JP2005288499A - Friction stir welding method and reforming method thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make welding and surface layer reforming possible by friction stir for a workpiece composed of a high melting point material, in a friction stir welding method in which a workpiece is welded through plastic flow by frictional heat produced between a rotary tool and the workpiece by inserting the rotary tool into the workpiece and rotatably moving it. <P>SOLUTION: Welding or reforming by friction stir is performed with a weld zone s heated by irradiating it with a laser beam, or with an insert 3 placed between welding faces, or with the above two means combinedly used. Irradiation of the laser beam fluidizes even a high melting point material. Also, placing the insert between the welding faces causes adiabatic effect to be imparted between the insert and the workpiece, preventing the frictional heat from diffusing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a joining method and a reforming method by friction stirring that are particularly suitable for joining high melting point materials such as Fe and Ni-based alloys and are also useful for surface treatment and modification of metal base materials. .

  Conventionally, a solid-phase joining method by friction stirrer has been known, and this joining method inserts a rotary tool made of a material substantially harder than a workpiece into the workpiece joint and moves the rotary tool while rotating it. This is a joining method that joins the workpiece by plastic flow due to frictional heat generated between the rotating tool and the workpiece, and is used for solid phase joining using metal plastic flow due to frictional heat between the rotating tool and the joining member. Therefore, it is possible to join without melting the joined portion, there are few deformations after joining, and since the joined portion is not melted, there are many advantages such as fewer defects.

The friction stir method is suitable not only for joining metal members but also for modifying a relatively thick portion of the metal material surface. For example, Patent Document 1 (Japanese Patent Laid-Open No. 2001-47261) discloses a metal material. As part of the composite material with different materials with various characteristics, to improve the characteristics of the metal material in that part, a protrusion is formed at the tip of the rod-shaped body against the metal material with the different material arranged A method of rotating and moving the provided hard rotary tool with the protrusions inserted into the metal material and the different material to stir the metal material and the different material, so that at least a part of the metal material is a composite material with the different material. Is disclosed.
According to the method of Patent Document 1, there is an advantage that a sufficiently thick modified layer having strong bonding and various characteristics can be easily and inexpensively formed at a necessary portion of the metal material.

  Further, in Patent Document 2 (Japanese Patent Application Laid-Open No. 2003-126970), there is a gap at a joint portion of a workpiece, and there is no defect even when the gap is not constant, and the joint strength is high. As a friction stir welding method, it is possible to fill the gap generated in the joint part of the workpiece with a powdery joining material, and insert a rotary tool into the joint part and rotate it along the joint part while rotating it. Friction stir welding is performed.

JP 2001-47261 A JP 2003-126970 A

However, such a conventional friction stirring method can be applied to joining or reforming a metal material having a relatively low melting point such as Al, Cu, Ti, etc., but has a high melting point such as Fe or Ni-based alloy, and the like. It was not easy for high-strength metal materials.
That is, Fe, Ni-based alloys and the like generally have a melting point near 1,400 ° C., phase change occurs from around 1,000 to 1,100 ° C., and fluidization starts. When applied to these high-melting-point materials, it is difficult to raise the temperature of the base material to around 1,100 ° C only by frictional heat input, and the high-temperature strength is high, so the tool is easily worn out, and a long distance is continuously applied. Therefore, there is a problem that it is difficult to weld. Further, since the bonding load becomes large, the reaction force is large, so that there is a problem that a strong facility is required.

  In order to solve these problems, a pattern that forcibly moves the frictional heat caused by the rotational movement of the shoulder surface from the outside of the shoulder surface to the center side on the shoulder surface of the rotary tool that presses against the processed surface of the conventional workpiece Although a method for forming the joint or a method for preheating the joint before stirring and the like has been tried, the above problems have not been solved.

  In view of the problems of the prior art, the present invention solves the above-mentioned problems that occur when applying a conventional friction stir welding method to a high melting point material, not only high melting point and high strength materials such as Fe and Ni-based alloys, It is an object of the present invention to provide a friction stir welding method and a reforming method that can be applied to high melting point heat resistant steels such as stainless steel, Inconel, and Hastelloy.

The present invention achieves such an object, and the first means thereof is to insert a rotary tool made of a material substantially harder than the workpiece into the joint portion of the workpiece and move the rotary tool while rotating it. In a joining method by friction stir that joins a workpiece by plastic flow due to frictional heat generated between the rotary tool and the workpiece, a laser is applied to the joint at the time of performing the welding by friction stirring or the preheating step in the previous stage. Irradiation is performed and heating is performed.
In this first means, preferably, laser irradiation is performed on the joint from the center of the rotary tool along the axial direction of the rotary tool, or laser is applied to the joint from the periphery of the rotary tool. Irradiate.

The frictional heat generated when the rotating tool rotates in contact with the workpiece surface plastically flows the workpiece to allow stirring, but especially when working with workpieces made of high melting point materials, only frictional heat input is required. Not enough plastic fluidization. Therefore, in the first means, the plastic flow can be easily generated even with a high-melting-point material by irradiating the joint with laser to compensate for the lack of heat.
Preferably, by performing laser irradiation from the central part of the rotary tool to the joint along the axial direction of the rotary tool, the laser beam can be efficiently concentrated on the joint at the shortest distance. Fluidization can be facilitated. Also, by irradiating the joint from the periphery of the rotary tool with a laser beam over the workpiece surface over a wide range, the entire workpiece surface can be heated uniformly, especially for surface treatment of the workpiece. It is suitable when performing.

As a result, even when the workpiece is made of a high melting point material such as stainless steel, Ni-base alloy, Inconel, Hastelloy, etc., it is possible to supply heat input sufficient to cause the workpiece to flow in a solid state, and to prevent a bonding defect. Allows no friction stir welding.
Further, when the joint portion has a groove portion, there is a problem that the frictional heat input is not sufficiently supplied to the groove lower portion. By irradiating the joint with laser light during the preheating step in the stage, the joint can be sufficiently heated, and even when a workpiece made of a high melting point material is joined, the joint has a groove. The fluidization required for friction stir welding is possible.

  Further, the second means of the present invention is to insert a rotary tool made of a material substantially harder than the workpiece into the joint portion of the workpiece, and move the rotary tool while rotating the rotary tool and the workpiece. In the reforming method by friction stirrer that modifies the surface layer of the work piece by plastic flow due to frictional heat generated during the process, the part to be reformed of the work piece at the time of reforming by friction stirrer or the preheating process in the previous stage Heating is performed by laser irradiation.

  According to the second means, when the modification by friction stirring is performed, the modification target portion of the workpiece is heated by laser irradiation at the time of the modification by friction stirring or the preheating process in the previous stage. Thus, sufficient heat necessary for the modification can be supplied, and the softening and flow of the workpiece can be promoted. In this case, the temperature condition can be adjusted by the number of rotations of the rotary tool and the degree of pressing force applied to the workpiece by the rotary tool. The irradiation position of the laser beam on the workpiece may be set as appropriate depending on the purpose and degree of modification.

  Further, at the time of modification, it is also possible to supply fine particles to the portion to be modified by fine particle beam irradiation and form a composite material composed of the same processed material and the same fine particles on the surface layer of the processed material. . By supplying a different material such as ceramic to the surface of the workpiece and irradiating it with laser light in this way, it is possible to perform high-quality overlay welding with no adhesion and strong adhesive force.

  According to a third means of the present invention, a rotary tool made of a material substantially harder than a workpiece is inserted into a joint portion of the workpiece, and the rotary tool is moved while being rotated. In a joining method by friction stir that joins workpieces by plastic flow due to frictional heat generated during insertion, an insert material made of the same material as the workpiece and wider than the diameter of the rotating tool is inserted between the joints. The rotary tool is inserted into the insert material and friction stirring is performed.

And according to this 3rd means, since the joint surface of a workpiece and the insert material are isolate | separated, the friction heat input supplied to an insert material may diverge | emit to the workpiece base material side through a joint surface. Therefore, the temperature of the insert material is likely to rise, and the time until solid phase fluidization is short. Therefore, even when friction stirrer is applied to a workpiece made of a high melting point material, the temperature rise to the solid phase fluidization temperature of the high melting point material can be achieved, and friction welding can be performed.
In addition, the diameter of the part inserted in insert material among rotary tools may be smaller than the width | variety of insert material. This is because the boundary region between the workpiece and the insert material is sufficiently heated and fluidized by the temperature rise of the insert material due to frictional heat input caused by the rotation of the rotary tool.
If this 3rd means is employ | adopted, the preheating process of the junction part before friction stirring enforcement conventionally proposed is not required.

In the third means, preferably, the thickness of the insert material to be inserted is made thicker than the thickness of the workpiece. In the friction stir welding, a dent is easily generated in the joint portion, and the dent can be prevented by making the thickness of the insert material thicker than the workpiece.
Preferably, an insert material formed by solidifying or sintering powder made of the same material as the workpiece is used. Thereby, since the insert material is further easily deformed, it is easy to be solid-phase fluidized, and a good joint portion having no joint defect is obtained.

More preferably, irregularities are formed on one or both of the joined surfaces of the workpiece or the insert material. This further promotes the thermal insulation state between the joint surface of the workpiece and the insert material, and prevents the frictional heat input supplied to the insert material from spreading to the workpiece side. Fluidization and stirring are promoted.
More preferably, the insert material inserted into the joint portion is energized and heated at the time of joining by friction stirring or at the preheating step in the previous stage. Thereby, the softening of the insert material can be further facilitated, and the joining load by the rotating tool can be reduced. As a method for energizing the insert material, for example, electrodes may be attached to both ends of the insert material.

Further, in the above energization method, if an electrical insulating material that evaporates or disappears by heating is interposed between the joint surface of the workpiece and the insert material, the current introduced into the insert material flows into the workpiece side. Is prevented completely, and the current flows concentrated in the insert material, which can further promote softening of the insert material, and the electrical insulation material evaporates or disappears after frictional stirring. There is no adverse effect on the material of the joined portion after the formation or joining.
As the electrically insulating material, for example, oils, brazing materials and the like can be used.

  Further, in the third means, preferably, the insert material inserted into the joint portion is heated by irradiating ultrasonic waves at the time of joining by friction stirring or the preheating step in the preceding stage. By adding ultrasonic waves, the softening of the insert material can be facilitated, the joint load applied to the joint by the rotary tool can be reduced, and the boundary region of the workpiece adjacent to the insert material can be easily fluidized and agitated. . As a specific means for irradiating the insert material with ultrasonic waves, an ultrasonic transducer may be attached to a member that supports the rotary tool.

More preferably, a groove is formed at least at the start portion of the insert material, and the groove may be filled with powder of the same material as the workpiece. Thereby, it becomes easier to deform | transform than when an insert material is solid, Therefore Fluidization and stirring become easy.
The fourth means of the present invention is to use the first means and the third means together. As a result, fluidization and stirring of the insert material and the peripheral workpiece boundary region can be achieved very easily, and the friction stir welding of the workpiece made of the high melting point material can be easily performed.

As described above, according to the present invention, the joining portion is heated by laser irradiation at the time of performing the welding by friction stirring or the preheating step in the previous stage, or the laser irradiation is performed on the workpiece surface layer. Insert the insert material made of the same material as the workpiece and wider than the diameter of the rotary tool between the joints of the workpiece, and insert the rotary tool into the insert material and friction By performing agitation, and further using both the laser irradiation and the insertion of the insert material between the joints, it is possible to facilitate solid phase fluidization and agitation of the insert material or the region around the joint, and thereby Friction stir welding of workpieces made of high melting point materials such as Fe and Ni base alloys, which has been difficult in the past, has been made possible.
Moreover, according to this invention, it is an economically advantageous method that said effect can be achieved by addition of a laser irradiation apparatus or addition of a simple apparatus required for insertion of an insert material.

The rotary tools used for friction stir welding include probe type and bobbin tool type rotary tools, but the probe type needs to press the rotary tool against the welding line, so to deal with this reaction force, A highly rigid backing metal is used and placed in close contact with the back of the workpiece.
On the other hand, the bobbin tool type includes a pair of shoulders (base material pressing members) that are spaced apart so as to sandwich both front and back surfaces of the workpieces to be joined, and a stirring shaft (pin shaft) is provided between the pair of upper and lower shoulders. Friction welding is performed while stirring the joints heat input by the pair of shoulders.
The present invention can be implemented when either of these two types of rotary tools is used.

  Hereinafter, the present invention will be described in detail using embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

FIGS. 1 and 2 relate to a first embodiment of the present invention, FIG. 1 is a perspective view when a laser beam is irradiated on a joint, and FIG. 2 is a schematic elevation view when a rotary tool is inserted.
1 and 2, 1 is a rotary tool body that performs friction stir welding, 1 a is a shoulder portion that presses the joint surface during friction stirring and generates friction heat input, and 2 is a stirring shaft that protrudes from the lower end of the rotating tool body. W, W ₁ , W ₂ are workpieces to be joined, a is the rotation direction of the rotary tool body 1 and the stirring shaft 2, b is the direction of rotation of the rotary tool body 1, and s is the workpiece W ₁ , The W ₂ junction, R, indicates the irradiated laser beam.

In this embodiment, the rotary tool main body 1 and the stirring shaft 2 descend while rotating, the stirring shaft 2 is inserted into the joint portion s of the workpiece W, and the shoulder portion 1a presses the joint surface to cause frictional heat input. In addition, the stirring shaft 2 inserted into the workpiece W joins the joint s while stirring. At this time, a laser beam R (for example, a high coherency parallel beam is used) is applied to the joint s from a gap provided in the rotary tool body along the central axis of the rotary tool 1 to heat the joint s. , Promote solid-phase flow and agitation of the joint s. Further, as shown in FIG. 2, the load when the stirring shaft 2 is inserted can be reduced by irradiating the joint s with the laser beam R before the tool is inserted and heating the joint s in advance.
In the case where workpieces made of a high melting point material are joined, the stirring shaft 2 also needs to have a high high temperature strength. Therefore, for example, the tip portion is made of a cemented carbide material such as ceramics or WC, or a material in which ceramics and metal are combined is used.

FIG. 3 shows a second embodiment in which the present invention is applied to a joint having a groove. Groove lower part W ₃ being a portion where frictional heat is hardly transmitted, bonding defects are likely to occur. By irradiating it with the laser beam R, solid-phase fluidization and stirring can be promoted, and joint defects in the groove lower portion W ₃ can be effectively prevented.

4, which has a groove portion W _3, third embodiment of one of the present invention to the base material W _h and the other made of a refractory material is applied to the case of bonding a base material W _l of a low melting point material In this case, in addition to the laser beam R ₁ that is irradiated along the central axis of the rotary tool main body 1 in the same manner as in the second embodiment, the axis of the rotary tool main body 1 is also formed on the high melting point material W ₁ side. irradiating a laser beam R ₂ along.
In the rotary tool main body 1, a gap for laser beam irradiation is provided in the central portion and the peripheral portion in the axial direction. Laser beams W ₁ and W ₂ are irradiated from this gap. Thereby, fluidization of the base material W _h made of the groove portion W ₃ and the high melting point material can be promoted, and friction stir welding without joining defects can be performed.

FIG. 5 shows a fourth embodiment in which the present invention is applied to a case where the surface layer of the base material W is modified. Laser beams R ₁ , R ₂ , and 3 from three gaps provided in the axial direction in the rotary tool body 1 are shown. While irradiating the modification target portion of the base material W with R ₃ , frictional stirring is performed with a rotating tool to form the modified layer W _k .

FIG. 6 shows a fifth embodiment in which the present invention is applied to the formation of a built-up layer on the surface of a base material. In this embodiment, a laser beam irradiation (not shown) is performed while supplying a fine particle beam F of ceramics or the like from a gap provided in the axial direction on the rotary tool main body 1 and supplying the fine particles to the build-up target portion of the base material W. At the same time, friction stir with a rotating tool. As a result, a built-up layer W _n made of a composite material of ceramic and base metal can be formed on the surface layer of the base material W.
In addition, the temperature conditions at the time of reforming can be controlled by the number of rotations of the rotary tool and the pressing force against the joint by the rotary tool.

Figure 7 shows a sixth embodiment of the present invention, upon insertion of the insert material 3 between the bonding surfaces of the bonding target workpiece W ₁ and W _2, performs friction stir welding by the rotary tool. The width of the insert material 3 needs to be larger than the diameter of the rotary tool body 1. In this embodiment, since the base materials W ₁ and W ₂ and the insert material 3 are separated from each other, thermal insulation is imparted between the insert material 3 and the base materials W ₁ and W _2. The frictional heat input generated in the material 3 is prevented from spreading to the surrounding base materials W ₁ and W ₂ . Therefore, there is an advantage that the insert material 3 is easily heated and fluidized and stirred.

FIG. 8 shows a seventh embodiment of the present invention, and is an example in which the insert material 3 is inserted between the joint surfaces of the base material as in the sixth embodiment. the thickness ti was larger than the thickness tb of the base material W ₁ and W ₂ points different from the sixth embodiment. According to the present embodiment, in addition to the effects obtained in the seventh embodiment, there is an advantage that a dent that tends to occur in the joint portion can be prevented.

Figure 9 shows an eighth embodiment of the present invention, the thickness ti of the insert member 3 is the point that greater than the thickness of the base material W ₁ and W ₂ are the same as the seventh embodiment, the present embodiment As the insert material 3, an insert material formed by hardening a base material powder with CIP or the like or sintering the powder is used. The width of the insert material 3 after molding is slightly wider than that of the stirring shaft 2 as in the sixth and seventh embodiments.
According to the present embodiment, the insert material 3 configured as described above is more easily deformed, and there is an advantage that fluidization is easily caused with a small amount of frictional heat input.

Figure 10 shows a ninth embodiment of the present invention, in addition to the configuration of the seventh or eighth embodiment, and further forming an uneven W _o the junction surface of the base material W _1, W _2, this embodiment According to the example, in addition to the effects of the seventh or eighth embodiment, by providing the base material joint surface with the unevenness _Wo , the thermal insulation between the insert material 3 and the base material side is further improved. There is an advantage that fluidization and stirring of the insert material 3 are further promoted.
The same effect can be obtained even if the unevenness _Wo is formed on the joint surface on the insert 3 side.

FIG. 11 shows a tenth embodiment of the present invention. In this embodiment, the insert material 3 has a groove 3a, and the groove 3a is filled with powder 5 made of the same material as the base materials W ₁ and W _2. To do. The thickness ti of the insert material 3 is larger than the thickness tb of the base material, and the width of the insert material 3 is larger than the diameter of the stirring shaft 2.
According to the present embodiment, the insert material 3 is more easily deformed than the above embodiment, and therefore, there is an advantage that fluidization at the time of performing the friction stirring is further facilitated.

  According to the present invention, friction of a workpiece made of a high-melting-point material, which has been difficult to solve conventionally by heating by irradiating a laser beam joint, inserting an insert material between joints, or using these means in combination. There is an advantage that joining or reforming by stirring can be easily realized, and expensive or complicated equipment is not required.

1 is a perspective view according to a first embodiment of the present invention. It is a schematic elevation view at the time of rotation tool insertion in the 1st example. It is a partial cross section elevation which concerns on 2nd Example of this invention. It is a partial cross section elevation which concerns on 3rd Example of this invention. It is a partial cross section elevation which concerns on 4th Example of this invention. It is a partial cross section elevation which concerns on 5th Example of this invention. It is a partial cross section elevation which concerns on 6th Example of this invention. It is a partial cross section elevation which concerns on 7th Example of this invention. It is a partial cross section elevation which concerns on 8th Example of this invention. It is a partial cross section elevation which concerns on 9th Example of this invention. It is a partial cross section elevation which concerns on 10th Example of this invention.

Explanation of symbols

1 rotary tool body 1a shoulder 2 stirring shaft 3 insert material 3a groove _{R, R 1, R 2,} R 3 laser beam s joint W _{1, W 2} workpiece (base material)
W ₃ groove lower part W _h high melting point material W _l low melting point material W _n overlaying layer W _o unevenness

Claims (17)

  A rotating tool made of a material that is substantially harder than the work piece is inserted into the joint of the work piece and moved while rotating the rotating tool, thereby processing by plastic flow due to frictional heat generated between the rotating tool and the work piece. In the joining method by friction stirring which joins things, the joining method by friction stirring which heats by performing laser irradiation to the above-mentioned joint part at the time of joining enforcement by friction stirring or the preheating process in the previous stage.   The joining method by friction stirring according to claim 1, wherein laser irradiation is performed on the joining portion from a central portion of the rotating tool along an axial direction of the rotating tool.   The joining method by friction stirring according to claim 1, wherein laser irradiation is performed on the joint from the periphery of the rotating tool.   2. The joining method by friction stirring according to claim 1, wherein the workpieces to be joined are made of a high melting point material such as stainless steel, Ni-based alloy, Inconel, Hastelloy or the like.   5. The joining method by friction stirring according to claim 4, wherein the joining portion has a groove portion and a laser beam is applied to the groove portion.   3. The friction stirrer according to claim 2, wherein when the workpiece made of the low melting point material and the workpiece made of the high melting point material are joined, the workpiece made of the high melting point material is used together with heating by laser irradiation. Joining method.   A rotating tool made of a material that is substantially harder than the work piece is inserted into the joint of the work piece and moved while rotating the rotating tool, thereby processing by plastic flow due to frictional heat generated between the rotating tool and the work piece. In the reforming method by friction stirrer that modifies the surface layer of the workpiece, the portion to be reformed of the workpiece is heated by laser irradiation at the time of reforming by friction stirrer or the preheating step in the previous stage. A reforming method by friction stirring.   8. The friction according to claim 7, wherein fine particles are supplied to a portion to be modified by irradiation with a fine particle beam when reforming is performed, and a composite material composed of the processed material and the same fine particles is formed on the surface layer of the processed material. A reforming method by stirring.   A rotating tool made of a material that is substantially harder than the work piece is inserted into the joint of the work piece and moved while rotating the rotating tool, thereby processing by plastic flow due to frictional heat generated between the rotating tool and the work piece. In the joining method by friction stirring for joining objects, an insert material made of the same material as the workpiece and having a width larger than the diameter of the rotary tool is inserted between the joints, and the rotary tool is inserted into the insert material. And a friction stir welding method.   10. The joining method by friction stirring according to claim 9, wherein the thickness of the insert material to be inserted is larger than the thickness of the workpiece.   The joining method by friction stirring according to claim 9, wherein an insert material formed by solidifying or sintering powder made of the same material as the workpiece is used.   The joining method by friction stirrer according to claim 9, wherein unevenness is formed on one or both of the joined surfaces of the workpiece or the insert material.   The joining method by friction stirrer according to claim 9, wherein the insert material inserted into the joint part is energized and heated at the time of joining by friction stirrer or a preheating step in the preceding stage.   14. The method of joining by friction stirring according to claim 13, wherein an electrical insulating material that evaporates or disappears by heating is interposed in advance between the joining surface of the workpiece and the insert material.   The joining method by friction stirrer according to claim 4, wherein the insert material inserted into the joint part is heated by irradiating ultrasonic waves at the time of joining by friction stirrer or a preheating step in the preceding stage.   The joining method by friction stirring according to claim 9, wherein a groove is formed at least at a start portion of the insert material, and the groove is filled with powder of the same material as the workpiece.   An insert material made of the same material as the workpiece and having a width larger than the diameter of the rotary tool is inserted between the joints, and the rotary tool is inserted into the insert material to perform friction stirring. Item 2. A joining method by frictional stirring according to Item 1.

Images