KR20000048268A - Method for manufacturing light metal forging material and method for manufacturing forging members using the same material - Google Patents

Abstract

PURPOSE: A production method of a material for forging a light metal material and a production method of a forging member using the material are provided to prevent a generation of a blister by a thermal treatment in a product by a forging processing. CONSTITUTION: A material for forging is molded with a semi melt injection molding by using an injection molding device and a metal mold. A solution heat treatment is performed in the material for forging by a thermal treating condition before a forging processing. A blister is previously generated in a step of the material for forging. The blister is generated in a water-blister shape on and/near a surface of the material and is easily detected by an observation with naked eyes. The forging processing is performed for the material for forging previously generated the blister by using a forging metal mold. An aged hardening processing is performed for a forging member by the thermal treating condition

Description

METHOD FOR MANUFACTURING LIGHT METAL FORGING MATERIAL AND METHOD FOR MANUFACTURING FORGING MEMBERS USING THE SAME MATERIAL}

The present invention relates to a method for producing a light metal forging material which is supplied as a raw material to a forging process for obtaining a light metal forging member, and a method for producing a forging member obtained in forging processing using the material.

Conventionally, for example, light metals made of light metals such as magnesium (hereinafter appropriately denoted by its element symbol Mg) and its alloy or aluminum (hereinafter, denoted by its element symbol Al) and the alloy As a method of manufacturing a member, the casting method is the most common. As a kind of this casting method, the so-called die-casting method is known in the art that the injection molding of light metal molten metal into the mold at high pressure enables the casting process to be speeded up and the productivity can be greatly improved. .

In addition, in the conventional melt casting method in which light metal molten metal is injected and filled into the mold in a state of complete melting above its melting point, the anti-melt casting method in which light metal molten metal is injected and filled in a mold in a semi-melt state (basically less than its melting point) is also employed. It is known.

In recent years, especially for Mg, its alloys, and the like, a method for producing a light metal member using an injection molding method has been put into practical use. In this method, the molten hard metal molten metal is injected and filled from the injection nozzle into the molding cavity of the molding die by using an injection molding apparatus, and a molded article (hard metal member) can be produced more efficiently with a shorter cycle time than the casting method. Can be. In addition, this injection molding method is relatively clean and more stable in terms of working environment than in casting methods such as die casting, and also in terms of quality, and also in shrinkage cavity. It is known as a process capable of producing a small number of defects and the like and a high precision and homogeneous light metal molded article.

Also in this injection molding method, a so-called semi-melt injection molding method is known in which a light metal molten metal is injected into an injection cavity from a injection nozzle into a semi-molten state (basically less than its melting point) (for example, Japan). Bureau, JK No. 2-15620).

When not only the injection molding method but also the casting method uses a semi-molten metal molten metal, the molten metal temperature (hereinafter referred to as "melt" also in a semi-molten state, not completely melted) is low. So-called casting fins are less likely to occur, which is suitable for injection at high speeds and / or high pressures, and is also advantageous from above to improve productivity.

Also, by filling the molten metal in the molten state with the molten metal in a semi-molten state, the molten metal in which the solid phase portion of the undissolved phase is mixed in the completely dissolved liquid phase is filled as it is, and thus close to laminar flow. It becomes filled in the state, and the curling of gas becomes comparatively small, and a comparatively homogeneous structure is obtained. Thereby, it becomes possible to improve the mechanical characteristics as the obtained whole member.

In addition, in this specification, "solid phase" means the "part which does not melt in the case of light metal molten metal in a molten state, and maintains a solid state", and "liquid phase" means "completely melted, and becomes a liquid state. Part ”. The " solid phase " is a " part that was kept in a solid state without melting in the molten metal molten state by observing the solidified structure of the obtained hard metal member. The " liquid portion " which is in a liquid state can be easily identified. In the case where the obtained member is referred to as a "solid phase", it means a "part that was solid (solid) without being melted in the light metal molten state of semi-melting".

In addition, in this specification, "solid state rate" means "the ratio of the solid state with respect to the whole molten metal (solid state + liquid state) in the metal melt of a semi-melt state", and observes the solidification structure of the molded article after injection, It can obtain numerically as a ratio (area ratio) of the part which was "solid state" with respect to the whole.

In addition, in this specification, with respect to a light metal molten metal, a "semi-molten state" basically means "a state in which the raw material (solid state) of a solid state and the raw material (liquid state) which melted and became a liquid state coexist." Usually, it is a state obtained by heating a raw material to less than its melting point. However, even when the temperature of light metal molten metal is substantially just above its melting point or melting point, the solid phase rate is substantially equal to 0%, and it is assumed to be contained in this "anti-melt state".

In addition, even when the molten metal molten metal has such a substantially solid phase rate of 0%, for example, in consideration of the actual injection molding process in the semi-melt injection molding method, once from the injection nozzle into the mold (one shot) Until the end of injection is completed and the next (next shot) injection is performed, the molten metal in the molten metal supply path of the injection nozzle is cooled, and the solidified portion (so-called cold plug) or the high solidity rate is high at the nozzle tip side. Since the upper portion is generated, the solid metal molten metal actually injected into the molding cavity inevitably contains a solid phase portion.

On the other hand, when it is required to obtain a hard metal member of higher strength than the casting method or the injection molding method described above, the forging method is most generally employed. Moreover, as one kind of manufacturing method which manufactures a light metal member by this forging method, it is suitable for the forging process by the casting method before a forging process, for example, as disclosed in Unexamined-Japanese-Patent No. 6-297127. A so-called casting forging method is known, in which a raw material (forging material) is molded and the raw material is placed in a predetermined forging mold to perform forging.

According to this casting forging method, it can be molded into a semi-finished product shape relatively close to the shape of the finished product (forging member) by forging processing in the casting (material) step. As a result, the forging step can be simplified to only one step of finishing forging, and even a member having a complicated shape can be forged. In addition, it is also possible to adjust the structure of the material so that the forging can be performed without any trouble even if the material is of poor forging.

In addition, molding of the forging material in the casting forging method may be performed by injection molding instead of the casting method.

However, in the casting step (forging material forming step) in the casting forging method, a gas containing air may be rolled in during the melting of the molten metal, and when the gas is dried and solidified in the inherent state, the inside of the cast product It remains as a gas defect in the. In particular, when a casting process capable of high-speed and high-pressure charging such as die-cast casting is used in the forging material forming process, the above-described gas defects are more likely to occur, and the problem becomes more remarkable.

As is well known, forged members made of light metals such as Al alloys and Mg alloys are generally heat treatments for improving their mechanical properties and increasing their strength, and are subjected to so-called T6 treatments which undergo age hardening treatment after solution treatment. In the case of forging a forged product obtained by the casting forging method, in the casting step (i.e., in the step of the forging material), forging the gas defects as described above, in the subsequent T6 treatment, In the solution treatment step of heating and maintaining at a high temperature, blockage occurs due to the expansion of the gas present therein (so-called blister), and the blister is good for the product (forging member) by forging. Since the mechanical properties are impaired and the effect of strength improvement by T6 treatment cannot be sufficiently obtained, and the appearance is also damaged, Processing is necessary. There was problem such as.

For this reason, a casting process (for example, die cast casting, etc.) capable of high-speed and high-pressure filling cannot be used in the casting step (forging material forming step) in the casting forging method, and the productivity is improved. Significantly disadvantageous in the stomach.

In addition, the problem of blister generation for the forged product obtained in the post process is similarly experienced when not only molding the forging material by casting but also employing another process, and in particular, the molding cavity When a process in which light metal molten metal is filled at high speed and / or high pressure is used (for example, when forging material is molded by injection molding method), the problem of blister generation for this forged product is more remarkable. Will be expressed.

In addition, in this specification, "solvation process" means the process of heating a raw material or a member for a predetermined time in the temperature range of the solid solution, and bringing this state to normal temperature, and thereby homogenizing a material structure. Can promote.

For example, in the case of Mg alloy containing 4% by weight or more of Al, the solution treatment is carried out, whereby the compound (Mg17 Al12) produced in the previous step is dissolved in the material structure to promote homogenization. . In the case where the Al content is less than 4% by weight, the compound as described above is not produced, so that the homogenization process by the solution treatment is generally unnecessary.

The present invention has been made in view of the above technical problem that may occur when forming a forging material and forging the material to obtain a light metal forging member, and a blister by heat treatment on a product (forging member) by forging. The purpose is to be able to surely prevent the occurrence of.

1 is a partial cross-sectional explanatory view showing a schematic configuration of an injection molding apparatus according to an embodiment of the present invention.

2 is a graph showing the test results of Test 1 showing the effect of improving the tensile strength of the forging member

3 is a graph showing the test results of Test 3, which shows the relationship between the hardness of the forging member and the solution treatment time.

4 is a graph showing the test results of Test 4 and showing a relationship between the tensile strength of the forging member manufactured by the method of the present invention and the relative density before forging of the forging material.

5 is a graph showing the test results of the test 5, showing a relationship between the hardness of the forging member produced by the method of the present invention and the age hardening treatment temperature

6 is a process explanatory diagram showing a method for manufacturing a forging member according to an embodiment of the present invention.

7 is a process explanatory diagram showing a manufacturing method of a forging member according to a conventional example;

[Explanation of symbols on the main parts of the drawings]

1: injection molding apparatus 10: mold

11: molding cavity

For this purpose, the manufacturing method of the light metal forging material which concerns on the 1st invention of this application is a manufacturing method of the light metal forging material supplied as a raw material to the forging process for obtaining a light metal forging member, The light metal molten metal is prescribed | regulated. The forging material is formed by filling into a molding cavity of a molding die, and before the forging process, a predetermined heat treatment is performed on the forging material to generate blisters caused by the expansion of the internal gas in the material. It is a feature.

In the second invention of the present invention, the predetermined heat treatment is a solution treatment.

Moreover, in the 3rd invention of this application, in the said 2nd invention, the heat processing temperature of the said solution treatment is 300 degreeC or more, It is characterized by the above-mentioned.

The lower limit of the heat treatment temperature of the solution treatment is set at 300 ° C. because the blister cannot be generated in advance in the forging material even before the solution treatment at a temperature lower than this value. .

Moreover, in the 4th invention of this application, in the said 2nd or 3rd invention, the heat processing time of the said solution treatment is characterized by being 1 hour or more.

The lower limit of the heat treatment time of the solution treatment is set to 1 hour because the homogenization of the material structure cannot be effectively promoted by the solution treatment at a time less than this value.

In the fifth invention of the present application, in any one of the second to fourth inventions, the solution treatment includes a heat treatment temperature of 350 ° C. or more and 450 ° C. or less, and a heat treatment time of 10 hours or more. It is characterized by the fact that it is carried out under the treatment conditions of 24 hours or less.

Here, the heat treatment temperature of the solution treatment is set at 350 ° C or higher because blistering can be surely generated in advance in the forging material by performing the solution treatment at this temperature or higher. The temperature is lower than or equal to that because when the solution treatment temperature exceeds this value, crystal grains grow in the material structure, and the mechanical properties of the product obtained by forging are lowered.

On the other hand, the heat treatment time of the solution treatment is 10 hours or more because the effect of material homogenization by solution treatment can be reliably obtained, and the time of 24 hours or less exceeds this time. This is because the effect is saturated and uneconomical even if the treatment is continued.

Moreover, the 6th invention of this application is set so that the relative density after the said predetermined heat processing may be 90% or more in any one of the said 1st-5th invention.

Here, the lower limit of the relative density is 90%, when the relative density is less than this value, the amount of blister generated in advance in the stage of the forging material is too large. This is because it cannot be reliably crushed, and as a result, it is difficult to secure the tensile strength which is generally required in practical use, and the nonuniformity between the maximum value and the minimum value becomes large and it is difficult to obtain stable strength.

In the sixth invention of the present application, in the sixth invention, the relative density after the predetermined heat treatment is set to be 95% or more.

Here, if the lower limit of the relative density is set to 95%, if the relative density is equal to or greater than this value, the blister that has been generated in advance in the step of the forging material can be crushed reliably to obtain a sound forging member. This is because the tensile strength generally required in practical use can be sufficiently secured, and the nonuniformity between the maximum value and the minimum value is very small and high tensile strength can be stably obtained.

In the eighth invention of the present application, in the invention of any one of the first to seventh inventions, the molding of the forging material includes filling a molten metal molten metal into a molding cavity of a predetermined molding mold in a semi-molten state. It is characterized by being carried out.

In the ninth invention of the present application, in any one of the first to eighth inventions, the forming of the forging material is performed by injection filling a light metal molten metal into a molding cavity of a predetermined molding mold. It is characterized by.

In a tenth aspect of the present invention, in the invention of any one of the first to ninth aspects, the light metal is a magnesium (Mg) alloy containing 4% by weight or more of aluminum (Al). It is.

The lower limit of the Al content is 4% by weight. When the Al content is less than this value, the compound (Mg17 Al12) which inhibits the homogenization of the material structure in the previous step is not produced. This is because the homogenization process is generally unnecessary.

In the method for manufacturing a forging member according to the eleventh invention of the present application, the forging material for the light metal forging according to any one of the first to tenth inventions is subjected to forging and is contained in the forging material. It is characterized by crushing the blister.

In the twelfth invention of the present application, in the eleventh invention, after the light metal forging material is heated in the predetermined heat treatment, the forging is performed as it is without any cooling process. It is a feature.

In the thirteenth invention of the present application, in the eleventh or twelfth invention, the second heat treatment is performed at a temperature lower than the heating temperature in the predetermined heat treatment after the forging process. will be.

The thirteenth invention of the present application is the thirteenth invention, wherein the second heat treatment is a heat treatment related to the predetermined heat treatment.

According to a fifteenth invention of the present application, in the fourteenth invention, the predetermined heat treatment is a solution treatment and the second heat treatment is an age hardening treatment.

In a sixteenth aspect of the present invention, in the fifteenth aspect, the heat treatment temperature of the aging hardening treatment is 100 ° C or more.

The lower limit of the heat treatment temperature of the aging hardening treatment is set to 100 deg. C, because an effective aging hardening cannot be generated in the forging member below this value.

Further, in the sixteenth invention of the present application, in the sixteenth invention, the aging hardening treatment is performed under the treatment conditions of which the heat treatment temperature is 100 ° C or more and 250 ° C or less, and the heat treatment time is 3 hours or more and 24 hours or less. It is characterized by losing.

Here, the lower limit value is 100 ° C for the heat treatment temperature of the aging hardening treatment, because an effective aging hardening cannot be generated at the forging member below this value, and the upper limit is 250 ° C. If it exceeds, it becomes overaging, and it becomes because it is impossible to obtain both tensile strength and elongation in an appropriate range.

On the other hand, with respect to the heat treatment time of the aging hardening treatment, the lower limit value of 3 hours cannot produce effective aging hardening in a short time of less than this, and the upper limit value of 24 hours is subjected to the above heat treatment. This is because the degree of effect is saturated and is not economical.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail, referring an accompanying drawing, for example, when the injection molding method is employ | adopted for the shaping | molding of a forging material.

First, the shaping | molding of the forging raw material which concerns on this embodiment is demonstrated. Fig. 1 is a partial cross-sectional explanatory view showing a schematic configuration of an injection molding apparatus for performing injection molding of a light metal forging material according to the present embodiment.

As shown in this figure, the injection molding apparatus 1 is of a so-called screw type, and has a cylinder 2 heated by a heater 4 arranged at an outer circumference with a nozzle 3 at a distal end, and A rotary drive device for rotationally driving a screw 6 rotatably supported in a cylinder 2 and a molded body 5 connected thereto and a screw 6 provided with, for example, a motor mechanism and a deceleration mechanism. 7), a hopper 8 into which raw materials are introduced and stored, and a feeder 9 for measuring and feeding the raw materials in the hopper 8 to the molding base 5.

In addition, although not specifically illustrated, the high speed injection mechanism for advancing the screw 6 toward the nozzle 3 is formed in the molding main body 5. This high-speed injection mechanism advances the screw 6 at a predetermined timing, detects it when the screw 6 retreats by a predetermined distance, stops the rotation of the screw 6, and simultaneously stops the retraction operation. It is configured to.

The injection molding apparatus 1 is positioned so that the inner passage of the nozzle 3 and the runner part 12 connected to the molding cavity 11 are connected in series, and then the cylinder 2 It is used to connect the distal end side of the mold to the mold 10.

The raw material introduced into the hopper 8 and stored therein is weighed by the feeder 9 and supplied into the molding main body 5, and the inside of the cylinder 2 in a heated state by the rotation of the screw 6. It is remitted. The fed raw material is heated to a predetermined temperature while being sufficiently stirred and kneaded by the rotation of the screw 6 inside the cylinder 2. In this embodiment, it is such a process that it is more preferable to obtain the light metal molten metal of the semi-molten state below the melting | fusing point of a raw material.

As the semi-molten light metal molten metal thus obtained is extruded toward the front of the screw 6, the screw 6 retreats at that pressure. As another numerical method, the screw may be forcibly retracted at a desired speed.

When the screw 6 retreats by a predetermined distance, the high speed injection mechanism (not shown) in the molding base 5 detects it, stops the rotation of the screw 6, and simultaneously stops the retraction operation. In addition, the measurement of the raw material may be performed by setting the retreat distance of the screw 6.

Then, by rotating the screw 6 in the retracted position by the high speed injection mechanism (not shown) and extruding with a predetermined force, the light metal molten metal in the semi-molten state from the nozzle 3 into the mold 10 is rotated. It is injected. That is, the molten metal molten metal is injected and filled into the molding cavity 11 from the nozzle 3 via the water supply part 12.

In this embodiment, magnesium (Mg) alloy, which is one kind of light metal, is used as a raw material, and this is supplied to the hopper 8 of the injection molding apparatus 1, for example, in the form of cutting pellets. More preferably, an inert gas (for example, argon gas) is filled in the passage leading from the hopper 8 into the molding main body 5, thereby preventing the oxidation reaction of the raw material (Mg alloy ferret).

The molding cavity 11 of the metal mold 10 is more preferably formed in a shape similar to the molding cavity of a forging die (not shown) used for forging after the injection molding, and is obtained in a later step. It is possible to obtain injection molded products (forging materials) in the form of semi-finished products that are similar to the forged members, which should be required.

As a result, the forging step can be simplified to only one step of finishing forging, and even a member having a complicated shape can be forged. In addition, even for materials with poor forging, the forging can be performed without any problems.

The forging material injection-molded using the injection molding apparatus 1 and the mold 10 is conventionally, as shown in FIG. 7, when forging processing (step S51) of the forging material is finished, forging processing ( Step S52) is performed and the obtained forging member is subjected to the T6 treatment performed by the solution treatment (step S53) and subsequent aging hardening treatment (step S54). As described above, there is a possibility that a so-called blister may occur in the solution treatment step, and when the blister appears as unsatisfactory state in the forging product (forging member) obtained in a later process, its mechanical properties are damaged and caused by T6 treatment. Since the effect of improving the strength cannot be sufficiently obtained, and the appearance of the article is also damaged, processing for removing it is necessary.

Therefore, in the present embodiment, in forming a forging material and forging the material to obtain a light metal forging product (forging member), the process order of forging processing and heat treatment is studied. It is possible to reliably prevent the occurrence of blisters and to obtain a sound forged member (that is, a high quality forged member having few defects and having a predetermined mechanical property).

That is, as shown in Fig. 6, first, the forging material is molded by the semi-melt injection molding using the injection molding apparatus 1 and the mold 10 (step S1), and then, before forging processing, The forging material is subjected to a solution treatment under a predetermined heat treatment condition (step S2). Thereby, a blister is generated beforehand at the stage of a forging material. Also, as is well known, this blister usually occurs in the shape of a blister of an image on the material surface and / or its vicinity, and thus can be easily detected by visual observation.

In this manner, forging processing is performed on the forging material in which blister has been generated in advance by using a predetermined forging die (step S3). As a result, blisters that have been generated on the material surface and / or in advance are crushed. In other words, the hollow portion, which is inherent in the material (surface and / or its surroundings) as a blister, is crushed by the compressive force at the time of forging, and this portion becomes a healthy base.

Thereafter, an aging hardening treatment is performed on the forging member under a predetermined heat treatment condition (step S4).

<Test 1>

Test 1 was performed as a confirmation test confirming the effect of improving the strength of the forging member according to the method of the present invention described above. The test results are shown in FIG. This confirmation test was performed using two types of Mg alloys (alloy A and alloy B) shown in following Table 1 as a raw material.

The Mg alloy of this raw material shall contain 4 weight% or more of Al. When the lower limit of the Al content is 4% by weight, when the Al content is less than this value, no compound (Mg17 Al12) which inhibits the homogenization of the material structure is produced in the previous step, This is because the homogenization process is inherently unnecessary.

(Unit: weight%) Al Zn Mn Fe Ni Cu Mg Alloy A 7.2 0.2 0.22 0.003 0.0008 0.001 Rest Alloy B 9.0 0.7 0.23 0.003 0.0008 0.001 Rest

In this test 1, the molding of the forged material was carried out by the above-mentioned semi-melt injection molding. In Comparative Example 1, the case where no heat treatment was performed after injection molding was shown, and Comparative Example 2 was injection molding. Later, the case where the T6 process is performed by the conventional process procedure (refer FIG. 7) is shown. In Comparative Example 2 and the Examples of the present invention, the heat treatment conditions of the solution treatment and the age hardening treatment were the same, and they were as follows.

Solvent Treatment

Alloy A: heat treatment temperature is 400 ℃ and holding time is 10 hours

Alloy B: heat treatment temperature is 410 ℃ and holding time is 16 hours

Aging hardening treatment

Alloy A: heat treatment temperature is 175 ℃ and holding time is 16 hours

Alloy B: heat treatment temperature is 170 ℃ and holding time is 16 hours

The forging was carried out by heating and maintaining at the heat treatment temperature in the solution treatment, and then putting the forging material into the forging die without cooling the raw material. Therefore, the heating step to the forging temperature prior to the forging process can be eliminated, and the forging step can be greatly simplified.

Tensile test pieces having a predetermined shape dimension were cut out from the respective forging members of Comparative Examples 1 and 2 and Examples of the present invention, and the tensile strengths were examined using these test pieces. The result is shown in FIG.

As can be seen from the graph of FIG. 2, the effect of the tensile strength shape based on Comparative Example 1 is about 20% or less in Comparative Example 2 for both materials of Alloy A and Alloy B. In the inventive example, it exceeds 50%, and it was confirmed that the forging member according to the inventive example had sufficiently obtained the effect of improving the strength by heat treatment as compared with that of the comparative example 2. In this regard, the standard tensile strength of JIS MD1 alloy, which is a general die cast alloy, is 230 [MPa], which is generally required for practical use, but in the case of the forging member according to the embodiment of the present invention, alloy A and In any of the materials of the alloy B, the strength (230 [MPa]) was sufficiently exceeded.

In addition, in the forging member according to Comparative Example 2, the occurrence of blister was found in a part thereof. In the forging member according to the embodiment of the present invention, the occurrence of blister was not recognized, and the appearance of the blister was not damaged.

As described above, in the embodiment of the present invention, in manufacturing a light metal forging material which is supplied as a material to a forging process for obtaining a light metal forging member, preferably, the light metal molten metal in a semi-molten state is formed into a predetermined mold. Since the forging material was molded by injection filling in the molding cavity, and the forging material was subjected to the solution treatment prior to the forging, the blister caused by the expansion of the internal gas was generated in advance in the material. By forging the forging material in the back step, blisters that have been generated beforehand on the material surface and / or in the vicinity thereof are crushed. That is, the cavity part inherent in the material (surface and / or its vicinity) as a blister is crushed by the compressive force at the time of forging, and this part becomes dry material. Subsequently, the aging hardening treatment is performed on the forging member under a predetermined heat treatment condition, whereby a healthy and high strength forging member without fear of blister generation can be obtained.

In the present embodiment, the forging process is performed by heating at the heat treatment temperature in the solution treatment and maintaining it for a prescribed time, and then putting the forging material into a forging mold without cooling it as it is. After the forging material is cooled, the forging may be performed by heating to the forging temperature.

In this case, for example, machining is performed on the once-cooled forging material, and the blister that has been generated on the surface and / or the surface of the material by the solution treatment is scraped off, and then forging is performed. You can do that. In this way, by removing the blister prior to forging, a sound forging member can be reliably obtained regardless of the degree of blister generation.

<Test 2>

Next, a test 2 was conducted to investigate the relationship between the heat treatment temperature and the blister generation conditions in the solution treatment. This test 2 was subjected to the solution treatment at various heat treatment temperatures (200, 250, 300, 350 and 400 ° C) of the forging material obtained by the above-mentioned semi-melt injection molding, and investigated the presence or absence of blister generation for each. will be. In addition, this blister generation test was performed using alloy A of the said Table 1 as a raw material.

The test results were as shown in Table 2.

Heat treatment temperature Blister Occurrence 200 ℃ none 250 ℃ none 300 ℃ none 350 ℃ has exist 400 ℃ has exist

From the results of this test 2, blistering was not observed at the heat treatment temperature of the solution treatment within the range of 300 ° C. or lower (200, 250, 300 ° C.), and when the temperature exceeds 300 ° C. (350, 400 ° C.), blistering occurred. I knew that.

Therefore, after forming the material for forging, in order to generate blister on the material in advance (prior to the forging), in order to generate the blister more reliably, it is preferable to use the heat treatment temperature of 350 ° C or higher. What is necessary is just to perform the embodied process.

<Test 3>

Next, a test 3 was conducted to investigate the effect of the heat treatment time in the solution treatment on the hardness of the forged member which is the final product. The test results are shown in FIG. In this test 3, semi-melt injection molding was performed using alloy A of Table 1 as a material, and the forging material thus obtained was subjected to a forging process as before, followed by T6 treatment (solution treatment + age hardening treatment). In the comparative example (J1 curve and J2 curve in the graph of FIG. 3) and the method of the present invention, the forging material was first subjected to the solution treatment, followed by the forging treatment, and then the aging hardening treatment. About the Example (K1 curve and K2 curve in the graph of FIG. 3) of this invention, the solution treatment time was changed and the hardness (Vickers hardness: Hv) of the surface and / or its vicinity was measured.

The heat treatment temperature of the solution treatment in this test 3 was made into the following two types.

J1 curve and K1 curve in the graph of FIG. 3: heat treatment temperature of 400 ° C.

J2 curve and K2 curve in the graph of FIG.

Moreover, the age hardening process was performed on the conditions which hold | maintain air-cooled after hold | maintaining at the temperature of 175 degreeC for 15 hours.

From the graph of FIG. 3, when the heat treatment temperature is 450 ° C., in the J2 curve of the comparative example, the hardness of the forged product (forging member) decreases corresponding to the length of the solution treatment time, and the crystal grains grow in the material structure. It can be seen that the phenomenon is occurring. In this case, therefore, the mechanical properties of the product obtained by forging are lowered. On the other hand, in the K2 curve according to the embodiment of the present invention, even when the heat treatment temperature is 450 ° C, the hardness of the forged part is not seen, which is equivalent to that of 400 ° C (K1 curve). It was found that the growth phenomenon of the crystal grains in the material structure did not occur even if Therefore, in this case, it is possible to shorten the time required for the solution treatment by increasing the heat treatment temperature within the range of 450 ° C or lower.

In addition, according to the graph of FIG. 3, when the heat treatment time of the solution treatment is less than 1 hour, the decrease in hardness is insufficient and unstable for any curve, and the effect of material structure homogenization by the solution treatment is effectively obtained. In order to achieve a more tangible effect, the heat treatment time of the solution treatment takes at least 1 hour, and more preferably, the heat treatment time should be 10 hours or more. Moreover, even if heat processing is performed over 24 hours, an effect is saturated and it is uneconomical.

<Test 4>

Next, a test 4 was conducted to investigate the effect of the relative density of the material before forging (i.e., forging after the solution treatment) on the tensile strength of the forging member.

This is because, in the method of the present invention, the solution is subjected to the solution treatment prior to the forging, and the blister is generated in advance, and the degree of the blister generation is forged and subjected to the age hardening treatment. It is investigating whether it affects. The test results are shown in FIG.

In this test 4, semi-melt injection molding was performed using alloy A of Table 1 as a material, and the forging material thus obtained was first subjected to the solution treatment of the forging material according to the method of the present invention, followed by forging. After processing, the tensile test pieces of a predetermined shape dimension were cut out from each product (forging member) obtained by carrying out an aging hardening process, and each tensile strength was investigated using these test pieces.

The relative density of the material before forging (material for forging) was changed in the range of about 84% to 97% by variously changing the solution treatment conditions.

From the graph of FIG. 4, when the relative density of the forging material before forging is 95% or more (that is, when the amount of blister generation is less than 5%), the blister previously generated at the stage of the forging material is It can be crushed reliably and a sound forged member can be obtained. As a result, a tensile strength of 250 [MPa] can be ensured even with a minimum value, and a nonuniformity between the maximum value and the minimum value is very small and a stable high tensile strength can be obtained. I knew you could. If the relative density is 90% or more, there is some nonuniformity. However, near the maximum value, strength generally required for practical use (230 [MPa]) can be ensured.

On the other hand, in the case where the relative density is less than 90%, the above-mentioned strength (230 [MPa]), which is generally required in practical use, cannot be secured, and the nonuniformity between the maximum value and the minimum value becomes very large and stable strength is achieved. I found it harder to get. This is considered to be due to the excessive amount of blisters generated in advance in the step of forging material, which cannot be reliably crushed.

In view of the above, in order to secure tensile strength (230 [MPa]), which is generally required in practical use, it is necessary to set the relative density of the forging material before forging to at least 90% or more, and to stably obtain higher tensile strength. In order to achieve this, more preferably, the relative density is set to 95% or more.

<Test 5>

Next, a test 5 was conducted to investigate the effect of the heat treatment temperature in the aging hardening treatment on the hardness of the forged product (forging member). The test results are shown in FIG. In this test 5, the semi-melt injection molding was performed using alloy B of Table 1 as a material, and the forging material thus obtained was first subjected to the solution treatment for the forging material according to the method of the present invention. The forging was performed, and then, the heat treatment temperature was variously changed, and the aging hardening treatment was performed, and the hardness (Vickers hardness: Hv) of the obtained product and / or its vicinity was measured.

The solution treatment in this test 5 was performed under the conditions of a heat treatment temperature of 410 ° C. and a holding time of 16 hours. In addition, the aging hardening process was performed on the conditions which hold | maintain air cooling after hold | maintaining at each temperature for 16 hours.

From the graph of FIG. 5, it turns out that when hardening treatment temperature is less than 100 degreeC, age hardening cannot generate | occur | produce in a forging member, and when it exceeds 250 degreeC, it becomes overaging and the hardness rises too much. In addition, when this overaging occurs in the forging member, the tensile strength is sufficiently obtained, but it is found that the elongation is lowered, and it is impossible to obtain both of them in an appropriate range.

Therefore, as the aging hardening treatment temperature, it is necessary to maintain the temperature at 100 ° C or higher, and the upper limit is preferably 250 ° C or lower. As the aging hardening treatment time, at least 3 hours or more is required in order to produce effective aging hardening for the forging member. However, even if the treatment is performed for more than 24 hours, the effect is saturated and becomes uneconomical.

In addition, although the above embodiment was about the case where the semi-fusion injection molding method was employ | adopted for the shaping | molding of a forging material, this invention is not limited to such a case, The semi-melt casting method or the hard metal molten metal of the complete melt state The present invention can also be effectively applied to the case where various processes, such as injection molding and casting, are employed for molding forging materials. Moreover, although the said embodiment was about the case where Mg alloy is used as an injection material, this invention can be effectively applied also when using another kind of light metal as a material.

Thus, this invention is not limited to the above embodiment, Needless to say that various changes, a design improvement, etc. are possible in the range which does not deviate from the summary.

According to the first invention of the present application, in manufacturing a light metal forging material which is supplied as a material to a forging process for obtaining a light metal forging member, the light metal molten metal is filled into a molding cavity of a predetermined molding mold, and the forging material The forging material was subjected to a predetermined heat treatment prior to forging, so that blister caused by the expansion of the internal gas was generated in advance in the forging material. By forging, blisters that have been previously generated on the material surface and / or in the vicinity thereof are crushed. In other words, any cavity part inherent in the material (surface and / or its vicinity) as a blister is crushed by the compressive force at the time of forging, and this part becomes a sound body. In other words, by causing the blister to be generated in the material step, the blister can be crushed by forging, and the blister can be reliably prevented from occurring in the forging member obtained in a later step.

Moreover, according to the 2nd invention of this application, the effect similar to the said 1st invention can be basically worked. In particular, since the predetermined heat treatment is a solution treatment, the homogenization of the material structure of the forging material can be promoted, the forging property can be improved in the forging processing of the post-process, and the mechanical properties of the forging member to be obtained. Can improve.

Moreover, according to the 3rd invention of this application, the effect similar to the said 2nd invention can be basically effected. In particular, when the heat treatment temperature of the solvent treatment is 300 ° C. or higher, the blister can be generated in advance (before forging) by the solution treatment.

Moreover, according to the 4th invention of this application, the effect similar to the said 2nd or 3rd invention can be basically effected. In particular, by setting the heat treatment time of the solution treatment to 1 hour or more, the homogenization of the material structure can be effectively promoted by the utilization solution treatment.

Moreover, according to the 5th invention of this application, the effect similar to the invention of either of the said 2nd-4th invention is basically effective. Particularly, with respect to the solution treatment condition, the heat treatment temperature is 350 ° C. or higher and 450 ° C. or lower, thereby effectively preventing a decrease in the mechanical properties of the forging member caused by the growth phenomenon of crystal grains in the material structure. The blister can be surely generated beforehand for forging materials. In addition, since the heat treatment time is 10 hours or more and 24 hours or less, the effect of material structure homogenization by the solution treatment can be reliably obtained, and the effect is not saturated and does not become uneconomical.

Moreover, according to the 6th invention of this application, the effect similar to any one invention of the said 1st-4th invention can fundamentally be effected. In particular, since the relative density after the predetermined heat treatment is set to be 90% or more, a blister that has been generated in advance in the step of the forging material can be crushed to obtain a sound forging member, which is generally required for practical use. The tensile strength can be secured.

Moreover, according to the 7th invention of this application, the effect similar to the said 6th invention can be basically worked. In particular, since the relative density after the predetermined heat treatment is set to be 95% or more, the blister that has been generated in advance in the forging step can be crushed more reliably to obtain a sounder forging member. Therefore, the tensile strength required in practical use can be sufficiently secured, and the nonuniformity between the maximum value and the minimum value is extremely asleep and high tensile strength can be stably obtained.

Moreover, according to the 8th invention of this application, the effect similar to the invention of any one of said 1st-7th invention can be found basically. In particular, by using the light metal molten metal in the semi-molten state to form the forging material, it is possible to obtain a high quality forging material with less shrinkage cavity and gas defects than in the case of the process using the molten state in the completely dissolved state Can be. In addition, since the molten metal temperature is low, so-called "moulding pins" are hard to come out and are suitable for high-speed and / or high-pressure processes, which are advantageous even from the above to improve productivity.

According to a ninth aspect of the present invention, in the case where the injection molding method in which blister by heat treatment is relatively easy to be used is employed for molding the forging material, any one of the first to eighth inventions described above. Effects similar to the invention can be obtained.

By employing injection molding for molding the forging material, it is possible to manufacture the forging material more efficiently with a shorter cycle time than in the case of the casting process. For example, when compared to casting methods such as the die casting method, the working environment is relatively clean (clean) and safety is higher, and also in terms of quality, there are fewer defects such as shrinkage cavities and high precision. It becomes possible to obtain a homogeneous light metal forging material.

According to the tenth invention of the present application, in particular, the content of Al is 4% by weight or more, and a compound (Mg17 Al12) which inhibits the homogenization of the material structure in the preceding step is produced, and the homogenization process by solution solution With respect to the case where the required Mg alloy is used as the material, the same effects as those of any of the first to ninth inventions can be obtained.

According to the eleventh invention of the present application, forging is performed on the light metal forging material according to any one of the first to tenth inventions, and the blister contained in the forging material is crushed. By doing so, the cavity part inherent in the material (surface and / or its vicinity) as a blister is crushed by the compressive force at the time of forging, and this part becomes a sound base. In other words, by producing blisters in the material stage, the blisters can be crushed by forging, and it is possible to reliably prevent blisters from occurring in the forging member obtained in the later step. Subsequently, the aging hardening treatment is performed on the forging member under a predetermined heat treatment condition, whereby a healthy and high strength forging member without fear of blister generation can be obtained. In this case, the same effect as the case in any one of the first to tenth inventions can be obtained.

According to the twelfth invention of the present application, basically the same effects as in the eleventh invention can be achieved. In particular, the light metal forging material is heated in the predetermined heat treatment and then subjected to forging without undergoing a cooling step, thereby eliminating the heating step at the forging temperature prior to the forging process. It can be greatly simplified.

Moreover, according to the thirteenth invention of the present application, the same effects as those of the eleventh or twelfth invention can basically be produced. In particular, since the second heat treatment is performed at a temperature lower than the heating temperature in the predetermined heat treatment after the forging, blistering does not occur by the heat treatment after the forging.

According to the fourteenth invention of the present application, basically the same effects as in the thirteenth invention can be achieved. In particular, by performing mutually-interfering heat treatment (the predetermined heat treatment and the second heat treatment) by dividing the front and back of the forging step, necessary heat treatment can be performed without generating blisters on the forging member.

According to the fifteenth invention of the present application, basically the same effects as in the fourteenth invention can be achieved. In particular, by performing a solution solution and an age hardening process that are related to each other before and after the forging step, necessary heat treatment can be performed without generating blisters on the forging member.

Moreover, according to the 16th invention of this application, the effect similar to the said 15th invention can be basically worked. In particular, since the heat treatment temperature of the aging hardening treatment is 100 ° C. or more, aging hardening can be effectively generated for the forging member.

According to the seventeenth invention of the present application, basically the same effects as those of the sixteenth invention can be achieved. Particularly, with respect to the heat treatment temperature of the aging hardening treatment, it is 100 ° C. or higher and 250 ° C. or lower, so that aging hardening can be effectively generated for the forged member, or both the tensile strength and the elongation are balanced in an appropriate range by preventing overaging. You can get it by In addition, since the heat treatment time of the aging hardening treatment is set to 3 hours or more and 24 hours or less, the effective aging hardening can be generated for the forging member, and the effect is not saturated and it is not economical.

Claims (17)

As a manufacturing method of a light metal forging material which is supplied as a material to forging processing to obtain a light metal forging member, The forging material is formed by filling the molten metal molten metal into a molding cavity of a predetermined molding mold, and prior to forging, a predetermined heat treatment is performed on the forging material, thereby blistering due to expansion of the internal gas in the material. Method for producing a light metal forging material, characterized in that for generating. The method for manufacturing a light metal forging material according to claim 1, wherein the predetermined heat treatment is a solution treatment. The method for manufacturing a light metal forging material according to claim 2, wherein the heat treatment temperature of the solution treatment is 300 ° C or more. The method for manufacturing a light metal forging material according to claim 2, wherein the heat treatment time of the solution treatment is 1 hour or more. The method for producing a hard metal forging material according to claim 2, wherein the solution treatment is performed under treatment conditions in which the heat treatment temperature is 350 ° C or more and 450 ° C or less, and the heat treatment time is 10 hours or more and 24 hours or less. Way. The method for manufacturing a light metal forging material according to claim 1, wherein the relative density after said predetermined heat treatment is set to be 90% or more. The method for manufacturing a hard metal forging material according to claim 6, wherein the relative fineness after said predetermined heat treatment is set to be 95% or more. The method for manufacturing a light metal forging material according to claim 1, wherein the forging material is formed by filling a light metal molten metal into a molding cavity of a predetermined molding mold in a semi-molten state. The method for manufacturing a light metal forging material according to claim 1, wherein the forging material is formed by injection-molding light metal molten metal into a molding cavity of a predetermined molding mold. The method for manufacturing a light metal forging material according to claim 1, wherein the light metal is a magnesium alloy containing 4% by weight or more of aluminum. A forging member manufacturing method for forging a light metal forging material according to any one of claims 1 to 10, and crushing the blister contained in the forging material. 12. The method for manufacturing a forging member according to claim 11, wherein the light metal forging material is heated in the predetermined heat treatment and then subjected to forging without undergoing a cooling step. 12. The method for manufacturing a forging member according to claim 11, wherein after the forging, the second heat treatment is performed at a temperature lower than the heating temperature in the predetermined heat treatment. The method for manufacturing a forging member according to claim 13, wherein the second heat treatment is a heat treatment related to the predetermined heat treatment. The forging member manufacturing method according to claim 14, wherein the predetermined heat treatment is a solution treatment and the second heat treatment is an aging hardening point. The method of manufacturing a forging member according to claim 15, wherein the heat treatment temperature of the aging hardening treatment is 100 ° C or more. 17. The method for manufacturing a forging member according to claim 16, wherein the aging hardening treatment is performed under treatment conditions of a heat treatment temperature of 100 占 폚 or more and 250 占 폚 or less, and a heat treatment time of 3 hours or more and 24 hours or less.