%, balance iron.

[Problems solved by the present invention] Conventional Y used for welding ferritic stainless steel
410. Welding materials such as Y430 become extremely brittle materials due to the precipitation of martensite due to carbon, oxygen, etc. in the shade gas. Like the YT434NB mentioned above, Y430
Although there are techniques to prevent cracking by adding niobium or titanium to the steel, or by reducing the amount of crystals due to the effect of titanium, the effects cannot be said to be sufficient. Further, these conventional welding materials have problems such as hydrogen embrittlement and reduced impact resistance if heat treatment before and after welding is omitted.

In addition, Y2O2 welding materials used for welding different types of stainless steels are susceptible to bulge phenomenon (compared to ferritic materials with low expansion coefficients) due to thermal stress (thermal fatigue) caused by differences in thermal expansion coefficients in parts that undergo thermal cycles of heating and cooling. When an austenitic material with a high coefficient of expansion is welded on top, repeated heating causes the weld bead to swell toward the outer circumference, resulting in deformation cracks. Moreover, Y410. When Y430 is used, carbon, nickel, etc. from the austenitic base material are injected into the weld bead and the structure within the weld bead becomes martensitic, resulting in poor impact resistance. Further, if hydrogen or oxygen enters the martensitic material in this way, delayed fracture (hydrogen embrittlement) etc. will occur.

The present invention overcomes the above-mentioned problems, and aims to provide a ferritic welding material that has excellent weldability between different types of stainless steel materials, as well as high oxidation resistance and workability. .

[Means for Solving the Problems] The ferritic welding material of the present invention contains less than 0.03% carbon, less than 1.00% silicon, less than 1.00% manganese, and 16.0 to 21% chromium. .0%,\1,2Apu:0.
30-0.80%, copper: 0.30-0.80%, nitrogen:
It is characterized by being composed of 0.025% or less, the balance being iron.

Further, the above composition may contain 5.0% or less of nickel.

The ferritic welding material of the present invention is less likely to cause bulge phenomena or hydrogen embrittlement due to thermal stress even when welding different types of stainless steel materials such as ferritic and austenitic stainless steel materials. Furthermore, the ferritic welding material of the present invention has excellent effects such as the ability to omit heat treatment before and after welding.

The welding material of the present invention is characterized by being lower in carbon, higher in chromium, lower in nickel than conventional Y430, and containing niobium and copper.

The reason why the carbon content is set to 0.03% or less is to make the structure 71-lite. The lower limit of carbon content is about 0.01%. The reason why the silicon content is set to 1.00% or less is that if the silicon content exceeds 1%, the toughness and ductility of the weld metal part will be significantly reduced. The lower limit of silicon content is 0.5
It is about %.

The reason why the manganese content is set to 1.00% or less is because if the manganese content exceeds 1%, the hardness of the material increases and the moldability deteriorates. The lower limit of manganese content is 0.4%
That's about it. The reason for increasing the chromium content to 16.0 to 21.0% is to increase the solid solution chromium (m) in combination with the low carbon content, thereby suppressing a decrease in strength and impact resistance. Further, chromium is an element necessary to improve oxidation resistance. The reason why the upper limit of the chromium content is set to 21.0% is that if it exceeds 21.0%, the toughness of the weld metal part will decrease. The lower limit is set to 16.0% because the corrosion resistance is lower than that of the base material. Niobium is incorporated to improve layering resistance and strengthen grain boundaries. A niobium content of 0.3% or less has almost no effect, and a niobium content of about 0.5% is best. However, if it exceeds 0.8%, it tends to break during wire drawing with a high area reduction and productivity tends to decrease, so the upper limit was set at 0.8%. Copper is an element incorporated to improve welding workability. Since the welding material of the present invention has a low content of carbon and nickel, muddy flow during welding is extremely poor. In the present invention, this flowability is improved by adding a small amount of copper to improve workability.

If the amount of copper added is less than 0.3%, it is not sufficient to improve workability, and if it exceeds 0.8%, copper compounds will precipitate due to the effects of welding heat and become hard, reducing ductility and toughness. There is a problem. When welding dissimilar stainless steel materials using a combination of austenitic stainless steel and ferritic stainless steel, nickel from the austenitic stainless steel may penetrate into the weld bead and transform the weld bead structure into martensite, resulting in poor impact resistance. . However, if the weld bead contains an appropriate amount of nickel, the workability will be improved, so it is desirable to use nickel rXh' within a range of 5% or less, and particularly preferably about 3%. By using the welding material of the present invention, it is possible to control the nickel content within the above range.

Since the welding material of the present invention has an extremely low carbon content of 0.03% or less, it absorbs little hydrogen and does not have the problem of hydrogen l1Iiii when a normal shielding gas is used. Furthermore, since no martensite is generated within the weld bead, heat treatment such as tempering is not required.

Therefore, compared to conventional ferritic welding materials, there is no need for pre- and post-heat treatment, which greatly improves workability.

Conventional shielding gases ranging from 100% argon to argon + 20% carbon dioxide can be used without any problem. In order to obtain particularly good workability, argon + 2% oxygen is preferred.

Note that flux may also be used.

When welding, the current, voltage, etc. are normal TIG (Tung).
sten Inert Qas) or MIG (Me
tal Inert Ga5) Work is possible within the range of arc welding conditions.

[Example] (First Example) As shown in Table 1, the compositions of N
No. 091 to No. 003 as comparative examples.

Welding materials No. 4 to No. 6 were manufactured by subjecting them to appropriate heat treatment and wire drawing. Using these six types of welding materials obtained, MIG arc welding was performed at a current of 120 A, 1 m, and a pressure of 1 m.
Welding was performed under the conditions of argon + 2% oxygen as an 8v1 shielding gas. The metal structures of each weld bead obtained by these weldings are shown in the photographs of FIGS. 1 to 6. In addition,
The composition shown in FIG. 1 is for welding material No. 001, and FIGS. 2 to 6 are for welding materials numbered No. 2 to No. 6, respectively. Comparative example No. 4, N005, N
When each welding material of 096 is used, Fig. 4, Fig. 5,
As can be seen from the metal structure shown in FIG. 6, black dendritic martensite is produced in all cases. On the other hand,
No, 1, no.

2. When using the welding material of the present invention of N003, the first
As can be seen from the metallographic structure shown in FIGS. 2 and 3, the structure within the weld bead is entirely ferrite.

Next, we will discuss the welding material of the present invention and Y430, which is a conventional standard product.
, Y2O2 were subjected to delayed fracture tests as shown below and each was evaluated.

As shown in Fig. 7, 5LJS430 is used as material A, SUSXM15J1 is used as material B, and welding materials include No. 2 of the present invention and conventional standard products Y430 and Y2O2.
Joint welding between dissimilar stainless steel materials was performed using each of these. The steel material used was in the form of a plate measuring 100 x 50 x 1.5 mm, and the overlapping portion was about 10 III m. The welding conditions are
The current was 120 A, the voltage was 19 mm, and argon + 2% oxygen gas was used as the shielding gas.

The metal structure within the weld bead using welding material No. 2 of the present invention is shown in the photograph of FIG. 8, and the structure within the weld bead of Y430 is shown in the photograph of FIG. From these photographs, the structure within the weld bead of the present invention is entirely ferrite,
In contrast, it can be seen that the structure within the weld bead of Y430 is martensite.

As shown in FIG. 10, the end of material B is held between the test pieces 1q thus prepared, and a load W (
I continued to give -1k (1 layer).

As a result, when Y430 was used, fine cracking occurred at the weld bead on the 8th day after the start of the test, whereas
Trial 11 when using Y2O2 and the present invention! start 30
No cracks were observed even after several days.

(Second Example) As shown in Table 2, the respective compositions are No. 1 as the welding material of the present invention and No. 1 as the comparative example.

2 to 7 welding materials were manufactured. Regarding the comparative example, compared to the welding material of the present invention, NO62, No. 6, has a higher carbon content and NO
13 is high niobium, No. 4 is low niobium, N005 is low chromium, and N007 is high silicon.

Next, these seven types of welding materials and conventional standard products such as Y
The following tests were conducted using 430 and Y2O2, and each was evaluated.

(1) Cold and heat test 5US430 pipe (φ-42, 7mm)
Fi current 140A, voltage 19V, sea) Lt gas: argon + 2% oxygen, and as a comparative example, TY304
The current was 160 A, the pressure was 18 V, the shielding gas was argon + 2% oxygen, and each welding speed was 300 mm.
, welded at a torch angle of 90° and a torch height of 10111, and as shown in the test pattern in Figure 11,
An oxidation test was conducted repeatedly by heating the sample from room temperature to 900°C and cooling it to room temperature for 18 minutes.

Measurement of pipe deformation was performed at 45''' as shown in Figure 12.
The inner diameter of the pipe was measured with a pitch and the average value was calculated.

The graph in FIG. 13 shows the increase in deformation rate as the number of cycles increases when each welding material is used. Y2O
When No. 2 was used, the pipe was significantly deformed, and the deformation rate at the end of 400 cycles was 1.4%. On the other hand, N
o. When using 1 to N007, the increase in the deformation rate of the pipe was extremely low, and when using N011, which is the present invention, only about 0.3% deformation was observed even after 400 cycles were completed. .

As a result of the thermal testing, it was confirmed that oxide scale was generated on the weld bead in Y430 at 86 cycles, and visible deformation was observed in Y2O2 at 127 cycles. No major deformation was observed in N011 according to the present invention even after 400 cycles. Further, in both Y2O2 and the present invention, almost no oxidized scale was observed even after 400 cycles.

Next, using the welding materials shown in Table 2,
An 8r continuous oxidation test was conducted. The results are shown in FIG. As you can see from the results, No.

When using No. 2, N085, No. 6, and No. 6, there was significant oxidation deterioration, whereas the aNb-Or type was found to have good oxidation resistance.

(2) Wire drawing test No. 011 to No. 7, and Y430 as conventional standard product
After applying appropriate heat treatment using 1Y308 welding material, wires were manufactured by cold continuous wire drawing using the same equipment and the same die, and the presence or absence of breakage was examined with respect to the area reduction rate during 10,000 m processing. The drawability was evaluated. No
,2,No.

When welding materials No. 3, No. 6, No. 7 were used, cracks started to occur when the area reduction rate was about 80%, but when welding materials No. No cracks are observed in the material even when the area reduction rate is quite high.
No wire breakage was observed even when the area reduction rate was 90%.

(3) Wire straightness test Here, a Matsushita HF-350 robot; Matsushita AW 550 was used as a testing machine, and a straightness test was conducted with a nozzle height of 1501111° and a wire diameter of φ1.2. We evaluated how much it deviates from the center and whether there is a lot of variation. As a result, as shown in Fig. 15, No. 11 showed excellent straightness of ±10 or less, No. 2 had a tendency to curve toward the negative side from the center, and No. 2 had a tendency to curve toward the negative side from the center, and No. 2 had a large variation toward the positive side and the weld bead It was observed that the stability of

[Effects of the Invention] As described above, the ferritic welding material of the present invention contains less carbon and nickel, has a relatively high chromium content, and further contains niobium and copper, compared to conventional welding materials. Regardless of the base metal of the weld metal, it was found that it exhibited excellent weldability not only between the same type of metal but also between different types of metal, and was also recognized to have excellent oxidation resistance and workability.

[Brief explanation of drawings]

Figures 1.2 and 3 are photographs showing the metallographic structure of the weld bead of the present invention, and Figures 4.5 and 6 are photographs showing the metallographic structure of the weld beet of the comparative example. FIG. 7 is a schematic diagram showing a method of joint welding. FIG. 8.9 is a photograph showing the metallographic structure of the weld bead of the present invention and a comparative example. FIG. 10 is a schematic diagram showing a method of delayed fracture testing. FIG. 11 is a pattern diagram of a thermal test. Figure 12 shows the method of the cold test. This is a schematic diagram. FIG. 13 is a graph showing the relationship between the number of cycles and the deformation rate in a thermal test. FIG. 14 is a graph showing the oxidation loss of each welding material in a thermal test. FIG. 15 is a graph showing the test results in the wire straightness test. Patent applicant: Toyota Motor Corporation, Sumitomo Electric Industries, Ltd., Japan Stainless Steel Co., Ltd. 100) Figure 7 Figure 10 Figure 11 Figure 12 Figure 13 Cycle number procedure correction calculation (voluntary) April 30, 1981 Patent application filed April 27, 1988 Address Toyota City, Aichi Prefecture 1 Toyota-cho Name (320) T-Yota Motor Co., Ltd. Representative Kiyoshi Matsumoto Address 5-15 Kitahama, Higashi-ku, Osaka Name (213) Sumitomo Electric Industries Co., Ltd. Representative Tadochi
Irobe Address Tokyo/gI 8 Honshio-cho, Shinjuku-ku 2 Name Nippon Stainless Co., Ltd. Representative Kuri 1) Mitsunobu 4 Agent address: 4 Kodama Pill, 3-3 Meieki, Nakamura-ku, Nagoya, Aichi Prefecture 450 (Telephone) <052> 583-97201 Sponsorship 6, Subject of amendment Column 7, Detailed explanation of Mei Ill's invention, Contents of amendment (1) Mei II, page 10, line 12.
Insert Table 1 of the attached sheet for the violation of the Act. (2) Mei 1111, page 12, line 7, line 1. After J.
Insert the attached Table 2. That’s all for Attachment 11! Table 2 Procedural amendment (method) 1. Indication of the case 1986 Patent Application No. 103780 1 Toyota-cho, Toyota City, Aichi Prefecture <320) T-Yota Automobile Co., Ltd. Representative Kiyoshi Matsumoto 1 5 Kitahama, South East Ward, Osaka 15-chome (213) Sumitomo Electric Industries Co., Ltd. Representative Tetsu Kawakami 8-2 Honshio-cho, Shinjuku-ku, Tokyo Japan Stainless Co., Ltd. Representative Kuri 1) Mitsuru Shin 4, Agent Address: 450 Nakamura-ku, Nagoya, Aichi Prefecture Meieki 3-3-3 Kodama Building (Episode N <052> 583-9720) 1988
July 1, 1988 (Delivery date: July 28, 1986) 6. Comparative drawings of the amendment (Figures 1 to 6) 7. Drawings (Figures 1 to 6) Figure) clearly rendered in black using appropriate paper. 8. List of attached documents (1) One copy of drawings (Figures 1 to 6)

Claims (4)

[Claims] (1) Carbon: 0.03% by weight or less, Silicon: 1.00% by weight or less, Manganese: 1.00% by weight or less, Chromium: 16
．． 0 to 21.0% by weight, niobium: 0.30 to 0.80% by weight, copper: 0.30 to 0.80% by weight, nitrogen: 0.02
A ferritic welding material characterized by comprising 5% by weight or less, the balance being iron. (2) Carbon: 0.01 to 0.03% by weight, Silicon: 0.5
The ferritic welding material according to claim 1, wherein the content of manganese is 0 to 1.00% by weight, and the content of manganese is 0.40 to 1.00% by weight. (3) Carbon: 0.03% by weight or less, Silicon: 1.00% by weight or less, Manganese: 1.00% by weight or less, Chromium: 16
．． 0 to 21.0% by weight, nickel: 5.0% by weight or less,
Niobium: 0.30-0.80% by weight, copper: 0.30-0
．． A ferritic welding material comprising 80% by weight, nitrogen: 0.025% by weight or less, and the balance iron. (4) Carbon: 0.01-0.03% by weight, Silicon: 0.5
The ferritic welding material according to claim 3, wherein the content of manganese is 0 to 1.00% by weight, and the content of manganese is 0.40 to 1.00% by weight.