JP4792271B2 - Method for modifying alloy compact and alloy compact - Google Patents

Description

  The present invention relates to a method for modifying an alloy compact, particularly a high strength magnesium alloy compact by friction stirring, and a modified alloy compact.

Since the magnesium (Mg) alloy is lightweight, it is promising as a material for a casing of a mobile device such as an aircraft or a vehicle, a portable personal computer or a mobile phone. However, compared to Ti alloys and Al alloys based on titanium (Ti) or aluminum (Al), which are known as light metal elements, like Mg, Mg alloys have lower specific strength, inferior corrosion resistance, and productivity. Is inferior.

Therefore, various attempts have been made to develop an Mg alloy having excellent mechanical properties. Among them, as a promising Mg alloy, Mg is a base material, and includes Mg (Zn) and yttrium (Y), and has excellent strength. -Y alloy is proposed (refer nonpatent literature 1). However, if cast as it is, the strength is insufficient and the specific strength (strength / density) is low as it is, so there is a problem that there is no reason to use Mg alloy as a lightweight material.

On the other hand, a friction stir process has been proposed in which the surface of an alloy formed body is modified by friction stir (hereinafter referred to as friction stir welding), which is a technique developed by friction stir welding (hereinafter sometimes referred to as “FSW”). The modification by stirring is sometimes referred to as “FSP”). For example, Patent Document 1 proposes a method for modifying the surface of an aluminum casting material, characterized by subjecting the surface of the aluminum casting material to a friction stir welding process in which a probe that rotates at high speed is brought into contact and softened by frictional heat. Has been.

In Patent Document 2, a rod having a high melting point and high hardness is rotated from a metal material and moved while pressing the surface portion of the metal material, and the surface portion of the metal material is heated to a temperature at which plastic deformation is possible. In addition, a method for modifying the surface of a metal material has been proposed in which the structure of the surface portion is refined after the metal material is cooled.

Patent Documents 3 and 4 also propose improvements in strength and workability of magnesium alloy compacts and aluminum alloy compacts by friction stirring.

However, any of the methods described in Patent Documents 1 to 4 is a method in which friction stirring is performed only once on one part of the alloy compact, and the reforming effect is not sufficient.

Therefore, a method for improving the reforming effect has been studied. In Non-Patent Document 2, the cast magnesium alloy was subjected to frictional stirring only once and partially overlapped twice. As a result of comparing the cases, in the part where the stirring part overlapped, it became a finer structure than the part where it did not overlap, and in the sample subjected to friction stirring, 1.5 times or more compared to the cast structure It is described that it exhibits a hardness of 2 and that it becomes harder and finer at the site where frictional stirring is repeated.

On the other hand, although different from FSP, in FSW, which is the friction stir welding technology that is the basis of FSP, FSW, a friction stir welding tool (tool) that performs friction stir welding is rotated, and the shoulder of the friction stir welding tool (tool) A protruding portion (probe) provided on the (shoulder) is buried under pressure at a contact portion between the non-joining materials. Along with this, frictional heat is generated in the vicinity of the contact portion, and the end surfaces including the end surfaces cause plastic flow due to the frictional heat, whereby the end surfaces are joined and integrated. The friction stir welding tool (tool) moves along the contact line to be joined, thereby joining the entire desired contact location.

In this FSW, as described in Patent Document 5, for example, on the forward side (advancing side) and the backward side (retreating side) where the rotation direction of the probe coincides with the movement direction of the probe. Details will be described later, but the stirring effect is different.

As described above, various techniques for modifying the surface of the molded body by friction stirring have been proposed, and further improvement of the modification, particularly hardness and strength is expected.

Norihito Kawamura and Akihisa Inoue, “Development of Nanocrystalline Strong Magnesium Alloy”, Materia, Japan Institute of Metals, 2002, Vol. 41, No. 9, p644-649 Maho Tanaka, Masato Sasakawa, Kenji Higashi, Masayuki Otsuka, Hideto Nishida, “Strengthening of Cast Magnesium Alloys by Friction Stirring”, Japan Foundry Engineering Society 145th National Lecture Meeting (October 13-14, 2004, Kitakyushu) Lecture Summary, p111 Japanese Patent Laid-Open No. 10-183316 JP 2001-32058 A Japanese Patent Laid-Open No. 2002-104289: Claim 6, paragraph 0018, FIG. JP 2004-74255 A JP 2004-314088 A

An object of the present invention is to provide a method for modifying an alloy compact that can provide an alloy compact with higher strength, and an alloy compact that has higher strength.

In the modification of the alloy molded body, the FSP is performed by shifting the position of the tool so that it becomes the retreating side again after the FSP is performed on the advanced side (advancing side). As a result, it was found that the hardness was improved compared to the modified product obtained by performing FSP on the retreating side and then shifting the position so as to become the advanced side again, and the present invention was completed.

That is, in the method for reforming an alloy compact according to the first aspect of the present invention, a probe at the tip of a tool rotating around an axis is press-fitted into the surface portion of the alloy compact, and the alloy is formed by friction with the rotating tool. Is heated and softened, the tool is rotated in a state where the probe is press-fitted to stir the alloy in the vicinity of the probe, and the tool is moved in parallel to the surface of the alloy compact, so that at least 2 in the same part of the alloy compact This is a method for modifying an alloy compact that is friction-stirred, and after first friction-stirring, the tool rotation direction and the parallel movement direction are the same side (advancing side), and the tool rotation direction and the parallel movement The friction stir is performed again on the opposite side (retreating side).

The method for reforming an alloy compact according to claim 2 is the method for reforming an alloy compact according to claim 1, wherein after first frictionally stirring in one direction, the tool is once pulled up, A probe is press-fitted into the surface portion of the alloy molded body at a constant interval equal to or smaller than the radius of the shoulder of the tool with respect to the side with the same translation direction (advancing side), and in the same direction as the translation direction. The tool is moved parallel to the surface of the molded body.

The method for modifying an alloy compact according to claim 3 is the method for reforming an alloy compact according to claim 1, wherein after first frictionally stirring in one direction, the rotational direction of the tool and the parallel movement direction are the same side. With respect to (advancing side), the tool is moved in a direction opposite to the parallel movement direction at a predetermined interval equal to or less than the radius of the shoulder of the tool and parallel to the surface of the alloy formed body.

The method for reforming an alloy compact according to claim 4 is the method for reforming an alloy compact according to claim 1, wherein after the friction stir is performed first, the rotation direction of the tool and the parallel movement direction are the same side (advanced It is characterized in that the tool is moved in a spiral shape with a constant interval less than the radius of the shoulder of the tool.

The method for modifying an alloy compact according to claim 5 is the method for reforming an alloy compact according to claim 4, wherein the tool is moved in a spiral shape extending from the center of the surface of the alloy compact toward the periphery. It is characterized by that.

The method for modifying an alloy compact according to claim 6 is the alloy compact according to claim 4, wherein the vortex that is a trajectory of the axis of the tool formed by moving the tool in a spiral shape is the alloy compact. It is those extending from the center to the beginning periphery, if vortex clockwise direction of rotation of the tool is also clockwise, when vortex counterclockwise direction of rotation of the tool is also a counter-clockwise It is characterized by that.

The method for modifying an alloy compact according to claim 7 is the alloy compact according to claim 4, wherein the vortex that is a trajectory of the axis of the tool formed by moving the tool in a spiral shape is an alloy compact. be one proceeds from the peripheral portion to the beginning center, if the vortex is clockwise, the direction of rotation of the tool and counter-clockwise, when vortex counterclockwise, the direction of rotation of the tool clockwise It is characterized by that.

The method for modifying an alloy compact according to claim 8 is the method for reforming an alloy compact according to claim 4, wherein the tool is first spread from the center of the surface of the alloy compact toward the periphery. When moving in a spiral, if the vortex that is the locus of the tool axis is clockwise, the rotation direction of the tool is clockwise, and if the vortex is counterclockwise, the rotation direction of the tool is counterclockwise, Subsequently, as the second vortex adjacent to the first vortex, the vortex in which the rotation direction of the vortex is opposite to the first vortex from the outer periphery to the center while maintaining the rotation direction of the first tool. It is formed.

The method for modifying an alloy compact according to claim 9 is the method for reforming an alloy compact according to any one of claims 1 to 8, wherein the alloy is a cast alloy.

The alloy compact of the present invention according to claim 10 is an alloy compact obtained by the method for modifying an alloy compact according to any one of claims 1 to 9.

Hereinafter, the method for modifying an alloy compact according to the present invention will be described in detail.

The material of the alloy molded body used in the present invention is not particularly limited, but a cast alloy is preferable, and the alloy refers to one containing two or more elements. Examples of the cast alloy include an aluminum alloy, A magnesium alloy, a titanium alloy, etc. are mentioned, A high strength magnesium alloy is especially preferable, and a magnesium base alloy containing zinc and yttrium is particularly preferable as the high strength magnesium alloy. The shape of the molded body is not particularly limited, and examples thereof include a plate shape, a rod shape, and a more complicated shape.

In the present invention, the tool is not particularly limited, and a tool used in FSW can be used as long as it is harder than a workpiece and has a high temperature resistance. The tool is a rotating body used to friction stir the alloy compact, and has a probe at the tip. The probe is embedded in the alloy compact to stir the alloy compact during frictional stirring. The tool shoulder means the shoulder portion of the tool, and is the surface that presses the surface of the alloy formed body during the friction stir processing. The shoulder radius means the radius of the pressing surface.

In the present invention, when a tool having a high melting point and a high hardness is rotated from the alloy compact and pressed against the surface portion of the alloy compact, the surface portion of the alloy compact is heated and softened by friction between the two. The tip (probe) protruding from the tool shoulder (shoulder) is inserted into the softened part while rotating further until the shoulder hits the surface of the alloy molded body and the embedding is temporarily stopped. When friction stir is performed with the tool in a state in which the tool is not pressed, the alloy formed body near the tip of the tool (probe) and the shoulder plastically flows, and the structure is refined. When the tool position is moved along the surface of the alloy compact in this state, the space where the tool tip is buried is filled with the plastic fluidized alloy after the movement, and the frictional heat source leaves and is cooled down. It is possible to obtain a uniform and fine structure without any defects.

The relative motion between the tool and the alloy compact is performed by moving either one or both. By moving either one or both of the tool and the alloy compact, the structure can be refined with an area in the surface portion of the alloy compact.

As described above, the tool has a protruding portion (probe) protruding on the shoulder portion (shoulder). The length of the probe is preferably 80 to 90% of the thickness of the alloy compact to be modified. Although it is preferable to use a long workpiece, it is easy to bend if it is too long.
The friction stirrability depends on the shape of the tool (mainly shoulder diameter, probe diameter, probe length), and the probe shape (cylindrical, truncated cone, threaded, deformed, probe center at the tool rotation axis) It also depends on the operating conditions (tool rotation speed, tool pressing force, moving speed) and the material and thickness of the material to be modified.

In the present invention, in reforming the alloy molded body, after FSP is performed on the advanced side, the position is shifted again so that it becomes the retreating side, and the FSP is performed and modified. By this method, the hardness of the alloy compact is improved. The degree to which the position is displaced needs to be a certain distance, but the distance is not limited as long as it is within the distance where frictional stirring is performed, but is preferably less than the shoulder radius, and the lower limit is the probe. Is about the radius of. When the radius is larger than the shoulder radius, a gap is generated between the stirring regions by the FSP, which is not preferable. When the radius is smaller than the radius of the probe, the working time of the FSP becomes long and the efficiency is deteriorated.

According to the method for modifying an alloy compact of claim 1, since FSP is performed again on the retreating side after the FSP is performed on the advanced side, the hardness is improved as compared with the reverse procedure.

According to the method for reforming an alloy molded body according to claim 2, in the modification, the tool is brought into contact with one end of the alloy molded body to start the modification, and after reaching the other end, the tool is extracted from the alloy molded body, Since the reforming process is performed again by returning to the initial start end side and again in contact with the alloy compact, the reforming process can be performed by a simple repetitive operation.

According to the method for reforming an alloy molded body according to claim 3, upon reforming, the tool is brought into contact with one end of the alloy molded body to start reforming, and after reaching the other end, the tool is extracted from the alloy molded body, Since the tool can be continuously reformed without removing the tool from the alloy compact, it can be processed more efficiently than when it is brought back to the initial start end and contacted with the alloy compact again. it can.

According to the method for reforming an alloy molded body according to claim 4, the tool can be continuously reformed without removing the tool from the alloy molded body and without changing the rotation direction of the tool. It can be processed more efficiently.

According to the method for reforming an alloy compact according to claim 5, the alloy can be continuously reformed and processed without removing the tool from the alloy compact and without changing the rotation direction of the tool. In addition to the effect of the fourth aspect, since the trace of the probe can be made only at one place toward the end of the molded body, the efficiency of the reforming treatment is further improved.

According to the method for reforming an alloy compact according to the sixth aspect of the present invention, it is possible to easily and reliably modify the surface shape in a short time.

According to the method for modifying an alloy compact of claim 7, it is possible to easily and reliably modify the surface shape in a short time.

According to the method for reforming an alloy compact according to the eighth aspect, the surface shape can be easily and reliably reformed in a short time.

According to the method for modifying an alloy compact according to the ninth aspect, the cast alloy compact is effectively modified.

The alloy compact of claim 10 has high hardness and high strength.

The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a schematic overall perspective view of an example showing a state in which a plate-shaped alloy molded body 10 is subjected to friction stirring using a surface modifying apparatus used in the method for modifying an alloy molded body of the present invention. In the surface modification apparatus of FIG. 1, 1 is a tool held by an apparatus (not shown) substantially similar to the apparatus used for friction stir welding, and 2 is a probe at the tip of the tool. The tool 1 rotates about the axis 3. The tool 1 is made of a material having a higher melting point and higher hardness than the alloy molded body 10, and is formed of, for example, tool steel, super hard metal, ceramics, or the like. In the present invention, the probe 2 at the tip portion of the tool 1 is press-fitted into the surface portion 10a of the alloy molded body 10, and the alloy molded body 10 is heated and softened by friction with the shoulder 1a of the rotating tool 1, and the probe The tool 1 is moved in parallel with the surface of the alloy compact 10 while the tool 1 is continuously rotated in a state where 2 is press-fitted to stir the alloy compact 10 near the probe 2. When the tool 1 moves, the alloy molded body is stirred one after another, and on the surface of the alloy molded body after the tool moves, an extremely shallow depression almost circular due to the contact of the shoulder is generated, and these are shifted intermittently one after another. Because of the overlap, arcuate scars lined up remain.

In FIG. 1, the tool 1 rotates clockwise and moves in the direction of arrow X parallel to the surface of the alloy compact 10. V1 and V2 are vector components in the rotational direction of the portion (the moving direction at the shoulder end and the reverse direction) that is farthest from the locus of the shaft 3 accompanying the movement of the tool 1. The side on which the translation direction and the translation direction of the tool are the same is referred to as an advance side, and the side on which the translation direction is opposite to the translation direction is referred to as a retrieving side.

In the invention of claim 2, after first frictionally agitating in one direction, the tool is once pulled up, and the tool rotation direction and the parallel movement direction are the same side (advancing side), and the tool shoulder radius is constant or less. The probe is press-fitted into the surface portion of the alloy molded body with an interval of and the tool is moved in the same direction as the parallel movement direction and parallel to the surface of the alloy molded body.

That is, after first stirring in one direction, the tool rotation direction and parallel movement direction are the same (advancing side), and the tool rotation direction and translation direction are opposite (retreating side) again. Friction stir. Specifically, one procedure of this implementation will be described. After the tool 1 is moved to the end of the alloy compact while friction stirring as shown in FIG. 1, the tool is pulled out of the alloy compact, and further before the movement. Move the tool to the first position. Then, after moving the tool 1 slightly in the direction of the arrow Y shown in FIG. 1 (for example, at a distance from about one half of the radius of the probe 2 to the shoulder radius), The probe 2 is again press-fitted into the surface portion 10a of the alloy molded body 10, and the tool is moved in parallel with the trajectory of the previous movement, and the part that has been frictionally stirred on the advanced side is friction stir on the retrieving side. To do. In addition, in FIG. 1, the state of the later friction stirring process was shown with the dashed-two dotted line.

According to a third aspect of the present invention, in the method for reforming an alloy compact according to the first aspect, after first frictionally stirring in one direction, the rotation direction of the tool and the parallel movement direction are on the same side (advancing side). On the other hand, the tool is moved in parallel with the surface of the alloy formed body in a direction opposite to the parallel movement direction with a certain interval equal to or less than the radius of the shoulder of the tool. In this case, if the distance is larger than the radius of the shoulder of the tool, it becomes difficult to frictionally stir the same portion of the alloy compact twice.

One procedure of this implementation will be specifically described. FIG. 2A is a schematic plan view in which the alloy molded body 10 is frictionally stirred by the tool 1 moving while frictionally stirring the alloy molded body 10 in the present invention. FIG. 2B and FIG. 2C are plan views showing the rotation direction and the movement direction of the tool 1. First, as shown in FIG. 2 (b), the tool 1 moves in the direction of the arrow X1 while rotating counterclockwise (V3 and V4 indicate vector components in the rotational direction at the respective positions), and the alloy molded body 10 is friction-stirred, leaving a scar 10b on the shoulder of the tool.

Next, the tool 1 is moved in the arrow Y1 direction by the radius of the tool shoulder. Next, as shown in FIG. 2C, the tool 1 rotates in the clockwise direction opposite to the above (V5 and V6 indicate vector components in the rotation direction at the respective positions), and the movement It moves in the direction of the arrow X2, which is the opposite direction to the direction X1, and the alloy compact is frictionally stirred, leaving a scar 10c on the shoulder of the tool. By the friction stirrer in the above two directions, the part 10s where the friction stirrer overlaps (the part surrounded by diagonal lines in FIG. 2 (a). The width is L) is first friction stir on the advanced side and then retreating. It becomes the part which was friction-stirred on the side. It should be noted that the scar 10b on the shoulder left on the friction-stirred portion previously disappears on the surface of the friction-stirring portion 10s, and thus the scar 10c remains. Reference numeral 100 denotes a trace that remains on the trace where the probe 2 is pulled up from the alloy compact after the tool 1 reaches the end of the alloy compact in the direction of the arrow X2.

FIG. 2D is a schematic plan view showing a state in which the alloy molded body 10 is continuously frictionally stirred by further repeating the above operation. In this figure, the trajectory and scar of the tool are schematically represented. Reference numeral 20 denotes a trajectory of the axis of the tool moved during the friction stir processing, which is not actually visible. Reference numeral 100 denotes a trace that remains in the trace where the probe is pulled out from the alloy molded body.

The method for reforming an alloy compact according to claim 4 is the method for reforming an alloy compact according to claim 1, wherein after the friction stir is performed first, the rotation direction of the tool and the parallel movement direction are the same side (advanced The tool is moved in a spiral shape with a certain distance below the shoulder radius of the tool. The method for modifying an alloy compact according to claim 5 is the method for reforming an alloy compact according to claim 4, wherein the tool is formed in a spiral shape extending from the center of the surface of the alloy compact toward the periphery. Move.

The procedure of this implementation will be specifically described. FIG. 3A is a schematic plan view showing a portion where the alloy molded body 10 is frictionally stirred as the tool 1 moves while frictionally stirring the alloy molded body 10 in the present invention. In addition, when the same portion of the alloy molded body is frictionally stirred with the same portion of the alloy formed body, the scar generated by the previous frictional stirring is erased by the subsequent frictional stirring. In (a), the scar generated by the previous process is drawn without being erased. FIG. 3B is a plan view showing the rotation direction of the tool 1. First, while the tool 1 rotates clockwise, the probe is press-fitted into the center portion 10e of the surface of the alloy molded body 10. Next, while rotating the tool 1, the tool 1 is moved in a spiral shape at equal intervals corresponding to the radius of the shoulder expanding from the central portion 10 e to the peripheral portion 10 f of the surface of the alloy molded body 10 (specifically, the tool 1 The axis trajectory 21 accompanying the movement is moved in a spiral shape (Note that the axis trajectory 21 depicted in FIG. 3A is not visible). At this time, if the part of the alloy compact that is frictionally stirred as the tool moves is always partly overlapped, friction stir is first performed on the alloy compact 10 on the advanced side, and then friction is performed on the retreating side. A stirred part is formed.

As described above, FIG. 3 shows the case where the degree of frictional stirring overlap is made equal to the radius of the tool shoulder, and the vortex winding width d in the axis trajectory becomes equal to the radius of the tool shoulder. However, by appropriately adjusting the overlapping portion, the overlapping stirring region of the alloy molded body can be made the portion that is first frictionally stirred on the advanced side and then frictionally stirred on the retreating side. In FIG. 3 (a), except for about one turn at the beginning of the vortex, all parts are first frictionally stirred on the advanced side and then frictionally stirred on the retreating side.

FIG.3 (c) shows another example at the time of moving a tool spirally, and has shown the case where the locus | trajectory 22 of the axis | shaft of the tool accompanying a movement exhibits a mosquito coil incense. 100 is the trace of the probe.
Moreover, FIG.3 (d) has shown the case where the locus | trajectory 23 of said mosquito coil incense-like axis | shaft is formed in multiple numbers on an alloy molded object, and the case where the locus | trajectory has overlapped. 100 is the trace of the probe.

In addition, when moving the tool so that the locus of the shaft is spiral, in order to first frictionally stir the alloy compact on the advanced side and then on the retreating side, The following relationship is required between the rotation direction and the rotation direction of the vortex that is the locus of the tool axis.
If the vortex starts at the center of the alloy compact and spreads to the periphery, and the vortex is clockwise, the tool must also be clockwise; if the vortex is counterclockwise, the tool is also counterclockwise Need to be clockwise. Also, if the vortex starts at the periphery of the alloy compact and goes to the center, and the vortex is clockwise, the tool must be counterclockwise, and if the vortex is counterclockwise, The tool needs to be clockwise.

The method for modifying an alloy compact according to claim 8 is the method for reforming an alloy compact according to claim 4, wherein the tool is first spread from the center of the surface of the alloy compact toward the periphery. When moving in a spiral, if the vortex that is the locus of the tool axis is clockwise, the rotation direction of the tool is clockwise, and if the vortex is counterclockwise, the rotation direction of the tool is counterclockwise, Subsequently, as the second vortex adjacent to the first vortex, the vortex in which the rotation direction of the vortex is opposite to the first vortex from the outer periphery to the center while maintaining the rotation direction of the first tool. It is formed.

FIG. 4A is a schematic plan view for explaining a specific example of claim 8. In FIG. 4A, reference numeral 24 denotes a trajectory of the tool axis that can be obtained by moving the tool in a spiral shape. A left vortex is formed toward the beginning. First, a vortex starts to be formed from the position of S in the center of the surface of the alloy molded body 10, and a clockwise vortex extending toward the periphery is formed. The tool is rotated clockwise in forming this vortex. Subsequently, a vortex on the right side is formed as a second vortex adjacent to the first vortex. At this time, while maintaining the clockwise rotation of the tool, a counterclockwise vortex is formed in which the rotation direction of the vortex from the outer periphery to the center is opposite to the first vortex. A probe trace 100 is created at the final E position of the vortex. This method has the advantage that it is not necessary to change the direction of rotation of the tool when forming the two left and right vortices.

FIG. 4B is a schematic plan view for explaining another specific example of claim 8. In FIG. 4B, reference numeral 24 denotes a trajectory of the tool axis that can be obtained by moving the tool in a spiral shape. A left vortex is formed toward the beginning. First, a vortex starts to be formed from the position of S at the center of the surface of the alloy molded body 10, and a counterclockwise vortex spreading toward the periphery is formed. The tool is rotated counterclockwise when forming the vortex. Subsequently, a vortex on the right side is formed as a second vortex adjacent to the first vortex. At this time, while maintaining the counterclockwise rotation direction of the tool, a clockwise vortex in which the rotation direction of the vortex is opposite to the first vortex from the outer periphery to the center direction is formed. A probe trace 100 is created at the final E position of the vortex. This method has the advantage that it is not necessary to change the direction of rotation of the tool when forming the two left and right vortices.

  FIG. 4C is not a specific example of claim 8, but is an embodiment of the present invention in which the tool is moved in a spiral shape. In FIG. 4C, reference numeral 24 denotes a trajectory of the tool axis that can be obtained by moving the tool in a spiral shape. A left vortex is formed toward the beginning. First, a vortex starts to be formed from the position S on the outer peripheral side of the alloy compact 10, and a counterclockwise vortex is formed toward the center. The tool is rotated clockwise in forming this vortex. When the tool reaches the center of the first vortex, the tool is moved linearly toward the center for forming the right vortex. Next, the tool is moved in a clockwise spiral shape from the central portion to the outer peripheral portion to form a right vortex. At this time, the rotation direction of the tool is clockwise as in the first rotation direction. A probe trace 100 is created at the final E position of the vortex. This method also has the advantage that it is not necessary to change the direction of rotation of the tool in forming the two left and right vortices. Further, since there is only one trace 100 on the outer periphery, there is an advantage that the efficiency of the reforming process is improved. In this method, the friction stir processing cannot be performed in the order of the advanced side first and then the retreating side only where the left and right vortices are adjacent to each other.

  FIG. 4 (d) is not a specific example of claim 8, but is one embodiment of the present invention in which the tool is moved in a spiral shape. In FIG. 4D, reference numeral 24 denotes a trajectory of the tool axis that can be obtained by moving the tool in a spiral shape. A left vortex is formed toward the beginning. First, the vortex starts to be formed from the position S on the center side of the alloy molded body 10, and the clockwise vortex is formed toward the outer peripheral portion. The tool is rotated clockwise in forming this vortex. When the tool reaches the outer periphery of the first vortex, it is moved linearly toward the center for forming the right vortex towards the tool. Next, the tool is moved in a clockwise spiral shape from the central portion to the outer peripheral portion to form a right vortex. At this time, the rotation direction of the tool is clockwise as in the first rotation direction. A probe trace 100 is created at the final E position of the vortex. This method also has the advantage that it is not necessary to change the direction of rotation of the tool in forming the two left and right vortices. Further, since there is only one trace 100 on the outer periphery, there is an advantage that the efficiency of the reforming process is improved. In this method, the friction stir processing cannot be performed in the order of the advanced side first and then the retreating side only where the left and right vortices are adjacent to each other.

FIG. 5 is a partial sectional view showing an example of the tool 1 used in the present invention and a state at the time of reforming by friction stirring. The tool 1 has a probe 2 at the tip of the main body. The probe 2 is preferably provided as a protruding portion at the center of the bottom surface of the tool 1 (the shoulder portion forms the shoulder 1a). The probe 2 is pushed into the alloy molded body 10 and has an action of stirring the internal structure. The shape of both the tool and the probe can be the same as that used in FSW, and is not particularly limited, but a cylindrical shape is preferable.

The tip 2a of the probe 2 may be a flat surface, but it may be a curved surface such as a spherical surface or a diameter-expanded shape in order to increase the stirring action. When the tip of the probe is enlarged, the enlarged diameter may be about 1.2 to 2.0 times the diameter of the probe. Moreover, you may provide one or more ring-shaped enlarged diameter parts in the front-end | tip part of a probe.

The shoulder diameter, probe diameter, probe length, and other form factors of the tool are appropriately selected in consideration of the type / properties and operating conditions of the alloy compact to be modified.
In the reforming treatment, the probe 2 is heated and stirred to a temperature at which the surface portion 10a of the alloy compact 10 can be plastically deformed, and after the alloy compact 10 is cooled, the crystals in the friction stir zone are refined and modified. A mass portion 10g is formed.

  The width of the modified region 10g by friction stirring depends on the shoulder diameter, the probe diameter, the material of the workpiece, and the friction stirring conditions, but is mainly influenced by the probe diameter. If the probe diameter is larger than the shoulder diameter, the modified region 10g has a width close to the shoulder diameter deeply below the shoulder 1a, and if the probe diameter is smaller than the shoulder diameter, the modified region 10g becomes narrower. Further, if the probe length is short, the modified region width in the deep part becomes narrow.

In FIG. 5, assuming that the tool moves toward the reader side from this page, the right side becomes the advanced side reforming portion 4 and the left side becomes the retreating side reforming portion 5. The friction stir effect varies depending on the side. The agitating region to be agitated by the friction stir processing is more in the retreating side reforming section 5 than in the advanced side reforming section 4.

  Accordingly, the interval for shifting the rotation axis of the tool between the first time and the second time is appropriately selected according to the combination conditions such as the probe diameter and the shoulder diameter, and is preferably 1/2 of the probe diameter and 1/2 of the shoulder diameter.

Hereinafter, the present invention will be described in more detail with reference to examples.

The Mg—Y—Zn alloy was melted and made into an ingot, a 120 × 100 × 6 mm plate was cut out, and this plate was subjected to friction stir processing by the modification method of the present invention. More specifically, a partially overlapped double bead (twice agitation) according to the method of claim 2 was used. At the time of this superposition, after the first pass (the first treatment), the second pass (the second treatment) is performed in the first pass so that the portion subjected to the friction stirring treatment on the advanced side is stirred later on the retreating side. Friction stir processing was performed on the advanced side of the path by shifting by 1/2 (2.0 mm) of the probe diameter (4 mm) of the tool. Further, after the second pass, the third pass was shifted to the advanced side of the second pass by 1/2 (2.0 mm) of the probe diameter of the tool, and the friction stir processing was performed.

The equipment used and the working conditions were as follows.
Tool shoulder diameter 14mm. The length of the probe is 3.0 mm and the diameter is 4.0 mm.
The probe shape is a right circular cylinder. The tool and probe material is JIS SKD61.
Tool rotation speed is 750 rpm. Friction load to tool alloy compact is 9kN. Tool moving speed 100 mm / min.

(Comparative Example 1)
A plate material similar to the plate material used in Example 1 but not subjected to friction stirring.
(Comparative Example 2)
The friction stirring treatment was performed in the same manner as in Example 1 except that the friction stirring treatment was performed only once.

(Comparative Example 3)
The friction stir processing was performed in the same manner as in Example 1 except that the friction stir processing was performed at the retreating side and then the friction stir processing was performed by shifting the position so that the same portion became the advanced side. Specifically, at the time of superposition, after the first pass, the second pass is set to the retreating side of the first pass so that the portion subjected to the friction stir processing on the retreating side is stirred on the advanced side later. Friction stir processing was performed by shifting the tool probe diameter by 1/2 (2.0 mm). Further, after the second pass, the third pass was shifted to the retreating side of the second pass by ½ (2.0 mm) of the probe diameter of the tool, and the friction stirring process was performed.

(Performance evaluation)
The alloy compacts obtained in Example 1 and Comparative Example 3 were cut in a direction perpendicular to the surface, and Vickers hardness (Hv) was measured at a load of 100 g at several points at a depth of 1.5 mm from the surface of the cross section. . The average value was determined for the portion that was heat affected for the third time after being stirred twice.
In the comparative example 1, it cut | judged in the orthogonal | vertical direction with respect to the surface in arbitrary parts, and in the comparative example 2, it cut | judged in the perpendicular | vertical direction with respect to the surface about the part stirred frictionally, and measured similarly to the above.

The Vickers hardness (Hv) measurement result of the alloy molded body obtained in Example 1 is shown in FIG. In the figure, 1st pass means the first path, 3rd pass means the third path, 1st means the first path, 2nd means the second path, and 3rd means the third path (described later). The same applies to FIGS. 7, 8 and 9 of FIG. This figure shows the relationship between the distance from the center of the 1st pass stirrer (that is, the distance from the center of the friction stirrer during the first pass friction stir processing) and the Vickers hardness (Hv). In the figure, a range indicated by a double-headed arrow described as “a portion that has been stirred twice and then subjected to the heat effect of 3rd pass” (the distance from the center of the 1st pass stirring portion is in the range of 0 to −2 (mm)). The measured value represents the Vickers hardness (Hv) of the portion processed on the advanced side and then processed on the retrieving side. The average value of Vickers hardness (Hv) of this part was 121 Hv.

The Vickers hardness (Hv) measurement result of the alloy molded body obtained in Comparative Example 3 is shown in FIG. This figure shows the relationship between the distance from the center of the 1st pass stirrer (that is, the distance from the center of the friction stirrer during the first pass friction stir processing) and the Vickers hardness (Hv). In the figure, a measurement of a range indicated by a double-headed arrow described as “a portion that has been stirred twice and then has been affected by heat of 3rd pass” (distance from the center of the 1st pass stirring portion is 0 to 2 (mm)). The value represents the Vickers hardness (Hv) of the portion processed on the advanced side after processing on the retreating side. The average Vickers hardness (Hv) of this portion was 113 Hv.

Moreover, what plotted the measured value of Example 1 and the comparative example 3 on one graph was shown in FIG. In the figure, no1 is the measured value of Example 1, and no2 is the measured value of Comparative Example 3.

The average Vickers hardness (Hv) of the alloy molded body of Comparative Example 1 was 60 Hv, and the average Vickers hardness (Hv) of the alloy molded body obtained in Comparative Example 2 was 92 Hv.

Therefore, when the reforming method of the present invention was used, an alloy molded body having a higher Vickers hardness (Hv) could be obtained.

Moreover, the photograph taken from the diagonally upper surface of the alloy molded body obtained in Example 1 and Comparative Example 3 is shown in FIG. no1 is a photograph of Example 1, and no2 is a photograph of Comparative Example 3. In FIG. 9, the A-side side means the advanced side, and the R-side side means the retrieving side.

The method for modifying an alloy compact of the present invention can be suitably used for modifying an alloy compact, particularly a magnesium alloy compact. The obtained alloy compact can be used in various industrial fields as a high-strength industrial material.

The schematic whole perspective view of an example which shows the state which is carrying out the friction stirring process of the plate-shaped alloy molded object. FIG. 2A is a diagram for explaining an embodiment of the present invention, FIG. 2A is a schematic plan view in which an alloy compact is frictionally stirred, and FIG. 2B and FIG. FIG. 2 (d) is a schematic plan view showing a state in which the alloy compact is continuously frictionally stirred. FIGS. 3A and 3B are views for explaining another embodiment of the present invention, FIG. 3A is a plan view showing a portion where the alloy molded body is friction-stirred, and FIG. 3B is a rotation direction of the tool. FIG. FIG. 3C and FIG. 3D are schematic plan views showing the axis trajectory of the tool and the trace of the probe accompanying the movement of the tool on the alloy molded body. FIG. 4 is a diagram for explaining another embodiment of the present invention, and FIGS. 4 (a), 4 (b), 4 (c), and 4 (d) show the axis of the tool as the tool moves. It is the typical top view which showed the locus | trajectory and the trace of the probe on the alloy molded object. The fragmentary sectional view which shows the state at the time of modification | reformation by an example and friction stirring of a tool. It is a figure showing the Vickers hardness (Hv) measurement result of the alloy compact obtained in Example 1. It is a figure showing the Vickers hardness (Hv) measurement result of the alloy molded object obtained by the comparative example 3. It is the figure which plotted the measured value of Example 1 and Comparative Example 3 on one graph. Drawing substitute photo. It is the photograph taken from the surface diagonally upper surface of the alloy molded object obtained in Example 1 and Comparative Example 3, no1 is a photograph of Example 1, and no2 is a photograph of Comparative Example 3.

Explanation of symbols

1 Tool 1a Shoulder (shoulder)
2 Probe 2a Tip 3 Axis 4 Advanced side modified part 5 Retreating side modified part 10 Alloy molded body 10a Surface part 10b, 10c Scar 10e Central part 10f Peripheral part 10g Modified part 10s Part where friction stir overlaps 20, 21, 22, 23, 24 Axis locus 100 (probe) extraction trace L width d Vortex winding width X, X1, X2, Y, Y1 Movement direction V1, V2, V3, V4, V5 , V6 vector component

Claims (10)

The probe at the tip of the tool rotating around the axis is pressed into the surface of the alloy compact, and the alloy is heated and softened by friction with the rotating tool, and the tool is rotated while the probe is pressed. A method of modifying an alloy compact that stirs the alloy near the probe while moving the tool parallel to the surface of the alloy compact and friction stirs at least twice in the same part of the alloy compact,
After friction stirring first, the tool rotation direction and the parallel movement direction are the same side (advancing side), and the tool rotation direction and the parallel movement direction are the opposite side (retreating side). A method for modifying an alloy compact characterized by the above.   First, after the friction stir in one direction, the tool is once pulled up, and the probe is spaced apart from the tool's shoulder radius by the same distance as the tool rotation direction and the parallel translation direction (advancing side). 2. A method of modifying an alloy compact according to claim 1, wherein the tool is pressed into a surface portion of the alloy compact and the tool is moved in the same direction as the parallel movement direction and parallel to the surface of the alloy compact. .   After first frictionally stirring in one direction, the tool rotation direction and the parallel movement direction are the same (advanced side), with a certain distance less than the tool shoulder radius, opposite to the parallel movement direction. The method of modifying an alloy compact according to claim 1, wherein the tool is moved in a direction parallel to the surface of the alloy compact.   After the friction stir first, the tool is moved in a spiral shape with a certain distance less than the radius of the shoulder of the tool with respect to the side where the rotation direction of the tool and the parallel movement direction are the same (advancing side) The method for modifying an alloy compact according to claim 1.   5. The method of modifying an alloy compact according to claim 4, wherein the tool is moved in a spiral shape spreading from the center of the surface of the alloy compact toward the periphery. When the tool is moved spirally, the vortex, which is the trajectory of the tool axis, starts from the center of the alloy compact and spreads to the periphery. If the vortex is clockwise, the tool rotation direction is also clockwise. 5. The method of modifying an alloy compact according to claim 4, wherein when the vortex is counterclockwise, the direction of rotation of the tool is also counterclockwise. If the vortex, which is the trajectory of the tool axis formed by moving the tool in a spiral shape, starts from the periphery of the alloy compact and proceeds to the center, and the vortex is clockwise, the tool rotation direction is reversed. 5. The method of modifying an alloy compact according to claim 4, wherein when the vortex is clockwise and the vortex is counterclockwise, the rotation direction of the tool is clockwise.   5. The method of modifying an alloy compact according to claim 4, wherein the tool is initially trajectory of a tool in a spiral shape extending from the center of the surface of the alloy compact toward the periphery. If the vortex is clockwise, the rotation direction of the tool is clockwise; if the vortex is counterclockwise, the rotation direction of the tool is counterclockwise, and then the second vortex adjacent to the first vortex, A method for reforming an alloy compact characterized by forming a second vortex from the outer periphery to the center while maintaining the rotation direction of the first tool, and forming a vortex whose vortex rotation direction is opposite to the first vortex. .   The method for modifying an alloy compact according to any one of claims 1 to 8, wherein the alloy is a cast alloy. An alloy compact obtained by the method for reforming an alloy compact according to any one of claims 1 to 9.