JP5756091B2 - Method for producing aluminum alloy forged member - Google Patents

Description

  The present invention relates to a method for producing an aluminum alloy forged member produced by forging a forged material made of an aluminum alloy to produce a forged member, and a related technique.

 From the viewpoint of weight reduction and the like, a tendency to use a forged member (forged product) made of an aluminum alloy as an undercarriage member for automobiles is increasing. Al-Mg-Si alloys are often used as alloy materials for such structural aluminum alloy forged members.

  As shown in Non-Patent Document 1 below, in JIS6061 alloy, which is generally used as an Al—Mg—Si alloy, the material temperature is set to a relatively high temperature of 435 to 480 ° C., giving priority to workability during forging. It is customary to forge.

  In addition, as shown in Non-Patent Document 2 below, as an improved Al-Mg-Si alloy in recent years, an alloy whose strength is improved by suppressing recrystallization during forging (hereinafter referred to as "6000 series high-strength"). "Strength material" has been developed. In order to avoid recrystallization, this alloy is forged at a higher temperature than a general 6061 alloy.

Light metal Vol11, No. 12, P741-758 “Forging of aluminum” Kobe Steel Engineering Reports Vol55, No. 3 "High-strength aluminum alloy for automobile suspension"

  However, as shown in Non-Patent Document 1, when a JIS6061 alloy is forged at 435 to 480 ° C., the forging member has a different processing rate for each part depending on its shape, so that the structure state differs depending on each part. End up. For example, an unrecrystallized structure part, a fine recrystallized structure part, and a coarse recrystallized structure part are mixed in one forged member. Thus, if the structure state is different for each part, mechanical characteristics (mechanical strength) such as tensile characteristics (tensile strength) are different for each part, resulting in a forged product having a large variation in mechanical characteristics. . For this reason, the mechanical property value that can be guaranteed as a forged product must be set to a value that is significantly lower than the standard test value, and in order to satisfy the guaranteed value of the mechanical property required for structural materials. It is necessary to increase the thickness of the member. As a result, the weight of the forged member is increased, and the weight reduction as the intended purpose is hindered.

  Here, in this specification, the non-recrystallized structure is a structure in a state where crystallized matter generated in the final solidified portion is present on the crystal grain boundary in a state where crystal grains at the time of casting are maintained.

  Furthermore, the coarse recrystallized structure is a state in which recrystallization occurs with the strain applied by plastic working as a driving force, and the crystal grain size after recrystallization is larger than the crystal grain size during casting. It is.

  Furthermore, the fine recrystallized structure is a state in which recrystallization occurs with the strain applied by plastic working as the driving force, and the crystal grain size after recrystallization is approximately the same as the crystal grain size during casting. It is an organization that has become or has become smaller.

  On the other hand, the 6000 series high-strength material shown in Non-Patent Document 2 can suppress recrystallization in almost the entire area of the forged member in a normal forging process, and also suppress variation in mechanical strength at each part. Can do. However, if a thin-walled forged member is formed in order to reduce the weight, the forging rate will be higher, and the heat dissipation from the forging material during forging will also increase at the thin-walled portion. The temperature decreases and recrystallization easily occurs. For this reason, even in the 6000 series high-strength material, when trying to manufacture a forged member having a thin shape and a high processing rate, the forged member contains an unrecrystallized structure, a coarse recrystallized structure, and a fine recrystallized structure. Therefore, it becomes difficult to obtain an excellent forged product due to the variation in mechanical characteristics. As a result, even if a 6000 series high-strength material is used, it is difficult to reduce the weight as in the case of using the JIS6061 alloy.

  The preferred embodiment of the present invention has been made in view of the above and / or other problems in the related art. Preferred embodiments of the present invention can significantly improve existing methods and / or apparatus.

  The present invention has been made in view of the above problems, and a method for producing an aluminum alloy forged member capable of producing a forged member capable of reducing the variation in mechanical properties of each part while reducing the weight, and the method thereof The purpose is to provide related technology.

  Other objects and advantages of the present invention will be apparent from the following preferred embodiments.

  In the technical field of forging, as described above, it has become common technical knowledge to improve the mechanical characteristics of a forged member by suppressing recrystallization as much as possible. Under such a technical background, the present inventor tried to solve the above problem from a viewpoint different from the suppression of recrystallization.

  And while this inventor performs experiment and research, in each site | part of a forged member (forged product), the area | region more than predetermined is made into a fine recrystallized structure state, The machine for every site | part in a forged member It was found that the variation in the mechanical characteristics can be suppressed to a small value, and that the above problems can be solved.

  Furthermore, the present inventor conducted experiments and research on the generation behavior of recrystallization during forging, and can control the generation behavior of recrystallization based on the alloy composition of the forging material and the material temperature during forging. I found out.

  The inventor has found a configuration capable of solving the above-mentioned problems by accurately controlling the occurrence of recrystallization in the forging process and increasing the region of the fine recrystallization structure in the forged member. It came to make.

  That is, the present invention comprises the following means.

[1] 0.35 to 1.2% by mass of Mg, 0.2 to 1.3% by mass of Si, 0.5% by mass or less of Cu, 0.15% by mass or more of Fe and 0.05% of Cr Preparation of an aluminum alloy forging material having a composition comprising at least mass%, 0.05% by mass or less of Mn, and the balance consisting of Al and inevitable impurities,
Forging material temperature (° C.) ≦ −260 (° C.) × [total content of Fe, Cr, Mn (mass%)] + 440 (° C.) Hot forging with respect to the aluminum alloy material under the temperature condition satisfying the relational expression A method for producing an aluminum alloy forged member characterized by comprising the steps of:

  [2] The method for producing an aluminum alloy forged member as recited in the aforementioned Item 1, wherein the [total content of Fe, Cr, Mn (mass%)] is adjusted to 0.5 mass% or less.

[3] Before performing the hot forging, the equivalent strain for each part is calculated based on the shape of the forged member to be manufactured and the forging material, and all the equivalent strain for each part is included. The equivalent distortion range of
From the entire equivalent strain range, based on the information for associating the forging material temperature prepared in advance and the equivalent strain range, the upper limit value of the forging material temperature is calculated,
3. The method for producing an aluminum alloy forged member according to item 1 or 2, wherein the upper limit of the total content of Fe, Cr, and Mn is specified from the upper limit value of the forging material temperature based on the relational expression.

[4] Before performing the hot forging, the total content of the Fe, Cr, Mn is calculated based on the composition of the forging material, and the forging material temperature is calculated from the total content based on the relational expression. Find the upper limit,
From the upper limit value of the obtained forging material temperature, based on information relating the forging material temperature prepared in advance and the range of the equivalent strain, the entire equivalent strain range allowed in the forging process is obtained,
3. The method for producing an aluminum alloy forged member according to item 1 or 2, wherein the forged material and the shape of the forged member are designed within the allowable range of equivalent strain.

[5] 0.35 to 1.2% by mass of Mg, 0.2 to 1.3% by mass of Si, 0.5% by mass or less of Cu, 0.15% by mass or more of Fe, and 0.05% of Cr An aluminum alloy forged member having a composition comprising at least mass% (preferably at least 0.15 mass%), 0.05 mass% or less of Mn, and the balance consisting of Al and inevitable impurities,
An aluminum alloy forged member characterized in that a region of 50% or more is adjusted to a state of a fine recrystallized structure and has a tensile strength value exceeding 250 MPa.

  [6] The aluminum alloy forged member according to item 5 above, wherein a region of 50% or more in each part is adjusted to a state of a fine recrystallized structure.

  [7] The aluminum alloy forged member according to item 5 or 6 above, wherein the variation in tensile strength at each part is adjusted within ± 5% with respect to the tensile strength without plastic working.

  [8] An automotive structural material comprising an aluminum alloy forged member manufactured by the manufacturing method according to any one of [1] to [4].

  According to the method for producing an aluminum alloy forged member of the invention [1], the occurrence of recrystallization during forging can be controlled, and a forged member having a predetermined many regions in a fine recrystallized structure can be obtained. As a result, a forged member that is lightweight and excellent in mechanical properties can be obtained.

  Further, according to the present invention, it is not necessary to make the material temperature at the time of forging so high, so that energy saving can be achieved.

  In addition, this invention can be used suitably when manufacturing the forge member 10 of the special shape which has a thin part and a thick part as shown, for example in FIG.

  The forged member 10 includes cylindrical portions 13 and 13 at both ends and a connecting portion 14 that connects both the cylindrical portions 13 and 13. The connecting portion 14 has a meat stealing portion 15, and the meat stealing portion 15 is configured as a thin portion 12 having a smaller thickness than the surrounding thick portion 11. Furthermore, the cylindrical parts 13 and 13 are comprised as the thin parts 12 and 12 where the surrounding body part has small thickness.

  In the present invention, for example, the thickness of the thin portion 12 is 10 mm or less, preferably 10 mm to 3 mm, and the thickness of the thick portion 11 is set to 4 times or more, preferably 4 to 10 times the thickness of the thin portion. It is preferable. Further, for example, in the state of plan view (single side view) when the forged member 10 of FIG. 1 is viewed from above, the ratio (%) of the area of the thin portion 12 to the area of the entire plane is 20 to 20%. It is preferably set to 70%.

  In particular, the present invention can suitably produce a forged member as an automotive structural material having a thin portion having a thickness of 10 mm or less and having a fine crystal structure region of 95% or more in the thin portion.

  Examples of the automobile parts constituted by the forged member having such a shape include an upper arm in a front suspension having a wishbone structure and a toe control arm in a rear suspension having a multi-link structure.

 Needless to say, the present invention is not limited to these automobile parts and the shapes shown in FIG. Further, the present invention is not limited to the above-described preferred range indicated by numerical values.

  According to the method for producing an aluminum alloy forged member of the invention [2] to [4], the above effect can be obtained more reliably.

  The aluminum alloy forged member of the invention [5] is lightweight and has excellent mechanical properties.

  According to the aluminum alloy forged member of the inventions [6] and [7], the mechanical properties can be further improved because the variation in mechanical properties of each part is small.

  The automobile structural material of the invention [8] is lightweight and has excellent mechanical properties.

FIG. 1 is a perspective view showing an example of a forged member that can be manufactured by the manufacturing method of the present invention. FIG. 2 is a graph showing the crystal structure state of the forged member under the relationship between the forging material temperature and the equivalent strain. FIG. 3 is a graph showing the relationship between the forging material temperature and the total content of Fe, Cr, and Mn in the examples of the present invention. FIG. 4 is a graph showing the relationship between the processing rate and equivalent strain in forging. FIG. 5 is a block diagram showing a procedure for manufacturing a forged member according to an embodiment of the present invention. FIG. 6 is a perspective view showing a disk sample for confirming the alloy composition used in the embodiment of the present invention. FIG. 7 is a graph showing the relationship between the center equivalent strain value (relative value) and the fine recrystallization region range in the forged member.

 In the method for producing an aluminum alloy forged member according to an embodiment of the present invention, the forging material is made of an Al—Mg—Si alloy. And in this embodiment, the forge member (forged product) which can solve said subject is obtained by specifying the alloy composition of this forge raw material, and the raw material temperature of a forge raw material.

  In this embodiment, the forging material is 0.35 to 1.2% by mass of Mg, 0.2 to 1.3% by mass of Si, 0.5% by mass or less of Cu, and 0.15% by mass or more of Fe. The alloy composition contains 0.15% by mass or more of Cr, 0.05% by mass or less of Mn, and the balance of Al and inevitable impurities.

In the present embodiment, Mg coexists with Si to form an Mg ₂ Si-based precipitate and contribute to improving the strength of the forged member (final product). Therefore, Mg needs to be contained.

  The Mg content needs to be adjusted to 0.35 to 1.2% by mass, preferably 0.8 to 1.2% by mass.

  When the content of Mg is too small, the effect of strengthening due to the formation of precipitates is reduced, which is not preferable. On the other hand, when the content of Mg is too large, workability (plastic workability) during forging is reduced and the toughness of the final product is lowered, which is not preferable.

As described above, Si coexists with Mg to form a Mg ₂ Si-based precipitate and contribute to improving the strength of the final product. Therefore, Si needs to be contained.

  The content of Si needs to be adjusted to 0.2 to 1.3% by mass, preferably 0.7 to 0.9% by mass.

If the Si content is too small, the effect of strengthening due to the formation of precipitates is reduced, which is not preferable. On the other hand, when the Si content is too large, grain boundary precipitation of Si increases, so that grain boundary embrittlement is likely to occur, and there is a risk of reducing the forging processability of the ingot and the toughness of the final product. In addition, Si can further increase the strength of the final product after the aging treatment by adding an excessive amount exceeding the amount sufficient to produce Mg ₂ Si-based precipitates.

Cu increases the supersaturation of apparent Mg 2 _Si based precipitate, by increasing the Mg 2 _Si based precipitate, in order to significantly accelerate the age hardening of a final product, preferably contained.

  It is necessary to adjust the Cu content to 0.5% by mass or less, and preferably 0.3 to 0.5% by mass.

  When there is too much content of Cu, since the workability at the time of a forging process and the toughness of a final product are reduced, and also corrosion resistance is deteriorated, it is not preferable.

  By the way, in this embodiment, each part of the forged member is not a simple recrystallized structure, but a region of 50% or more (preferably all) for each part is in a fine recrystallized state. It is possible to sufficiently suppress variations in mechanical properties.

  Furthermore, the behavior of recrystallization during forging is a non-recrystallized structure when the amount of equivalent strain described below is small, with the composition of the forging material and the material temperature being constant, and coarse recrystallization occurs as the amount of equivalent strain increases. A crystal structure is formed, and when the amount of considerable strain is further increased, a fine recrystallized structure is changed.

  Here, the non-recrystallized structure, the coarse recrystallized structure, and the fine recrystallized structure are as described in the above-mentioned [Summary of the Invention] section.

  That is, the non-recrystallized structure is a state that is not changed from the crystal structure at the time of casting. For example, the average crystal grain size is 50 to 300 μm.

Furthermore, the coarse recrystallized structure is a structure in a state where the crystal grain size after recrystallization is larger than the crystal grain size at the time of casting. For example, it can be expressed as “average crystal grain size after recrystallization” = M × “average crystal grain size at casting” (M = 10 to 100). Further, the fine recrystallized structure is the crystal grain size after recrystallization. Is a structure in which the grain size is smaller than the crystal grain size during casting. For example, it can be expressed as “average crystal grain size after recrystallization” = N × “average crystal grain size during casting” (N = 0.05 to 10).

  The average particle diameter can be obtained by a section method from an image obtained by observing the crystal structure with a microscope by a conventional method, for example, the following procedure.

  First, a microphotograph of the cross-sectional structure of the forged product is taken at a magnification of 100 times, and straight lines of “L1” and “L2” are drawn arbitrarily on the vertical and horizontal lengths on this photo, respectively.

  Next, the number of grain boundaries existing in the form of intersecting the straight lines of the lengths “L1” and “L2” is counted as “n1” and “n2”, respectively, and the average particle diameter is calculated by the following mathematical formula (1). The average grain size of the crystal grains obtained from the microphotograph is obtained. The average particle size can be obtained without depending on the lengths of “L1” and “L2”.

  Average particle size = (L1 + L2) / (n1 + n2) (1)

  On the other hand, in the forged member, the state of the recrystallized structure of the forged member in the relationship between the equivalent strain amount and the forging heating temperature is the state shown in the graph of FIG. In the figure, the horizontal axis indicates the equivalent strain, and the vertical axis indicates the forging heating temperature (forging material temperature). Furthermore, black diamonds in the figure indicate an uncrystallized structure state, black circles indicate a coarse recrystallized structure state, and black square marks indicate a fine recrystallized structure state.

  As shown in the figure, when the range of the equivalent strain value is assumed, when the forging heating temperature is high, the proportion of the unrecrystallized state is large, and as the forging heating temperature is lowered, the proportion of the coarse recrystallized state is As the forging heating temperature increases and the forging heating temperature decreases, the proportion of the fine recrystallized state increases. That is, the non-recrystallized state, the coarse recrystallized state, the fine recrystallized state, and the texture state change from the upper left to the lower right in the figure. Further, in FIG. 2, the boundary between the coarse recrystallized structure region and the fine recrystallized structure region can be represented by a substantially straight line (boundary line E1), and the upper left region from the boundary line E1 is an amorphous structure region and / or It is a coarse recrystallized texture region, and the lower right region is a fine recrystallized texture region.

  In the present invention, based on the graph of FIG. 2, for example, the recrystallization occurrence behavior during forging is controlled as follows, and the fine recrystallized structure region in the forged member is 50% or more, preferably 90%. It can adjust to the above.

  (1) When the forging material is forged into a forged product shape, the processing rate of each part is obtained, or the equivalent strain of each part is obtained directly, and from there, the range of the processing rate of the forged member as a whole with respect to the forging material Alternatively, the equivalent distortion range K (see FIG. 2) is obtained. The equivalent distortion of each part can be obtained by simulation as will be described later. As shown in FIG. 4, the processing rate and the equivalent strain have a monotonically increasing correlation. For reference, the linear equation of the approximate straight line of the graph plot in the figure is represented by [y: processing rate] = 41.786 × [x: equivalent strain] −1.3857.

  (2) As shown in FIG. 2, when the forging material temperature is set to “Ta”, the entire strain range K is an upper left region from the boundary line E1, that is, a coarse recrystallized structure region.

  (3) When the forging material temperature is lowered to “Tb”, the region at the lower right of the boundary line E1, that is, the fine recrystallized structure region can be obtained in the entire range K of the equivalent strain.

  (4) When the forging material temperature is set, for example, within the range of “Ta” to “Tb”, the boundary line E1 is straddled in the equivalent strain range K at any temperature within the range. When viewed as the entire forged member having the equivalent strain value range of “K”, the coarse recrystallized structure region and the fine recrystallized structure region are mixed.

  (5) For example, in FIG. 2, if the forging material temperature is set to “Tc” within the range of “Ta” to “Tb”, the coarse recrystallized structure region in the forged member at the set temperature Tc, The average ratio (ratio) to the crystal structure region is the ratio (Kb /%) between the coarse recrystallized structure region range Ka and the fine recrystallized structure region range Kb in the equivalent strain range K at the set temperature Tc. Approximately equal to Ka). Therefore, the forging material temperature can be set by calculating backward from the desired ratio (Kb / Ka). That is, in order to obtain a forged member in a desired mixed state, for example, a state in which the fine recrystallized structure region is 50%, a desired ratio corresponding to the desired mixed state in the entire range K of the equivalent strain or the entire range of the processing rate. What is necessary is just to set a forge raw material temperature so that it may become (Kb / Ka).

  (6) More specifically, as shown in FIG. 2, the linear equation of the boundary line E1 between the coarse recrystallized structure region and the fine recrystallized structure region is forging material heating temperature [° C.] = 85.7 × target equivalent It can be expressed as strain [%] + 263.6. Therefore, of the entire range K of the equivalent strain, the boundary position between “Ka” and “Kb” when the range Ka of the coarse recrystallized structure region and the range Kb of the fine recrystallized structure region have a desired ratio. The strain value Kc is obtained, the equivalent strain value Kc at the boundary position is set as the target equivalent strain, and the forging material heating temperature is calculated by applying it to the linear equation of the boundary line E1, and the temperature is set as the forging material temperature during forging. Just do it.

  Here, when the distribution of the equivalent strain value is not uniform and the bias is large in the entire forged member (for example, when only one part has a high processing rate and many other parts have a low processing rate), for example, As shown in the methods (a) to (c), it is more preferable that Ka and Kb are corrected using a distribution function of equivalent strain values so that Kc becomes a predetermined value.

  (A) A distribution function f (equivalent strain value) of the equivalent strain value of the entire forged member is obtained, and f (equivalent strain value) is integrated from the minimum value to the Kc value as “Ka”, and f (equivalent strain) Kc value is determined so that Kb / Ka is equal to or greater than a desired value when “Kb” is obtained by integrating the value) from the Kc value to the maximum value. Forging raw material heating temperature can be calculated | required from the Kc value using the linear type | formula of the said boundary line E1, for example.

  (B) The necessity of correction may be determined based on whether the distribution can be regarded as uniform or whether accuracy is required. Incidentally, when no correction is made, the distribution function f (equivalent distortion value) = 1, and the distribution becomes uniform and the above-described simplified type.

  (C) The equivalent strain distribution function of the entire forged member may be obtained by sampling an appropriate portion to obtain an equivalent strain value, and then obtaining the distribution function.

  It is preferable to design with correction as described above because the accuracy of the value of the region is improved.

  Further, the values of the vertical axis and the horizontal axis of the graph of FIG. 2 can be applied as they are within a slight difference range where the amounts of Fe, Cr, and Mn are about 0.01% by mass, respectively. When the mass% is increased, an upset product is created using the alloy, a cross-sectional macroscopic structure is observed, and a recrystallized state is observed to create a graph similar to FIG. The above-mentioned setting concept can be applied using a graph.

  By the way, in each part of the forged member, if the mixed state of the non-recrystallized structure, the fine recrystallized structure and the coarse recrystallized structure is different, the mechanical characteristics will be different for each part. It becomes difficult to obtain a forged product.

  Therefore, it is possible to manufacture a forged member having a small variation in mechanical properties for each part by controlling the occurrence of recrystallization in the entire forging material in the forging process and increasing the region of the fine recrystallization structure. It becomes possible.

  Therefore, in the present embodiment, as described below, a desired forged member is manufactured by controlling the generation behavior of recrystallization during forging.

  First, there are Fe, Cr, and Mn as components (elements) that are largely involved in the recrystallization occurrence behavior during forging. Fe, Cr, and Mn are contained as inevitable impurities in a forged material made of an Al—Mg—Si alloy.

  In this embodiment, when the content of Fe, Cr, and Mn is small, recrystallization easily occurs. Therefore, in order to promote recrystallization, the total content (% by mass) of Fe, Cr, and Mn should be adjusted to 0.5% by mass or less, preferably 0.3 to 0.5% by mass. It is good to adjust.

  In addition, when there is much mixing amount as an unavoidable impurity, it can adjust to the target range by adding aluminum to the molten metal for casting, for example.

  Moreover, in this embodiment, it is necessary to adjust Fe to 0.15 mass% or more, Preferably it is good to adjust to 0.2-0.3 mass%.

  Moreover, it is necessary to adjust Cr to 0.05 mass% or more, Preferably it is good to adjust to 0.05-0.2 mass%.

  Furthermore, it is necessary to adjust Mn to 0.05 mass% or less. Note that the content of Mn is 0%, that is, Mn may not be contained.

  If the total content of these elements (Fe, Cr, Mn) is too large, recrystallization at the forging process does not proceed sufficiently, and the region of the fine recrystallized structure may not be sufficiently secured. Therefore, it is not preferable.

  If the total content is too large and the added amount exceeds 0.5% by mass, a crystallized product may be generated depending on the balance of Fe, Cr, and Mn, and this does not affect the action of recrystallization. This is not preferable because it may be sufficient and the toughness may be simply impaired.

  Accordingly, in order to sufficiently secure the region of the fine recrystallized structure, the content is preferably 0.5% by mass or less.

  In the present embodiment, as will be understood from the examples described later, the following relational expression needs to be satisfied with respect to the material temperature of the forging material (forging material temperature) during forging.

Forging material temperature (° C.) ≦ −260 (° C.) × [total content of Fe, Cr, Mn (mass%)] + 440 (° C.)
In other words, by adjusting the forging material temperature within the above specific range, sufficient strain as a driving force for recrystallization is introduced during plastic processing during forging, and recrystallization proceeds sufficiently, and in the thick part In addition, a forged member having a preferable fine recrystallized structure can be obtained with certainty.

  Therefore, in this embodiment, by setting the material temperature of the forging material to a temperature corresponding to the content of Fe, Cr, Mn and forging the forging material, fine recrystallization is performed throughout the forged member. Thus, a forged member (forged product) with less variation in mechanical properties between the respective parts can be produced.

  Next, some examples of specific design procedures will be described in carrying out the manufacturing method of the present invention. In addition, as described in detail below, the present invention is a method for manufacturing a forged member using a predetermined shape, composition, and forging material temperature condition in accordance with these design procedures.

<Design procedure 1>
The design procedure 1 includes the following steps S11 to S15, and is a procedure for determining an optimal composition and the like from the shape of the product (forged member).

  Step S11: When each shape of the forged material to be used and the forged product (forged member) to be manufactured is given, the equivalent strain at each part is formed from the forged material shape to the forged product shape. Obtained by simulating the process. An example of software used in this simulation is forging analysis software “DEFFORM”.

  Step S12: The equivalent strain range including all the equivalent strains of the respective parts, that is, the equivalent strain range of the entire forged member is obtained, and the range is set as the equivalent strain range on FIG. In the present invention, the graph of FIG. 2 is used as information associating the forging material temperature prepared in advance with the range of the equivalent strain.

  Step S13: A ratio of a desired fine recrystallization region range, for example, 50%, is set for the entire molded product (forged member) within the set equivalent strain range, and the equivalent strain (target equivalent strain) corresponding to the ratio is set in FIG. The upper limit value of the forging heating temperature is obtained from the target equivalent strain based on the graph of FIG.

 Step S14: When the upper limit value of the forging heating temperature is determined, the upper limit of the total amount of (Fe, Cr, Mn) is obtained from the temperature using the graph of FIG. The graph of FIG. 3 is a graph showing the relationship between the forging material temperature (forging heating temperature) and the total content of Fe, Cr, and Mn, and details thereof will be described later.

  Step S15: The alloy composition and the forging material temperature condition are obtained by the above procedure.

<Design procedure 2>
The design procedure 2 includes the following steps S21 to S25, and is a procedure for determining an optimum shape from the composition.

  Step S21: When the material to be used is given, the total amount of (Fe, Cr, Mn) is obtained from the composition of the material.

  Step S22: The upper limit of the forging material temperature is obtained from the total amount of (Fe, Cr, Mn) using the graph of FIG.

  Step S23: The obtained upper limit of the forging material temperature is set as the forging material temperature on the vertical axis of the graph of FIG. In the present invention, the graph of FIG. 2 is used as information associating the forging material temperature prepared in advance with the range of the equivalent strain.

  Step S24: Based on the graph of FIG. 2, at the set forging material temperature, a predetermined fine recrystallization region range as a whole molded product (forged member), for example, an equivalent strain range satisfying 50% is obtained, and the range is determined. Allowable equivalent strain range. Specifically, based on the graph of FIG. 2, the target equivalent strain corresponding to the set forging material temperature is obtained, and from the target equivalent strain value to the strain value small side, the large side (the strain axis lateral direction in the figure), The equivalent strain range (Ka, Kb) is determined so that Kb / Ka is, for example, 50% or more.

  Step S25: The forging material and the shape of the forged (forged member) are designed within the allowable equivalent strain range.

<Design procedure 3>
The design procedure 3 includes the following steps S16 to S19 in addition to the design procedure 1 (steps S11 to S15), and is obtained by adding a fine adjustment loop to the setting procedure 1.

  Steps S11 to S15: As described in the design procedure 1 above.

  Step S16: The recrystallized state of the product (forged member) manufactured using the alloy composition and the forging material temperature condition obtained in steps S11 to S15 is evaluated by macro structure observation.

  Step S17: The relationship between the obtained recrystallization state and the forging load is evaluated, and a forging load that can secure a predetermined fine recrystallization region range (for example, 50%) is used for the forging process based on the evaluation result. If it is necessary to make the value larger than the maximum load capacity value of the forging machine (preferably 80% of the maximum load capacity value) (if fine adjustment is necessary), the process returns to step S14 and the total amount of Fe, Cr, Mn Review the ingredients so that there is less.

  Step S18: The relationship between the obtained recrystallization state and the forging load is evaluated, and a forging load that can secure a predetermined fine recrystallization region range (for example, 50%) is used for the forging process based on the evaluation result. If there is a margin for the maximum load capacity value of the forging machine (preferably 80% of the maximum load capacity value) (if fine adjustment is required), the process returns to step S13 and the forging temperature is lowered. Review material temperature.

  Step S19: If there is no need for fine adjustment in steps S17 and S18, the setting procedure is terminated.

  In the present embodiment, it is preferable that the lower limit of the forging material temperature is determined by a load at the time of forging forming. For example, lowering the material temperature during forging increases the load during molding, but the material temperature when the load matches the maximum load capacity value of the forging machine (preferably 80% of the maximum load capacity value) is the lower limit temperature. can do. More preferably, “(−260 (° C.) × [total content of Fe, Cr, Mn (mass%)] + 440 (° C.)) − 60 ° C.” is set as the lower limit temperature of the material temperature.

  Needless to say, in the present embodiment, other elements are added for the purpose of precipitation strengthening within a range in which the object of the present invention can be achieved, for example, within a range not affecting the generation behavior of recrystallization. Also good.

  Here, in this embodiment, the equivalent strain amount is defined by a physical quantity ε equivalent to the forging rate. As described above, the equivalent strain amount and the forging rate are correlated, as shown in FIG. Specifically, it can be expressed by the equivalent strain amount = α × forging rate + β (α: 0.41-0.42, β: 1.2-1.5).

  The equivalent strain amount “ε” can be obtained based on the following relational expression.

dε = [(2/9) {(dε _x −dε _y ) ² + (dε _y −dε _z ) ² + (dε _z −dε _x ) ² + (3/2) (dγ _xy ² + dγ _yz ² + dγ _zx ² )}] ^1/2
ε = ∫dε (integral along history)
However,
ε _x : stretch strain in X direction ε _y : stretch strain in Y direction ε _z : stretch strain in Z direction γ _xy : shear strain in XY plane γ _yz : shear strain in YZ plane γ _zx : in ZX plane Shear strain at

  As a reference for the equivalent strain, “Corporation Processing Handbook” P1077 edited by the Japan Society for Technology of Plasticity “P1077” can be exemplified.

  In this embodiment, in order to set the actual forging material temperature to the above-mentioned specific material temperature condition (target forging material temperature), a method of sequentially performing the following processes (1) to (4) is preferable. Can be adopted.

  (1) The temperature decrease rate when the forging material is taken out from the heating furnace is determined (temperature decrease rate calculation process).

  (2) The forging material is heated in the heating furnace based on the time until the forging material heated to the target forging material temperature is taken out of the heating furnace and forged, and the temperature reduction rate calculated in the temperature reduction rate calculation process. The temperature drop width from when it is taken out to forging is obtained (temperature drop width calculation process).

  (3) When the forging material is put into the forging die, the forging material is preheated at a temperature obtained by adding the temperature reduction width calculated in the temperature reduction width calculation process to the actual forging material temperature ( Preheating treatment).

  (4) In order to prevent a temperature drop during forging, a forging die is heated by being provided with a heating device (heat treatment by the die). It is desirable to set the mold temperature as close to the target forging material temperature as possible. However, if the temperature is too high, the effect of the lubricant during forging will be impaired, so the specified temperature range of the lubricant used. It should be set according to the upper limit of.

  In the present embodiment, it is not always necessary to perform all the processes (1) to (4), and the forging materials can be appropriately combined so as to satisfy the above-described relational expression. For example, the process (1) to (3) may be sequentially performed by omitting the process (4), or the process (1), (2), and (4) may be performed by omitting the process (3). May be performed sequentially.

  As illustrated in FIG. 5, in the method for manufacturing a forged member of the present embodiment, a casting process, a soaking process, a forging process (hot forging process), and a post-forging process are performed in this order, and forging is performed. A member (forged product) is manufactured.

  The casting process is a process for obtaining a forged material. That is, in this embodiment, the forging material which consists of said composition is obtained by the continuous casting method. As the continuous casting method, a casting method such as a hot top vertical continuous casting method, a gas pressure type hot top vertical continuous casting method, a horizontal continuous casting method, or the like can be suitably used. The casting speed is preferably as high as possible (for example, 200 to 1000 mm / min) within a range in which ingot breakage does not occur from the viewpoint of refinement of the ingot structure.

  In the soaking process, soaking is performed on the casting rod as the forging material. In other words, the cast rod obtained in the casting process has a coarse Fe-Cr-Mn precipitate in order to remove microsegregation and prevent the movement of grain boundaries during recrystallization and maintain a fine recrystallized structure. A soaking process is performed for the purpose of achieving the above. The soaking condition is to hold the cast bar at, for example, 570 to 550 ° C. for 4 to 10 hours.

  In the forging process, forging (processing) can be performed using a known forging apparatus (forging machine) under known forging conditions from the past, except for the conditions specific to the present application such as the material components and temperature conditions described above. .

  The forging material is subjected to peripheral cutting and cutting processing to a predetermined length, if necessary, before being put into a die of a forging device. Further, the forging material and the forging die are subjected to a lubricant coating treatment as necessary.

  In the post-forging treatment step, solution treatment, quenching treatment, and aging treatment can be performed as necessary, for example, for the purpose of improving strength. The solution treatment conditions are to hold the forged member (forged product) at 525 to 570 ° C., for example, 560 ° C., and for 0.5 to 3 hours, for example, 4 hours after the forged member reaches the target temperature. The quenching treatment conditions are such that the forged member is hot-quenched at 60 ° C., for example. Under these quenching conditions, the temperature should be as low as possible (5 to 25 ° C.) for improving the characteristics, and as high as possible (40 to 70 ° C.) for preventing distortion. Aging treatment conditions hold | maintain a forged member at the temperature of 175-185 degreeC for 5.5 to 6.5 hours. For example, the forged member is held at 180 ° C. for 6 hours.

  In this embodiment, the forged member (forged product) obtained through these steps is in a recrystallized structure state depending on the amount of equivalent strain at each part, but at least 50% or more in the equivalent strain at each part. The region is in a fine recrystallized state. Since the region of 50% or more is in the state of fine recrystallized structure, for each part, there is little variation in the mechanical properties, especially the tensile properties with respect to the difference in the plastic working rate, and the structural aluminum alloy forged member with excellent corrosion resistance Become. The forged member obtained by the present embodiment has a tensile strength value exceeding 250 MPa, which is considered preferable. The reason is that if the fine recrystallization region in each part is 50% or more, the crystal grains in the coarse recrystallized region are also refined to some extent, so that the strength of the coarse recrystallized grain region is hardly reduced, and the member cross section This is because the mechanical strength as a whole is improved.

  The aluminum alloy forged member produced according to the present embodiment is small and light, and is excellent in mechanical properties and corrosion resistance. Therefore, it can be a high-strength and lightweight structural material excellent in corrosion resistance. Therefore, the aluminum alloy forged member obtained by the present invention is a structural material for automobiles, for example, an automobile underbody member, an automobile frame member, an automobile bumper member, an automobile steering member, a motorcycle frame member, and a motorcycle steering member. It can be suitably employed for bicycle frame members, bicycle steering members, bicycle crank members, and the like.

  And when the forge member by this invention is applied to the structural material for motor vehicles, it becomes possible to improve the exercise | movement performance and environmental performance of the vehicle in which it is mounted.

  As shown in Table 1, a molten aluminum alloy to which a predetermined metal was added was used to continuously cast a round bar having a diameter of 55 mm using a hot top casting machine, and Al alloys of Examples 1 to 8 and Comparative Examples 1 to 10 Continuous cast round bars corresponding to the composition were prepared. The casting speed was 400 mm / min.

  Before starting continuous casting, each aluminum alloy molten metal is cast into a mold, a disk sample having a shape as shown in FIG. 6 is taken, and each component is analyzed by emission spectroscopic analysis in accordance with JIS H 1305. Each was analyzed, and the alloy composition of the disk sample corresponding to each continuously cast round bar was confirmed.

  Thereafter, the round bar obtained by continuous casting was cut into a standard length and subjected to a homogenization treatment at 560 ° C. for 7 hours. The outer periphery of the continuous cast round bar after the homogenization treatment was cut to a diameter of 50 mm and cut to a length of 60 mm to produce a round bar-like forging material.

  The round bar-shaped forging material thus obtained was preheated at the forging material temperature described in Table 1, and then forged using a conventional forging machine, for example, a knuckle joint press device. At this time, as shown in Table 2, from the side of the round bar, the equivalent strain at the center is 0 (no upset), 0.67, 1.33, 1.67, 2.00, 4.00. In this way, the thickness after installation was changed. These upset products were subjected to a solution treatment at 540 ° C. for 4 hours, followed by quenching in warm water at 60 ° C., and an aging treatment at 180 ° C. for 5 hours. Thereafter, the upsetting product was air-cooled to obtain forged members (samples) of Examples 1 to 8 and Comparative Examples 1 to 10.

  The equivalent strain amount was calculated by simulating the same process as the upsetting process. At this time, the processing rates are 0, 25, 50, 75, 80, and 95%, respectively. The processing rate is defined below.

[Processing rate] = (Material height before installation−Material height after installation) / Material height before installation × 100
About each sample obtained as mentioned above, the JIS14A proportional test piece was extract | collected from the direction parallel to the original raw material longitudinal direction, and the tensile strength was measured.

  And it was determined that there was little variation in tensile strength as an effect of the present invention when the tensile strength value was within ± 5% with respect to the tensile strength of the test piece with equivalent strain of 0. The reason for the determination is that it was considered that the variation in the tensile strength value within ± 5% was caused by factors other than the factor of the present invention (fine recrystallization region).

  The results of these tensile tests are shown in Table 2.

  About the sample of Examples 1-8, since all the requirements of this invention were satisfy | filled, the outstanding characteristic was acquired about tensile strength, and there were also few variations in tensile strength.

  On the other hand, for the samples of Comparative Examples 1 to 10, the forging material temperature condition of the present invention, that is, [forging temperature (° C.)] ≦ −260 × [total content of Fe, Cr, Mn (mass%)] + 440 Since this condition was not satisfied, coarse recrystallization occurred in all or part of the equivalent strain from 0.67 to 4.00, and variations in tensile strength occurred.

  Moreover, about each sample of Examples 1-8 and Comparative Examples 1-10, the structure | tissue state was observed as follows.

  First, the cross section of the sample was mirror-finished with a milling cutter, the processed surface was etched with an aqueous sodium hydroxide solution, the corrosion products were removed with nitric acid, and then dried to reveal a macrostructure. The revealed macrostructure was visually observed to determine the tissue state.

  For samples that have a fine structure and are difficult to discriminate, cut out the sample for micro observation, mirror-polished the observation surface, and electrolytically etched, then observed with a metal microscope with polarizing glass inserted in the optical path. Was determined.

  As a result of the observation, in the structure states of Examples 1 to 8, the fine recrystallized structure state was 50% or more in all the center equivalent strains of 0.67 or more.

  In addition, in the center equivalent strain 0.67 of Example 1, when compared with the central part and the peripheral part in the cross section of the installed product, the equivalent distortion spreads around the center equivalent strain 0.67. The fine recrystallized structure state region in was 65%.

  That is, as a result of observing the macro structure on the cross section of the upsetting product, the fine recrystallization region was 65% within the observation range. Incidentally, the coarse recrystallized region was 25%, and the other part was an unrecrystallized structure.

  In this example, the fine recrystallization region is a structure region having an average particle size of (0.05 to 10) × “crystal average particle size at the time of casting”, and the coarse recrystallization region is (10 × 100) × A structure region of “crystal average grain size at casting”.

  Similarly, in the center equivalent strain 1.33 of Example 1, the fine recrystallized texture region was 90%, and in the center equivalent strain 1.67 or more, the fine recrystallized texture region was 100%.

  Here, the equivalent strain of 0 means that forging is not performed, and at least a processing rate is 25% or more (equivalent strain of 0.67 or more) in an actual forged product.

  FIG. 7 is a graph showing the relationship between the range of the fine recrystallized structure region and the equivalent strain value in the forged member.

  As shown in the graph, in Example 1, when only the equivalent strain is changed at the same composition and the same forging material temperature, the change of the fine recrystallization region range is monotonously increased. For example, it means that the fine recrystallization region range can be 50% or more by setting the center equivalent strain of each part of the forged product to a predetermined value or more. As a result, variation in tensile strength can be reduced as a whole forged product.

  On the other hand, in all or part of the structural states of Comparative Examples 1 to 10, coarse recrystallization occurred.

  In Comparative Examples 1 and 2, since the composition is a JIS6061 alloy and the forging material temperature is high, the recrystallized grains become coarse, the tensile strength decreases as a result of the evaluation, and the tensile strength variation is larger than ± 5%. It has become. Incidentally, Comparative Examples 1 and 2 differ from Example 1 only in the material temperature, and correspond to Example 1 when forging at a lower material temperature.

  Comparative Examples 5 and 6 are high-strength materials having a composition of 6000 series, but because the forging material temperature is low, coarse recrystallization occurs, the tensile strength decreases as a result of the evaluation, and further, the tensile strength variation is ± 5. It is larger than%.

  FIG. 3 is a graph showing the relationship between the forging material temperature (° C.) shown on the vertical axis (Py) and the total content (mass%) of Fe, Cr, and Mn shown on the horizontal axis (Px). In the graph, examples are indicated by black rhombus marks, and comparative examples are indicated by black square marks. Here, the numbers attached to these marks are the numbers of the examples or comparative examples. For example, the black diamonds attached with the numbers “1” are the data of Example 1, and the numbers “3”. The black square mark with “” is data of Comparative Example 3.

  In this graph, when the forging material temperature (° C.) is “Py” and the total content (mass%) of Fe, Cr, and Mn is “Px”, the linear equation is expressed as Py = −260 · Px + 440. A straight line (temperature condition upper limit value).

  As is clear from the graph, the temperature conditions of the samples of Examples 1 to 8 are arranged below Py = −260 × Px + 440, and the temperature conditions of the samples of Comparative Examples 1 to 10 are arranged above. Has been. Accordingly, in Examples 1 to 8 in which the forging material temperature is “−260 ° C. × Px + 440 ° C.” or less, desired good mechanical properties are obtained, whereas the forging material temperature is “−260 ° C. × The thing of Comparative Examples 1-10 exceeding "Px + 440 degreeC" is inferior to a mechanical characteristic.

  In the same manner as described above, using a hot top casting machine, a round bar having a diameter of 55 mm was continuously cast to produce continuous cast round bars corresponding to the Al alloy compositions of Comparative Examples 11 to 15 as shown in Table 3. . The alloy composition was confirmed by taking a sample similar to the above (see FIG. 2) and similarly performing emission spectroscopic analysis.

  Thereafter, the continuous cast round bar was cut into a fixed length in the same manner as described above and subjected to a homogenization treatment at 560 ° C. for 7 hours. The outer periphery of the continuous cast round bar after the homogenization was cut to a diameter of 50 mm and cut to a length of 60 mm to produce a round bar-shaped forging material.

  Thereafter, in the same manner as described above, after preheating at the forging material temperature described in Table 3, forging is performed so that the equivalent strain at the center is 1.33 from the side surface direction of the round bar. It is. These upset products were subjected to a solution treatment at 540 ° C. for 4 hours, followed by quenching in warm water at 60 ° C., aging treatment at 180 ° C. for 5 hours, air cooling, and Comparative Examples 11-15. A forged member (sample) was obtained.

  For the samples of Comparative Examples 11 to 15 and the samples of Examples 1 to 8 (forged members) thus obtained, proportional test pieces were taken from the direction parallel to the original material longitudinal direction in accordance with JIS 14A, and the tensile strength was obtained. Was measured.

  And about the value of the tensile strength of 250 Mpa or less, it determined with not satisfy | filling the requirements as a structural member.

  Further, a 2 mm × 4.3 mm × 42.4 mm test piece was cut out from the sample prepared in the above procedure, and a proof stress was obtained using a three-point bending jig at the center of the 4.3 × 42.4 surface. A stress corresponding to 90% was applied. During the load, the test piece and the jig were electrically insulated. As a corrosive solution, a solution in which 36 g of chromium (IV) oxide, 30 g of potassium dichromate and 3 g of sodium chloride were dissolved per liter of pure water and maintained at 95 to 100 ° C. was prepared. After immersing the stressed test piece in this corrosive solution for 16 hours, the appearance of the test piece is observed, it is checked whether cracks have occurred, and those with cracks are judged to have poor corrosion resistance. did. These test results are shown in Table 4.

  As can be seen from these test results, Examples 1 to 8 satisfied all the requirements of the present invention, and thus were excellent in tensile strength and stress corrosion cracking property.

  On the other hand, since comparative example 11 had too little Si, the precipitation strengthening component decreased and the strength was insufficient.

  Furthermore, in Comparative Example 12, since there was too much Si, the sensitivity to stress corrosion cracking was high, and stress corrosion cracking occurred.

  Furthermore, in Comparative Example 13, since there was too much Cu, the corrosion resistance was lowered, and as a result, stress corrosion cracking occurred.

  Furthermore, in Comparative Example 14, since there was too little Mg, the precipitation strengthening component decreased and the strength was reduced.

  Furthermore, since Comparative Example 15 had too much Mg, coarse recrystallization occurred and the strength was reduced.

  As is clear from the above experimental results (Examples), in Examples 1 to 8 that satisfy the specific alloy composition and the specific temperature condition (Py ≦ −260 × Px + 440 ° C.) as the gist of the present invention, the equivalent strain In the range of 0.67 to 4, that is, the processing rate of 25 to 95, at least 50% or more of each part has a fine recrystallized structure, and as a result, mechanical characteristics (tensile for each part in the forged member. It is possible to produce a forged product that is light in weight and excellent in mechanical properties and corrosion resistance.

<Example based on design procedure 1>
With respect to the shape shown in FIG. 1, the composition and forging material temperature conditions are determined and the forged member is manufactured based on the design procedure 1 described above, as shown in the following steps S11 to S15. Was 60%, and a forged member having sufficient mechanical properties and excellent corrosion resistance was obtained.

  For evaluation of the fine recrystallization region, three test pieces were collected from the thick part and thin part respectively, and the cross section of each test piece was observed for each of five fields of view, and the observation results of 15 points were summed up. The ratio (percentage) of the fine recrystallized region to the whole.

  Step S11: From the forging material to be used and each shape in FIG. 1, the equivalent strain at each part was obtained by simulating the forming process from the forging material shape to the forged product shape (software used in the simulation) Wear is forging analysis software "DEFFORM"). The distribution of relative strain values was 0.7 to 2.0. The distribution of the equivalent strain value was processed as a uniform distribution because it is difficult to obtain the distribution in the actual product exactly.

  Step S12: 0.7 to 2.0 was set as the equivalent strain range in FIG.

  Step S13: The ratio of the fine recrystallization region range is set to 60%, the equivalent strain corresponding to the ratio (target equivalent strain) is set to 1.15 from the graph of FIG. 2, and the upper limit of the forging material heating temperature based on the graph The value was 360 ° C.

  Step S14: Since the upper limit value of the forging heating temperature is 360 ° C., the upper limit of the total amount of (Fe, Cr, Mn) is set to 0.37% from the temperature using the graph of FIG.

  Step S15: By the above procedure, the upper limit of the total amount of the alloy composition (Fe, Cr, Mn) was set to 0.37%, and the forging material temperature condition upper limit was set to 360 ° C.

<Example based on design procedure 2>
With respect to the shape shown in FIG. 1, based on the design procedure 2 described above, as shown in the following steps S21 to S25, the shape and forging material temperature conditions are determined and the forged member is manufactured. A forged member having an area of 60% and having sufficient mechanical properties and excellent corrosion resistance was obtained.

  Step S21: It was decided to use a material having a total amount of (Fe, Cr, Mn) of 0.37% or less.

  Step S22: Using the graph of FIG. 3, the upper limit of the forging material temperature was set to 360 ° C. from the total amount of (Fe, Cr, Mn).

  Step S23: The upper limit 360 ° C. of the obtained forging material temperature was set as the forging material temperature on the vertical axis of the graph of FIG.

  Step S24: The ratio of the fine recrystallization region range is set to 60%, and based on the graph of FIG. 2, at the set forging temperature of 360 ° C., Kb / Ka is equivalent to 60% at the intersection with the formula E1. When the strain range (Ka, Kb) was determined, the lower limit value was 0.7 = Kc−Ka, and the upper limit value was 2.0 = Kb−Kc.

  Step S25: For the shape shown in FIG. 1 (but without the meat stealing part), from the forging material to be used and each shape in FIG. 1, the equivalent strain at each part is changed from the forging material shape to the forged product shape. When the molding process was determined by simulation, the equivalent strain range was 0.5 to 2.0. Since the lower limit is lower than the upper and lower limits obtained in step 24, the shape was changed to increase the lower limit of the equivalent strain value, and a meat stealing portion was provided. As a result, the equivalent strain lower limit value was 0.7, so the final shape was determined.

  Note that. Although it was possible to raise the lower limit of the equivalent strain by changing the shape of the forging material, it was not adopted this time.

  This application is accompanied by the priority claim of Japanese Patent Application No. 2010-95145 filed on Apr. 16, 2010, the disclosure of which constitutes a part of the present application as it is. .

  The terms and expressions used herein are for illustrative purposes and are not to be construed as limiting, but represent any equivalent of the features shown and described herein. It should be recognized that various modifications within the claimed scope of the present invention are permissible.

  While this invention may be embodied in many different forms, this disclosure is to be considered as providing examples of the principles of the invention, which examples are hereby incorporated by reference. Many illustrated embodiments are described herein with the understanding that they are not intended to be limited to the preferred embodiments described and / or illustrated.

  Although several illustrated embodiments of the present invention have been described herein, the present invention is not limited to the various preferred embodiments described herein, and is equivalent to what may be recognized by those skilled in the art based on this disclosure. Any and all embodiments having various elements, modifications, deletions, combinations (eg, combinations of features across the various embodiments), improvements and / or changes are encompassed. Claim limitations should be construed broadly based on the terms used in the claims, and should not be limited to the embodiments described herein or in the process of this application, as such The examples should be construed as non-exclusive.

  The forged member manufacturing method of the present invention is applicable to a forging technique using a forging material made of an aluminum alloy.

10: Forged member

Claims (8)

Mg 0.35 to 1.2% by mass, Si 0.2 to 1.3% by mass, Cu 0.5% by mass or less, Fe 0.15% by mass or more, Cr 0.05% by mass or more In addition, an aluminum alloy forging material having a composition containing 0.05% by mass or less of Mn and the balance of Al and inevitable impurities is prepared,
Forging material temperature (° C.) ≦ −260 (° C.) × [total content of Fe, Cr, Mn (mass%)] + 440 (° C.) Hot forging with respect to the aluminum alloy material under the temperature condition satisfying the relational expression A method for producing an aluminum alloy forged member characterized by comprising the steps of:   2. The method for producing an aluminum alloy forged member according to claim 1, wherein the total content of Fe, Cr, and Mn (mass%) is adjusted to 0.5 mass% or less. Before performing the hot forging, the equivalent strain for each part is calculated based on the shape of the forged member to be manufactured and the forging material, and the entire equivalent strain including all the equivalent strains for each part. Find the range of
The upper limit value of the forging material temperature is determined based on the information relating the forging material temperature prepared in advance and the range of the equivalent strain, based on the total equivalent strain range and the ratio of the desired fine recrystallization region range. Calculate
The manufacturing method of the aluminum alloy forged member of Claim 1 or 2 which specified the upper limit of the content total of the said Fe, Cr, and Mn based on the said relational expression from the upper limit of the forge raw material temperature. Before performing the hot forging, the total content of the Fe, Cr, Mn is calculated based on the composition of the forging material, and the upper limit value of the forging material temperature is calculated from the total content based on the relational expression. Asking
Forging process based on information relating the forged material temperature prepared in advance and the equivalent strain range from the upper limit of the forged material temperature obtained and the predetermined fine recrystallization region range of the entire molded product To obtain the range of the equivalent distortion allowed in
The method for producing an aluminum alloy forged member according to claim 1 or 2, wherein the shape of the forged material and the forged member is designed within the allowable range of equivalent distortion. Mg 0.35 to 1.2% by mass, Si 0.2 to 1.3% by mass, Cu 0.5% by mass or less, Fe 0.15% by mass or more, Cr 0.15% by mass or more A forged aluminum alloy member having a composition comprising 0.05% by mass or less of Mn and the balance consisting of Al and inevitable impurities,
An aluminum alloy forged member characterized in that a region of 50% or more is adjusted to a state of a fine recrystallized structure and has a tensile strength value exceeding 250 MPa.   The aluminum alloy forged member according to claim 5, wherein an area of 50% or more in each part is adjusted to a state of a fine recrystallized structure.   The aluminum alloy forged member according to claim 5 or 6, wherein the variation in tensile strength for each part is adjusted within ± 5% of the tensile strength without plastic working. It is comprised by the aluminum alloy forge member manufactured by the manufacturing method of any one of Claims 1-3, The structural material for motor vehicles characterized by the above-mentioned.

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