JPWO2013069573A1 - Curved overlay welding method and lance manufacturing method using the same - Google Patents

Abstract

An iron or stainless steel mesh material (29-31) is formed in a welded area formed on the radially outer side of the bent portion (16) inside the inner tube (14) of the lance (10) partially or entirely curved. ) To temporarily fix), and overlay welding of a metal having heat resistance and wear resistance is performed from above the mesh material (29-31), and the overlay portion (19-21) is formed in the welded region. 2 steps. Thereby, overlay welding of a metal having heat resistance and wear resistance can be smoothly performed on the inner surface of a steel structure having a curved surface (for example, a pipe having a vent portion).

Description

The present invention is, for example, a method of overlay welding performed to improve wear resistance on a part of a steel structure having a curved surface such as a lance used in a steel mill (specifically, an “injection lance”) and the like. The present invention relates to a lance manufacturing method using the same.

As shown in Patent Document 1, for example, when hot metal discharged from a blast furnace is subjected to hot metal pretreatment with a topped car or the like, a lance with a bent front side is used, and a bent pipe (vent pipe) is usually used at the bent portion. ) And is welded to the front and back straight pipes. And in patent document 1, the metallic protrusion which has the height of 1 / 20-1 / 2 of the internal diameter of a bending pipe is provided in the inner surface of the bending part, and a processing agent is positively provided in the clearance gap part of this protruding piece. This increases the wear resistance of this part.

On the other hand, Patent Document 2 proposes a method of overlay welding a clad metal made of high carbon steel on the inside of a steel pipe, thereby ensuring wear resistance on the inside of the steel pipe.
Moreover, as shown in Patent Document 3, the applicant has proposed that the base material is welded with a nickel-base alloy, a stainless alloy, or the like to increase the wear resistance of the base material.

JP 2010-222592 A Japanese Patent Laid-Open No. 10-8191 JP 2008-93732 A

However, the technique described in Patent Document 1 has a problem in that the treatment agent accumulated in the gap between the projecting pieces grows, and the effective diameter of the lance becomes smaller with time, and the lance is sometimes blocked.
Therefore, the present applicant has intensively studied to prevent clogging of the processing agent by overlay welding a wear-resistant metal inside the lance.

However, the pipe (core metal) used inside the lance is usually a small diameter pipe having a diameter of 100 mm or less. In the case of a straight pipe, if the pipe is rotated with the welding torch facing downward, a certain amount of buildup is achieved. Welding is possible, but when overlay welding is performed on a bent part in the middle, there is no other way than to perform the welding torch corresponding to the unevenness of the welding location, and in this case, the welding location is not necessarily a plane or approximate plane. For this reason, there existed a problem that the molten metal used as a build-up part flowed on the inclined surface, and the stable welding could not be performed.

This invention is made | formed in view of this situation, Comprising: It is a to-be-welded object (for example, steel pipe which has a vent part) which has a curved surface, Comprising: Wear-resistant overlay welding can be smoothly performed on the inner surface. An object of the present invention is to provide a method of overlay welding of a possible curved surface and a method of manufacturing a lance using the same.

The curved surface overlay welding method according to the first invention that meets the above-mentioned object includes a first step of temporarily fixing an iron or stainless steel mesh material to a welded region of a steel structure that is partially or entirely curved. And a second step of performing overlay welding from above the mesh material. Here, the steel structure may be, for example, a steel pipe (including both a carbon steel pipe and a stainless steel pipe), and the welded area may be an inner surface thereof.

In the method for overlay welding of curved surfaces according to the first invention, the mesh material is preferably a steel expanded metal. However, if it interferes with the flow of the molten metal, it may be another wire mesh material. Can also be used.

The curved surface overlay welding method according to the second invention is the curved surface overlay welding method according to the first invention, wherein the steel structure is carbon steel, and the welding material for the overlay welding is heat resistant and resistant. It is said that it is a high chromium cast iron-based wire having wear characteristics. Here, the molten material may be another metal as long as it is a weldable metal having wear resistance at a high temperature.

A curved surface overlay welding method according to a third aspect of the invention is the curved surface overlay welding method according to the first and second aspects of the invention, wherein the steel structure is a steel pipe, wherein the steel pipe is a molten metal used at a steel mill. The welded region is a radially outer region of the bent portion of the lance. In this case, the area to be welded is preferably in a range of 180 degrees or more (for example, 180 to 280 degrees) around the radially outer ridge line of the bent portion of the lance.

In the overlay welding method of the curved surface according to the third invention, the bent portion of the lance is composed of a bent pipe and a part of the first and second straight pipes welded to the end of the bent pipe, The welded area is an area in the vicinity of the welded portion of the bent pipe and the first and second straight pipes, excluding the welded part between the first and second straight pipes and the bent pipe. Is preferred.

The lance manufacturing method according to the fourth aspect of the present invention applies the curved surface overlay welding method according to the above first to third aspects of the invention. In addition, about parts other than the curved surface (bending part) of the inner tube | pipe of a lance, it is possible to manufacture a lance using a well-known method.

In the lance manufacturing method according to the fourth invention, the surface of the overlay welding can be further covered with an irregular refractory material. In this case, the amorphous refractory material can be applied by spraying or spraying, and in some cases by application. The thickness of the amorphous refractory material is preferably about 1 to 4 mm.

The curved surface overlay welding method according to the present invention performs overlay welding after temporarily fixing an iron or stainless steel mesh material to a welded region of a steel structure in which a part or all of the curved surface is curved. Is blocked by the mesh material and remains at the overlay welding position. Therefore, overlay welding of wear-resistant metal can be performed without hindrance.

In particular, when the welded region of the steel structure is, for example, the radially inner surface of the bent portion of the inner tube of a lance used in a steel mill, the heat-resistant and wear-resistant metal is overlay welded to that portion. As a result, the portion is hardened, the progress of wear due to the passing powder or particulate matter is delayed, and the lance has a long life.
By using a high chromium cast iron-based wire, which is an example of a metal having heat resistance and wear resistance, as a molten material for overlay welding, welding becomes easier and a hard overlay surface is formed.

Furthermore, the use of steel expanded metal as the netting material makes it easy to obtain materials and facilitate welding. In addition, although this expanded metal melt | dissolves and the component of overlay metal is diluted, since a base material may also be steel, even if it uses steel expanded metal, there will be no trouble in particular.

Further, in the lance manufacturing method to which the curved surface overlay welding method according to the present invention is applied, overlay welding is performed on the bent portion of the lance inner surface by an easy construction method, so that the welding operation is stable, and the The reliability of the welded area is also improved.
Moreover, if the surface of the overlay metal is covered with an irregular refractory material, the life of the lance is further extended.

(A) is explanatory drawing of the lance (inner tube) to which the overlay welding method of the curved surface which concerns on 1st Example of this invention is applied, (B) is PP 'sectional drawing of the same figure (A). . (A)-(C) are top views of the expanded metal used for the overlay welding method of the same curved surface, respectively. It is a side view of a lance. It is a schematic explanatory drawing of the test apparatus of an abrasion test. It is a graph which shows the result of an abrasion test. It is explanatory drawing of the lance which applies the overlay welding method of the curved surface which concerns on the 2nd Example of this invention. (A) is an arrow QQ 'and RR' sectional view in FIG. 6, (B) is an arrow SS 'sectional view in FIG. 6 (however, the outer refractory is omitted) ) (A)-(C) are each a top view of the expanded metal used for the overlay welding method of the curved surface which concerns on the 2nd Example of this invention.

Next, a curved surface overlay welding method and a lance manufacturing method according to a first embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 3 shows a lance 10 used for blowing fuel gas and additives (for example, iron oxide powder and lime powder) into molten steel (molten metal) with a topped car used at a steel mill. It has a tube region 11 and a bent region 12 at the tip, and each straight region 11 and the bent region 12 are covered with a refractory 13 on the outside, and an inner tube 14 (a part or all of which is a curved steel structure) An example of a steel pipe which is an object) and a double pipe structure of the outer pipe 15.

A small gap is formed between the inner pipe 14 and the outer pipe 15, and propane gas flows through this gap, and an additive is added to the inside of the inner pipe 14, for example, air, oxygen gas, nitrogen gas, argon gas or Using these mixed gases, the structure is such that the air current is conveyed.
As shown in FIGS. 1 (A) and 1 (B), in the radially outer region (becomes a welded region) of the inner side surface 18 of the bent portion 16 of the inner tube 14, there is a built-up portion 19 to 21 made of high chromium cast iron. Is formed. Hereinafter, the built-up portions 19 to 21 will be described in detail.

In this embodiment, a carbon steel pipe (STPG) having an outer diameter of 60.5 mm is used as the inner pipe 14, and the first straight pipe 23 and the short second straight pipe 24 are elbows (115 degrees). It is connected by welding via a bent pipe (bent) 25. Reference numerals 26 and 27 denote these welds. The built-up portions 19 to 21 are formed in regions near the welded portions 26 and 27 excluding the welded portions 26 and 27. The outer tube 15 is provided outside the inner tube 14 with a small gap (for example, 5 to 10 mm) via a spacer or the like, but the structure is well known and will be omitted. The bent portion 16 includes an elbow 25 and a part of the first and second straight pipes 23 and 24 welded to the end portions of the elbow 25.

As shown in FIGS. 2A and 2C, the first and second straight pipes 23 and 24 are in a state where the first and second straight pipes 23 and 24 and the elbow 24 are not welded. Steel expanded metals 29 and 30 which are examples of a mesh material having a width of 8 to 15 mm are arranged in a state bent to a circular arc of 180 degrees at a position of 5 to 15 mm from the end, and temporarily fixed by welding. As the expanded metals 29 and 30, those having a mesh size of 12 to 25 mm and a plate thickness of 1.2 to 1.6 mm (for example, JISG3351, XS31 or XS41) are used.

Further, as shown in FIG. 2 (B), the inner surface of the elbow 25 is provided with a gap of 5 to 15 mm from both ends in a portion having a large bending radius (that is, a radially outer region) on the inner surface of the elbow 25. The expanded metal 31 formed according to the half is placed and temporarily fixed by welding. The expanded metal 31 is the same as that used for the first and second straight pipes 23 and 24.
In this state, build-up welding of a high chromium cast iron metal, which is an example of a metal having heat resistance and wear resistance, is performed on the expanded metals 29 to 31. In FIG. 1 (B), the angle α indicates the angle of the welded area, and the areas of 90 degrees or more (that is, 180 degrees or more in total) are circumferentially welded around the ridge line f on the outer side in the radial direction. doing.
In this case, it is possible to build-up the entire circumferential region, but it is not necessary actively because the additive does not collide on the radially inner side. Providing the non-build-up weld on the radially inner side has the advantage that the gas cross-sectional area increases (the same applies to the following examples).

As a high chromium cast iron metal melt, high chromium cast iron flux cored wire is used, and overlay welding is performed by a carbon dioxide arc welding method. As a result, the inner surface of the inner pipe 14 is melted and the expanded metals 29 to 31 are also partially melted. However, each wire of the expanded metals 29 to 31 forms a weir and restricts the flow of the molten metal. Of course, a part of the expanded metals 29 to 31 is melted to dilute the high chromium cast iron metal. Further, some of the expanded metals 29 to 31 may remain in an unmelted state, but the wear resistance is not affected.

Here, if necessary, two or more layers of high chromium cast iron metal may be stacked. The dilution rate increases as the number of plates increases. However, it takes time and effort, and it is necessary to take these into consideration. The thickness of the overlay metal is, for example, about 3 to 5 mm.

Thereafter, the first and second straight pipes 23 and 24 are aligned with each other, temporarily attached to both ends of the elbow 25, and then welded. In this case, the melt used for welding usually uses a wire for welding a steel plate. As a result, welds 26 and 27 are formed. A groove having a width of about 20 mm is formed in the welded portions 26 and 27 on the inner peripheral surface of the inner pipe 14, and an additive passing through the lance 10 is deposited in the groove, and as a result. This clogged additive protects the welded portions 26 and 27 arranged on the radially outer side.

The characteristics of the built-up portions 19 to 21 will be described. In the formation of the built-up portions 19 to 21, a large amount of chromium carbide and carbides such as Nb, Mo, W, and V are generated in the weld metal, and extremely high hardness is exhibited. The minimum hardness of the Vickers hardness HV with a load of 10 kg is 882, the maximum hardness is 960, and the average hardness is 921. In addition, HV is represented by a constant x a test force / a surface area of a dent (constant = 0.102).

Next, the wear test results of the built-up portions 19 to 21 will be shown using the endless emery test device 32 shown in FIG. In FIG. 4, 33 is a belt (SiC, # 40), 34 is a test piece, 35 is a stopper, and 36 is a holder. The result was as shown in FIG. That is, assuming that the wear amount of SS400 is 1, the wear amount of the built-up portions 19 to 21 was 0.012. HCR represents a high-chromium cast iron filler-containing wire used for this overlay welding. Table 1 shows the components of the deposited metal of the built-up portions 19 to 21 welded using various HCRs.

From Table 1, the weld metal is 5 to 6.5 wt% C, Si 1.9 to 2.3 wt%, Mn 0.3 to 0.45 wt%, Cr 22 to 26 wt%, Mo 0 or It can be seen that it may be in the range of more than 0 and 5 wt%, V of 0 or more than 0 and 1.2 wt%, Nb of 3 to 7 wt%, and W of 0 or more than 0 and 4.5 wt%.

Next, a curved surface overlay welding method according to a second embodiment of the present invention will be described with reference to FIGS. 6, 7 </ b> A, and 7 </ b> B. The same components as those in the first embodiment shown in FIGS. 1 to 5 are denoted by the same reference numerals and detailed description thereof is omitted.
As shown in FIG. 6, the lance 38 has a straight tube region 11 and a bent region 12 at the tip, and each straight region 11 and the bent region 12 are covered with a refractory 13 on the outside, and the inner tube 14 is formed on the inside. A double pipe structure of an outer pipe 15 and an example of a steel pipe that is a steel structure partly or entirely made of a curved surface.

Similar to the first embodiment, propane gas flows between the inner tube 14 and the outer tube 15, and the additive material is air-conveyed inside the inner tube 14.
As shown in FIGS. 7A and 7B, the inner side surface 18 of the bent portion 16 of the inner tube 14 has a circle centered on the ridgeline of the inner cylindrical portion, that is, the radially outer ridgeline 40 of the bent portion 16. Overlaying portions 41 to 43 made of high chromium cast iron that are spread, for example, by 90 to 135 degrees (a total welded area of 180 to 270 degrees) are formed on both sides in the circumferential direction. Although the thickness of this built-up part 41-43 is 3-4 mm, for example, this invention is not limited to this figure.

In the formation of the built-up portions 41 to 43, as shown in FIG. 7A, the first and second straight pipes 23 and 24 and the elbow 25 are not joined by welding. A steel expanded metal 45 (see FIG. 8A), which is an example of a mesh material having a width of 8 to 15 mm, is placed at an inner position of 5 to 15 mm from the pipe end of the straight pipe (inner pipe) 23, for example, 210 to 220 degrees. It arrange | positions in the state bent in the circular arc shape at the angle of, and is temporarily fixed by welding. In this state, build-up welding of a chromium cast iron metal is performed from above the expanded metal 45.

Moreover, as shown to FIG. 7 (A), the clearance gap of 5-15 mm from both ends is provided in the part (namely, radial direction outer area | region) with a large bending radius in the inner surface 18 of the elbow (inner tube) 25, An expanded metal 46 (see FIG. 8 (B)) molded in accordance with the position of 210 to 220 degrees is placed and temporarily fixed by welding. In this state, build-up welding of a chrome cast iron metal is performed from above the expanded metal 46.

And in formation of the build-up part 43, as shown in FIG.7 (B), it is an example of the net | network material of width 8-15mm in the inner position 5-15mm from the pipe end of the 2nd straight pipe 24. A certain steel expanded metal 47 (see FIG. 8C) is arranged in a state of being bent in an arc shape at an angle of 260 to 270 degrees, for example, and temporarily fixed by welding. In this state, build-up welding of a chromium cast iron metal is performed from above the expanded metal 47. The expanded metals 45 to 47 are the same as those described in the first embodiment.

The reason why the area of the built-up part 43 is wider in the circumferential direction than the areas of the built-up parts 41 and 42 is that the flow of the additive material spreads in this part, and the wear of the non-build-up part exceeding 220 degrees becomes severe. Because. As a high chromium cast iron metal melt, high chromium cast iron flux cored wire is used, and overlay welding is performed by a carbon dioxide arc welding method. As a result, the inner surface of the inner tube 14 is melted, and the expanded metals 45 to 47 are partially melted. However, each wire of the expanded metals 45 to 47 forms a weir and restricts the flow of the molten metal. Other welding conditions and actions are the same as those of the curved surface overlay welding method according to the first embodiment.

A lance is manufactured by using this curved surface overlay welding method, except for performing overlay welding by the above-described method on the bent portion, Japanese Patent Publication No. 2011-17529, Japanese Patent Publication No. 2010-222592. Since it is a well-known method also known in the art, detailed description is omitted.
In addition, it is possible to cover a part of the built-up portions 19 to 21 and 41 to 43 (for example, the built-up portions 20 and 42) or the entire surface with an amorphous refractory material, thereby extending the life of the lance. be able to. In this case, the amorphous refractory material is preferably made of known alumina and silica powder and a necessary binder.

The present invention is not limited to the above-described embodiments. For example, as long as the weld metal forming the build-up portion has heat resistance and wear resistance, other melt materials can be used. Moreover, although the said Example restrict | limited and demonstrated the numerical value, this invention is not limited to the numerical value as described in an Example.
Furthermore, in the said Example, although limited and demonstrated to the inner pipe | tube of a lance, this invention is applicable also when building up on curved surfaces other than a pipe. In addition, after depositing on the inner surface of the pipe, a thermal spray coating having heat resistance or wear resistance can be formed on the cladding surface or on the outside or inside of the pipe of the overlay.
In the above embodiment, steel expanded metal is used as the mesh material. However, other metal meshes, and in some cases, stainless steel expanded metal, or iron or stainless steel wire mesh can also be used.

10: Lance, 11: Straight pipe region, 12: Bending region, 13: Refractory material, 14: Inner tube, 15: Outer tube, 16: Bent part, 18: Inner side surface, 19-21: Overlaying part, 23: First straight pipe, 24: second straight pipe, 25: elbow, 26, 27: welded part, 29-31: expanded metal, 32: endless emery test device, 33: belt, 34: test piece, 35: Stopper, 36: holder, 38: lance, 40: radially outer ridge line, 41-43: overlay, 45-47: expanded metal

Claims (9)

A first step of temporarily fixing an iron or stainless steel mesh material to a welded region of a steel structure partly or entirely of a curved surface; and a second step of performing overlay welding from above the mesh material. A method of overlay welding of curved surfaces characterized by the above. 2. The curved surface overlay welding method according to claim 1, wherein the mesh material is a steel expanded metal. 3. The curved surface overlay welding method according to claim 1 or 2, wherein the steel structure is carbon steel, and the molten material for the overlay welding is a high chromium cast iron-based wire having heat resistance and wear resistance. A method of overlay welding of a curved surface, characterized in that there is. The curved surface overlay welding method according to any one of claims 1 to 3, wherein the steel structure is a steel pipe, and the welded region is an inner surface of the steel pipe. Overlay welding method. 5. The curved surface overlay welding method according to claim 4, wherein the steel pipe is a lance for blowing an additive into a molten metal used in an ironworks, and the welded region is a radially outer region of a bent portion of the lance. A curved surface overlay welding method characterized by 6. The method of overlay welding of curved surface according to claim 5, wherein the welded region is in a range of 180 degrees or more around a radially outer ridge line of the bent portion of the lance. . The curved surface overlay welding method according to claim 5 or 6, wherein the bent portion of the lance is composed of a bent pipe and a part of the first and second straight pipes welded to the end of the bent pipe. The welded region is a region in the vicinity of the welded portion of the bent pipe and the first and second straight pipes, excluding a welded portion of the first and second straight pipes and the bent pipe. Characteristic curved surface overlay welding method. A method for manufacturing a lance, wherein the method for overlay welding of curved surfaces according to any one of claims 5 to 7 is applied. 9. The method of manufacturing a lance according to claim 8, wherein a surface of the overlay welding is further covered with an irregular refractory material.

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