JPH01237079A - Welding method for clad steel - Google Patents

Abstract

PURPOSE:To obtain a weld zone having characteristics equal to base metal by welding first the clad side by material to be welded for cladding material and forming an intermediate layer by material to be welded in the specific component range thereon and subsequently, welding the base metal side by material to be welded for the base metal. CONSTITUTION:A V type groove with the base metal 2 side as an opening is provided and the cladding material 1 side is welded by weld metal 3 for cladding material and various characteristics required for the cladding material 1 are secured. More than one layer is then welded on the cladding material weld metal 3 by the material to be welded consisting of, by weight, 20-30% Cr, 2-4.5% Mo, 4-13 Ni <=0.06% C, <=0.20% N, (Ni+30C+20N)/(Cr+Mo) in the range of 0.20-0.70 and the balance Fe with impurities and the intermediate layer 4 is formed. The intermediate layer 4 has strong resistivity to the component change caused by melting the cladding material and the base metal and a weld crack does not take place. Further, welding is performed on the intermediate layer 4 by the material to be welded for the base metal. Base metal side weld metal 5 does not cause the weld crack and other harmful weld defects and is provided with satisfactory ductility.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for welding stainless clad steel or nickel-based alloy clad steel, and more specifically to a method for welding these clad steels together economically and with high efficiency. Moreover, the present invention relates to a welding method that makes it possible to obtain a sound weld.

[Prior Art] Clad steels are used in large quantities in large quantities for containers and piping in chemical plants, etc., due to their economic efficiency, as well as stainless steel and nickel-based alloys themselves, which have excellent corrosion resistance and heat resistance. ing. The most common method of joining these clad steels is as shown in FIGS. 2(a), 2(b), and 2(c).

That is, in FIG. 2 (a), V-shaped openings are provided on both the composite material 1 side and the mild steel or low alloy steel (hereinafter referred to as base material) 2 side,
In (b), the base metal 2 side is the weld metal 5 that matches the base metal 2.
In (c), if the composite material is stainless steel, the composite material is welded with a weld metal 4 such as a high alloy type austenitic stainless steel used for dissimilar metal welding etc. on the base weld metal 5. In the case of nickel-based alloys, Ni-
After welding with a weld metal 4 such as the so-called Inconel type of Cr-Fe alloy, weld a composite material 1 with a weld metal 3 that matches the composite material 1.
welding. The main reasons for adopting this construction procedure are to prevent weld cracking, reduce welding material costs,
Improving welding efficiency 1. Ensuring the properties of the composite material. However, depending on the shape and dimensions of the structure, it may not be possible to adopt the bevels and procedures shown in Figure 2 (for example, the inner surface of a small diameter pipe is made of composite material), and in such cases, especially ) (b) and (c).

That is, in Fig. 3 (a), a V-shaped opening is provided with the opening on the base metal 2 side, and in (b), the composite l side at the bottom of the groove is welded with weld metal 3 that is compatible with composite material 1. , in (c), if the composite weld metal 3 is stainless steel, the weld metal 5 is a high-alloy type austenitic stainless steel used for dissimilar metal welding, etc., and the composite material is a nickel-based alloy. In this case, the final welding was performed using a weld metal 5 such as a so-called Inconel-based Ni-Cr-Fe alloy. In this case, a large amount of welding material for dissimilar metal welding, which is expensive and has poor weldability, has to be used for welding, and the current situation is that large sacrifices have to be made in terms of economy and efficiency. Furthermore, there were problems in ensuring properties such as deformation and strength due to the large coefficient of thermal expansion.

In addition, Japanese Patent Application Laid-open No. 52-155151 discloses that in welding stainless clad steel, after performing automatic welding of the groove on the carbon steel side with a welding material for carbon steel, the groove to be welded is dug from the stainless steel side. However, a method is disclosed in which economical efficiency is ensured by welding using a welding material that is almost the same as the material stainless steel.

Problems remained, such as that it could not be applied to cases where the inner surface of a small-diameter pipe was made of composite material.

Furthermore, in JP-A-58-167094, in welding stainless clad steel, the composite part is first welded with a filler metal having almost the same chemical composition as the composite material, and C, C, One or more intermediate layers are welded by TIG or MIG welding using filler metals containing Si and T1 and/or Nb, and furthermore, this intermediate layer contains an alloying element equal to or greater than that of the base metal. A method of improving the properties of the weld metal and ensuring economic efficiency by welding up to the final layer with filler metal is disclosed, but the crack resistance of the intermediate layer and the crack resistance of the weld metal on the intermediate layer are Issues remained, such as insufficient support.

As described above, there is a strong demand for a welding method for joining stainless clad steels or nickel-base alloy clad steels without cracking or property deterioration, and without sacrificing economy or efficiency.

[Problems to be Solved by the Invention] That is, the present invention solves the problems of conventional clad steel welding methods, such as difficulty in construction, sacrifices in economy and efficiency, and
This was developed to solve problems in the characteristics of welded parts, and its purpose is to solve problems in the characteristics of welded parts, and its purpose is to
without compromising quality such as corrosion resistance or heat resistance on the cladding side.
The object of the present invention is to provide a welding method that ensures the soundness of a welded part and enables economical and highly efficient welding.

[Means for Solving the Three Problems] The present inventors have discovered that when joining stainless clad steel or nickel-based alloy clad steel, even in cases where the groove and welding procedure cannot be freely adopted, the cladding The purpose of this study was to find a method that would enable economical and highly efficient welding without impairing the properties of the welding material or causing harmful defects such as weld cracks. The details of the resulting method of welding stainless clad steel or nickel-based alloy clad steel together according to the present invention will be explained with reference to the drawings.

In FIG. 1 (a), a V-shaped opening is provided with the opening on the base metal 2 side, and in (b), the composite material 1 side is first welded with the weld metal 3 for the composite material. In (c), on the composite weld metal 3, Cr 20-30%, Mo2-4°5%, Ni4
~13%, C 0.06% or less, N 0.20% or less, and (Ni+30C+20N)/(Cr+Mo) is in the range of 0.20 to 0.70, with the balance consisting of Fe and inevitable impurities. The intermediate layer 4 is formed by welding one or more layers. Intermediate M4 obtained from welding materials in this composition range is resistant to composition fluctuations resulting from melting of the composite stainless steel or Nichel base alloy and melting of the base metal of mild steel or low alloy steel. In (d), the weld metal 5 on the base metal side is strong and does not cause weld cracks. Welding cracks and other harmful defects do not occur, and welding is healthy with good ductility.In other words, it is inexpensive, has good welding workability, and has a strength that matches the base material and has minimal deformation due to welding. It has become clear that it will be possible to use welding materials.

The present invention is based on the above-mentioned new knowledge, and its gist is that in welding stainless steel or nickel-based alloy clad steel, the cladding side is first welded with the welding material for the composite material. , then on top of that composite weld metal,
Cr20-30%, M.

2 to 4.5%, Ni 4 to 13%, G 0.06% or less, N 0.20% or less, and (Ni+30C+20N
)/(Cr+Mo) is in the range of 0.20 to 0°70, the balance is Fe and unavoidable impurities, weld one or more layers to form an intermediate layer, and then weld on the intermediate layer. A welding method for clad steel is characterized in that the base metal side is welded to the final stage using a welding material for the base metal.

Note that the stainless steel used as the composite material herein refers to austenitic, austenite-ferritic, ferritic, martensitic, precipitation hardening stainless steel, etc. specified in Japanese Industrial Standards JIS G 4305 and the like.

The nickel-based alloy used as the composite material is ASME (A+me
rican 5ociety of Mechanic
It refers to the so-called Inconel-based and Hastelloy-based alloys, which are standardized by Al Engineers, etc., and whose main component is nickel.

Welding materials for alloys are JIS Z 3, which is usually used for welding stainless steel together when the composite material is stainless steel.
221.3321. AWS (American We)
lding 5ociety) A5.4. Refers to welding materials standardized by A5.9 etc., and when the composite material is a nickel-based alloy, JIS Z 3224° AWS A5.11. A
Refers to welding materials standardized by 5.14 etc.

Welding materials for base metals are JIS Z 3211゜32 commonly used for welding mild steel or low alloy steel as base metals.
12, 3213.3214.3223.3241.33
11.3312.3313, 3314.3315. A
VS A5.1. A5.5. A5.1? , A5.
23°A5.18. A5.28. A5.20. A
Refers to welding materials standardized by 5.29 etc.

Stainless clad steel or nickel-based alloy clad steel refers to a joining material of the above-mentioned stainless steel or nickel-based alloy and mild steel or low alloy steel, and further contains 20 to 30% Cr, M
o 2 to 4.5%, Ni 4 to 13%, C 0.06% or less, N 0.20% or less, and (Ni + 30C + 20N)
/(Cr100) is in the range of 0.20 to 0.70,
A welding material consisting of the remainder Fs and unavoidable impurities is:
In the case of TIG, MIG, and submerged arc welding methods, this means that the wire composition is within the above range, and in the case of coated arc welding rods, the composition of the deposited metal specified by JIS Z 3221 etc. is within the above range. This means that the ingredients are within the range.

[Function] First, in order to satisfy various properties required of the composite material as clad steel, the cladding side is first welded using the welding material for the composite material as the welding procedure.

In this case, it is desirable to select the groove shape, welding conditions, etc. to avoid dilution from the base metal as much as possible in order to maintain the properties of the weld metal at a higher quality.

Next, regarding the composition of the welding material that forms the intermediate layer on the cladding side weld metal, if the Cr content is less than 20%, the composition will change due to melting the stainless steel or nickel-based alloy as a composite material and melting the base metal. When ecr exceeds 30%, the hot cracking resistance of the intermediate layer becomes insufficient.
The heat affected zone due to welding of the next layer becomes brittle and its ductility and toughness deteriorate, and at the same time, the amount of Cr in the next layer becomes excessive and the ductility of the next layer deteriorates. Therefore, Cr should be 20 to 30%.

If Mo is less than 2%, the hot cracking resistance of the next layer will be insufficient.

If it exceeds 4.5%, the intermediate layer becomes brittle. Therefore, Mo is 2
~4.5%.

If Ni is less than 4%, the heat affected zone due to welding of the next layer will become brittle and the ductility and toughness will deteriorate. At the same time, the next layer becomes brittle and has low ductility. If it exceeds 13%, the intermediate layer will have insufficient high-temperature cracking resistance against compositional fluctuations caused by melting the stainless steel or nickel alloy as a composite material and melting the base material. Therefore, Ni should be 4 to 13%.

If C exceeds 0.06%, the heat affected zone due to welding of the next layer becomes brittle, resulting in deterioration of ductility and toughness. At the same time, the ductility of the next layer deteriorates, so it is limited to 0.06% or less.

If N exceeds 0.2%, welding defects such as blowholes will occur in the next layer and welding workability will deteriorate, so it should be kept at 0.2% or less.

Next, if the value of (Ni+30G+20N)/(Cr+Mo) is less than 0.20, the intermediate layer itself will have a brittle structure with low ductility, and at the same time, the next layer will also have a brittle structure with low ductility.

When it exceeds 0.70, the susceptibility to hot cracking of the intermediate layer and the next layer becomes very large. Therefore, it is set in the range of 0.20 to 0.70.

Furthermore, in order to perform welding using the welding material on the base metal side as the next layer and ensure the soundness of the weld metal, the number of intermediate layers must be 1.
It is effective with multiple layers, and the effect remains the same even with two or more layers.

In addition, for welding the intermediate layer and subsequent layers, appropriate welding materials are used depending on the steel type of the base metal in order to enable inexpensive and highly efficient welding and to maintain properties equal to or better than those of the base metal. In welding using the welding material for the base metal directly above the intermediate layer, in order to prevent cracks from occurring in the weld metal and to ensure other characteristics such as ductility, toughness, and strength, the intermediate layer made of the welding material for the base metal is required. It is desirable to control welding conditions such as current and speed so that the dilution rate from the intermediate layer of the weld metal directly above is 30% or less. Note that the dilution rate from the intermediate layer here refers to the welding material for the base metal. It refers to the percentage of the ratio of the area of the weld metal directly above the intermediate layer to the area of the molten intermediate layer weld metal, and is expressed by the following formula.

D=B/AX 100 However, D: Dilution rate (%) A: Area of the weld metal directly above the intermediate layer due to the base metal welding material (am″) B: Area of the intermediate layer weld metal (■2) As above The present invention provides a welding method in which the cladding side is first welded, then an intermediate layer is formed using a welding material having a specific composition range, and then the base metal welding material is welded to the end of the base metal side. By employing this method, a sound weld can be obtained economically and with high efficiency when joining stainless steel or nickel-based alloy clad steel.

The effects of the present invention will be specifically explained below using Examples.

[Example] Table 1 shows the clad steels tested. In all of these clad steels, the thickness of the composite material is 3 mm, the thickness of the base material is 22 mm, and the clad steel is 25 mm.

Table 2 shows the welding materials used for forming the intermediate layer.

These welding materials with internal symbol f contain less than 4% Ni and (
Ni+30C+20N) / (Cr+No) value is 0
．． If it is less than 20, it is outside the scope of the present invention. , and the welding material with symbol g is (Ni+30C+20N) / (Cr◆Mo)
The value exceeds 0.70 and is outside the scope of the present invention. Furthermore, the welding materials marked with symbols have an MO content of less than 2% and are outside the scope of the present invention.

Table 3 shows the results of joint welding tests between clad steels and the combinations of these clad steels and intermediate layer forming materials.

The groove shape is v-shaped as shown in Figure 1 (a), and first, weld the composite material 1 side using a welding material compatible with composite material 1 as shown in Figure 1 (b) and Table 3. Alternatively, Uranami welding was performed using a circular arc to obtain composite weld metal 3. For Uranami welding with TIG, wire diameter 2.4eu*, welding current 1
20A, welding voltage 12■, welding speed 8cm/+min
, Manual welding was performed at a shielding gas flow rate of 20 Q/win. In addition, in the case of Uranami welding using a covered arc, the rod diameter is 4. Manual welding was performed at a welding current of 120 A, a welding voltage of 24 V, and a welding speed of 8 cm/win.

Second, as shown in FIG. 3(c), zero to two layers of intermediate layer weld metal 4 were formed on composite weld metal 3 in the manner shown in Table 3. In the case of covered arc welding, the rod diameter is 4.0 mm, welding current 140 A, welding voltage 24 V, and welding speed 15 am/win.
Manual welding was performed. For MIG welding, wire diameter 1,
2mm, welding current 220A, welding voltage 22V, welding speed 20cm/win, Ar shielding gas flow rate 20g
/@in semi-automatic welding was performed. For TIG welding,
Wire diameter 2.4+am, welding current 160A, welding voltage 1
Semi-automatic welding was performed at a voltage of 2V, a welding speed of 13 cm/+min, and an Ar shielding gas flow rate of 20 Q/win. In the case of C01 welding with flux-cored wire, the wire diameter is 1.2 mm, the welding current is 220 A, the welding voltage is 20 V, the welding speed is 20 cm/win, and C0. Shield gas flow rate 20
Semi-automatic welding of Q7 heavy-in was performed.

Thirdly, as shown in Figure 1 (d), weld metal 5 is laminated on intermediate layer weld metal 4 using a base metal welding material that is compatible with the base metal as shown in Table 3, and welded to the final stage. Ta. In the case of covered arc welding, the rod diameter is 5. Omm, welding current 190~2
40A, welding voltage 24~28v, welding speed 14~25
Manual welding was performed at cm/win. For MIG welding, wire diameter is 1.2+m, welding current is 220-290A, welding voltage is 18-22V, welding speed is 20-30cm/win,
Ar+ 10% CO2 shielding gas flow rate 20 Q/
Semi-automatic welding of min. For CO□ welding with flux-cored wire, wire diameter is 1 mm, 2 mm, welding current is 200 to 280 A, welding voltage is 18 to 22 mm, welding speed is 20 to 30 cm/win, Go, and shielding gas flow rate is 2.
Semi-automatic welding of 0 n/win was performed.

In order to evaluate the soundness of the intermediate layer, a color check test was performed on the first layer weld metal to check for cracks, and to evaluate the soundness of the layer immediately above the middle layer, a color check test was performed to check for cracks. Furthermore, in order to evaluate the soundness of the entire clad steel joint weld after completion of all welding, JIS Z 31
A side bending test based on JIS Z 3121 and a joint tensile test based on JIS Z 3121 were conducted.

Results of these clad steel joint welding tests 1 Welding method test No. of the present invention, 1.2.4.5.6.8.9.10.12
+3.15.16.17.19.20.21.23 and 24 had no cracks in the intermediate layer or the layer directly above the intermediate layer, and showed sufficient ductility with no defects in the side bending test. Furthermore, in the joint tensile test, the clad steel was fractured in the original part, and it is clear that it has a strength greater than that of the base metal.

On the other hand, in test N003, welding on the base metal side was performed using high-alloy type austenitic stainless steel welding material AWS 1.
11309, the deformation caused by welding was large and the weldability was poor, resulting in welding defects in the side bending test.

1 wiping test No. 7 is welding of the intermediate layer (Ni+30C+2
Since the welding material for forming the intermediate layer was used with a value of 0N)/(Cr+Mo) exceeding 0.70, a 1-year tear occurred in the intermediate layer and the layer directly above the intermediate layer, and cracks were also observed in the bending test on one side. Occurred. Furthermore, in the joint tensile test, the weld metal broke and there was also a problem with the strength.

In test No. 11, the intermediate layer was welded using an intermediate layer forming welding material containing less than 4% Ni and the value of (Ni + 30C + 20N) / (Cr + Mo) less than 0.20, so the intermediate layer and the intermediate layer were directly welded. Cracks occurred in the upper layer and also in the side bending test. Furthermore, in the joint tensile test, the weld metal broke and there was also a problem with the strength.

In test No. 14, welding on the base metal side was performed using the Ni-Cr-Fe alloy welding material is ENiCrFe-3, so the deformation caused by welding was large and the weldability was poor, resulting in welding defects in the side bending test. did. Furthermore, in the joint tensile test, the weld metal broke and there was also a problem with the strength.

In test No. 18, the base metal welding material was welded directly onto the cladding side weld metal without forming an intermediate layer, so cracks occurred in the layer directly above the cladding side weld metal, and cracks were also observed in the side bending test. There has occurred. Furthermore, in the joint tensile test, the weld metal broke, and there were also problems with the strength.

In test No. 22, because the intermediate layer was welded using an intermediate layer forming welding material containing less than 2% Mo, cracks occurred in the intermediate layer and the layer directly above the intermediate layer, and cracks also occurred in the side bending test. did. Furthermore, in the joint tensile test, the weld metal broke and there was also a problem with the strength.

Test No. 25 welded the intermediate layer (Ni+30C+20
Since a welding material for forming an intermediate layer having a value of N)/(Cr+Mo) exceeding 0.70 was used, cracks occurred in the layer immediately above the intermediate layer, and cracks also occurred in the side bending test.

Furthermore, in the joint tensile test, the weld metal broke and there was also a problem with the strength.

[Effects of the Invention] As described above, the present invention provides 1. In welding stainless steel or nickel-based alloy clad steel, first welding the clad side with a welding material normally used for welding the materials together;
Next, an intermediate layer is formed using a welding material with a specific composition range on top of the composite weld metal, and then the base metal side is welded to the final stage with a welding material for the base metal, so that the deformation is minimal and the welding material is welded to the base metal. It makes it possible to economically and efficiently obtain extremely sound welds with the same or better properties,
This makes a wide range of stainless clad steels or nickel-based alloy clad steels truly economical steels.

[Brief explanation of the drawing]

Figures 1 (a), (b), (c), and (d) are illustrations of the welding method of the present invention, and Figures 2 (a), (b), and (c) are illustrations of the conventional welding method from the base metal side. Figures 3(a), 3(b), and 3(c) are explanatory diagrams of the conventional welding method from the composite material side. 1: Composite material, 2: Base material, 3: Composite weld metal, 4: Intermediate layer,
5: Base metal side weld metal. Patent applicant Nippon Steel Corporation

Claims (1)

[Claims] When welding clad steel with mild steel or low alloy steel as the base material and stainless steel or nickel-based alloy as the composite material, the cladding side is first welded with a welding material for the composite material, and then the composite weld metal is welded. On top of that, Cr20-30% in weight%, Mo2
~4.5%, Ni4~13%, C0.06% or less, N0
．． 20% or less and (Ni+30C+20N)/(Cr
+Mo) is in the range of 0.20 to 0.70, and the balance is Fe
A method for welding clad steel, characterized by forming an intermediate layer by welding one or more layers with a welding material containing unavoidable impurities, and then welding the base metal side with the welding material for the base metal.