JP2009203508A - Crystal grain micronizing method and crystal grain micronizing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crystal grain micronizing method capable of improving material characteristics. <P>SOLUTION: This method is characterized in that a container, in which a cylindrical space filled with a metallic material and which is composed of a plurality of containers 5 and 6 divided into two relatively rotatably in the axial direction of the cylindrical space, and upper and lower punches 1 and 2, which pressurize the metallic material, are used to relatively rotate the unit containers 5 and 6 while pressurizing the metallic material by the upper and lower punches 1 and 2. Namely, the plurality of unit containers are made freely rotatable respectively independently, so that twisting is imparted to the optional part of the material to be worked, thereby micronizing the crystal grain. Concretely, since twisting can be efficiently imparted to the part in the vicinity of the divided face with which the unit containers 5 and 6 are in contact with each other, in the metallic material as the material to be worked charged into the cylindrical space, by arranging the divided face of the container in the vicinity of the part requiring crystal grain micronizing, the crystal grains of the desired part can be micronized. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and apparatus for improving various properties such as strength and toughness by refining crystal grains of a metal or alloy.

  Conventionally, the strength of aluminum alloy materials has been increased by various methods such as solid solution strengthening heat treatment, precipitation strengthening heat treatment, and cold working. Among these, in recent years, material properties such as strength and elongation have been applied to the shear extrusion method (ECAP: Patent Document 1), the repeated lap joint rolling method (ARB: Patent Document 2), etc., in which a large strain is applied to an aluminum alloy material. As a technique for greatly improving

  However, since the technique described in Patent Document 1 cannot continuously apply strain, processing several times is required, and low productivity is a problem. In addition, the technique disclosed in Patent Document 2 has a problem that the shape of the material is restricted to a plate shape because the plate shape is overlapped and rolled.

In response to such a problem, the material is loaded into the container (case), and the material loaded with the upper punch and the lower punch is twisted while applying pressure to continuously apply strain to crystal grains. A technique for improving the characteristics of a material by miniaturization is disclosed (Patent Document 3).
Japanese Patent No. 3367269 JP 2001-234239 A Japanese Patent No. 3616591

  However, in the method disclosed in Patent Document 3, the contact surface between the inner peripheral surface of the container and the metal material that is a workpiece slides in a state in which a high pressure is applied by the punch, which causes the following problems. I understood.

  In the method of Patent Document 3, when the action applied to the metal material is examined, first, after being compressed by the punch to some extent, the rotational force by the punch is transmitted and twisted, so that at the contact surface between the metal material and the container Adhesion may progress.

  In other words, since the force in the twisting direction from the punch is transmitted by friction, the force in the twisting direction is not transmitted to the metal material unless a force in the compression direction is applied by the punch to some extent. Accordingly, when a torsional force is applied to the metal material and sliding occurs on the contact surface between the inner peripheral surface of the container and the metal material, the metal material is high toward the inner peripheral surface of the container. Since the hydrostatic pressure is applied, a high frictional force corresponding to the friction coefficient may be applied between the inner peripheral surface of the container and the metal material, leading to adhesion.

  When the adhesion progresses between the inner peripheral surface of the container and the metal material, it is considered that the frictional force at the site where the adhesion has progressed increases and the adhesion further progresses to shorten the life of the container. In addition, as the adhesion progresses, it becomes difficult to apply sufficient torsion in the vicinity of the portion where the adhesion of the metal material has progressed, resulting in a portion where the crystal grains cannot be sufficiently refined. It is conceivable that the refinement of crystal grains may be uneven and the characteristics of the entire material cannot be improved.

  Moreover, even if the adhesion between the inner peripheral surface of the container and the metal material has not been reached, the twist to the metal material cannot be sufficiently achieved due to the frictional force between the inner peripheral surface of the container and the metal material. Sites sometimes occurred. In other words, there is a limit to the transmission of rotational force by the punch, and the part where the rotation of the metal material is restricted due to the friction between the inner peripheral surface of the container and the metal material, and all the parts in the axial direction of the metal material It was found that the grain refining action could not proceed evenly.

  The present invention has been completed in view of the above circumstances, and the material loaded in the container is continuously distorted by applying a twist while applying pressure with a punch to refine crystal grains. An object of the present invention is to solve the problem of suppressing the occurrence of adhesion between a metal material as a workpiece and an inner peripheral surface of a container. In addition, even if it does not lead to adhesion, a method for refining a crystal grain and a device for refining a grain can be made to compensate for a decrease in twisting action due to contact of a metal material in a container and a desired part can be refined. Providing this is also an issue to be solved.

A feature of the crystal grain refining method according to claim 1 for solving the above-mentioned problem is that a container for partitioning a bottomless or bottomed cylindrical space in which a metal material is loaded;
A punch for pressurizing the metal material in the cylindrical space;
Use
A grain refinement step of applying twist while pressing the metal material with the punch;
A relative movement step of relatively moving between the inner surface of the container and the outer peripheral surface of the metal material while pressing the metal material with the punch.

The crystal grain refinement method according to claim 2 is characterized in that, in claim 1, the container includes a plurality of unit containers divided into two or more so as to be relatively rotatable in the axial direction of the cylindrical space defined by the container. Become
The relative movement step is a step of relatively rotating at least two of the plurality of unit containers.

  The crystal grain refinement method according to claim 3 is characterized in that, in claim 2, the punch and the plurality of unit containers are rotated relative to each other between the adjacent punch and / or the unit container. is there.

  The crystal grain refinement method according to claim 4 is characterized in that, in any one of claims 1 to 3, the relative movement step is performed before pressurizing the metal material in the crystal grain refinement step. It is a process of performing a relative movement between the inner surface of the container and the outer peripheral surface of the metal material.

The crystal grain refinement method according to claim 5 is characterized in that, in any one of claims 1 to 4, the cylindrical space defined by the container is bottomless,
The punch includes an upper punch and a lower punch that are inserted into the cylindrical space from above and below to pressurize the metal material.

  The crystal grain refinement method according to claim 6 is characterized in that, in claim 5, the upper and lower punches and the container are relatively moved in the axial direction of the cylindrical space while pressing the metal material with the upper and lower punches. That is.

The crystal grain refinement method according to claim 7 is characterized in that, in claim 6, the container is divided into two unit containers,
The upper and lower punches and the two unit containers are moved relative to each other so that the joint surfaces of the two unit containers are positioned throughout the entire axial direction of the cylindrical space of the metal material.

The crystal grain refining device according to claim 8 is characterized in that a container for partitioning a bottomless or bottomed cylindrical space in which a metal material is loaded;
A punch for pressurizing the metal material in the cylindrical space;
Crystal grain refining means for applying twist while pressing the metal material with the punch,
Relative moving means for relatively moving between the inner surface of the container and the outer peripheral surface of the metal material while pressing the metal material with the punch.

The crystal grain refiner according to claim 9 is characterized in that, in claim 8, the container comprises a plurality of unit containers divided into two or more so as to be relatively rotatable in the axial direction of the cylindrical space defined by the container. Become
The relative movement means is means for relatively rotating at least two of the plurality of unit containers.

  The crystal grain refining device according to claim 10 is characterized in that in claim 8 or 9, the relative movement means pressurizes the metal material with the punch before the inner surface of the container and the metal material. It is a means for performing relative movement with the outer peripheral surface.

  In the crystal grain refining method according to the first aspect configured as described above, since there is a relative movement step, adhesion between the inner peripheral surface of the container and the metal material can be suppressed. Adhesion between the inner peripheral surface of the container and the metal material is likely to proceed as the friction force between the two increases, so that the metal material is added by a punch in the relative movement process so that the friction coefficient is always low. The frictional force is reduced by relatively moving between the inner surface of the container and the outer peripheral surface of the metal material during pressing.

  In the crystal grain refining method according to claim 2 configured as described above, the container is divided into two or more unit containers, and relative rotation is performed between at least two of the unit containers. Thus, in addition to the transmission of the rotational force from the punch, it is possible to transmit the rotational force from those unit containers.

  In the method disclosed in Patent Document 3, the transmission of torsion does not sufficiently proceed to the part of the workpiece away from the upper and lower punches due to the sliding resistance between the inner periphery of the container and the part of the workpiece. Crystal grain refinement did not progress sufficiently, and shear fracture progressed from the portion near the upper and lower punches to the workpiece, so that sufficient strain could not be transmitted in the portion far from the upper and lower punches. For this reason, there are cases where sufficient crystal grain refinement cannot proceed even if desiring to refine crystal grains at a site away from the punch.

  As in the invention according to claim 2, by rotating relative to two or more of the unit containers formed by dividing, the rotational force from the relative rotating unit container to the metal material via the contact portion Are directly added, and the portion between the unit containers (if the unit containers are in contact as in the crystal grain refining method according to claim 3, the contact surface (divided surface) ) Can be positively applied by twisting, and a sufficient crystal grain refining action can be exhibited in that portion. Here, twisting (strain) can be applied to any part of the metal material by changing the position and number of the container divisions, the combination of unit containers to be relatively rotated after the division, and the magnitude of the relative rotation. For example, as a form of the unit container, by providing a divided surface in the vicinity of a portion where the metal material crystal grain refinement is desired, the crystal grain refinement effect can be exhibited in the vicinity of the divided surface.

  In the crystal grain refining method according to claim 4 configured as described above, the relative movement between the container and the metal material is performed before the metal material is pressurized in the crystal grain refinement process as the relative movement process. By performing the above, adhesion can be effectively prevented in the crystal grain refining step.

  The crystal grain refining process is a process of applying twist to the metal material while applying pressure to the metal material. Therefore, if a certain amount of force is not applied to the metal material by the punch, the twisting (and crystal grain refining action) is applied. ) Also does not proceed. Therefore, when a twist is applied to the metal material by the crystal grain refining process, a high hydrostatic pressure is transmitted from the metal material toward the inner peripheral surface of the container. Therefore, when torsion is applied, when the sliding between the inner peripheral surface of the container and the metal material starts, a high hydrostatic pressure is applied between the inner peripheral surface of the container and the metal material, and the sliding starts. Sometimes very high frictional forces are generated and adhesion may occur.

  Therefore, the relative friction between the inner peripheral surface of the container and the outer peripheral surface of the metal material is preliminarily moved before the crystal grain refining step, thereby reducing the frictional force generated when sliding first in the crystal grain refining step. And the occurrence of adhesion can be effectively suppressed. That is, when the hydrostatic pressure before pressurization in the crystal grain refining process is small, the container and the metal material are moved relative to each other, and the inner peripheral surface of the container and the metal material are continuously slid in advance. Since the friction coefficient between the two can be reduced, the sliding between the inner peripheral surface of the container and the metal material is stopped after the pressure between the inner peripheral surface of the container and the metal material is increased by the pressurization by the punch. Rather than starting from the state, it is possible to reduce the maximum value of the frictional force and reduce the risk of adhesion.

  In the crystal grain refining method according to claim 5 configured as described above, a bottomless form is adopted as the cylindrical space defined by the container, and the punch is inserted into the cylindrical space from above and below. By adopting a configuration consisting of an upper punch and a lower punch that pressurizes the metal material, it is possible to apply pressure or twist to the metal material from the vertical direction of the metal material. The degree of freedom can be improved. Further, as in the crystal grain refining method according to claim 6, it is possible to relatively move the upper and lower punches and the container in the axial direction of the cylindrical space while pressing the metal material with the upper and lower punches. Compared with the case where a rotational movement is adopted as the movement, an excellent anti-adhesion effect can be exhibited. Specifically, the metal material has a large plastic flow in the vicinity of the upper and lower punches in the cylindrical space of the container, and the temperature rises in the vicinity of the upper and lower punches. By making the relative movement, a local temperature rise can be suppressed. This is because as the temperature rises, adhesion at that portion is likely to occur. Further, in the crystal grain refining method according to claim 7, the unit container in which the upper and lower punches are divided by combining the crystal grain refining method according to claim 6 and the crystal grain refining method according to claim 2. By rotating relative to each other in the axial direction while rotating, the position where the twist is imparted to the metal material by the unit container is also moved in the axial direction, and the twist imparting in the axial direction of the metal material is made uniform. That is, uniformity in the axial direction of crystal grain refinement can be achieved.

  In the crystal grain refining device according to the eighth aspect configured as described above, since the relative movement means is provided, adhesion between the inner peripheral surface of the container and the metal material can be suppressed. Adhesion between the inner peripheral surface of the container and the metal material is likely to proceed as the friction force between the two increases, so the relative movement means applies the metal material with a punch so that the friction coefficient is always low. The frictional force is reduced by relatively moving between the inner surface of the container and the outer peripheral surface of the metal material during pressing.

  In the crystal grain refining apparatus according to claim 9 configured as described above, the container is divided into two or more unit containers, and relative rotation is performed between at least two of the unit containers. Thus, in addition to the transmission of the rotational force from the punch, it is possible to transmit the rotational force from those unit containers. By performing relative rotation on two or more of the unit containers formed by dividing, a rotational force is directly applied to the metal material from the unit container that is rotating relative to each other through the contact portion. It is possible to positively apply a stress due to twisting to the portion between the unit containers, and a sufficient crystal grain refining action is exhibited in that portion.

  In the crystal grain refining device according to claim 10 configured as described above, before the relative movement means pressurizes the metal material by the crystal grain refinement means, the inner peripheral surface of the container and the outer circumference of the metal material. By performing relative movement between the surfaces, adhesion between the inner peripheral surface of the container and the metal material can be effectively prevented. When the metal material is first slid between the inner peripheral surface of the container and the metal material by first relatively moving between the inner peripheral surface of the container and the metal material before pressurizing the metal material by means of grain refinement. It is possible to reduce the frictional force generated in the film, and it is possible to effectively suppress the occurrence of adhesion.

  Hereinafter, the crystal grain refining method and apparatus of the present invention will be described in detail based on embodiments. The method and apparatus of the present embodiment is applied to a metal material, and is a method and apparatus that can refine crystal grains of the metal material. In the method or apparatus of the present invention, it is desirable to carry out the treatment until the diameter of the crystallized product or precipitate in the metal material is 5 μm or less.

  The type of metal material that can be applied is not limited. For example, it can be applied to an aluminum alloy. For example, an aluminum alloy composed of one or more elements selected from iron, copper, magnesium and nickel and Al and Si, the second phase being an aluminum alloy composed of primary Si, eutectic Si, or It is preferable to apply to an aluminum alloy whose two phases are primary crystal Si, eutectic Si, and Al—Si—Fe intermetallic compound. When applied to aluminum alloys such as these, it is possible to form a structure in which primary Si, eutectic Si, and Al—Si—Fe intermetallic compounds are uniformly and finely distributed on an aluminum substrate (matrix). In addition, since the crystal grains of the matrix itself can be made finer, mechanical characteristics, heat resistance, forging characteristics, and friction characteristics are improved.

(Grain refinement method)
The crystal grain refinement method of this embodiment is a method performed using a container and a punch. The container defines a cylindrical space. The cylindrical space is a space for loading a metal material for refining crystal grains in the crystal grain refining method of the present embodiment.

  A metal material, which is a workpiece, is loaded in the cylindrical space. The form of the metal material to be loaded is not particularly limited, and can be a solid cylindrical member formed according to the shape of the cylindrical space or a powdered member.

  The cylindrical space is bottomless or bottomed. The bottomless cylindrical space has a form in which the cylindrical space of the container penetrates in the axial direction, and the bottomed cylindrical space has a form in which one end thereof is closed.

  A container can be composed of a plurality of unit containers. In that case, these unit containers are combined to define a cylindrical space. The unit container is formed so as to divide the cylindrical space in the axial direction. The unit container has a shape that allows relative rotation.

  The punch is a member that pressurizes and twists the metal material loaded in the container. The portion where the punch abuts on the metal material can be formed with irregularities so that it does not slip when twisting is applied. When a bottomless form is adopted as the cylindrical space, the punch can be composed of two punches, an upper punch and a lower punch. The metal material in the cylindrical space is pressurized by moving at least one of the two punches. When the bottomed form is adopted as the cylindrical space, one punch may be used.

  The crystal grain refinement method of this embodiment includes a crystal grain refinement process and a relative movement process.

  The crystal grain refining step is a step of applying twist while pressing a metal material with a punch. The pressurization is performed by moving the punch in the cylindrical space of the container in the axial direction. When the punch is composed of upper and lower punches, twisting is performed by applying a relative rotation between the upper and lower punches (for example, rotating in the reverse direction), and the punch is a single punch when the cylindrical space has a bottom. In some cases, this is done by relatively rotating the punch and the container. By applying a twist, a force such as stretching of the crystal grains in the metal material is applied to refine the crystal grains. The part where the crystal grain refinement proceeds in the metal material is a part located between members of the punch and the container that rotate relative to each other.

  In the method of the present embodiment, it is desirable that the appropriate temperature range of the metal material when pressurizing is lower than the recrystallization temperature of the metal material. When the treatment is performed at a temperature higher than the recrystallization temperature, the relative rotation and the like are controlled so that the speed of crystal grain refinement becomes larger than the progress speed of recrystallization. Further, when an aluminum alloy is used as the metal material, it is preferably 50 ° C. or higher and 300 ° C. or lower, and more preferably 50 ° C. or higher and 200 ° C. or lower.

  The relative movement process is a process of relative movement between the inner peripheral surface of the container and the outer peripheral surface of the metal material while the metal material is pressed by the punch. In this process, since the relative movement is made between the inner peripheral surface of the container and the outer peripheral surface of the metal material, the friction coefficient can always be reduced, and it occurs between the inner peripheral surface of the container and the outer peripheral surface of the metal material. The frictional force is reduced. That is, it is sufficient for the degree of relative movement in the relative movement process to be a slippage between the inner peripheral surface of the container and the outer peripheral surface of the metal material.

  The relative movement step is a step of relatively moving between the inner peripheral surface of the container and the outer peripheral surface of the metal material, but is simply a step realized by relatively moving between the container and the punch. . The relative movement between the container and the punch includes rotation (the container and the punch are rotated about the axis of the cylinder in the cylindrical space), and reciprocation in the axial direction (the container and the punch in the axial direction of the cylindrical space). The punch can be reciprocated), and any one of them can be performed alone, or both can be combined. The

  The relative movement between the inner peripheral surface of the container and the outer peripheral surface of the metal material may be either the circumferential direction or the axial direction of the cylindrical space of the container. In the circumferential direction, the container and the punch are relatively rotated, and in the axial direction, the container and the punch are relatively moved in the axial direction. It may be desirable to apply the relative movement between the punch and the container in combination of the rotational direction and the axial direction.

  When the container is composed of a plurality of unit containers, the unit container can be relatively rotated while pressurizing the metal material with a punch. By making the relative rotation, the rotational movement of the unit container is transmitted to the portion of the metal material that comes into contact with each of the relatively rotating unit containers. As a result, twisting is transmitted to the metal material, and a force such as stretching is applied to the crystal grains in the metal material, so that the crystal grains are refined. In the metal material, the portion where the crystal grain refinement proceeds is a portion located between members that rotate relative to each other among the punch and the plurality of unit containers.

  In the relative movement process, it is desirable that the unit container is relatively rotated and the punch is also relatively rotated. More preferably, all punches and unit containers are rotated relative to adjacent punches and / or unit containers. Furthermore, it is more desirable to rotate the punch and the unit container in the reverse direction in order from the extreme end. The magnitude of relative rotation between adjacent punches and / or unit containers is not particularly limited.

  Furthermore, the cylindrical space defined by the container is made bottomless, and the container and the punch are vertically pressed to move the relative position in the axial direction between the container and the punch. The position of twist imparted to the metal material also moves in the axial direction, and by controlling the movement, crystal grains can be refined at a desired position in the axial direction of the metal material.

  According to this method, twisting can be applied to the vicinity of the center in addition to both ends of the workpiece without deforming the shape of the workpiece, and the fineness of the crystal grains with respect to the workpiece that has been limited in the past has been conventionally achieved. Can be expanded.

  Further, as the relative movement step, it is desirable to perform the relative movement between the inner surface of the container and the outer peripheral surface of the metal material before pressurizing the metal material with a punch in the crystal grain refining step. In the crystal grain refining process, the metal material is twisted while being pressed, so that the outer peripheral surface of the metal material starts to slide with a high pressure applied to the inner peripheral surface of the container. Therefore, before the pressure between the inner peripheral surface of the container and the outer peripheral surface of the metal material is increased by pressurization, the friction between the inner peripheral surface of the container and the outer peripheral surface of the metal material is previously determined by relative movement. Since the coefficient can be changed from a high coefficient (static friction coefficient) to a small condition (dynamic friction coefficient), and the frictional force acting between the inner peripheral surface of the container and the outer peripheral surface of the metal material can be reduced. Can be suppressed.

(Crystal grain refiner)
The crystal grain refining device of this embodiment has a container, a punch, and a rotating means. The container defines a cylindrical space. A container can also be composed of a plurality of unit containers. These unit containers are combined to define a cylindrical space. The same punch and container as those used in the crystal grain refining method in the above-described embodiment can be employed.

  The punch is a member that pressurizes the metal material loaded in the container. For a bottomless cylindrical space, a metal material is pressurized from both ends thereof. When pressurizing from both ends, at least one of two punches (upper and lower punches) is inserted into one end to pressurize. The same punch as that used in the crystal grain refining method in the above-described embodiment can be employed.

  The relative movement means is means for moving the container relative to the metal material while pressurizing the metal material with a punch. When the container is formed of a plurality of unit containers, the relative movement means can relatively rotate at least two of the plurality of unit containers described above. Relative rotation is also possible between unit containers.

  The timing for the relative movement means to move relative to the punch and the container (during pressurization and before pressurization), the selection of the relative movement direction (reciprocating movement in the rotational direction or axial direction), and the degree of relative rotation are described in the above embodiment. This is the same as in the above method.

(Test 1: Test in which a relative movement process is performed before the grain refinement process is started)
Workpiece as a metal material is 16.8% Si, 3.0% Cu, 0.92% Mg, 6.5% Fe, less than 0.2% Ti, and the balance on a mass basis An aluminum alloy in which Al is Al was employed, and processing was performed using a crystal grain refining apparatus described below. The workpiece was cylindrical with a diameter of 15 mm and a length of 10 mm.

  As shown in FIG. 1, the crystal grain refining apparatus of the present embodiment includes a punch composed of a container 7, an upper punch 1 and a lower punch 2, and a rotating means (relative moving means) capable of rotating these upper and lower punches 1 and 2 independently. : Pressing means (not shown) for pressurizing the upper and lower punches 1 and 2, punches 1 and 2, heating means (not shown) for heating the container 7 and workpiece W, container 7 and punches 1 and 2 Relative movement means (not shown) for relatively moving between the two in the axial direction. The container 7 and the upper and lower punches 1 and 2 are formed from the SKD 11.

  The container 7 has a cylindrical shape (outer diameter is 80 mm, length is 80 mm), and defines a bottomless cylindrical space (inner diameter is 15 mm, length is 80 mm) that is coaxial with the cylinder. The surfaces of the punches 1 and 2 that are in contact with the workpiece W are wedge-shaped so that they do not slide with respect to the workpiece W during pressing and twisting.

  With the workpiece W loaded in the cylindrical space, the upper and lower punches 1 and 2 and the container 7 were rotated relative to each other while applying a pressure of 100 MPa to the upper and lower punches 1 and 2. At this time, the upper and lower punches 1 and 2, the container 7, and the workpiece W were heated to 300 ° C.

  The upper punch 1 was rotated 10 times with respect to the lower punch 2 at 5 rpm. The container 6 was rotated 10 times at a speed of 5 rpm in the opposite direction to the upper punch 1. The container 6 and the punches 1 and 2 were moved in the axial direction at a speed of 1 mm / second. This movement was performed before pressurization began.

  As a comparative example, a test was performed using the same workpiece W, the same apparatus, and the same method as in the example except that the relative movement between the container 7 and the punches 1 and 2 was not performed. That is, the relative movement between the container 7 and the punches 1 and 2 was not performed even while the workpiece W was being pressurized and twisted.

  FIG. 2 (Example) and FIG. 3 (Comparative Example) show cross-sectional metal micrographs of the workpieces W processed by the apparatuses of the Examples and Comparative Examples. The micrographs of FIGS. 2 and 3 are photographs of a portion A of a cross section in a direction parallel to the axis, as shown in FIG.

  Comparing the example and the comparative example, as can be seen from FIGS. 2 and 3, it can be seen that the workpiece W of the example has finer crystal grains even in the structure at the same site. . This is because the frictional force between the inner peripheral surface of the container 7 and the outer peripheral surface of the workpiece W becomes large when there is no relative movement means (the relative movement process is not performed) as in the comparative example. It is considered that a site where the workpiece W adheres to the container 7 is generated, and a sufficient force is not applied in the twisting direction. That is, it was found that the crystal grains were refined over a wide range by the method of the example. It has been found that the refinement of crystal grains in the workpiece W proceeds from the surface where the punches 1 and 2 abut. The range was found to be narrower in the comparative method than in the examples.

(Test 2: Relationship between relative movement process and coefficient of friction (friction force))
In order to examine the effect of the relative movement process of relative movement between the container and the workpiece, the change of the friction coefficient (friction force) when the relative movement process was performed was examined. Specifically, the following tests were conducted using the friction test apparatus shown in FIG.

  As the friction test apparatus, as shown in FIG. 5, a ring-on-plate friction and wear tester was used. A ring material 81 (outer diameter: 26.6 mm, inner diameter: 20 mm, height: 17 mm) made of the same material as the workpiece W and a plate 82 (32 mm × 32 mm × thickness 5 mm) made of the same material as the container 7 are used. did. Such a test apparatus was prepared and measured by the following method.

  A state in which no load is applied between the ring plates (before pressurization) in order to simulate the method of the present invention (example: sliding between the container and the workpiece by relative movement from before pressurization) Then, the ring 81 is rotated, and the ring 81 and the plate 82 are slid. Thereafter, pressurization was started, and the friction coefficient and friction force between them were measured.

  Further, in order to simulate a method not using the method of the present invention (comparative example: sliding is started after pressurization), the ring 81 is rotated while a pressure is applied between the ring and the plate in advance and a load is applied. The friction coefficient and the friction force when the ring 81 and the plate 82 were slid were measured.

  The test conditions were a sliding speed of 4 mm / second and a pressure of 100 kN. Lubrication was not lubricated. The results are shown in FIG. 6 (Example) and FIG. 7 (Comparative example).

  As apparent from FIG. 7, in the method of the comparative example, it was found that the friction coefficient between the ring 81 and the plate 82 showed a peak at the start of sliding, and then decreased and became constant. On the other hand, in the method of the example, as is clear from FIG. 6, the friction coefficient has a peak immediately after pressing (at the time of material contact), but the value is lower than that of the comparative example. Moreover, it turned out that the coefficient of friction of the method of an Example is smaller than the method of a comparative example also if it sees generally. When sliding is started from a static state with sufficient pressure, the contact pressure (Hertz pressure) of the contact surface is high, and the frictional force in this state is maximum throughout the process in this method. Guessed.

  From this result, it was found that the friction coefficient (= friction force) is smaller and the adhesion is less likely to occur when the pressure is started after the relative movement in advance than before the pressure.

(Test 3: Difference in crystal grain refining effect depending on presence / absence of container division)
Workpiece as a metal material is 16.8% Si, 3.0% Cu, 0.92% Mg, 6.5% Fe, less than 0.2% Ti, and the balance on a mass basis An aluminum alloy in which Al is Al was employed, and processing was performed using a crystal grain refining apparatus described below. The workpiece has a cylindrical shape with a diameter of 20 mm and a length of 15 mm.

  As shown in FIG. 8, the crystal grain refining apparatus of the present embodiment can independently rotate a container made up of unit containers 5 and 6, a punch made up of an upper punch 1 and a lower punch 2, and these upper and lower punches 1 and 2. Rotating means (relative movement means: not shown), pressurizing means (not shown) for pressurizing the upper and lower punches 1 and 2, punches 1 and 2, containers 5 and 6 and heating means for heating the workpiece W (not shown) And have.

  The container defines a penetrating bottomless cylindrical space, and the unit containers 5 and 6 are in contact with each other at a plane perpendicular to the axis of the cylindrical space.

  With the workpiece W loaded in this cylindrical space, the upper and lower punches 1 and 2 and the unit containers 5 and 6 were rotated while applying a pressure of 100 MPa to the upper and lower punches 1 and 2. At this time, the upper and lower punches 1 and 2, the unit containers 5 and 6, and the workpiece W were heated to 200 ° C.

  The upper and lower punches 1 and 2 were rotated 10 times at 5 rpm in the opposite direction. The unit container 5 located on the upper punch 1 side was rotated twice in the same rotational direction as the upper punch 1 at a speed of 1 rpm. The unit container 6 located on the lower punch 2 side was rotated twice in the same rotational direction as the lower punch 2 at a speed of 1 rpm.

  The unit containers 5 and 6 rotate in conjunction with the rotation of the upper and lower punches 1 and 2. The rotational speed of the unit containers 5 and 6 can be adjusted by adjusting the frictional force between the unit containers 5 and 6.

  As a comparative example, the crystal grain refinement of the workpiece W was performed using an apparatus as shown in FIG. The apparatus of the comparative example includes a punch composed of upper and lower punches 91 and 92, a container 95 partitioning a cylindrical space with one member, a rotating means (not shown) capable of independently rotating the upper and lower punches 1 and 2, and upper and lower punches 1 and 2. And a heating means (not shown) for heating the punches 91 and 92, the container 95, and the workpiece W.

  The apparatus has the same configuration as that of the apparatus of the embodiment except that an integrated container 95 that is not divided is adopted. In the comparative apparatus, the container 95 remains stationary even when the upper and lower punches 91 and 92 are rotated in opposite directions.

  Sections of the workpieces W processed by the apparatus of the example and the comparative example are shown in FIG. 10 (Example) and FIG. 11 (Comparative example). 10 and 11 schematically show the state of the crystal grains in the cross section.

  W1, W4, and W7 in FIG. 10 and R1 and R4 in FIG. 11 have progressed to the same degree of crystal grain refinement, and the crystal grains are generally finer. Grain refinement is also progressing to the same extent for W2 and W6 in FIG. 10 and R2 and R5 in FIG. 11, and fine crystal grains and large crystal grains are mixed. W3 and W5 in FIG. 10 and R3 in FIG. 11 have not undergone crystal grain refinement, and the crystal grains remain large as before processing.

  As typical parts, microphotographs of A to C in FIG. 10 observed with a metallographic microscope are shown in FIGS. A portion (FIG. 12) in which the crystal grains are finely refined, a B portion (FIG. 13) that is a boundary between the well refined portion and the partially refined portion, and the refinement proceeds. The part of C (FIG. 14) which is not well understood.

  The crystal grain size is more than 10 times different between the part where the crystal grains are refined (part A) and the part where the grains are not refined (part C). It can be seen that In the apparatus of the embodiment, by dividing the container into two parts and positioning the divided surface at the center in the axial direction of the workpiece W, it may be possible to proceed with the miniaturization even for the portion with the divided surface. It was revealed. Therefore, it has been estimated that the region where crystal grain refinement proceeds can be expanded by moving the position of the dividing surface during processing or increasing the number of dividing surfaces.

(Test 4: Relative rotational speed dependence between unit containers of grain refinement effect)
In the apparatus shown in FIG. 8, the effect of crystal grain refinement by controlling the rotation direction and speed of the unit containers 5 and 6 was examined.

  As shown in FIG. 15, the upper punch 1 and the unit container 5 are configured to be interlocked by a gear. Specifically, the sun gear 33 that moves in conjunction with the upper punch 1, the planetary gears 41 to 44 that are disposed around the sun gear 33 and are rotatably fixed to the pedestal 31, and the planetary gears 41 to 44 are disposed. And a ring gear 37 fixed so as to rotate in conjunction with the unit container 5. The sun gear 34 that moves in conjunction with the lower punch 2, the planetary gears 45 to 48 that are arranged around the sun gear 34 and are rotatably fixed to the pedestal 32, and the unit containers arranged around the planetary gears 45 to 48. 6 and a ring gear 38 fixed so as to rotate in conjunction with the motor 6.

  As a result, as shown in FIG. 15B, when the lower punch 2 rotates counterclockwise, the planetary gears 45 to 48 rotate clockwise and the ring gear 38 also rotates clockwise. The rotation ratio between the lower punch 2 and the ring gear 38 can be arbitrarily controlled by the gear ratio of each gear, but in this experiment, it was set to half.

  After loading the workpiece W, the upper and lower punches 1 and 2 were rotated 10 times in the opposite directions at 5 rpm each. Then, the unit containers 5 and 6 also rotated 5 times at 2.5 rpm in the opposite direction. Since the unit containers 5 and 6 are rotated more than in the case of the test 1, the region where the crystal grains corresponding to W4 in FIG. 10 are refined expands in the vertical direction, so that the crystal grains can be refined over a wider range. Realized. That is, it became clear that the degree of crystal grain refinement can be increased by increasing the relative rotation of the unit containers 5 and 6 as well.

1 is a schematic cross-sectional view showing a crystal grain refining device used in Test 1. FIG. It is a microscope picture which shows the structure | tissue of the workpiece processed by the method of the Example. It is a microscope picture which shows the structure | tissue of the workpiece processed by the method of the comparative example. 2 is a schematic cross-sectional view of a workpiece processed in Test 1. FIG. 3 is a schematic view of a friction test apparatus used in Test 2. FIG. It is a graph which shows the time change of the friction coefficient in the Example of Test 2. FIG. 6 is a graph showing a change in friction coefficient with time in a comparative example of test 2. It is a schematic sectional drawing which shows the crystal grain refiner used in the Example. It is a schematic sectional drawing which shows the crystal grain refiner used in the comparative example. It is a schematic sectional drawing of the workpiece processed with the apparatus of FIG. It is a schematic sectional drawing of the workpiece processed with the apparatus of FIG. It is a microscope picture which shows the structure | tissue of the workpiece shown in FIG. It is a microscope picture which shows the structure | tissue of the workpiece shown in FIG. It is a microscope picture which shows the structure | tissue of the workpiece shown in FIG. It is a schematic sectional drawing which shows the crystal grain refiner used in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 91 ... Upper punch 2, 92 ... Lower punch 5, 6 ... Unit container 95 ... Container 33, 34 ... Sun gear 41-48 ... Planetary gear 37, 38 ... Ring gear 31, 32 ... Base

Claims (10)

A container that defines a bottomed or bottomed cylindrical space that is loaded with a metallic material;
A punch for pressurizing the metal material in the cylindrical space;
Use
A grain refinement step of applying twist while pressing the metal material with the punch;
A crystal grain refining method comprising: a relative movement step of relatively moving between an inner surface of the container and an outer peripheral surface of the metal material while the metal material is pressed by the punch. The container is composed of a plurality of unit containers divided into two or more so as to be relatively rotatable in the axial direction of the cylindrical space defined by the container,
The crystal grain refining method according to claim 1, wherein the relative movement step is a step of relatively rotating at least two of the plurality of unit containers.   The crystal grain refining method according to claim 2, wherein the punch and the plurality of unit containers are rotated relative to each other between the adjacent punch and / or the unit container.   The relative movement step is a step of performing a relative movement between the inner surface of the container and the outer peripheral surface of the metal material before pressurizing the metal material in the crystal grain refining step. 4. The crystal grain refining method according to any one of 3 above. The cylindrical space defined by the container is bottomless,
The crystal grain refining method according to any one of claims 1 to 4, wherein the punch includes an upper punch and a lower punch that are inserted into the cylindrical space from above and below to pressurize the metal material.   The crystal grain refining method according to claim 5, wherein the upper and lower punches and the container are relatively moved in the axial direction of the cylindrical space while pressing the metal material with the upper and lower punches. The container is divided into two unit containers,
The crystal grains according to claim 6, wherein the upper and lower punches and the two unit containers are relatively moved so that the joint surfaces of the two unit containers are positioned throughout the entire axial direction of the cylindrical space in the metal material. Refinement method. A container that defines a bottomed or bottomed cylindrical space that is loaded with a metallic material;
A punch for pressurizing the metal material in the cylindrical space;
Crystal grain refining means for applying twist while pressing the metal material with the punch,
A crystal grain refining device, comprising: a relative movement means for relatively moving between an inner surface of the container and an outer peripheral surface of the metal material while the metal material is pressurized by the punch. The container is composed of a plurality of unit containers divided into two or more so as to be relatively rotatable in the axial direction of the cylindrical space defined by the container,
The crystal grain refining apparatus according to claim 8, wherein the relative movement unit is a unit that relatively rotates at least two of the plurality of unit containers.   The said relative movement means is a means to perform relative movement between the inner surface of the said container and the outer peripheral surface of the said metal material, before pressurizing the said metal material with the said punch. Crystal grain refiner.