JP6035645B2 - Method for producing magnesium alloy material - Google Patents

Description

  The present invention relates to a method for producing a magnesium alloy material having a rolling process.

  Magnesium alloys are known to be the lightest material among practical metal materials, and at the same time, are excellent in specific strength, machinability and damping ability, and are expected as environment-friendly lightweight materials. On the other hand, due to the fact that the crystal structure of the magnesium alloy is a close-packed hexagonal lattice, the plastic working is performed hot, and the use as casting material and die casting material occupies much.

  Recently, the development of alloys that can solve both high strength and workability by adding various elements to a magnesium alloy in minute amounts has been promoted, and in particular, the Long Period Stacking Order phase (hereinafter referred to as the “LPSO phase”). ”Is also drawing attention (for example, see Patent Document 1).

Japanese Patent No. 3905115

  An object of one embodiment of the present invention is to reduce anisotropy of strength at the stage of a processed material while having high strength and high ductility. Another object of one embodiment of the present invention is to reduce anisotropy by performing heat treatment before rolling.

  One aspect of the present invention includes an extrusion process for performing extrusion processing on a magnesium alloy material, and a rolling process for performing hot rolling on the extruded material produced by the extrusion process. A method for producing a magnesium alloy material having a structural phase, wherein the rolling step is rolled in a direction substantially perpendicular to an extrusion direction of the extruded material.

  In one embodiment of the present invention, the long-period laminated structure phase may be formed substantially parallel to the extrusion direction of the extrusion process.

  One aspect of the present invention includes a rolling step of performing warm rolling or hot rolling on a magnesium alloy material having a long-period laminated structure phase, and the rolling step is substantially perpendicular to the long-period laminated structure phase. It is the manufacturing method of the magnesium alloy material characterized by being rolled.

  In one embodiment of the present invention, the rolled material produced by the rolling step has a curved or bent long-period laminate structure phase, a long-period laminate structure phase having a crystal orientation difference, and a continuous grain boundary. It is preferable to have at least one of a long-period laminated structure phase that is curved or bent.

In one embodiment of the present invention, the rolled material produced by the rolling step has an α-Mg phase, and the α-Mg phase has a high-angle crystal grain boundary and a low-angle crystal grain boundary. When the amount of the high-angle crystal grain boundary is X and the amount of the low-angle crystal grain boundary is Y, the following formula (1) may be satisfied.
(1) 0.7 ≦ X / (X + Y)

  Further, in one embodiment of the present invention, after the rolling step, the rolling material produced by the rolling step further includes a heat treatment step of performing a heat treatment at a temperature of 573 K or less, and the heat treatment material produced by the heat treatment step includes: A long-period laminated structure phase having a curved or bent shape, a long-period laminated structure phase having a crystal orientation difference, and a long-period laminated structure phase having a crystal grain boundary and continuously curved or bent. .

  Moreover, 1 aspect of this invention WHEREIN: It is good to further comprise the process of heat-processing the said extrusion material between the said extrusion process and the said rolling process. Thereby, anisotropy can be reduced.

By applying one embodiment of the present invention, strength anisotropy can be reduced at the stage of a processed material while having high strength and high ductility.
According to one embodiment of the present invention, anisotropy can be reduced by performing heat treatment before rolling.

It is a schematic diagram for demonstrating the manufacturing method of the magnesium alloy material which concerns on 1 aspect of this invention. It is a schematic diagram for demonstrating the manufacturing method of the magnesium alloy material which concerns on 1 aspect of this invention. (A) is a photograph showing the crystal structure of the extruded material (without heat treatment), and (b) is a photograph showing the crystal structure of the extruded material after heat treatment. It is a figure which shows the result of the tension test of a rolling material (without heat processing). It is a figure which shows the relationship between each of the yield strength YS which is the result of the tensile test of a rolling material, tensile strength UTS, and elongation El, and heat processing temperature. (A)-(c) is a figure which shows the grain-boundary map by the optical micrograph of a rolling material (without heat processing), an IPF map, and EBSD. It is a TEM photograph of a rolled material (without heat treatment). (A) is a structure photograph of a rolled material that has been heat treated at 573 K, 3.6 ks, (b) is a structure photograph of a rolled material that has been heat treated at 623 K, 3.6 ks, and (c) is a structure image of 673 K, 3.6 ks. The structure photograph of the rolling material which heat-processed, (d) is a structure photograph of the rolling material which heat-processed 773K and 3.6 ks. (A) is the crystal structure of the extruded material (no heat treatment), and (b) is the crystal structure of the extruded material after the heat treatment. It is a figure which shows the nominal stress-strain curve of the rolling material without heat processing, and the rolling material after heat processing. It is a figure which shows the optical microscope structure result and crystal orientation analysis result of the longitudinal cross-section of a rolling material. (A) Light microstructure after heat treatment of 573K on the rolled material, (b) Light microscope structure after heat treatment of 623K on the rolled material, and (c) after heat treatment of 673K on the rolled material. It is a light microscopic organization.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below.

(Embodiment 1)
FIG. 1 is a schematic view for explaining a method for producing a magnesium alloy material according to one embodiment of the present invention.

  First, a casting material made of a magnesium alloy having an α-Mg phase and a long-period laminated structure phase is prepared. The composition of this magnesium alloy should just be what a long period laminated structure phase produces | generates, for example, the following are mentioned.

The first magnesium alloy contains a atom% of Zn, b atom% of Y, the balance is Mg, and a and b satisfy the following formulas (1) to (3).
(1) 0.5 ≦ a ≦ 5.0
(2) 1.0 ≦ b ≦ 5.0
(3) 0.5a ≦ b

The second magnesium alloy contains a atom% of Zn, contains a total of at least one element selected from the group consisting of Dy, Ho, and Er, and contains b atom% in total, with the balance being Mg, and a and b Satisfies the following formulas (1) to (3).
(1) 0.2 ≦ a ≦ 5.0
(2) 0.2 ≦ b ≦ 5.0
(3) 0.5a-0.5 ≦ b

The third magnesium alloy contains Zn by a atom%, contains at least one element selected from the group consisting of Dy, Ho, and Er in total, and contains b atom%, with the balance being Mg, and a and b Satisfies the following formulas (1) to (3).
(1) 0.2 ≦ a ≦ 3.0
(2) 0.2 ≦ b ≦ 5.0
(3) 2a-3 ≦ b

The fourth magnesium alloy contains Zn at a atom%, contains at least one element selected from the group consisting of Gd, Tb, Tm and Lu in total b atom%, with the balance being Mg, And b satisfy the following formulas (1) to (3).
(1) 0.1 ≦ a ≦ 5.0
(2) 0.25 ≦ b ≦ 5.0
(3) 0.5a-0.5 ≦ b

The fifth magnesium alloy contains Zn by a atom%, contains at least one element selected from the group consisting of Gd, Tb, Tm and Lu in total b atom%, with the balance being Mg, And b satisfy the following formulas (1) to (3).
(1) 0.1 ≦ a ≦ 3.0
(2) 0.25 ≦ b ≦ 5.0
(3) 2a-3 ≦ b

The sixth magnesium alloy contains at least one metal of Cu, Ni, and Co in total a atom%, and is selected from the group consisting of Y, Dy, Er, Ho, Gd, Tb, and Tm. The total amount of the above elements is b atom%, the balance is Mg, and a and b satisfy the following formulas (1) to (3). More preferably, a and b satisfy the following formulas (1 ′) to (3 ′).
(1) 0.2 ≦ a ≦ 10
(2) 0.2 ≦ b ≦ 10
(3) 2 / 3a-2 / 3 <b
(1 ′) 0.2 ≦ a ≦ 5
(2 ′) 0.2 ≦ b ≦ 5
(3 ') 2 / 3a-1 / 6 <b

  In addition, it is also possible to contain another element in the said 1st-6th magnesium alloy in the range which a long period laminated structure phase produces | generates.

  Next, by performing a warm extrusion process or a hot extrusion process on the cast material, as shown in FIG. 1, an extruded material in which the longitudinal direction of the LPSO phase is aligned substantially parallel to the extrusion direction is produced. Here, “substantially parallel” means a direction in which 70% by volume or more of the LPSO phase has an angle of ± 20 ° or less with respect to the extrusion direction. Moreover, hot extrusion refers to extrusion performed at a temperature equal to or higher than the recrystallization temperature of the material, and warm extrusion refers to extrusion performed at a temperature lower than the temperature of hot extrusion.

Next, the extruded material is cut and hot rolled in a direction substantially perpendicular to the extrusion direction of the extruded material, thereby producing a rolled material in which the LPSO phase is greatly curved or bent as shown in FIG. To do. Here, the substantially vertical direction means a direction having an angle of ± 20 ° or less with respect to the extrusion direction.
Moreover, in this Embodiment, although the hot rolling process is performed to the extruded material, you may perform a warm rolling process to an extruded material. The hot rolling process refers to a rolling process performed at a temperature equal to or higher than the recrystallization temperature of the material, and the warm rolling process refers to a rolling process performed at a temperature lower than the temperature of the hot rolling process.

  Note that performing the rolling process in a direction substantially perpendicular to the extrusion direction of the extruded material is also performing the rolling process in a direction substantially perpendicular to the LPSO phase. The term “substantially perpendicular to the LPSO phase” as used herein means a direction having an angle of 70 ° to 110 ° with the rolling direction with respect to the LPSO phase of 70% by volume or more.

  According to the present embodiment, by performing the rolling process in a direction substantially perpendicular to the LPSO phase, the strength anisotropy of the rolled material can be reduced as compared with the extruded material. For example, when the anisotropy of the strength of the extruded material is 30 to 35%, the anisotropy of the strength of the rolled material can be reduced to half or less (for example, about 10%) compared to that of the extruded material.

From the viewpoint of mechanical properties, when the rolling direction of the produced rolled material is defined as 0 °, even if the 45 ° and 90 ° directions are cut out in the longitudinal direction of the tensile test piece, the proof stress, tensile strength, and elongation in the 0 ° direction Both were within about 10%, and the material strength was isotropic even if it was not an isotropic material. From the structural point of view, Mg alloys are easily oriented to a specific orientation after processing, but at the same time a random structure can be formed, and at the same time that the LPSO phase is oriented in one direction, the introduction of kink bands, bending / bending of the LPSO phase, and LPSO As a result of introducing grain boundaries in the phase, it is considered that anisotropy was prevented from the structural viewpoint.
The introduction of the kink band is a bent / curved portion introduced into the LPSO phase by applying plastic deformation to the LPSO type Mg alloy.

  In addition, the manufacturing method of the magnesium alloy material according to the present embodiment is a method capable of reducing the strength anisotropy, and therefore, before processing, compared to a case where a magnesium alloy material having equivalent mechanical characteristics is manufactured by extrusion processing. Thus, it can be expected that the preheating temperature can be lowered, and as a result, the process cost can be reduced. For example, while the extrusion process is performed at a preheating temperature of about 673K, the preheating temperature can be set to about 643K in the rolling process according to the present method.

The α-Mg phase of the rolled material produced by the rolling process has a high-angle crystal grain boundary and a low-angle crystal grain boundary. The amount of the high-angle crystal grain boundary is X, and the low-angle crystal grain boundary When the amount is Y, the following formula (1) is satisfied.
(1) 0.7 ≦ X / (X + Y)

  Thus, it is thought that the anisotropy of the strength of the rolled material can be reduced by having a high-angle crystal grain boundary of 70% or more and a low-angle crystal grain boundary of 30% or less. Incidentally, in the α-Mg phase of the rolled material of the conventional LPSO phase type magnesium alloy, the high-angle crystal grain boundary is about 20% and the low-angle crystal grain boundary is about 80%.

  In addition, the low-angle crystal grain boundary means that the orientation difference between adjacent crystal grains sandwiching one grain boundary is less than 15 ° (or 5 ° to 15 °), and the high-angle crystal grain boundary is 1 An orientation difference between adjacent grains sandwiching one grain boundary is 15 ° or more.

  In addition, by rolling in a direction substantially perpendicular to the LPSO phase, or having a high-angle crystal grain boundary of 70% or more and a low-angle crystal grain boundary of 30% or less, High strength can be achieved even when the particle size is about 5 μm.

  Further, even if the rolled material is heat-treated at a temperature of 573 K or lower after the rolling step, the bending or bending of the LPSO phase of the heat-treated material does not disappear, so that the high strength is maintained.

(Embodiment 2)
FIG. 2 is a schematic diagram for explaining a method for manufacturing a magnesium alloy material according to one embodiment of the present invention.

  The manufacturing method of the magnesium alloy material shown in FIG. 2 is the same as the manufacturing method of the magnesium alloy material shown in FIG. 1 except that it includes a step of performing a heat treatment on the extruded material before the rolling step.

  Also in the present embodiment, the same effect as in the first embodiment can be obtained.

An Mg ₉₆ Zn ₂ Y ₂ alloy containing 2 atomic% Zn and 2 atomic% Y and the balance being Mg and inevitable impurities was put into a vacuum melting furnace for melting. Next, the heat-dissolved material was placed in a mold and cast to prepare an ingot (cast material) of φ29 mm × L60 mm. Next, the ingot was extruded at an extrusion temperature of 350 ° C. with an extrusion ratio of 10 and an extrusion speed of 2.5 mm / second. Next, in order to reduce the anisotropy resulting from the increased elongation, the extruded material was heat treated at a temperature of 673 K for 3.6 ks, and then the extruded material was cooled with water. The α-Mg phase showed static recrystallization and grain growth. The kink band in the LPSO phase was recovered by heat treatment.

Here, SEM photographs of the extruded material and the heat-treated material are taken, and the photographs are shown in FIGS. 3 (a) and 3 (b). FIG. 3A shows the crystal structure of the extruded material (without heat treatment), and FIG. 3B shows the crystal structure of the extruded material after heat treatment. The alloy shown in FIGS. 3A and 3B includes an LPSO phase, an α-Mg phase, and an Mg ₃ Zn ₃ Y ₂ compound, and the LPSO phase is a bright portion. The LPSO phase of the heat treated extrudate is more finely dispersed than the LPSO phase of the extrudate without heat treatment. It can be seen that the LPSO phase is changed from the block shape to the plate shape by performing the heat treatment. Further, the longitudinal direction of the LPSO phase is formed in a direction substantially parallel to the extrusion direction, and the LPSO phase not parallel to the extrusion direction is finely dispersed.

  Next, a 5 mm (plate thickness) × 20 mm (width) × 50 mm (length) rolling plate material was cut out from the heat treated material by cutting. Next, this rolling plate was heated at a temperature of 673 K for a time of 0.6 ks, and then subjected to rolling, and immediately after the processing, it was cooled with water. The rolling direction was a direction perpendicular to the extrusion direction, the rolling process was performed at a roll temperature of 493 K, the roll peripheral speed was 0.17 m / s, and a plate material having a thickness of 1 mm was produced by a 4 pass rolling process.

Next, a tensile test piece having dimensions of 12 mm (length) × 2.5 mm (width) × 1 mm (thickness) was produced by cutting the rolled material. The test piece was subjected to a heat treatment of 3.6 ks at a temperature of 473 to 773K and then cooled with water. Thereafter, a room temperature tensile test was performed at an initial strain rate of 5 × 10 ⁻⁴ / s. And the structure of the rolled material without heat treatment and the rolled material after heat treatment is observed by optical microscopy, SEM (scanning electron microscopy), TEM (transmission electron microscopy), and crystal orientation analysis is performed by EBSD (electron back-scattered). diffraction). The EPSD was performed in a 200 × 200 μm region with a 0.3 μm measurement step. The structure was observed on the longitudinal section of the tensile test piece. A longitudinal section refers to a section parallel to the length direction of the tensile test piece and parallel to the thickness direction.

  FIG. 4 is a diagram showing the results of a tensile test of a rolled material (without heat treatment). FIG. 4 shows the anisotropy of the tensile properties. A tensile test direction of 0 ° means that the tensile direction and the rolling direction of the rolling process are parallel, and a tensile test direction of 45 ° means that the tensile direction is 45 ° with respect to the rolling direction of the rolling process. The direction of 90 ° in the tensile test means that the tensile direction is 90 ° with respect to the rolling direction of the rolling process. In FIG. 4, YS is the yield strength, UTS is the tensile strength, and El is the elongation.

  As shown in FIG. 4, the rolled material has a maximum anisotropy of yield strength YS of about 14%, which is less than half of the anisotropy of the extruded material. Incidentally, in the extruded material, the strength value differs by about 30% between 0 ° and 90 °. Further, the tensile strength UTS is almost constant without depending on the direction of the tensile test. Further, the elongation El showed a maximum value in the direction of the tensile test at 45 °. An important factor for controlling the tensile strength is considered to be fine dispersion of the LPSO phase before plastic deformation. This is achieved by heat treatment. The decrease in strength anisotropy is considered to be caused by the dispersion of the LPSO phase at the grain boundaries of the α-Mg phase by heat treatment and rolling.

  FIG. 5 is a diagram showing the relationship between the yield strength YS, the tensile strength UTS, the elongation El, and the heat treatment temperature, which are the results of the tensile test of the rolled material. The direction of the tensile test is 0 °.

  FIGS. 6A to 6C are diagrams showing an optical micrograph, an IPF (inverse pole figure) map, and a grain boundary map by EBSD of a rolled material (without heat treatment). The dark regions shown in FIGS. 6B and 6C correspond to the LPSO phase.

  As shown in FIG. 6A, by performing the rolling process, the LPSO phase can be greatly curved (having a large curvature) as can be seen from the light microscopic structure. In the rolling process, the plate thickness decreases and the length increases, but there is almost no deformation in the width direction. The force acting in the rolling process is a shearing force. A kink band is formed in the LPSO phase.

  As shown in FIG. 6C, the ratios of the high-angle crystal grain boundary and the low-angle crystal grain boundary in the α-Mg phase are 80.7% and 19.3%.

  FIG. 7 is a TEM photograph of a rolled material (without heat treatment), which shows that the LPSO has a bent or curved shape and a crystal tilt angle higher than that at low and high magnifications. The continuous deformation of the kink band introduced into the LPSO phase indicates that the LPSO phase, which is a hard phase, is greatly deformed by rolling. The LPSO phase with continuous kink deformation is formed after rolling and exhibits a large curvature. The kink band has an angle (crystal orientation difference) in many observation regions, and it is considered that the kink band changed to a grain boundary.

  The continuous bending or bending or bending of the LPSO phase continuously extends over a long distance, and the curvature is about 70 °. That is, it can be seen that the LPSO phase has a large ductility (deformability). In addition, the LPSO phase changes in a stepwise manner, and it is thought that the deformability of the LPSO phase is enhanced by the fact that the LPSO phase faces in multiple directions instead of flowing in one direction. However, no voids or separation is observed at the interface between the LPSO phase and the α-Mg phase.

  FIG. 8A is a structural photograph obtained by imaging a rolled material that has been heat treated for 3.6 ks at a temperature of 573 K with an optical microscope, and FIG. 8B is a heat image for 3.6 ks that is heated at a temperature of 623 K. FIG. 8C is a structural photograph of a rolled material that has been subjected to a heat treatment of 3.6 ks at a temperature of 673 K using an optical microscope. FIG. ) Is a structure photograph of a rolled material that has been heat treated for 3.6 ks at a temperature of 773 K, taken with an optical microscope.

  8A to 8C, the dark region corresponds to the LPSO phase, and the bright region corresponds to the α-Mg phase. As the heat treatment temperature increased, α-Mg phase grains grew, but until the heat treatment temperature of 623 K, the LPSO phase and α-Mg phase showed little difference compared to those before heat treatment. As the heat treatment temperature increased, the α-Mg phase grains became larger, but this occurred very slowly. The reason is that grain growth is controlled by the LPSO phase.

  FIG. 8 shows how the microstructure of the rolled material with respect to the slight change in mechanical properties and the heat treatment of 573K occurred. In the tensile test results shown in FIG. 5, the yield strength and the tensile strength were significantly reduced by the heat treatment at 623K. 3 and 6 that the static recrystallization temperature of the α-Mg phase of this alloy is 623 K or higher. When the alloy was heat treated at temperatures above 673 K, the yield strength and tensile strength dropped to approximately 200 MPa and 330 MPa, but the elongation was improved to over 20%.

  As shown in FIG. 8 (c), it can be seen that the LPSO phase in the rolled material subjected to the heat treatment of 3.6 ks at the temperature of 673 K is clearly deformed. Since the intensely curved or bent LPSO phase does not change even when heat-treated, the α-Mg phase sandwiched between the LPSO phase and the LPSO phase is inhibited from crystal grain growth. This tendency is stronger than the extruded material. Moreover, the anisotropy of the rolled material heat-treated at a temperature of 673 K is lower than that of the extruded material.

An Mg ₉₆ Zn ₂ Y ₂ alloy containing 2 atomic% Zn and 2 atomic% Y and the balance being Mg and inevitable impurities was put into a vacuum melting furnace for melting. Next, the heat-dissolved material was placed in a mold and cast to prepare an ingot (cast material) of φ29 mm × L60 mm. Next, the ingot was extruded at an extrusion temperature of 350 ° C. with an extrusion ratio of 10 and an extrusion speed of 2.5 mm / second. Next, the extruded material was subjected to a heat treatment of 3.6 ks at a temperature of 773K.

  Here, SEM photographs of the extruded material and the heat-treated material are taken, and the photographs are shown in FIGS. 9 (a) and 9 (b). FIG. 9A shows the crystal structure of the extruded material (no heat treatment), and FIG. 9B shows the crystal structure of the extruded material after the heat treatment. By making the extruded material highly ductile by heat treatment, the 0.2% yield strength is reduced to about 200 MPa, but the elongation reaches 20%. It can be seen that the LPSO phase is changed from a block shape (see FIG. 9A) to a plate shape (see FIG. 9B) by performing the heat treatment.

  Next, a plate material for rolling having a thickness of 5 mm was cut out from the heat treated material by cutting. Next, this rolling plate was heated at a temperature of 673 K for a time of 0.6 ks, and then subjected to rolling, and immediately after the processing, it was cooled with water. The rolling process was performed at a roll temperature of 493 K, a roll peripheral speed of 0.17 m / s, and a plate material having a plate thickness of 1 mm was produced by a 4 pass rolling process.

Next, by cutting the plate material, a plate-like tensile test piece having a parallel part size of 12 mm (length) × 2.5 mm (width) × 1 mm (thickness) was produced, and the test piece was measured at 473 to 773K. After heat treatment at a temperature of 3.6 ks, a room temperature tensile test and a structure observation were performed at an initial strain rate of 5 × 10 ⁻⁴ / s. The tensile direction of the tensile test and the rolling direction of the rolling process were parallel, and the structure observation was performed on the longitudinal section of the plate-like tensile test piece. In addition, the structure observation was performed using a light microscope and SEM, and the crystal orientation analysis was performed by EBSD.

  FIG. 10 is a diagram showing nominal stress-strain curves of a rolled material without heat treatment and a rolled material after heat treatment. It was found that the 0.2% yield strength of the rolled material without heat treatment was 350 MPa and the elongation was 4%, and that the 0.2% yield strength and the tensile strength were not significantly reduced up to the heat treatment temperature of 573K. As can be seen from the light microscopic structure described later, it is considered that the kink band was introduced into the LPSO phase even by rolling, and the strength was dramatically improved. On the other hand, when the heat treatment temperature reaches 623K, the strength decreases and the elongation improves, so that it can be seen that static recrystallization of the α-Mg phase occurs, without depending on the shape of the LPSO phase before processing, It was found that the mechanism of strength improvement and ductility improvement was the same as that of the extruded material.

  FIG. 11 shows the optical microstructure results and crystal orientation analysis results of the longitudinal section of the rolled material. It can be seen that the LPSO phase has a large curvature with respect to the rolling direction and is very deformed, and formation of a kink band is recognized inside the LPSO phase. Although the LPSO phase, which is a hard phase with respect to the α-Mg phase, was plastically deformed while increasing the curvature, no delamination phenomenon was observed at the interface between the LPSO phase and the α-Mg phase. It is considered that a kink band, which is a strengthening mechanism, was introduced inside the LPSO phase, and the α-Mg phase sandwiched between the LPSO phases was changed to a fine structure by rolling and the strength was improved. From the EBSD analysis shown in FIG. 11, the ratios of the high-angle and low-angle grain boundaries in the α-Mg phase in the rolled material are 80.7% and 19.3%, respectively, and the average grain size is 5 μm. Met.

  FIG. 12 (a) shows the light microstructure after the heat treatment of 573K on the rolled material, FIG. 12 (b) shows the light microscope structure after the heat treatment of 623K on the rolled material, and FIG. ) Shows the light microscopic structure after the heat treatment of 673K on the rolled material.

  10 and 12, no change was observed in the light microstructure of the rolled material without heat treatment and the rolled material after heat treatment of 3.6 ks at a temperature of 573 K, and the structure and mechanical properties are stable even when the heat treatment temperature is increased. Was. On the other hand, as the heat treatment temperature rises, α-Mg phase grain growth occurs in the rolled material as well as the extruded material, but it is also observed in the light microscopic structure that the kink band remains in the rolled material after the heat treatment of 673K. Therefore, the growth of crystal grains in the α-Mg phase was suppressed.

  According to the present embodiment, the kink band can be introduced into the LPSO phase by rolling, the deformation curvature of the LPSO phase increases with the number of rolling processes, and the formation of the kink band promotes the deformation of the LPSO phase. I found out that In addition, it was found that by thinly dispersing the LPSO phase in the α-Mg phase at the stage of the structure before rolling, a thin plate material can be easily produced even by rolling, and high strength was achieved with a low number of times of processing.

Claims (6)

An extrusion process for extruding a magnesium alloy material having a long-period laminated structure phase ;
A rolling process for hot rolling the extruded material produced by the extrusion process;
Have,
Before SL rolling step is a step that is rolled in the extrusion direction substantially perpendicular direction of the extruded material,
The rolled material produced by the rolling process has a tensile strength of 0 ° and 90 ° in the tensile test of the rolled material, and the difference in yield strength is 14% or less,
The 0 ° is such that the tensile direction is parallel to the rolling direction of the rolled material,
The method for producing a magnesium alloy material, wherein the 90 ° is 90 ° with respect to the rolling direction . In claim 1,
The method for producing a magnesium alloy material, wherein the long-period laminated structure phase is formed substantially parallel to an extrusion direction of the extrusion process. It has a rolling process for performing warm rolling or hot rolling on a magnesium alloy material having a long-period laminated structure phase,
The rolling step is a step of rolling in a direction substantially perpendicular to the long-period laminated structure phase ,
The rolled material produced by the rolling process has a tensile strength of 0 ° and 90 ° in the tensile test of the rolled material, and the difference in yield strength is 14% or less,
The 0 ° is such that the tensile direction is parallel to the rolling direction of the rolled material,
The method for producing a magnesium alloy material, wherein the 90 ° is 90 ° with respect to the rolling direction . In any one of Claims 1 thru | or 3 ,
The rolled material produced by the rolling step has an α-Mg phase,
The α-Mg phase has a high-angle crystal grain boundary and a low-angle crystal grain boundary,
A method for producing a magnesium alloy material, wherein X is the amount of the high-angle crystal grain boundary, and Y is the amount of the low-angle crystal grain boundary.
(1) 0. 7 ≦ X / (X + Y) In any one of Claims 1 thru | or 4 ,
After the rolling step, further comprising a heat treatment step of heat treating the rolled material produced by the rolling step at a temperature of 573 K or less,
The heat treatment material produced by the heat treatment step includes a long-period laminated structure phase having a curved or bent shape, a long-period laminated structure phase having a crystal orientation difference, and a long-period laminated film having a crystal grain boundary and continuously curved or bent. A method for producing a magnesium alloy material, comprising at least one of structural phases. In claim 1 or 2,
The magnesium alloy material further comprising a step of changing the long-period laminated structure phase from a block shape to a plate shape by performing a heat treatment on the extruded material between the extrusion step and the rolling step. Production method.