Steel materials, welding method for steel materials, and unit

Abstract

An object of the present disclosure is to provide a steel material capable of ensuring the corrosion resistance of the brazed surface. Another object of the present disclosure is to provide a welding method and unit for steel materials capable of ensuring the corrosion resistance of the brazed surface. 【Solution means】According to the present disclosure, there is provided a steel material 1 having a brazed surface 11, characterized in that a build-up welded portion 13 is formed on at least a part of an exposed surface 12 of the brazed surface 11 that is exposed to a corrosive environment. Further, according to the present disclosure, a welding method for steel materials is provided. Further, according to the present disclosure, a unit including a plurality of steel materials is provided.

Description

Technical Field

[0001] The present disclosure relates to steel materials, a welding method for steel materials, and units.

Background Art

[0002] Steel materials exposed to severe corrosion environments such as in the sea are required to have a certain corrosion resistance. For example, with respect to the plate surface of plate-shaped steel materials, corrosion resistance may be ensured by applying a coating or providing a stainless lining. Also, in a joint structure where the end faces of plate-shaped or pipe-shaped steel materials are abutted and joined, since the edge surfaces (also referred to as end faces) of the steel materials are covered by welding, it can be said that there is little concern about corrosion. For example, in the techniques disclosed in Patent Document 1 or Patent Document 2, the edge surfaces of members made of different metals are joined to each other by build-up welding.

[0003] However, there is a problem that the edge surfaces other than the joint portions as described above are often exposed to the corrosion environment.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The inventors have found that particularly when the thickness of the steel material increases, due to component segregation in the plate thickness direction of the steel material, the corrosion resistance of the edge surface cannot be ensured. Therefore, the inventors have studied a method for guaranteeing the corrosion resistance of the edge surface. An object of the present disclosure is to provide a steel material capable of ensuring the corrosion resistance of the edge surface.

Means for Solving the Problems

[0006] The steel material according to the present disclosure is a steel material having a cobalt surface, characterized in that a build-up welding part is formed on at least a part of the exposed surface of the cobalt surface that is exposed to a corrosive environment.

Advantages of the Invention

[0007] According to the present disclosure, it is possible to provide a steel material capable of ensuring the corrosion resistance of the cobalt surface. According to the present disclosure, it is possible to provide a welding method and a unit of a steel material capable of ensuring the corrosion resistance of the cobalt surface.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described with examples, but it is obvious that the present disclosure is not limited to the examples described below. In the following description, specific numerical values and materials may be exemplified, but other numerical values and materials may be applied as long as the effects of the invention according to the present disclosure can be obtained. Also, the components of the following embodiments can be combined with each other. Also, in this specification, a numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. In this specification, the term "step" includes not only an independent step but also a step in which the intended purpose of the step can be achieved even if it cannot be clearly distinguished from other steps.

[0010] [First Embodiment] Hereinafter, with reference to the drawings, a steel material 1 according to an embodiment of the present disclosure will be described. FIG. 1 shows a schematic cross-sectional view for explaining the steel material 1 according to this embodiment. In the example of FIG. 1, the steel material 1 is a plate-shaped member. FIG. 1 is a view of the vicinity of the end of the steel material 1 and is a cross-sectional view in a cross-section parallel to the plate thickness direction of the steel material 1. As shown in FIG. 1, the steel material 1 is a steel material 1 having a bevel surface 11. In the example of FIG. 1, the bevel surface 11 is an exposed surface 12 exposed to a corrosive environment. A build-up welded portion 13 is formed on the exposed surface 12.

[0011] Note that the X-axis, Y-axis, and Z-axis in FIGS. 1 to 7 are orthogonal to each other. In the example of FIG. 1, the plate thickness direction of the steel material 1 is parallel to the Z-axis.

[0012] (Steel Material) The steel material 1 is not particularly limited, but as a chemical composition, it may be a steel material (for example, SS400) containing P: 0.05 mass% or less and S: 0.05 mass% or less. The chemical composition of the steel material 1 may be determined with reference to a mill sheet on which the steel type and chemical components are described. Note that, without relying on such a method, the steel plate used may be specified by a trade name or the like, and it may be determined based on the specifications of this steel material.

[0013] The steel material 1 may be stainless steel. Examples of the steel material 1 include SUS312L, SUS430, etc. When applied to marine structures, it is more preferably SUS312L.

[0014] Also, the steel material 1 may be a nickel-based alloy or the like. A nickel-based alloy is an alloy having nickel as a main component (nickel content is 50% by mass or more). The chemical composition of the steel material 1 may be determined by referring to a mill sheet on which the steel type and chemical components are described. Note that, without relying on such a method, if the material to be used is specified by a trade name or the like, the material of the steel material 1 may be specified based on the specifications of this material.

[0015] The steel material 1 may be a plate-shaped member made of the above-mentioned materials. It may be a steel plate or a stainless steel plate. The steel material 1 may be a pipe-shaped steel material made of the above-mentioned materials.

[0016] The thickness of the steel material 1 is not particularly limited. However, when the thickness of the steel material 1 is 6 mm or more, the corrosion resistance of the bevel surface 11 tends to decrease. Therefore, for example, the thickness of the steel material 1 may be 6 mm or more, 10 mm or more, 20 mm or more, etc. The thickness of the steel material 1 can be measured using a caliper.

[0017] The steel material may be a material that exceeds a predetermined pitting potential. The predetermined pitting potential is not particularly limited. For example, it is 800 mV. The pitting potential is measured according to the pitting potential test of JIS G 0577.

[0018] Also, the steel material 1 may be a stack of a plurality of steel materials. For example, a plurality of steel plates may be stacked so that the plate surfaces of different steel plates face each other to form the steel material 1. The thicknesses of the steel plates to be stacked may be different from each other. In this case, the steel materials to be overlapped may have substantially the same shape when viewed from a direction perpendicular to the plate surface of the steel material, and the respective edge surfaces of the steel materials to be overlapped may be flush and substantially coincide. The overlapped steel materials may be joined to each other by welding, an adhesive, caulking, bolt tightening, etc., or a combination thereof.

[0019] Further, the steel material 1 may be formed by joining a plurality of steel materials by welding. For example, a plurality of steel materials may be joined by welding to form the steel material 1. For example, the edge surfaces of a plurality of steel plates may be butt-welded to form a plate-shaped steel material 1 composed of a plurality of steel plates.

[0020] (Edge surface) The edge surface 11 is included in the end portion of the steel material 1, and in the case of a plate-shaped steel material, it is a surface having an angle with respect to the plate surface of the steel material. The edge surface 11 may be perpendicular to the plate surfaces 1a and 1b of the steel material 1, but is not limited thereto. In the case where the steel material is a pipe, the edge surface is included in the end portion of the steel material and is a surface that intersects the inner surface or the outer surface of the pipe.

[0021] For example, when the edge surface 11 is perpendicular to the plate surface 1a of the steel material 1, the height of the edge surface 11 in the plate thickness direction of the steel material 1 (the length of the edge surface 11 in the plate thickness direction of the steel material 1) coincides with the plate thickness of the steel material 1. Further, when a tapered portion is provided at the end portion of the steel material 1, the tapered portion is also included in the edge surface 11.

[0022] Generally, compared with the chemical composition of the plate surface of the steel material being uniform, component segregation occurs near the center in the plate thickness direction of the steel material. Since the edge surface is a surface parallel to the plate thickness direction of the steel material, component segregation can be observed in the in-plane direction of the edge surface. Therefore, by examining the distribution of the chemical components in the thickness direction of an arbitrary surface and confirming the presence or absence of component segregation, it is possible to determine whether the surface is an edge surface or not. Further, since such component segregation becomes more prominent as the plate thickness of the steel material 1 increases, as described above, when the thickness of the steel material 1 is equal to or greater than a predetermined value, the corrosion resistance of the edge surface 11 tends to decrease. In general, the sum of the areas of the plate surfaces 1a and 1b of the steel material 1 is larger than the sum of the areas of the flange surfaces 11.

[0023] (Exposed surface) On the flange surface 11, the portion exposed to the corrosive environment is defined as the exposed surface 12. The corrosive environment is, for example, in the sea, in the air, etc. Specifically, the sea refers to the submerged part in contact with flowing seawater, and the air refers to the upper part of the water receiving sea salt particles and seawater droplets. For example, within the flange surface 11, the portion covered by a lining member or the like is not exposed to the corrosive environment, so it is not the exposed surface 12. Also, the portion where the flange surfaces 11 of the steel materials 1 are butted against each other and joined by welding or the like is not the exposed surface 12 for the same reason. The exposed surface 12 may be the entire flange surface 11. Alternatively, the exposed surface 12 may be a part of the flange surface 11. For example, when a part of the flange surface 11 is covered by a lining member and the other parts of the flange surface 11 are exposed to the corrosive environment, the exposed part of the flange surface 11 is the exposed surface 12.

[0024] Next, the case where steel materials with different thicknesses are joined at the flange surface will be described. FIG. 2 shows a schematic cross-sectional view for explaining the exposed surface 12 in the case where steel materials (1, 2) with different thicknesses are joined. As shown in FIG. 2, when the steel material 1 and the steel material 2 with different thicknesses are joined with their flange surfaces 11 and 21 facing each other, the joined portion of the steel material 1 and the steel material 2 is not included in the exposed surface 12. The exposed surface 12 at such a joint portion is the portion excluding the joint location by the joint portion 10.

[0025] In the steel material 1 according to the present embodiment, the thickness of the steel material 1 may exceed a predetermined thickness. Here, the predetermined thickness may be, for example, the thickness related to the quality assurance that guarantees the corrosion resistance performance of the flange surface.

[0026] Here, FIG. 3 illustrates another form in which steel materials with different thicknesses are joined at the edge surface. In the example of FIG. 3, similar to FIG. 2, steel materials (1, 2) with different thicknesses are joined. A tapered portion 15 is provided at the end of the thicker steel material 1.

[0027] When a tapered portion 15 is provided at the end of the steel material 1 as in the example of FIG. 3, the tapered portion 15 also has a corrosion resistance performance similar to that of the edge surface 11. Therefore, when no lining or the like is provided on the tapered portion 15 and it is exposed to a corrosive environment, the tapered portion 15 is also included in the exposed surface 12.

[0028] (Overlay welding) In the steel material 1 according to this embodiment, an overlay welded portion 13 is formed on at least a part of the exposed surface 12 of the edge surface 11 that is exposed to the corrosive environment. As described above, since component segregation occurs in the thickness direction of the steel material 1, component segregation can be observed on the edge surface 11 of the steel material 1. At the locations where such component segregation occurs, the corrosion resistance performance is inferior compared to other locations. Therefore, even if a desired chemical composition is obtained on the plate surface 1a or the plate surface 1b of the steel material 1 and it has a certain corrosion resistance performance, the corrosion resistance performance may not be ensured particularly at the central portion of the edge surface 11 in the thickness direction. However, in the steel material 1 according to this embodiment, by providing the overlay welded portion 13 on the exposed surface 12, the exposed surface 12 can be prevented from being exposed to the corrosive environment. For this reason, in the steel material 1 according to this embodiment, the corrosion resistance performance of the edge surface 11 can be ensured.

[0029] In the steel material 1 according to this embodiment, the overlay welded portion 13 may be formed over the entire exposed surface 12. For example, providing the overlay welded portion 13 has the effect of improving the strength more than providing a SUS lining on the edge surface 11. Therefore, by forming the overlay welded portion 13 over the entire exposed surface 12, the strength of the steel material 1 can be improved.

[0030] In the steel material 1 according to the present embodiment, the build-up welded portion 13 may be composed of one or a plurality of layers. When the build-up welded portion 13 is composed of one or a plurality of layers, when the build-up welded portion 13 is a single layer, there is an effect that the welding period is shortened. Further, when the build-up welded portion 13 is a plurality of layers, there is an effect that the corrosion resistance of the surface layer of the build-up welded portion 13 is improved.

[0031] In the steel material 1 according to the present embodiment, the welding material constituting the build-up welded portion 13 may have corrosion resistance. The welding material constituting the build-up welded portion 13 is, for example, a nickel-based alloy. Preferred welding materials constituting the build-up welded portion 13 are not particularly limited, and examples include Hastelloy (registered trademark) and Inconel (registered trademark). By forming the build-up welded portion 13 itself with a welding material having corrosion resistance, the corrosion resistance of the exposed surface 12 can be more reliably ensured.

[0032] (Modification example) Hereinafter, a modification example of the steel material 1 according to Embodiment 1 will be described with reference to FIG. 4. FIG. 4 is a plan view of the steel material 1 viewed from a direction perpendicular to its plate surface 1a. The steel material 1 shown in FIG. 4 is a plate material having a first bevel surface 11A, a second bevel surface 11B, and a corner portion 14 connecting the first bevel surface 11A and the second bevel surface 11B. FIG. 4 is a view showing the vicinity of the corner portion 14 of the plate-like steel material 1. In this steel material 1, the exposed surface 12 includes a first exposed surface 12A corresponding to the first bevel surface 11A and a second exposed surface 12B corresponding to the second bevel surface 11B. In the example of FIG. 4, the first exposed surface 12A is the entire first bevel surface 11A, and the second exposed surface 12B is the entire second bevel surface 11B. In this steel material 1, a build-up welded portion 13 is formed across the first exposed surface 12A and the second exposed surface 12B with the corner portion 14 interposed therebetween. By forming the build-up welded portion 13 across the first exposed surface 12A and the second exposed surface 12B with the corner portion 14 interposed therebetween and connected at the corner portion 14, the corrosion resistance at the corner portion 14 can be ensured.

[0033] In the example of Fig. 4, the build-up welded portion 13 is formed on a part of the first fillet surface 11A and the second fillet surface 11B. However, the build-up welded portion 13 may be formed over the entire first fillet surface 11A and the second fillet surface 11B. Further, the build-up welded portion 13 may be formed at other corner portions or other fillet surfaces not shown in Fig. 4.

[0034] As illustrated in Fig. 4, when forming a build-up welded portion across a corner portion, for example, build-up welding may be continuously performed from one of the fillet surfaces sandwiching the corner portion to the other fillet surface to form the build-up welded portion. Alternatively, after forming build-up welded portions on each fillet surface, a build-up welded portion may be further formed at the corner portion so as to connect these build-up welded portions.

[0035] Note that the shape of the steel material 1 is not limited to a plate material having a rectangular shape when viewed from a direction perpendicular to the plate surface as shown in Fig. 4, and the shape when viewed from a direction perpendicular to the plate surface may be circular, elliptical, triangular, polygonal, or a shape combining some of these. Further, the corner portion may be chamfered to a curved surface or a flat surface.

[0036] Also, the fillet surface 11 of the steel material 1 does not necessarily extend in a certain direction and may be curved or bent. For example, in the case of a plate-shaped steel material subjected to bending processing on the plate surface, its fillet surface is also deformed along the shape of the plate surface of the steel material. When the steel material is a pipe, its fillet surface is included at the end of the steel material and intersects the inner surface or the outer surface of the pipe.

[0037] [Second Embodiment] Hereinafter, a welding method according to an embodiment of the present disclosure will be described. The welding method according to the second embodiment is the welding method of the steel material 1 according to the first embodiment described above. Therefore, various configurations described in the first embodiment are also applicable to the second embodiment. In this embodiment, a plate-shaped steel material (plate material) will be described as an example, but it is not intended that the steel material is limited to a plate material.

[0038] The welding method according to the present embodiment will be described with reference to FIG. 5. FIG. 5 is a plan view of a plate-shaped steel material 3 as viewed from a direction perpendicular to the plate surface 3a. The welding method according to the present embodiment includes a plate material preparation step of preparing a plate material as the steel material 3, a first build-up welding step of forming a build-up welded portion in a first range of the exposed surface, and a second build-up welding step of forming a build-up welded portion in a second range of the exposed surface.

[0039] In the plate material preparation step, a plate material as the steel material 3 is prepared. As shown in FIG. 5, the steel material 3 has a plate surface 3a, a plate surface 3b, and side surfaces (31A, 31B, 31C, 31D). In the example of FIG. 5, each of the side surfaces (31A, 31B, 31C, 31D) corresponds to an exposed surface (32A, 32B, 32C, 32D). Further, the side surface 31A and 31B are connected at the corner 34A, the side surface 31B and 31C are connected at the corner 34B, the side surface 31C and 31D are connected at the corner 34C, and the side surface 31D and 31A are connected at the corner 34D.

[0040] In the first build-up welding step, a build-up welded portion is formed in a first range of the exposed surface. In the example of FIG. 5, the first range is the exposed surface 32B, and a build-up welded portion 33A is formed in the direction indicated by the arrow P1 from the corner 34A. Note that the starting point of the build-up welding step (the point where the build-up welded portions 33A and 33B start to be formed) is not limited to a corner as illustrated in FIG. 5, and may be any location on the exposed surface.

[0041] In the second build-up welding step, a build-up welded portion is formed in a second range of the exposed surface. In the example of FIG. 5, the second range is the exposed surface 32D, and a build-up welded portion 33B is formed in the direction indicated by the arrow P2 from the corner 34C.

[0042] Note that the first range is not limited to the exposed surface 32B, and may include the exposed surface 32A and the exposed surface 32C. Similarly, the second range is not limited to the exposed surface 32D, and may include the exposed surface 32A and the exposed surface 32C. Further, the direction in which the build-up welding is performed (the direction in which the build-up welding bead is formed) is not limited to P1 or P2.

[0043] In the welding method according to this embodiment, the first build-up welding step and the second build-up welding step are performed in parallel. That is, in the example of FIG. 5, the step of forming the build-up welded portion 33A on the exposed surface 32B in the direction indicated by the arrow P1 from the corner 34A and the step of forming the build-up welded portion 33B on the exposed surface 32D in the direction indicated by the arrow P2 from the corner 34C are performed in parallel. Here, performing the build-up welding in parallel means that the first build-up welding step and the second build-up welding step are performed at a timing where they partially overlap, even if the build-up welding is not necessarily performed simultaneously.

[0044] In this way, by performing the first build-up welding step and the second build-up welding step in parallel, the time for the entire welding process can be shortened.

[0045] Also, the first range and the second range may be in the same bevel surface or in different bevel surfaces. For example, when the steel material is a plate-shaped steel material 3 having a rectangular plate surface 3a as shown in FIG. 5, the first range and the second range may be set in any range of the exposed surfaces (32A, 32B, 32C, 32D) of the bevel surfaces (31A, 31B, 31C, 31D) corresponding to the respective sides of the rectangle. For example, when the steel material 3 is a plate material having a disk-shaped or elliptical plate surface, the bevel surface is not divided at the corners and has one bevel surface. In this case, the first range and the second range may be set within one bevel surface. Also, although the first range and the second range are basically different ranges, a part of them may overlap.

[0046] [Third Embodiment] Hereinafter, a welding method according to an embodiment of the present disclosure will be described with reference to FIG. 6. FIG. 6 is a cross-sectional view in a cross-section parallel to the plate thickness direction of the plate-shaped steel material 1, and shows the vicinity of the end of the steel material 1. Each of FIGS. 6(a) to 6(c) is a diagram for explaining the flow of the welding method of the present embodiment. The welding method according to the third embodiment is the welding method of the steel material 1 according to the first embodiment described above. Therefore, various configurations described in the first embodiment can also be applied to the third embodiment. In the present embodiment, a plate-shaped steel material (plate material) will be described as an example, but the steel material is not limited to the plate material.

[0047] The welding method according to the present embodiment includes a first plate material preparation step of preparing a first plate material 4 as a steel material, a second plate material preparation step of preparing a second plate material 5 as a steel material, a first build-up welding step of forming a build-up welding portion 43 on the exposed surface 42 of the first plate material 4, and a second build-up welding step of forming a build-up welding portion 53 on the exposed surface 52 of the second plate material 5.

[0048] As shown in FIG. 6(a), in the first plate material preparation step, the first plate material 4 is prepared. Similarly, in the second plate material preparation step, the second plate material 5 is prepared. The first plate material 4 or the second plate material 5 can adopt the same configuration as the steel material 1 of the first embodiment.

[0049] As shown in FIG. 6(b), in the first build-up welding step, a build-up welding portion 43 is formed on the exposed surface 42 of the prepared first plate material 4. Similarly, in the second build-up welding step, a build-up welding portion 53 is formed on the exposed surface 52 of the prepared second plate material 5. The build-up welding portion 43 or the build-up welding portion 53 can adopt the same configuration as the build-up welding portion 13 of the first embodiment. In the example of FIG. 6, each of the bevel surfaces (41, 51) corresponds to the exposed surface (42, 52).

[0050] In the welding method of the present embodiment, the above-described first build-up welding step and the second build-up welding step are performed in parallel. Therefore, there is an effect that the time of the entire welding process can be shortened. Here, performing build-up welding in parallel means that, as in the second embodiment, even if the build-up welding is not necessarily performed simultaneously, it includes cases where the first build-up welding process and the second build-up welding process are performed at timings where they partially overlap.

[0051] Also, in the welding method according to this embodiment, after the first build-up welding process and the second build-up welding process are completed, as shown in FIG. 6(c), the first plate material 4 with the build-up welded portion 43 formed and the second plate material 5 with the build-up welded portion 53 formed may be overlapped. For example, as shown in FIG. 6(c), they are overlapped so that the plate surface 4b of the first plate material 4 faces the plate surface 5a of the second plate material 5. The overlapped first plate material 4 and second plate material 5 may be joined to each other by welding, an adhesive, caulking, bolt tightening, etc., or a combination thereof.

[0052] In the example of FIG. 6, for convenience, the thicknesses of the first plate material 4 and the second plate material 5 are made approximately the same, but the thicknesses of the first plate material 4 and the second plate material 5 may be different. Also, in the example of FIG. 6, the edge surfaces 41 and 51 are arranged flush, but it is not limited to this. That is, in the direction parallel to the plate surface, the arrangements of the edge surfaces 41 and 51 may be different.

[0053] By the welding method according to this embodiment, a unit including a plurality of steel plate materials can be manufactured. This unit is, for example, the unit 100 as shown in FIG. 6(c).

[0054] In this unit 100, for the plurality of plate materials (4, 5), the plate surface 4b of one plate material (the first plate material 4) and the plate surface 5a of the other plate material (the second plate material 5) are overlapped, and the plate surface 4a on the opposite side of the plate surface 4b of one plate material (the first plate material 4) and the plate surface 5b on the opposite side of the plate surface 5a of the other plate material (the second plate material 5) are exposed. In this unit 100, build-up weld joints (43, 53) are formed on at least a part of the exposed surfaces (42, 52) of the edge surfaces (41, 51) of the plate materials (4, 5) that are exposed to the corrosive environment. Also, in this unit, there is a cut S between the build-up weld joint 43 of one plate material (the first plate material 4) and the build-up weld joint 53 of the other plate material (the second plate material 5). As described above, since this unit 100 superposes the first plate material 4 on which the build-up weld joint 43 is formed and the second plate material 5 on which the build-up weld joint 53 is formed, the build-up weld joint 43 and the build-up weld joint 53 are not joined, and a cut S can be confirmed at their boundary.

[0055] [Fourth Embodiment] Hereinafter, a welding method according to an embodiment of the present disclosure will be described with reference to FIG. 7. FIG. 7 is a cross-sectional view of a plate-shaped steel material 1 in a cross-section parallel to the plate thickness direction, and shows the vicinity of the end of the steel material 1. Each of FIGS. 7(a) to 7(c) is a diagram for explaining the flow of the welding method of the present embodiment. The welding method according to the fourth embodiment is the welding method of the steel material 1 according to the first embodiment described above. Therefore, various configurations described in the first embodiment can also be applied to the fourth embodiment. In the present embodiment, a plate-shaped steel material (plate material) will be described as an example, but the steel material is not limited to a plate material.

[0056] The welding method according to the present embodiment includes a first plate material preparation step of preparing a first plate material 6 as a steel material, a second plate material preparation step of preparing a second plate material 7 as a steel material, a superposition step of superposing the first plate material 6 and the second plate material 7, and a build-up welding step of forming build-up weld joints on the exposed surfaces (62, 72) of the superposed first plate material 6 and second plate material 7.

[0057] As shown in FIG. 7(a), the first plate material 6 is prepared in the first plate material preparation step. Similarly, the second plate material 7 is prepared in the second plate material preparation step. The first plate material 6 or the second plate material 7 can adopt the same configuration as the steel material 1 of the first embodiment.

[0058] As shown in FIG. 7(b), in the overlapping step, the first plate member 6 and the second plate member 7 are overlapped. In the example of FIG. 7(b), they are overlapped such that the plate surface 6b of the first plate member 6 faces the plate surface 7a of the second plate member 7. The overlapped first plate member 4 and second plate member 5 may be joined to each other by welding, an adhesive, caulking, bolt tightening, etc., or a combination thereof.

[0059] Next, in the build-up welding step, as shown in FIG. 7(c), a build-up weld portion 63 is formed on the exposed surfaces (62, 72) of the overlapped first plate member 6 and second plate member 7.

[0060] According to the above welding method, there is an effect of simplifying the working process by combining the welding of the corner surfaces of the first plate member and the second plate member into one step.

[0061] In the welding method according to the present embodiment, the build-up welding step includes a first build-up welding step of forming a build-up weld portion in a first range of the exposed surfaces (62, 72) of the overlapped first plate member 6 and second plate member 7, and a second build-up welding step of forming a build-up weld portion in a second range of the exposed surfaces (62, 72) of the overlapped first plate member 6 and second plate member 7, and the first build-up welding step and the second build-up welding step may be performed in parallel. By performing build-up welding on the exposed surfaces (62, 72) of the overlapped first plate member 6 and second plate member 7 in parallel with respect to the first range and the second range, as in the welding method of the second embodiment, the time for the entire welding process can be shortened.

[0062] A unit including a plurality of steel plate members can be manufactured by the welding method according to the present embodiment. This unit is, for example, the unit 200 as shown in FIG. 7(c).

[0063] In this unit 200, the plate surface 6b of one plate member (the first plate member 6) and the plate surface 7a of the other plate member (the second plate member 7) are overlapped, and the plate surface 6a on the opposite side of the plate surface 6b of one plate member (the first plate member 6) and the plate surface 7b on the opposite side of the plate surface 7a of the other plate member (the second plate member 7) are exposed. In this unit 200, a build-up welding portion 63 is formed on at least a part of the exposed surfaces (62, 72) of the edge surfaces (61, 71) of the plate materials (6, 7) that are exposed to the corrosive environment. In this unit 200, the build-up welding portion 63 of one plate material (the first plate material 6) and the build-up welding portion 73 of the other plate material (the second plate material 7) are continuous. In other words, a build-up welding portion 83 composed of the build-up welding portion 63 and the build-up welding portion 73 is formed across the edge surfaces (61, 71) of the plate materials (6, 7).

[0064] Further, the first plate material 6 and the second plate material 7 may have the same shape in a plan view from a direction perpendicular to the plate surface. Alternatively, the first plate material 6 and the second plate material 7 may have different shapes from each other in a plan view from a direction perpendicular to the plate surface.

[0065] In the above-described embodiment, the build-up welding portion may be formed by any one of TIG (Tungsten Inert Gas) welding, MIG (Metal Inert Gas) welding, and MAG (Metal Active Gas) welding.

[0066] (Supplementary Note) The structure and welding method according to the above embodiment are understood as follows, for example. (1) The steel material according to one aspect of the present disclosure is a steel material having an edge surface, and a build-up welding portion is formed on at least a part of the exposed surface of the edge surface that is exposed to the corrosive environment, which is characterized in that. According to the above steel material, the corrosion resistance of the edge surface can be ensured by the build-up welding portion formed on the exposed surface.

[0067] (2) In the steel material of the above (1), the length of the exposed surface in the thickness direction of the steel material is the thickness of the steel material, and may exceed a predetermined thickness.

[0068] (3) In the steel material of the above (1) or (2), a build-up welding portion may be formed on the entire exposed surface. According to the above-mentioned steel material, there is an effect that the strength of the steel material can be improved.

[0069] (4) In the steel material according to any one of (1) to (3) above, The build-up welded portion may be composed of one or a plurality of layers. According to the above-mentioned steel material, when the build-up welded portion is a single layer, there is an effect that the welding period is shortened. Also, when the build-up welded portion is a plurality of layers, there is an effect that the corrosion resistance performance of the surface layer of the build-up welded portion is improved.

[0070] (5) In the steel material according to any one of (1) to (4) above, The steel material is a plate material, The plate material has a first edge surface, a second edge surface, and a corner portion connecting the first edge surface and the second edge surface, The exposed surface includes a first exposed surface corresponding to the first edge surface and a second exposed surface corresponding to the second edge surface, The build-up welded portion may be formed across the first exposed surface and the second exposed surface with the corner portion therebetween. According to the above-mentioned steel material, by forming a build-up welded portion across the first exposed surface and the second exposed surface that sandwich the corner portion and are connected at the corner portion, the corrosion resistance performance at the corner portion can be ensured.

[0071] (6) In the steel material according to any one of (1) to (5) above, The steel material may be stainless steel. According to the above-mentioned steel material, there is an effect of imparting high corrosion resistance performance to the steel material itself.

[0072] (7) In the steel material according to any one of (1) to (6) above, The welding material constituting the build-up welded portion may have corrosion resistance. According to the above-mentioned steel material, by forming the build-up welded portion itself with a welding material having corrosion resistance, the corrosion resistance performance of the exposed surface can be more reliably ensured.

[0073] (8) In the steel material according to (7) above, The welding material constituting the build-up welding portion may be made of a nickel-based alloy. According to the above steel material, there is an effect of imparting high corrosion resistance to the welded portion.

[0074] (9) In the steel material according to any one of the above (1) to (8), The steel material may be a material exceeding a predetermined pitting potential.

[0075] (10) In the steel material according to any one of the above (1) to (9), The build-up welding portion may be formed by any one of TIG welding, MIG welding, and MAG welding.

[0076] (11) The welding method of the steel material according to one aspect of the present disclosure is The welding method of the steel material according to any one of the above (1) to (10), A plate material preparation step of preparing the steel material, A first build-up welding step of forming a build-up welding portion in a first range of the exposed surface, A second build-up welding step of forming a build-up welding portion in a second range of the exposed surface, and The first build-up welding step and the second build-up welding step are performed in parallel, which is characterized by this. According to the above welding method, there is an effect that the time of the entire welding process can be shortened.

[0077] (12) The welding method of the steel material according to one aspect of the present disclosure is The welding method of the steel material according to any one of the above (1) to (10), A first steel material preparation step of preparing a first steel material as the steel material, A second steel material preparation step of preparing a second steel material as the steel material, A first build-up welding step of forming a build-up welding portion on the exposed surface of the first steel material, A second build-up welding step of forming a build-up welding portion on the exposed surface of the second steel material, and The first build-up welding process and the second build-up welding process are performed in parallel, which is characterized in that. According to the above welding method, there is an effect that the time of the entire welding process can be shortened.

[0078] (13) The welding method of the steel material according to one aspect of the present disclosure is The welding method of the steel material according to any one of the above (1) to (10), A first steel material preparation step of preparing a first steel material as the steel material, A second steel material preparation step of preparing a second steel material as the steel material, An overlapping step of overlapping the first steel material and the second steel material, It is characterized by including a build-up welding step of forming a build-up welding portion on the exposed surface of the overlapped first steel material and second steel material. According to the above welding method, there is an effect that the working process can be simplified by combining the welding of the corner surfaces of the first steel material and the second steel material into one step.

[0079] (14) In the welding method of the steel material of the above (13), The build-up welding step is A first build-up welding step of forming a build-up welding portion in a first range of the exposed surface of the overlapped first steel material and second steel material, A second build-up welding step of forming a build-up welding portion in a second range of the exposed surface of the overlapped first steel material and second steel material, and The first build-up welding step and the second build-up welding step may be performed in parallel. According to the above welding method, there is an effect that the time of the entire welding process can be shortened.

[0080] (15) A unit according to one aspect of the present disclosure is A unit including a plurality of steel materials, The plurality of steel materials have the plate surface of one of the steel materials and the plate surface of the other steel material overlapped, A build-up welding portion is formed on at least a part of the exposed surface of the corner surface of the steel material that is exposed to the corrosion environment. There is a gap between the build-up welded part of one of the steel materials and the build-up welded part of the other steel material, which is a feature. According to the above unit, due to the gap between the build-up welded parts, there is an effect that the separation of the steel materials can be easily achieved when separating the joined steel materials.

[0081] (16) The unit according to one aspect of the present disclosure is A unit including a plurality of steel materials, Among the plurality of steel materials, the plate surfaces of one of the steel materials and the other steel material are overlapped, Build-up welded parts are formed on at least a part of the exposed surface that is exposed to the corrosion environment among the edge surfaces of the steel materials, The build-up welded part of one of the steel materials and the build-up welded part of the other steel material are continuous, which is a feature. According to the above unit, there is an effect that the gap between the steel materials is sealed and the edge surface of the unit becomes smooth.

Industrial Applicability

[0082] According to the steel material according to the present disclosure, the corrosion resistance of the edge surface can be ensured. Further, according to the welding method and unit of the steel material according to the present disclosure, the corrosion resistance of the edge surface can be ensured. Therefore, the invention according to the present disclosure is extremely useful industrially.

Explanation of Signs

[0083] 1, 2, 3, 4, 5, 6, 7 Steel materials 11, 11C, 11D Edge surfaces 11A First edge surface 11B Second edge surface 12, 12C, 12D Exposed surfaces 12A First exposed surface 12B Second exposed surface 13, 23, 33 Build-up welded parts 14, 14A, 14B, 14C, 14D Corners 10 Joint part 100, 200 Units

Claims

1. A steel material having a bevel surface, wherein at least a part of an exposed surface of the bevel surface that is exposed to a corrosive environment is formed with a build-up welding portion, the steel material is stainless steel, at least a part of the portion of the stainless steel other than the bevel surface is exposed to a corrosive environment, the build-up welding portion is located outside, a steel material characterized by the above.

2. The steel material is applied to a building, the steel material according to Claim 1, characterized by the above.

3. The steel material is applied to an offshore structure, the steel material according to Claim 1, characterized by the above.

4. the thickness of the steel material exceeds a predetermined thickness, the steel material according to any one of Claims 1 to 3, characterized by the above.

5. the build-up welding portion is formed on the entire exposed surface, the steel material according to any one of Claims 1 to 3, characterized by the above.

6. the build-up welding portion is composed of one or more layers, the steel material according to any one of Claims 1 to 3, characterized by the above.

7. A steel material having a bevel surface, wherein a build-up welding portion is formed on at least a part of an exposed surface of the bevel surface that is exposed to a corrosive environment, the steel material is a plate material, the plate material has a first bevel surface, a second bevel surface, and a corner portion connecting the first bevel surface and the second bevel surface, the exposed surface includes a first exposed surface corresponding to the first bevel surface and a second exposed surface corresponding to the second bevel surface, the build-up welding portion is formed across the first exposed surface and the second exposed surface with the corner portion interposed therebetween, a steel material characterized by the above.

8. the welding material constituting the build-up welding portion has corrosion resistance, the steel material according to any one of Claims 1 to 3, characterized by the above.

9. the welding material constituting the build-up welding portion is made of a nickel-based alloy, the steel material according to Claim 8, characterized by the above.

10. the steel material is a material exceeding a predetermined pitting potential, the steel material according to any one of Claims 1 to 3, characterized by the above.

11. the build-up welding portion is formed by any one of TIG welding, MIG welding, and MAG welding, the steel material according to any one of Claims 1 to 3, characterized by the above.

12. A welding method for the steel material according to any one of Claims 1 to 3, a steel material preparation step of preparing the steel material, a first build-up welding step of forming a build-up welding portion in a first range of the exposed surface, A second build-up welding step of forming a build-up welding part on the second range of the exposed surface, and The first build-up welding step and the second build-up welding step are performed in parallel, A welding method for steel materials, characterized in that.

13. A welding method for steel materials according to any one of Claims 1 to 3, A first steel material preparation step of preparing a first steel material as the steel material, A second steel material preparation step of preparing a second steel material as the steel material, A first build-up welding step of forming a build-up welding part on the exposed surface of the first steel material, A second build-up welding step of forming a build-up welding part on the exposed surface of the second steel material, and The first build-up welding step and the second build-up welding step are performed in parallel, A welding method for steel materials, characterized in that.

14. A steel material having a bevel surface, A welding method for steel materials, characterized in that a build-up welding part is formed on at least a part of an exposed surface of the bevel surface that is exposed to a corrosive environment, A first steel material preparation step of preparing a first steel material as the steel material, A second steel material preparation step of preparing a second steel material as the steel material, A superposition step of superposing the first steel material and the second steel material, A build-up welding step of forming a build-up welding part on the exposed surfaces of the superposed first steel material and the second steel material, A welding method for steel materials, characterized in that.

15. The build-up welding step is A first build-up welding step of forming a build-up welding part on a first range of the exposed surfaces of the superposed first steel material and the second steel material, A second build-up welding step of forming a build-up welding part on a second range of the exposed surfaces of the superposed first steel material and the second steel material, and The first build-up welding step and the second build-up welding step are performed in parallel, A welding method for steel materials according to Claim 14, characterized in that.

16. A unit including a plurality of steel materials, The plurality of steel materials are such that the plate surface of one steel material and the plate surface of another steel material are superposed, A build-up welding part is formed on at least a part of an exposed surface of the bevel surface of the steel material that is exposed to a corrosive environment, There is a cut between the build-up welding part of one steel material and the build-up welding part of another steel material, A unit, characterized in that.

17. A unit including a plurality of steel materials, The plurality of steel materials are such that the plate surface of one steel material and the plate surface of another steel material are superposed, A build-up welding part is formed on at least a part of an exposed surface of the bevel surface of the steel material that is exposed to a corrosive environment, The build-up welded portion of one of the steel materials and the build-up welded portion of the other steel material are continuous. A unit characterized by this.

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