JP3112447B2 - Composite wire for hardfacing self-shielded arc welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite wire used for hardfacing hard-to-wear parts such as rollers and tables of a crusher for coal, ore, scouring slag and the like by self-shielded arc welding. is there.

[0002]

2. Description of the Related Art Rollers and tables of pulverized coal production machines used in thermal power plants are difficult to manufacture entirely from wear-resistant special cast iron due to the enlargement of the equipment, and are economically disadvantageous. In recent years, however, hardfacing welds on ordinary steel materials have been used. Most of the hardfacing welding performed in the manufacturing process of such parts is performed by submerged arc welding.
% And Cr is 20%. Since it is impossible to use an iron material having such a component to have flexibility as a welding wire, a composite wire in which powder of a required alloy component is filled inside with a mild steel or the like as an outer skin. Is common.

For example, Japanese Unexamined Patent Publication (Kokai) No. 59-141396 entitles "High Chromium Tubular Wire for Latent Arc Welding", and describes a submerged arc welding method capable of obtaining a build-up deposited metal having good wear resistance and hardly peeling off. Composite wire is disclosed. According to this, C: 2.0-5.0%, Si:
0.1-1.5%, Mn: 0.2-3.0%, Cr: 1
5.0-28.0%, B: 0.3-1.5%,
Further, if necessary, Mo: 5.0% or less, V: 5.0%
Hereinafter, it is a component containing one or more of Nb: 5.0% or less and Zr: 0.5% or less. As a countermeasure against the generation of cracks, which is a major problem of such a material, the feature is that the content of carbon in a free state such as graphite as a carbon source is set to 1.0% or less by weight% based on the entire wire. . However, this has not completely solved the problem, and if the hardness is increased to further increase the wear resistance, the problem of crack generation increases accordingly.

As described above, the composite wire for overlay welding is generally intended for submerged arc welding, and even in the patent application of the hardfacing welding wire other than the above, it is not necessary to limit the wire for submerged arc welding. In most of the examples, only data on submerged arc welding is described. By the way, even such wear-resistant parts are inevitable to be worn by use, and the worn parts are regenerated on site by repair welding. In this case, there is no need to use a positioner or the like to level the welding point as in submerged arc welding. Welding) is often used. The welding wire used in this case is the same as that in the case of submerged arc welding as an alloy component, and is not particularly different.

[0005]

Even if the above-mentioned repair welding of the worn parts is performed, the wear is naturally repeated, and in the case of the parts of the pulverized coal producing machine used in the thermal power plant, the repair is performed again in about one year. I do. In such a case, since the line is completely stopped during the inspection and repair period, extending the wear life is a major issue. The present invention provides a welding wire which can provide a weld metal having an excellent wear life and is particularly suitable for performing hardfacing by self-shielded arc welding.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems. In a composite wire for hardfacing self-shielded arc welding comprising a tubular sheath and a filler, a chemical component is contained in a weight% with respect to the total weight of the wire. And C: 4-7%,
Si: 0.2 to 2.0%, Mn: 0.2 to 2.0%, C
r: 20 to 28%, Ni: 1 to 5%, Mo: 1 to 5%, further contains at least one of Al: 3% or less, Ti: 3% or less, and the balance is a slag forming agent, Fe And a composite wire for hardfacing self-shielded arc welding characterized by being an unavoidable impurity. It also has a tubular shell
Hardfacing self-shielded arc welding consisting of steel and filler
In composite wire, the chemical composition is based on the total weight of the wire
% By weight, C: 5-6%, Si: 0.2-2.0%, M
n: 0.2 to 2.0%, Cr: 20 to 28%, Ni: 1
-5%, Mo: 1-5%, and Al: 3% or less
Lower, at least one of Ti: 3% or less, and Nb: 1
-4%, V: at least one of 1-4%, the balance being
Is a slag forming agent, Fe and inevitable impurities
Characteristic composite wire for hardfacing self-shielded arc welding
It is unpleasant. Further, each of the above-mentioned wires is characterized by containing W: 0.5 to 4% as required.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The composition of a weld metal obtained by overlay welding using the welding wire of the present invention is a high-carbon high-chromium-based iron alloy. The same is true. However, the conventional general idea is disclosed in Japanese Patent Laid-Open Publication No.
No. 96, high carbon and high chromium iron alloy
By adding carbide-forming elements such as o, V, and Nb, the hardness is increased only to improve the wear resistance. However, according to the knowledge of the present inventors, in a high-carbon high-chromium-based iron alloy, even if the hardness is increased, not only the welding susceptibility is increased by increasing the crack sensitivity of the weld metal, but also the wear resistance is not necessarily improved. It turned out that it was not connected. This is considered to be due to the fact that when there is a fine crack in the build-up weld metal, the material is peeled off and the wear proceeds.

When the hardness is high, the grinding finish after the overlay welding becomes correspondingly difficult. As described above, in the overlay welding of a high-carbon high-chromium iron alloy, it is not advisable to simply increase the hardness to improve the wear resistance. Therefore, the present inventors have studied a method of suppressing the abrasion due to material peeling while improving the toughness while sufficiently maintaining the hardness of the weld metal. As a result, it was found that the addition of Ni was effective in improving the toughness of the weld metal of the high-carbon high-chromium iron alloy. Ni is known to have the effect of improving the toughness by forming a solid solution in the ferrite phase in steel materials, but this is not the case in the overlaid metal of the pig iron component mainly composed of a carbide phase having a carbon content of about 4%. No such effect was known. Rather, the addition of Ni to the high-carbon high-chromium iron alloy for overlay welding promotes the tendency of weld cracking,
Therefore, it was generally considered to be harmful to toughness. For this reason, at present, high-carbon, high-chromium-based iron alloy wires for overlay welding containing Ni are not manufactured.

Under such circumstances, the present inventors
Certainly, in the overlay by submerged arc welding, N
The addition of i promotes the tendency of weld cracks to occur, but this is not the case in overlaying by self-shielded arc welding, and has been found to have the effect of improving toughness and suppressing wear due to material peeling. is there. It is not clear why such a difference occurs between submerged arc welding and self-shielded arc welding.However, in submerged arc welding, even if the bead surface is covered with thick slag and the welding heat input is not very different, the welding metal It is considered that the speed of solidification and cooling is slow, and the structure of the weld metal is different between the two.

[0010] The hardfacing welding wire of the present invention further comprises Mo in addition to the above-mentioned Ni in a high-carbon high-chromium iron alloy.
Is added to form a high-hardness carbide together with Cr to improve wear resistance. In particular, by adding W, the wear resistance can be further improved due to the combined effect with Mo. Further, if necessary, Nb and / or V can be added to generate these carbides to improve wear resistance. The reasons for limiting each component are described below.

[0011] C combines with Cr, Mo, W and the like to form a carbide of high hardness, and increases the hardness of the weld metal to improve wear resistance. If the C content in the wire is less than 4%, crystallization or precipitation of carbides is small, and the wear resistance becomes insufficient. On the other hand, when it exceeds 7%, the tendency of the weld metal to crack is increased, and the peeling wear due to embrittlement is promoted. Therefore, the range of the amount of C is set to 4 to 7%.
６6%. Since it is impossible to add such an amount of C from the outer shell, C is contained in the filler. However, in addition to simple carbon such as graphite, carbon such as high-carbon ferrochrome, high-carbon ferromanganese, and chromium carbide. Can be added from an alloy material containing.

Si is a deacidifying element. Particularly, in self-shielded arc welding in which there is no means for shielding from the atmosphere except for the welding wire itself, Si is necessary to reduce oxygen in the weld metal and clean it. It is. Si also has the effect of forming slag and improving welding workability. If the Si content in the wire is less than 0.2%, blowholes may be generated in the weld metal due to insufficient deoxidation. On the other hand, if the Si content is more than 2.0%, weld cracks are likely to occur, and welding workability is also increased. become worse. Therefore, the range of the amount of Si is set to 0.2 to 2.0%, particularly preferably 0.5 to 2.0%.
1.5%. Part of Si enters from the outer skin, but most of the Si is added to the filler. In addition to metal Si, powder of ferro-silicon or ferro-alloy such as silicomanganese is used.

Mn is a deacidifying element and an element effective for preventing high-temperature cracking caused by S for increasing the melting point of sulfide. When Mn in the wire is less than 0.2%, blow holes are likely to occur due to insufficient deoxidation, while
If it exceeds 2.0%, welding cracks are likely to occur, and the wear resistance also decreases. Therefore, the range of the amount of Mn is 0.2 to 2.0.
%, Particularly preferably 0.5 to 1.5%. Mn is added in such a manner that metal manganese, ferromanganese, silicomanganese or the like is added to the filler as required, in addition to the amount from the outer skin.

Cr is an element that improves the wear resistance by crystallizing or precipitating chromium carbide having high hardness, and is a major alloying component in the welding wire of the present invention. If the Cr content in the wire is less than 20%, the amount of carbide is small and the wear resistance becomes insufficient. On the other hand, if it exceeds 28%, the hardness of the carbide decreases and the wear resistance decreases. Therefore, the range of the amount of Cr is set to 20 to 28%, and particularly preferable is the range of 22 to 28%.
26%. Cr is added by adding metallic chromium, ferrochrome, etc. to the filler, but can also be added from the outer skin by using stainless steel instead of mild steel.

As described above, Ni improves the toughness of the weld metal in self-shielded arc welding, suppresses wear due to peeling of the material, and improves wear resistance. If the amount of Ni in the wire is less than 1%, the effect of improving the wear resistance is insufficient, and if it exceeds 5%, the effect of improving the wear resistance is not improved, which is uneconomical. Therefore, the range of the Ni content is 1 to 5%, and particularly preferably 2 to 4%.
Ni is usually added to the filler, but can also be added from the outer skin.

Mo forms carbides of high hardness to improve wear resistance. If the amount of Mo in the wire is less than 1%, the effect is insufficient, and if it exceeds 5%, the effect is not improved much and it becomes uneconomical. Therefore, the range of the Mo amount is 1 to 5%.
The content is particularly preferably 2 to 4%. Mo can be added by adding ferromolybdenum or the like to the filler.

Al is an element inevitably contained to some extent from the additives of other elements such as ferrosilicon, but in order to clean the weld metal by the deoxidizing and denitrifying effects in self-shielded arc welding, a filler is further added. Is preferably added. Ti also has a deoxidizing and denitrifying effect similarly, and an effect can be obtained by adding at least one of them. It is appropriate that the amount of Al in the wire is 3% or less and the amount of Ti is 3% or less. If the amount exceeds 3%, the excess will remain in the weld metal and deteriorate the toughness. Particularly preferred ranges of the Al amount and the Ti amount are each 0.5 to 1.5%.

In addition to the above elements, the following components can be added as needed to further improve the characteristics. W forms a carbide with high hardness together with Mo to improve wear resistance. If the amount of W in the wire is less than 0.5%, the effect is small, and if it exceeds 5%, the effect is not improved much and it is uneconomical. Therefore, the range of the W amount is W: 0.5 to 5%, and particularly preferably 2 to 4%. W can be added by adding ferrotungsten or the like to the filler.

Nb and V form carbides and improve wear resistance. In each case, the content in the wire is 1
If it is less than 4%, the effect is small. On the other hand, if it exceeds 4%, the improvement of the effect is small and uneconomical. Therefore, Nb: 1
-4%, V: 1-4%.

The alloy components of the welding wire of the present invention are as described above, and the balance is Fe and inevitable impurities. However, a flux component is generally added to the filler as a slag forming agent for a self-shielded arc welding wire. May be. This is different from submerged arc welding in that flux is not used separately from the wire, so that the flux component is supplied from the wire itself. Materials include, for example, calcium carbonate, calcium fluoride, sodium fluoride,
Silica sand can be used. The appropriate amount of addition of these flux components is 1 to 4% of the total weight of the wire.

The composite wire of the present invention comprises a tubular sheath and a filler. The filling rate, that is, the ratio of the filler to the total weight of the wire, is usually in the range of 30 to 50%. Regardless of the manufacturing method, any of a method with a seam having a seam in the length direction of the wire and a method without a seam that is completely sealed may be used. Those with a seam are manufactured by supplying a filler while continuously bending a hoop, which is a material of the outer skin, into a U-shape, and folding and hulling both sides of the hoop as needed. For those without seams, feed the filler while continuously bending the hoop into a U-shape, round it into a circular shape, butt the sides of the hoop, weld continuously, and then draw the wire, or vibrate the material tube It is manufactured by a method of supplying and filling a filler from one end thereof while drawing and drawing the filler.

[0022]

EXAMPLE A hoop of one type of cold-rolled steel strip specified in JIS G3141 was used as a material for the outer skin, and a filler of various test components was supplied while continuously bending the hoop into a U-shape. Both sides were folded and rounded to obtain a composite wire. The wire diameter is 3.2 mm and the filling rate of the filler is about 40%. The components of the wire are shown in Table 1. These are the alloy component amounts of the outer shell and the filler with respect to the total weight of the wire. 1.8% of calcium iodide is added. Overlay welding tests were performed by self-shielded arc welding using these wires. The welding method is as follows: JIS SUS309 stainless steel (22% Cr-1)
After underlay welding of a material equivalent to 2% Ni) by carbon dioxide gas arc welding, overlay welding of a 20 mm thick multilayer overlay was performed in a range of 90 mm × 200 mm. The welding conditions were as follows: arc voltage: 29 V AC, arc current: 400 A, welding speed: 5
0 cm / min, and the temperature between passes is 200-350.
° C.

[0023]

[Table 1]

The test pieces subjected to overlay welding were subjected to a hardness measurement (Rockwell C scale) and a wear test. The abrasion test used the rubber wheel tester shown in FIG. In FIG. 1, 1 is a diameter 200 wound with rubber.
The rubber wheel is rotating at 50 rpm. On the other hand, the test piece 2 is given a predetermined pressing load by the weight 3 and pressed against the rubber wheel 1.
In this test, the pressing load was 196 N (20 kg).
f). At this time, 260 g / min of silica sand was dropped from the hopper 4 between the rubber wheel 1 and the test piece 2. The test was performed for 1 hour, that is, until the total number of revolutions of the rubber wheel reached 3000 times. Table 1 shows the results of the hardness measurement and the abrasion test together with the above wire components.

In Table 1, Nos. 1 to 8 are obtained by overlay welding using the composite wire for welding of the present invention, and all show good wear resistance. On the other hand, numbers 9 to 15 are comparative examples. Numbers 9 and 10
Since Ni is not added, abrasion due to peeling of the material is large and abrasion resistance is poor. No. 11 has low hardness and poor abrasion resistance because Mo is not added. Also number 12
Is too low in hardness, and has poor wear resistance. On the other hand, in the case of No. 13, the hardness is low and the wear resistance is poor because Cr is insufficient. In the case of No. 14, too much C causes the material to be brittle and has poor wear resistance due to peeling wear. On the other hand, number 1
Sample No. 5 has insufficient C and therefore has extremely low hardness and poor wear resistance.

[0026]

According to the composite wire for hardfacing self-shielding arc welding of the present invention, the material is focused on the effect of Ni which has been considered to be rather harmful in the high carbon high chromium iron based overlay welding. Since wear due to peeling is suppressed and other alloy components are contained in a well-balanced manner, both hardness and toughness can be achieved, and a weld metal with extremely good wear resistance can be obtained. Therefore, in hardfacing welding of wear parts such as mechanical devices, the wear life can be improved and the frequency of repair welding can be reduced as compared with the case where a conventional high-carbon high-chromium iron-based composite wire is used.

[Brief description of the drawings]

FIG. 1 is a diagram showing a rubber wheel testing machine for testing abrasion resistance.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naruo Yasui 2-3-13 Aoi, Higashi-ku, Nagoya City, Aichi Prefecture Inside of Tokai Melting Co., Ltd. No. 13 Inside Tokai Melting Co., Ltd. (72) Inventor Minoru Hattori 2-3-13 Aoi, Higashi-ku, Nagoya City, Aichi Prefecture Tokai Melting Co., Ltd. (56) References JP-A-61-283489 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) B23K 35/368 B23K 9/04

Claims (3)

(57) [Claims] 1. A composite wire for hardfacing self-shielded arc welding comprising a tubular sheath and a filler, wherein the chemical component is 4 to 7% by weight of C based on the total weight of the wire,
i: 0.2 to 2.0%, Mn: 0.2 to 2.0%, C
r: 20 to 28%, Ni: 1 to 5%, Mo: 1 to 5%, further contains at least one of Al: 3% or less, Ti: 3% or less, and the balance is a slag forming agent, Fe And a composite wire for hardfacing self-shielded arc welding characterized by being an unavoidable impurity. 2. A hardfacing cell comprising a tubular shell and a filler.
Chemical composition of composite wire for shielded arc welding
Is the weight% based on the total weight of the wire, C: 5-6%, S
i: 0.2 to 2.0%, Mn: 0.2 to 2.0%, C
r: 20 to 28%, Ni: 1 to 5%, Mo: 1 to 5%
Al: 3% or less, Ti: 3% or less
At least one of Nb: 1 to 4% and V: 1 to 4%, with the balance being a slag forming agent, Fe and
A composite wire for hardfacing self-shielded arc welding , characterized by being an unavoidable impurity . 3. A further W: claim 1 or 2 hardfacing self-shielded arc welding composite wire according, characterized in that it contains 0.5-4%.