Friction stir welding tool and method for producing a friction stir welding tool

Abstract

The invention relates to a friction stir welding tool (1) for welding a component (7), which friction stir welding tool (1) has a pin and a shoulder (3) rigidly connected to the pin, the component (7) consisting of a base metal, in particular steel, having a melting point of more than 900°C. According to the invention, in order to achieve a particularly long service life of the tool even for thick-walled components (7), the shoulder (3) consists at least partially of a first material and the pin consists at least partially of a second material. The invention also relates to a shoulder (3) consisting at least partially of a first material and a pin consisting at least partially of a second material. The invention also relates to a method for joining a component (7) consisting of one or more base metals having a melting temperature of more than 900°C.

Description

Technical Field

[0001] The present invention relates to a friction stir welding tool, comprising a pin and a shoulder rigidly connected to the pin, for welding components made of a base material, particularly steel, having a melting point exceeding 900°C.

[0002] Furthermore, the present invention relates to a method for producing a friction stir welding tool having pins and shoulders, by means of which components of a base material having a melting temperature exceeding 900°C can be joined by friction stir welding.

[0003] In addition, the present invention relates to a method for joining components of one or more base materials having a melting temperature of over 900°C by friction stir welding, particularly for joining components of steel (preferably structural steel). Background Technology

[0004] Friction stir welding tools for joining components with melting temperatures exceeding 900°C, particularly for joining steel or various steel alloys, are known from the prior art. This type of tool includes a pin and a shoulder typically arranged perpendicular to the pin. When two adjacent components are joined, a compressive force is applied to the components being joined via the shoulder. Simultaneously, the components are heated due to the rotation of the friction stir welding tool relative to the components about its axis of rotation, causing the components to be plasticized and mixed in the joining zone within the area of ​​the friction stir welding tool, thereby achieving joining. The pin thus ensures the mixing of the plasticized material in the joining zone and is therefore subjected to large mechanical and thermal loads during friction stir welding, while the shoulder of the friction stir welding tool is responsible for most of the heat generation. The size of the shoulder is thus typically determined by the maximum surface pressure beneath the shoulder and the necessary compressive force in the axial direction on the components being joined.

[0005] It has been demonstrated that when used in friction stir welding tools, materials with beneficial properties for use as pin materials (e.g., high melting temperature) can result in excessive or insufficient heat generation at the shoulder due to excessive friction with the base material of the parts being joined, thus preventing the achievement of an optimal weld.

[0006] To prevent excessively high or low temperatures during the welding process, it is known from the prior art that the shoulder is correspondingly made larger or smaller. However, because the compression in the joint area is not optimal, this in turn causes quality problems in the welded joint.

[0007] Furthermore, it is known from the prior art that the shoulder and pin are formed from separate component parts, and the shoulder is driven at a different speed than the pin, so that the rotational speed of the shoulder, regardless of its size, affects the heat input via the shoulder. However, it has been shown that while the desired effect can be achieved in this way when welding aluminum and other materials with low melting temperatures, when base materials with melting temperatures exceeding 900°C (such as, for example, steel) are welded, plasticizing material from the joint zone seeps into the gap between the pin and the shoulder, causing tool damage and thus shortening the tool's lifespan. Summary of the Invention

[0008] This is addressed by the present invention. The objective is to specify a friction stir welding tool of the type described at the beginning, by which particularly high-quality weld joints and a very long tool life can be achieved, even if the geometry of the friction stir welding tool is given.

[0009] Additionally, a method for producing friction stir welding tools of the type described at the beginning is specified, by which such friction stir welding tools can be produced.

[0010] Finally, a method for joining components of the type described at the beginning is specified, by which particularly high-quality connections can be achieved in an efficient manner.

[0011] According to the invention, the first objective is achieved using a friction stir welding tool of the type described at the beginning, wherein the shoulder is at least partially composed of a first material and the pin is at least partially composed of a second material.

[0012] In the context of this invention, it has been found that the disadvantages of prior art friction stir welding tools can be overcome if the friction stir welding tool in the shoulder region is composed at least partially of a material different from the material in the pin region. In terms of chemical composition, mechanical properties, and / or thermal properties, the first material is generally different from the second material to which the first material is rigidly bonded. As a result, an optimized friction stir welding tool can be readily formed according to the desired application.

[0013] It is advantageous if the first material has a melting temperature of more than 900°C, preferably more than 2000°C.

[0014] Preferably, the second material is specified to have a melting temperature exceeding 900°C, preferably exceeding 2000°C, and particularly exceeding 3000°C. This allows for an exceptionally long service life of the friction stir welding tool. Typically, the melting temperature of the second material is higher than that of the first material.

[0015] It has been proven effective that the first and second materials have different strengths. As a result, tools that are particularly well adapted to the required conditions can be made, especially since particularly high strength is often necessary in the area of ​​the pin, while lower strength is often sufficient in the area of ​​the shoulder.

[0016] It is advantageous if the material pairing of the first material and the base material has a first coefficient of kinetic friction, and the material pairing of the second material and the base material has a second coefficient of kinetic friction, wherein the first coefficient of kinetic friction differs from the second coefficient of kinetic friction, particularly being lower than the second coefficient of kinetic friction. In this way, the tool can be implemented such that it has a lower coefficient of kinetic friction in the shoulder region than in the pin region. This ensures, in a simple manner, that sufficiently high compressive force can be introduced via the shoulder while maintaining low surface pressure, without excessive heat generation, and that friction in the pin region is also sufficient to agitate and plasticize the parts in the mating area for a particularly good connection.

[0017] Depending on the desired conditions during the welding process, or the necessary compressive force at the shoulder, the material can of course be selected such that the first coefficient of kinetic friction is greater than the second coefficient of kinetic friction.

[0018] Although it can be specified that the shoulder is entirely formed of the first material and the pin is entirely formed of the second material, the shoulder can also be formed using only part of the first material and part of the second material, and possibly one or more other materials. Similarly, the pin can also be formed using only part of the second material and the first material, and possibly other materials. By correspondingly dividing the areas of the shoulder and the pin into partial regions composed of different materials having a different coefficient of kinetic friction than the parent material, the desired coefficient of kinetic friction can be easily achieved in both the shoulder region and the pin region, wherein the average coefficient of kinetic friction of the shoulder is typically different from that of the pin.

[0019] This can be achieved, for example, by implementing a first component portion as annular, wherein the outer diameter of the first component portion corresponds to the outer diameter of the shoulder, but the inner diameter of the first component portion is implemented to be larger than the inner diameter of the shoulder, which may coincide with the outer diameter of the pin. In the region of the shoulder, a first material then extends from the outer diameter of the shoulder to the inner diameter of the first component portion in a first portion region of the shoulder, and a second material extends from the inner diameter of the first component portion to the inner diameter of the shoulder or the pin in the region of the shoulder. Alternatively, the pin may also be formed of a second material such that a second component portion can partially or completely form the second portion region of the shoulder and the pin.

[0020] Typically, the average coefficient of dynamic friction of the shoulder is lower than that of the pin. The average coefficient of dynamic friction can thus be achieved through a corresponding area ratio. If the coefficient of dynamic friction also depends on the relative velocity of the friction stir welding tool relative to the base material, the velocity of the corresponding area portion during the friction stir welding process can also be considered for the selection of the portion of the shoulder composed of the first or second material.

[0021] Even if the mathematical determination of the achievable average coefficient of dynamic friction over an area formed by a single material is preferred, the corresponding friction stir welding tool can certainly be formed, since the necessary configuration of the shoulder region for the desired weld quality (that is, the dimensions of the partial area of ​​the shoulder composed of the first material, and possibly the second and / or third material) is determined in tests.

[0022] Preferably, the chemical affinity of the first material to the base material is different from, and in particular lower than, that of the second material. Here, chemical affinity refers to the tendency of the corresponding material to bond with the base material. Therefore, in the pin region, it is advantageous to have a high chemical affinity to achieve good mixing and thus high strength of the weld joint. In the shoulder region, a lower affinity than in the pin region can be advantageous to achieve a weld with a smooth surface and to prevent excessive heat input and excessive wear of the friction-stirring welding tool in the shoulder region. Therefore, it is beneficial if the chemical affinity of the first material to the base material is lower than that of the second material.

[0023] To form a friction stir welding tool, the first material can, in principle, be attached to the second material in any desired manner, for example, by means of force fit, form fit, and / or material bonding methods. For example, the friction stir welding tool can be substantially composed of the second material, and the first material can be partially or completely coated in the shoulder region. It is also possible that, in the shoulder region, the first material is applied to a larger portion of the friction stir welding tool by means of overlay welding, and that portion of the tool is composed of the second material.

[0024] Similarly, it is also possible that a pin made of a second material or a portion of a pin made of a second material is connected to a larger first component portion of a friction stir welding tool made of a first material, in particular by force fit, form fit, and / or material bonding, for example, by being welded to it or screwed into it.

[0025] Preferably, the friction stir welding tool includes a ring made of a first material, which is connected by a welding method (particularly friction stir welding) to a second component portion made of a second material, the component portion forming a portion of the pin and shoulder not formed by the ring. The ring made of the first material may form the outer end of the shoulder, or it may be arranged in a groove such that the ring forms a first portion of the shoulder in the middle or inside.

[0026] Of course, the first part of the friction stir welding tool formed of the first material or the second part of the friction stir welding tool formed of the second material may also form at least partially or completely the handle of the friction stir welding tool.

[0027] Specifically, for cost optimization purposes, friction stir welding tools can be specified to have a shank comprising a third material, particularly one formed of a third material. In this way, the use of cost-intensive materials for the shoulder and pin can be minimized, thereby allowing the friction stir welding tool to be manufactured at a particularly low cost. Individual component parts of the friction stir welding tool, particularly the pin area, shoulder area, and shank area, can be connected to each other in any possible form-fit, force-fit, and / or material-bonding manner, for example, by friction welding.

[0028] Of course, friction stir welding tools can include very different materials depending on one or more different base materials that make up the parts being welded in the area being welded, and the first material can be formed from virtually any desired material. In particular, it has proven especially effective to achieve the beneficial frictional properties at the shoulder if the first material contains molybdenum, especially if it is implemented as a molybdenum alloy.

[0029] The second material can, in principle, be formed of any desired material suitable for the corresponding application. In order to achieve a particularly long service life even when high temperatures occur in the joint area, it is preferable that the second material contains tungsten, particularly formed of tungsten-rhenium.

[0030] To achieve the corresponding advantageous properties, the first and / or second materials may also be specified to include ceramic materials, particularly oxide ceramic materials, and / or non-oxide ceramic materials (such as carbides, nitrides, or silicides), or to be formed of such materials.

[0031] A particularly long service life can be achieved if the first and / or second materials include refractory metals, refractory metal alloys, nickel alloys, cobalt alloys, and / or ferroalloys, or are formed from materials of this type. Refractory metals (i.e., the base metals of groups 4, 5, and 6, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten) have extremely high melting temperatures and mechanical properties beneficial for their application as friction stir welding tools. A further objective is achieved using a method of the type described at the beginning, in which a first component portion composed of the first material is rigidly connected to a second component portion composed of the second material, such that at least a portion of the shoulder is formed of the first material, and at least a portion of the pin is formed of the second material.

[0032] In this way, the properties of the friction stir welding tool in the shoulder region can be easily achieved independently of the properties in the pin region.

[0033] For the purpose of forming a friction stir welding tool, the first component can, in principle, be connected to the second component in any desired manner, for example, by force fit and / or form fit. However, it is particularly preferred that the first component be connected to the second component by a material bonding manner. A particularly robust connection is thus achieved.

[0034] Although the first component can, in principle, be attached to the second component in any desired material bonding manner (e.g., by sintering, 3D printing, etc.), or the second component can be attached to the first component in any desired material bonding manner (e.g., by sintering, 3D printing, etc.), it is preferably specified that the first component is welded to the second component. Unlike sintering, coating, or 3D printing, it is not absolutely necessary for the outer contour of the first component to be completely altered or for the first component to be completely fused during this method. Therefore, it can also be specified that the first and second component components substantially maintain their outer contours during the method used to form the friction stir welding tool. For example, the first component can thus be implemented as a ring welded to the second component, the second component including a portion of a shoulder and a pin, particularly having a groove for the first component. Welding can then occur in ways quite different from those known in the prior art, for example, by laser welding, diffusion welding, electron beam welding, etc.

[0035] It has been shown that a particularly robust connection between the first and second component parts can be achieved if the first component part is connected to the second component part by means of friction welding.

[0036] Preferably, the first component is connected to the second component using pressure welding. Alternatively, a combination of friction welding and pressure welding is also possible.

[0037] It has been proven effective that, based on a desired average coefficient of kinetic friction—acting during contact between the shoulder and the base material and between a first coefficient of kinetic friction and a second coefficient of kinetic friction—a first portion of the shoulder is formed of a first material, and a second portion of the shoulder is formed of a second material, in order to achieve the desired average coefficient of kinetic friction. In other words, if the shoulder is not entirely formed of the first material, the size of the portion of the shoulder formed of the first material is selected according to which average coefficient of kinetic friction is desired in the region of the shoulder. For example, if the average coefficient of kinetic friction of the first material in the material pairing with the base material, particularly with steel (especially high-strength structural steel for pipelines), is 0.1, and the coefficient of kinetic friction of the second material in the material pairing with the same base material is 0.3, then an average coefficient of kinetic friction of, for example, 0.2, for the shoulder can thus be achieved, because the area of ​​the shoulder in contact with the component being welded during the welding process is 50% formed of the first material and 50% of the second material. The surface of the shoulder is thus composed of a first part and a second part, although additional parts of other materials are of course possible in principle. Because the speed of the shoulder in the region adjacent to the pin or axis of rotation is lower than that at the outer edge, and the coefficient of kinetic friction can also depend on the relative speed, the ratio of the area of ​​the shoulder formed by the first material to that formed by the second material can be different, depending on whether the first material is arranged on the inner or outer side of the shoulder.

[0038] To achieve a particularly large effect when a first material, preferably having a lower coefficient of kinetic friction than the second material, is used, the first material is typically arranged at the outer edge of the shoulder, for example, as an outer ring. Therefore, not only is the area of ​​the shoulder formed by the first or second material related to the quality of the weld or the heat input to the component being welded, but also, at least to a small extent, the location of the shoulder formed by the first or second material, or the distance of that location from the rotation axis of the friction stir welding tool, is related to the quality of the weld or the heat input to the component being welded.

[0039] Preferably, the friction stir welding tool is implemented to be approximately rotationally symmetrical.

[0040] To achieve particularly simple production, it is advantageously stipulated that, before the first component portion is connected to the second component portion, the first component portion is formed with a contour corresponding to the portion of the shoulder formed of the first material. The first component portion can therefore be implemented, for example, as a ring located in a groove in the second component portion to form the corresponding portion of the shoulder. In principle, the first component portion can also, of course, be implemented as a polygon or the like to achieve a connection that mates with the shape of the second component portion. The second component portion can form either a part of the pin, the entire pin, or a part or the entire handle of a tool.

[0041] Preferably, the first component portion is specified to have a substantially rotationally symmetrical outer contour, particularly being implemented as a generally annular shape. This makes it particularly easy to manufacture friction stir welding tools.

[0042] Of course, the friction stir welding tool according to the present invention can be formed by the method according to the present invention.

[0043] The third objective is achieved according to the invention, using a method of the type described at the beginning, in which a friction stir welding tool according to the invention is used. As a result, welds of particularly high quality are achieved, while the friction stir welding tool has a long service life.

[0044] While in principle any desired component can be joined using the friction stir welding tool according to the invention, it has been shown that the corresponding friction stir welding tool is particularly suitable for use in corresponding methods where the components being joined are implemented as tubular structures. Pipes used to construct pipelines can therefore be welded without having to change the friction stir welding tool while forming a weld that extends in the circumferential direction. This is crucial for the construction of pipelines that can be laid at depths of 3000m below the ocean surface (e.g., in a particularly efficient manner).

[0045] This method is particularly preferred when the component has a wall thickness exceeding 10 mm, especially exceeding 20 mm, and the weld extends particularly along the entire wall thickness. Components, typically implemented as flat and preferably tubular, are thus laid close together before welding along a small facet of the component, such that when the weld extends from one surface of the component to the opposite surface, the weld has a height corresponding to the arm thickness or the height of the small facets of the components laid close together.

[0046] To achieve stable friction stir welded joints even with correspondingly large wall thicknesses, a particularly precise amount of heat input is necessary, especially since excessive or insufficient heat will render the friction stir welded joint suboptimal, at least in a portion of the weld thickness. With the friction stir welding tool according to the invention, such precise heat input is readily achievable, particularly because the dynamic friction coefficient of the shoulder can be achieved independently of the dynamic friction coefficient of the pin and the material. Attached Figure Description

[0047] Further features, advantages, and effects of the invention will become apparent from the exemplary embodiments described below. In the accompanying drawings, which are thus referenced:

[0048] Figures 1 to 3 Different friction stir welding tools according to the present invention are shown;

[0049] Figure 4 The friction stir welding tool according to the invention is shown during the welding of two components;

[0050] Figures 5 to 7 Further friction stir welding tools are shown;

[0051] Figure 8 This illustrates a further friction stir welding tool used during the joining of the two components. Detailed Implementation

[0052] Figure 1 A cross-section of a friction stir welding tool 1 according to an embodiment of the present invention is shown. It can be seen that the friction stir welding tool 1, implemented as substantially rotationally symmetrical about a rotation axis 9, includes a shank 4, a pin 2, and a shoulder 3, wherein the shoulder 3 is oriented substantially perpendicular to the rotation axis 9 and is formed of a first component portion 5 of a first material (in this case, a molybdenum alloy), and the pin 2 and shank 4 are formed of a second component portion 6 of a second material (in this case, tungsten-rhenium). As illustrated, the first component portion 5 is implemented as annular, wherein the inner diameter 13 of the first component portion 5 corresponds to the outer diameter 11 of the pin, which in turn corresponds to the inner diameter 13 of the shoulder. The outer diameter of the annular first component portion 5 corresponds to the outer diameter 12 of the shoulder. The shoulder 3 is therefore formed entirely of the first component portion 5 or the first material in this case.

[0053] High-temperature resistance is achieved using this type of tool by employing tungsten-rhenium in the pin 2 region. By using a molybdenum alloy in the shoulder 3 region, a lower coefficient of dynamic friction is achieved at the shoulder 3 than in the pin 2 region when steel (especially structural steel) components 7 are being welded. This results in lower heat input via the shoulder 3 compared to a friction stir welding tool 1 composed solely of tungsten-rhenium, given the same process parameters (such as contact pressure in the axial direction, rotational speed of the friction stir welding tool 1 about the rotation axis 9, and forward speed). The higher coefficient of dynamic friction exhibited by the tungsten-rhenium material pairing with structural steel in the pin 2 region is beneficial for achieving dense stirring in the joint area. Therefore, using friction stir welding, components 7 with a large wall thickness 10 can also be welded together in a manner that achieves both a long service life of the friction stir welding tool 1 and a high-quality weld joint.

[0054] Figure 2 A further friction stir welding tool 1 according to the invention is shown. The shoulder 3 is again entirely formed of a first annular component portion 5 of molybdenum alloy, while portions of the pin 2 and handle 4 are formed of a second component portion 6 of tungsten-rhenium. However, with Figure 1 In contrast to the friction stir welding tool 1 illustrated, the handle 4 here is formed only partially by the second component portion 6 and partially by the third component portion 8 of a third material, which may be more advantageous than tungsten-rhenium in terms of production cost, for example.

[0055] Figure 3A further exemplary embodiment of the friction stir welding tool 1 according to the invention is shown. In this exemplary embodiment, the first component portion 5 does not extend across the entire shoulder 3, but only forms a first partial region 14 of the shoulder 3, such that a second partial region 15 of the shoulder 3 is formed by the second component portion 6, and the pin 2 is also formed by the second component portion 6. Thus, only the outer first partial region 14 of the shoulder 3 is formed by the first component portion 5, in which case the first component portion 5 is also implemented as annular and is composed of a molybdenum alloy. In this case, the annular first component portion 5 therefore does not extend from the outer diameter 12 of the shoulder to the pin 2 or the outer diameter 11 of the pin, but only to the inner diameter 13, which is approximately located in the middle between the inner diameter 13 and the outer diameter 12 of the shoulder. Here, the inner diameter 13 of the shoulder also corresponds to the outer diameter 11 of the pin. By changing the inner diameter 13 of the first component portion 5, or by changing the first portion region 14 formed of the first material and the second portion region 15 formed of the second material of the shoulder 3, the desired average coefficient of kinetic friction of the shoulder 3, occurring when used with a base material (such as, for example, steel), can therefore be arbitrarily adjusted between a first coefficient of kinetic friction for the material pairing of the first material and the base material, and a second coefficient of kinetic friction for the material pairing of the second material and the base material. In an exemplary embodiment, the first coefficient of kinetic friction for the material pairing of the molybdenum alloy and steel is lower than the second coefficient of kinetic friction for the material pairing of tungsten-rhenium and steel, so that in Figure 3 In the exemplary embodiment illustrated in the figure, an average coefficient of dynamic friction is obtained in the region of shoulder 3 that is higher than that of a molybdenum alloy paired with steel and lower than that of a tungsten-rhenium paired with steel.

[0056] Figure 4 The welding process of the second component 7 is shown again in the cross-sectional view. Figure 1 Friction stir welding tool 1. It can be seen that pin 2 extends substantially across the entire wall thickness 10 of component 7, in which case component 7 is implemented, for example, in plate shape, composed of steel, preferably pipeline steel, and having a melting temperature exceeding 900°C. By using a first material in the region of shoulder 3, a lower coefficient of dynamic friction is achieved in the region of shoulder 3 than in the region of pin 2, thereby enabling advantageously dense stirring of the parent material of component 7 in the region of pin 2, while relatively low heat input occurs via shoulder 3.

[0057] Figures 1 to 4 In the exemplary embodiment illustrated in the figure, the shoulder 3 is at least partially formed by a first component portion 5 of an annular shape. In the exemplary embodiment, the second component portion 6 is connected to a second component portion 6 by means of a friction welding process, which forms at least a portion of the area of ​​the pin and handle 4.

[0058] This results in a rigid, stable connection, which also ensures that there is no gap between the first component part 5 and the second component part 6, so that plasticizing material from the weld cannot seep into such a gap, such as the multi-component friction stir welding tool 1 in which the shoulder 3 rotates at a speed lower than that of the pin 2.

[0059] Figures 5 to 7 A further exemplary embodiment of the friction stir welding tool 1 according to the invention is shown in a cross-sectional view. In these exemplary embodiments, the shoulder 3 and pin 2 of the friction stir welding tool 1, which are substantially composed of a third material, are at least partially coated with different materials so as to obtain different frictional properties in the region of pin 2 and the region of shoulder 3 when friction stir welding is performed. The friction stir welding tool 1 can thus be substantially composed of a third material and, as illustrated, coated only in the region of shoulder 3 and the region of pin 2 to obtain the desired properties in these partial regions. Figure 5 In the exemplary embodiment illustrated in the figure, the surface forming the shoulder 3 is completely coated with the first material, and the surface forming the pin 2 is completely coated with the second material. Therefore, in Figure 5 In the exemplary embodiment illustrated herein, the first component portion 5 is implemented as a coating in the region of the shoulder 3, and the second component portion 6 is implemented as a coating in the region of the pin 2, wherein the first component portion 5 may also be composed of a molybdenum alloy, for example, and the second component portion 6 may again be composed of a tungsten alloy.

[0060] exist Figure 6 In the exemplary embodiment illustrated in the figure, the first component portion 5, formed by the coating, similarly only partially covers the surface of the area of ​​the shoulder 3. Here, the coating not composed of the first material, or the portion of the shoulder 3 not formed by the first component portion 5, is formed by a coating of a second material, or by a second component portion 6, which also forms the surface of the pin 2. In this way, the coefficient of kinetic friction of the shoulder 3, located between the first and second coefficients of kinetic friction, can again be achieved.

[0061] Figure 7 A further embodiment is shown in which the surface in the region of the shoulder 3 is formed by a first component portion 5 composed of a first material, which is implemented as a coating. Here, the surface of the pin 2 is partially coated with the first material and partially coated with a second material in order to obtain properties between those of the first material and the second material in this case.

[0062] Figure 8 The method for joining the corresponding component 7 is shown again in the cross-sectional view. Figure 5 The use of friction stir welding tool 1.

[0063] exist Figures 5 to 8 As can be seen, the friction stir welding tool 1 can therefore also be formed essentially of a third material or a third component portion 8, the third component portion 8 having its end sides in the region of the shoulder 3 and the region of the pin 2 coated with the first material forming the first component portion 5 and the second material forming the second component portion 6, in order to obtain corresponding properties. Figures 1 to 4 Contrary to the exemplary embodiments illustrated in the figures, in Figures 5 to 8 In the exemplary embodiment illustrated in the figure, the outlines of the first component portion 5 and the second component portion 6 are thus first formed during the production of the friction stir welding tool 1, that is, by coating the surface of the third component portion 8.

[0064] The corresponding friction stir welding tool 1 can, in principle, be used for vastly different purposes. Preferably, the tool is used to weld structural steel, particularly high-strength and ultra-high-strength steel, and, for example, thick-walled pipes that can be composed of structural steel and have a wall thickness 10 exceeding 10 mm, together along a weld seam extending in the circumferential direction. This pipe can be used for pipelines, for example, at great depths. Even thick-walled steel pipes can therefore be welded using a single friction stir welding tool 1 without changing the tool, thereby allowing the corresponding pipelines to be produced in a particularly cost-effective manner.

Claims

1. A friction stir welding tool (1), the friction stir welding tool (1) comprising a pin (2) and a shoulder (3) rigidly connected to the pin (2), the friction stir welding tool (1) being used for welding steel having a diameter of more than 900 mm. ° The component (7) of the parent material with melting point C, wherein the shoulder (3) is at least partially composed of a first material and the pin (2) is at least partially composed of a second material, characterized in that The first material and the parent material have a first coefficient of kinetic friction when paired together, and the second material and the parent material have a second coefficient of kinetic friction when paired together, wherein the first coefficient of kinetic friction is lower than the second coefficient of kinetic friction. The shoulder (3) includes a first component portion (5) having a substantially rotationally symmetrical outer contour and being configured as approximately annular, wherein the outer diameter of the first component portion (5) corresponds to the outer diameter of the shoulder, and the inner diameter of the first component portion (5) is configured to be larger than the inner diameter of the shoulder, the inner diameter of the shoulder being consistent with the outer diameter of the pin; and In the region of the shoulder (3), the first material extends from the outer diameter of the shoulder to the inner diameter of the first component portion (5) in the first part region (14) of the shoulder (3), and the second material extends from the inner diameter of the first component portion (5) to the inner diameter of the shoulder or pin (2).

2. The friction stir welding tool (1) according to claim 1, characterized in that... The first material has more than 900 ° The melting temperature of C.

3. The friction stir welding tool (1) according to claim 1 or 2, characterized in that... The second material has more than 900 ° The melting temperature of C.

4. The friction stir welding tool (1) according to claim 1, characterized in that... The first material and the second material have different strengths.

5. The friction stir welding tool (1) according to claim 1, characterized in that... The first material has a lower chemical affinity for the parent material than the second material.

6. The friction stir welding tool (1) according to claim 1, characterized in that... The friction stir welding tool (1) has a handle (4) which comprises a third material.

7. The friction stir welding tool (1) according to claim 1, characterized in that... The first material contains molybdenum.

8. The friction stir welding tool (1) according to claim 1, characterized in that... The second material contains tungsten.

9. The friction stir welding tool (1) according to claim 1, characterized in that... The first material and / or the second material includes ceramic materials, or are formed from materials of this type.

10. The friction stir welding tool (1) according to claim 1, characterized in that... The first material and / or the second material comprises refractory metals and / or refractory metal alloys, or is formed from materials of this type.

11. The friction stir welding tool (1) according to claim 2, characterized in that... The first material has more than 2000 ° The melting temperature of C.

12. The friction stir welding tool (1) according to claim 3, characterized in that... The second material has more than 2000 ° The melting temperature of C.

13. The friction stir welding tool (1) according to claim 3, characterized in that... The second material has more than 3000 ° The melting temperature of C.

14. The friction stir welding tool (1) according to claim 6, characterized in that... The handle (4) is formed of the third material.

15. The friction stir welding tool (1) according to claim 7, characterized in that... The first material is a molybdenum alloy.

16. The friction stir welding tool (1) according to claim 8, characterized in that... The second material is formed from tungsten and rhenium.

17. The friction stir welding tool (1) according to claim 9, characterized in that... The first material and / or the second material includes oxide ceramic materials and / or non-oxide ceramic materials, or are formed from such materials.

18. The friction stir welding tool (1) according to claim 17, characterized in that... The non-oxide ceramic material includes carbides, nitrides, or silicides.

19. The friction stir welding tool (1) according to claim 1, characterized in that... The first material and / or the second material comprises refractory metals, nickel alloys, cobalt alloys and / or iron alloys, or are formed from materials of this type.

20. A method for producing a friction stir welding tool (1) according to any one of claims 1 to 19, the friction stir welding tool (1) having a pin (2) and a shoulder (3), wherein components (7) of a base material formed of steel can be joined by means of friction stir welding, the base material having a thickness of more than 900 mm. ° The melting temperature of C, wherein a first component portion (5) composed of a first material is rigidly connected to a second component portion (6) composed of a second material, such that at least a portion of the shoulder (3) is formed of the first material, and at least a portion of the pin (2) is formed of the second material, characterized in that The first material and the parent material have a first coefficient of kinetic friction when paired together, and the second material and the parent material have a second coefficient of kinetic friction when paired together, wherein the first coefficient of kinetic friction is lower than the second coefficient of kinetic friction. The first component portion (5) has a substantially rotationally symmetrical outer contour and is configured to be generally annular, wherein the outer diameter of the first component portion (5) corresponds to the outer diameter of the shoulder, and the inner diameter of the first component portion (5) is configured to be larger than the inner diameter of the shoulder, the inner diameter of the shoulder being consistent with the outer diameter of the pin; and In the region of the shoulder (3), the first material extends from the outer diameter of the shoulder to the inner diameter of the first component portion (5) in the first part region (14) of the shoulder (3), and the second material extends from the inner diameter of the first component portion (5) to the inner diameter of the shoulder or pin (2).

21. The method according to claim 20, characterized in that... The first component part (5) is attached to the second component part (6) by means of material bonding.

22. The method according to claim 20 or 21, characterized in that... The first component part (5) is welded to the second component part (6).

23. The method according to claim 20, characterized in that... The first component part (5) is connected to the second component part (6) by using friction welding.

24. The method according to claim 20, characterized in that... The first component part (5) is connected to the second component part (6) by pressure welding.

25. The method according to claim 20, characterized in that... Based on a desired average coefficient of dynamic friction that acts during contact between the shoulder (3) and the matrix material and lies between a first coefficient of dynamic friction of the first material and the matrix material and a second coefficient of dynamic friction of the second material and the matrix material, the first portion region (14) of the shoulder (3) is formed of the first material and the second portion region (15) of the shoulder (3) is formed of the second material in order to achieve the desired average coefficient of dynamic friction.

26. The method according to claim 20, characterized in that... Before the first component portion (5) is connected to the second component portion (6), the first component portion (5) is formed with a contour corresponding to the portion area of ​​the shoulder (3) formed by the first material.

27. The method according to claim 20, characterized in that... The component (7) is formed of structural steel.

28. A method for joining materials made of steel and having a cross-sectional area of ​​over 900 mm by friction stir welding. ° The base material of C has a melting temperature exceeding 900°C, or is made of steel or various other steels. ° The method for the component (7) of the parent material with melting temperature C, characterized in that... Use the friction stir welding tool (1) according to any one of claims 1 to 19.

29. The method according to claim 28, characterized in that... The component (7) is implemented as a tubular shape.

30. The method according to claim 28 or 29, characterized in that... The component (7) has a wall thickness (10) of more than 10 mm.

31. The method according to claim 28, characterized in that... The component (7) is formed of structural steel.

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