JPH11285890A - High c/high cr-ni based welding rod - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a welding rod for automatic welding that uses, as a welding base material, a high C/high Cr-Ni based alloy member such as a cracking tube for manufacturing ethylene. SOLUTION: This welding rod is so constituted that a Cr-Ni alloy plate or the like suitable for wire drawing is used as a sheath material, with which a high C/high Cr alloy powder is covered to form a base wire material, and which is further formed to have a desired wire diameter by drawing. The chemical composition (total value of the sheath material and the alloy powder) consists of, in weight %, 0.15-1% C, 3% or less Si, 3% or less Mn, 40-55% Cr, 10% or less Fe, and the balance Ni, and further adjustably contains, if desired, at least one kind of element selected from the group of Nb, W, Mo, Ti, Zr and B, and/or at least one kind of element selected from the group of Al, Ca, Hf, and Y.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-C, high-Cr-N material such as a cracking tube for a reactor for producing ethylene and a heating tube (reheater tube) for a reheater furnace of direct reduction steelmaking.
The present invention relates to a welding rod used for welding an i-type alloy member.

[0002]

2. Description of the Related Art As a material for the above cracking tube and Richter tube, HK40HiSi material (C 0.35-0.45%, Si 1.5-2.0%, C
r 23-27%, Ni 19-22%), HP material (C 0.35-0.75%, Cr 24-
28%, Ni 33-37%) and its improved material (HP-Nb, W, Mo), or a 0.45C-35Cr-45Ni-Nb alloy has been used. Welding rods used for welding such as forming pipe joints using such pipe materials as the welding base material, overlay repair, etc., must have the same chemical composition as the welding base material,
Further, as a welding rod for performing automatic welding such as TIG welding and MIG welding, a thin wire having a wire diameter of about 1 to 2 mm is required. As the welding rod, a thin wire manufactured by wire drawing is industrially supplied.

[0003]

Recently, as an improving material for the cracking tube or the like, C is about 0.15% or more.
The use of a high C, high Cr-Ni heat resistant alloy material having a composition of about 40 to 55% Cr and about 40 to 55% Ni is expected. The welding rod used for welding using this high alloy material as a welding base material has the same high C.I. It is important to have a high Cr-Ni composition. However, a welding rod having a high C and high Cr-Ni composition in which the Cr content exceeds about 40% and the C content exceeds about 0.15% is extremely hard and brittle, and is necessary for TIG welding, MIG welding, and the like. It is impossible to produce a wire with a small diameter by wire drawing. For this reason, it is inevitable to use, as the above-mentioned welding rod, a ring-shaped thin piece cut out of a cast material (centrifugally cast pipe or the like) adjusted to a required chemical composition, which is extremely uneconomical. The present invention solves the above problems, and provides a high C / high Cr-Ni welding rod that is efficiently manufactured as a wire having a desired wire diameter by drawing.

[0004]

According to the present invention, high C and high Cr-
The Ni-based welding rod is a welding rod formed by encapsulating a high-C / high-Cr alloy powder in a sheath material made of a Cr-Ni-containing alloy plate that can be drawn and forming the wire to a required wire diameter by drawing. The total chemical composition (weight%, hereinafter the same) of the sheath material and the alloy powder is as follows: C: 0.15% to 1%, Si:
3% or less, Mn: 3% or less, Cr: 40 to 55%, Fe:
10% or less, with the balance substantially consisting of Ni.

[0005] The welding rod of the present invention, if desired, together with the above elements, (i) Nb: 1-4%, W: 0.5-3%, M
o: 0.5-3%, Ti: 0.02-0.5%, Zr:
0.01 to 0.5%, B: one or more elements selected from 0.005 to 0.05%, and / or (ii) Al: 0.02 to 0.5%, Ca : 0.001
A chemical composition containing one or more elements selected from 0.5%, Hf: 0.5% or less, and Y: 0.5% or less is provided. The elements of the group (i) are effective for improving the creep properties and the like, and the elements of the group (ii) are effective for improving the carburization resistance and the like.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A welding rod according to the present invention is a Cr-Ni alloy capable of drawing hard and brittle high C / high Cr content alloy.
It can be efficiently manufactured as a wire having a required wire diameter suitable for TIG welding, MIG welding, or the like by wire drawing, having a form wrapped by a contained alloy plate (sheath). The chemical composition (total composition of the alloy powder and the sheath material) of the welding rod of the present invention is arbitrarily adjusted according to the chemical composition of the alloy powder and the sheath material and the ratio between the two.

The sheath material is, for example, a Cr—Ni alloy plate,
Stainless steel plate, etc., especially a Cr-Ni alloy with a Cr content of 18-30%, SUS 304 (Ni 8-10.
Stainless steel plates such as 5%, Cr 18-20%) and SUS 310 (Ni 19-22%; Cr 24-26%) are also suitable sheath materials because they can be easily melted.

The alloy powder encapsulated in the sheath material is C:
0.15-1.5%, Si: 1-4%, Mn: 1-4
%, Cr: 65 to 75%, Fe: 10% or less, balance Ni
Is a basic component because of ease of melting. The alloy powder is provided with a composition containing various elements as desired, and the specific chemical composition is set according to the target chemical composition of the welding rod (the total composition of the sheath material and the alloy powder).

The reasons for limiting the component composition of the welding rod of the present invention are as follows. C: 0.15% to 1% C is an element that increases the high-temperature strength of the deposited metal, particularly the creep rupture strength, and requires 0.15% or more. The effect is increased by increasing the amount, but if it exceeds 1%, the weld metal becomes hard and embrittled, so this is made the upper limit.

Si: 3% or less Si imparts carburizing resistance required for cracking tubes and the like to the deposited metal. If the addition amount exceeds 3%, the weldability deteriorates, so this is made the upper limit. Mn: 3% or less Mn has a deoxidation and desulfurization action of a molten bead during welding. This effect is ensured by the content of 3% or less,
There is no need to increase further.

Cr: 40 to 55% Cr is an element which is usually added in an amount of about 20 to 30% as an element for improving the oxidation resistance, high-temperature strength, etc. of a heat-resistant alloy, but by increasing this to 40% or more. In addition, the carburization resistance required for cracking tubes and the like is significantly enhanced. 55
%, The ductility of the deposited metal in a high-temperature use environment tends to decrease significantly.

Fe: 10% or less Fe is not an essential constituent element, and if it is 10% or less, there is no substantial adverse effect on the material of the deposited metal. This broadens the selection range of the alloy powder and the sheath material, which are components of the welding rod, and is advantageous for cost reduction.

The welding rod of the present invention is provided with a composition containing at least one element selected from the following element group, if desired.

Nb: 1 to 4% Nb forms carbides and double carbides such as NbC and (Nb, Ti) C and precipitates at crystal grain boundaries, strengthens grain boundary fracture resistance in high-temperature creep, and increases creep. Increase rupture life.
In addition, it has an effect of improving the resistance to welding cracking. To obtain these effects, at least 1% is required. 4%
If it exceeds, the creep rupture strength decreases, so this is made the upper limit.

W: 0.5-3% W substitutes and dissolves in the austenitic matrix of the deposited metal,
Some of them precipitate at the grain boundaries and increase the high-temperature strength of the deposited metal, especially the creep rupture strength. This effect can be obtained by adding 0.5% or more, and the carburization resistance is improved as the amount is increased. Excessive addition impairs the ductility of the deposited metal, so the upper limit is 3%.

Mo: 0.5 to 3% Mo enhances the high-temperature strength by the action of solid solution strengthening of the austenite matrix and the strengthening of grain boundaries by the formation of Cr-Mo double carbides. This effect can be obtained by adding 0.5% or more. If a large amount is added, excessive precipitation of double carbides causes a decrease in tensile ductility, so the upper limit is 3%.

Ti: 0.02 to 0.5% Ti suppresses the growth and coarsening of the secondary Cr carbide in a high temperature environment and increases the high temperature creep rupture strength. Also, Al
In a component configuration in which is present, carburization resistance is enhanced as a synergistic effect with Al. This effect can be obtained by adding 0.02% or more. If it exceeds 0.5%, the effect is almost saturated,
In addition, the creep rupture strength is reduced.

Zr: 0.01-0.5% Zr solid-solution strengthens the austenite matrix and increases the high temperature creep rupture strength. Also improves thermal shock resistance. To obtain this effect, 0.01% or more is required. 0.5
%, The creep rupture strength is reduced due to a decrease in cleanliness due to an increase in the amount of Zr oxide.

B: 0.005 to 0.05% B strengthens the crystal grain boundaries of the deposited metal and increases the high temperature creep rupture strength. This effect can be obtained by adding 0.005% or more. If it exceeds 0.05%, the weldability will deteriorate.

Al: 0.02 to 0.5% Al forms a dense oxide film on the surface of the deposited metal in a high temperature environment, and enhances the oxidation resistance and carburization resistance of the welded portion. This effect can be obtained by adding 0.02% or more. If a large amount is added, the weldability and elongation characteristics will decrease.
The upper limit is 0.5%.

Ca: 0.001 to 0.5% Ca forms an oxide film on the surface of the deposited metal in a high temperature environment, and enhances carburization resistance. This effect can be obtained by adding 0.001% or more. However, if added in large amounts, the weldability is impaired, so the upper limit is 0.5%.

Hf: 0.5% or less Hf enhances carburization resistance. The amount of addition to obtain this effect is sufficient up to 0.5%, and an increase of more than that will impair economic efficiency. Y: 0.5% or less Y is effective in improving carburization resistance similarly to the above Hf. This effect can be sufficiently obtained by adding 0.5% or less,
There is no benefit to add beyond that.

Ni: balance component Ni is a main component element forming an austenite matrix of the deposited metal, and is an element necessary for securing the oxidation resistance and the carburizing resistance of the deposited metal in a high temperature range.

The welding rod of the present invention is manufactured by wrapping an alloy powder in a sheath material to form a wire having an appropriate cross-sectional diameter, and performing drawing. As the alloy powder, a powder obtained by a SWAP method (spinning water atomizing process) or other various manufacturing methods is appropriately used. The particle size of the powder is preferably about 75 to 250 μm from the viewpoint of the filling property into the sheath material, the fluidity at the time of drawing, and the like. The filling rate of the powder to be encapsulated in the sheath material (weight ratio of the alloy powder to the welding rod) is suitably about 35 to 40%. The wire drawing of the element wire is performed according to a conventional method of drawing with a die. The drawing rate (area reduction rate) is, for example, 30 to 8
0%. As a result, a wire having a desired wire diameter and an amount ratio of the alloy powder and the sheath material is finished.

[0025]

[Example] [1] Production of welding rod (alloy powder) Composition: C 0.86, Si 2.15, Mn 2.93, Cr 70.3, Ni 10.
9, Nb 4.68, Ti 0.46.Zr 0.23, Fe Bal (wt%) Grain size: 75-250 μm (sheath material) Grade: 20Cr-80Ni alloy plate Plate thickness: 0.35 mm

The above alloy powder (by the SWAP method) is wrapped in a sheath material to form a strand (outer diameter: 3 mm), and is subjected to cold drawing (reduction in area: 70%) using a die to form a welding rod ( Wire diameter 1.
6 mm).

[2] Welding test A centrifugally cast pipe made of a high Cr-Ni alloy is used as a welding base material, and a butt pipe joint is formed by TIG welding. (1) Base metal tube composition: C 0.30, Si 2.00, Mn 0.42, Cr 40.0, Ni 47.7,
W 1.45, Ti 0.23, Zr 0.07, Fe Bal (wt%) Size: outer diameter 72.5, wall thickness 6.85.

(2) Welding method: GTAW (downward manual welding) (3) Groove shape: U type (groove angle 20 °, bevel angle 10 °,
Groove depth 5.25mm, root radius 4mm, root thickness 1.6mm,
Route interval 0). (4) Welding conditions: current 105A (first layer), 90-120A (2-5
Layer). Voltage 15V (first layer to 5 layers).

[3] Weld quality (1) Composition of weld metal (center position of weld metal) C 0.32, Si 1.81, Mn 1.27, Cr 40.7, Ni 49.5, Nb 1.5
9, Ti 0.09, Zr 0.04, Fe Bal (wt%) (2) Weld color check: no defects

(3) Result of mechanical test of welded part A test piece (parallel part diameter: 5.99 mm) was cut out from the welded part and subjected to a creep rupture test to obtain the results shown in FIG. The horizontal axis P is the Larson-Miller parameter [T: specimen temperature (° K), tr:
Rupture time (Hrs), stress: MPa). In the figure, ○ indicates the creep rupture strength of the welded portion, the solid line indicates the average strength of the base material, and the broken line indicates the minimum strength of the base material. As described above, by using the welding rod of the present invention, automatic welding has been successfully achieved, and sound welding quality has been ensured.

[0031]

The high C / high Cr-Ni welding rod of the present invention can be efficiently manufactured at low cost by wire drawing.
Adjustment of the desired composition and wire diameter can be easily and arbitrarily performed. The welding rod of the present invention can be used for TIG welding, MIG welding, etc. for the piping configuration of high C / high Cr-Ni alloys, which is expected as a cracking tube for ethylene production or a reheater tube material for direct reduction steelmaking. It is useful as a welding rod for plasma welding, etc.
This enables improvement and stabilization of welding quality.

[Brief description of the drawings]

FIG. 1 is a graph showing a creep test result of a welded portion of a welding test material.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI B23K 35/40 310 B23K 35/40 310Z C22C 27/06 C22C 27/06

Claims (4)

[Claims] 1. A welding rod formed by encapsulating a high-C / high-Cr alloy powder in a sheath material made of a Cr—Ni-containing alloy plate that can be drawn and forming it into a required wire diameter by drawing. , The total chemical composition of the sheath material and the alloy powder is
% By weight, C: 0.15 to 1%, Si: 3% or less, M
n: 3% or less, Cr: 40 to 55%, Fe: 10% or less, and the balance is substantially composed of Ni.
-High Cr-Ni welding rod. 2. A welding rod formed by encapsulating a high C / high Cr alloy powder in a sheath material made of a Cr—Ni-containing alloy plate capable of being drawn and forming the wire to a required wire diameter by drawing. , The total chemical composition of the sheath material and the alloy powder is
% By weight, C: 0.15 to 1%, Si: 3% or less, M
n: 3% or less, Cr: 40 to 55%, Fe: 10% or less, Nb: 1 to 4%, W: 0.5 to 3%, Mo:
0.5-3%, Ti: 0.02-0.5%, Zr: 0.
01-0.5%, B: contains one or more elements selected from 0.005-0.05%, and the balance is substantially composed of Ni. Cr-Ni
System welding rod. 3. A welding rod formed by encapsulating a high C / high Cr alloy powder in a sheath material made of a Cr—Ni-containing alloy plate capable of being drawn and forming it into a required wire diameter by drawing. , The total chemical composition of the sheath material and the alloy powder is
% By weight, C: 0.15 to 1%, Si: 3% or less, M
n: 3% or less, Cr: 40 to 55%, Fe: 10% or less, Al: 0.02 to 0.5%, Ca: 0.00
1 to 0.5%, Hf: 0.5% or less, Y: 0.5% or less, containing at least one element selected from the group consisting of substantially Ni. High C, high C
r-Ni welding rod. 4. A welding rod formed by encapsulating a high C / high Cr alloy powder in a sheath material made of a Cr—Ni-containing alloy plate that can be drawn and forming it into a required wire diameter by drawing. , The total chemical composition of the sheath material and the alloy powder is
% By weight, C: 0.15 to 1%, Si: 3% or less, M
n: 3% or less, Cr: 40 to 55%, Fe: 10% or less, Nb: 1 to 4%, W: 0.5 to 3%, Mo:
0.5-3%, Ti: 0.02-0.5%, Zr: 0.
01 to 0.5%, B: one or more elements selected from 0.005 to 0.05%, Al: 0.02 to
0.5%, Ca: 0.001 to 0.5%, Hf: 0.5
% Or less, Y: one or more selected from 0.5% or less
A high-C, high-Cr-Ni-based welding rod comprising at least one element and the balance substantially consisting of Ni.