JP2014147958A - High strength 7000 aluminum alloy member and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high strength 7000 aluminum alloy member manufacturing method that can improve moldability itself even after natural aging and can greatly improve strength by subsequent artificial aging curing treatment, and to provide a high strength 7000 aluminum alloy member.SOLUTION: A high strength 7000 aluminum alloy member manufacturing method is characterized by conducting extremely partial restoration processing of 7000 system aluminum alloy extrusions, for example, under particular conditions like shown in Fig. 1, without artificial refining other than natural aging, after manufacturing the extrusions; and manufacturing the high strength 7000 aluminum alloy member by performing molding in a short time to form a member after the restoration processing and performing the refining to the member.

Description

  The present invention relates to a high-strength 7000 series aluminum alloy member and a method for producing a high-strength 7000 series aluminum alloy member. The aluminum alloy member referred to in the present invention refers to a material obtained by molding an extruded shape as a material into a product shape (use shape).

  As is well known, the 7000 series aluminum alloy member is an artificial aging treatment (artificial aging treatment) using the age hardening property by adjusting the amount of alloying elements such as Zn, Mg and Cu as main components as the composition of the extruded shape of the material. The required high strength is ensured by tempering such as age hardening. Examples of main applications include bumper reinforcements (bumperin hoses), automotive reinforcement members such as door beams, and structural members such as aircraft, and higher strength is also required to reduce weight by reducing the thickness. , 0.2% proof stress and high strength of 300 MPa or more are required.

  However, it is known that the 7000 series aluminum alloy member has a low SCC resistance (stress corrosion cracking resistance) as compared with other alloy series because of the large amount of the alloy elements.

  As is well known, the 7000 series aluminum alloy member is hardened by natural age hardening (hereinafter also referred to as natural aging or room temperature aging) after being manufactured as an extruded shape as a raw material because of its age hardening. For example, the strength which was about 150 MPa at 0.2% proof stress immediately after hot extrusion is cured to about 240 MPa at 0.2% proof stress after 20 days of natural aging (room temperature aging).

  Such naturally aged material extruded shapes are formed during bending, cross-section crushing (pressing), molding selected from stamping (plastic processing), or a combination of these. Sexually decreases. And when natural aging progresses further, the uniform elongation and local elongation of an extrusion shape material will fall, and the moldability to a member and shaping accuracy will fall further. On the other hand, from the side of molding to the product or the side of using the molded product, for the purpose of expanding the degree of design freedom, materials and processing methods that can improve the processing limit than the current situation are required, In particular, bending with a small radius and pressing with a large overhang have been required.

  Incidentally, such a problem is the same even after the manufactured material extruded shape is reheated separately and subjected to solution treatment (solution treatment and quenching treatment). After that, natural aging progresses as the time until molding elapses.

  In addition, even if the molding process is possible, the strength of the extruded profiles depends on the difference in time from the production of the extruded material to the molding process, that is, the degree of natural age hardening (progress). However, since the strength of the extruded shapes varies, there is also a problem that the amount of spring back varies during the molding process and the molding accuracy is inferior.

  Further, in the forming process to the member accompanied by plastic working, which is selected from the bending process, the crushing process of the cross section, and the punching process as described above, the residual stress is likely to be added. There is also a problem that the SCC resistance at the site is significantly reduced.

  For this reason, in order to improve the formability of naturally aged extruded shapes, conventionally, prior to molding, a naturally aged extruded shape is heat-treated in advance to perform a recovery process to reduce the strength such as the proof stress. It has been broken.

  For example, Patent Document 1 describes a method for manufacturing an aircraft frame or the like. And in the molding method of the part which plastically processes the extruded shape member or the plate member of the 7000 series aluminum alloy material after the solution treatment, immediately before the molding, the heating temperature is 150 to 350 ° C., and the heating time is 30 seconds. Restoration treatment is performed for ˜5 minutes (170 to 200 ° C. × 20 seconds to 3 minutes when rapid heating is possible). As a result, the material cured by the natural aging after the solution heat treatment is softened to ensure moldability, and the variation in springback due to the difference in the progress of natural aging is eliminated before molding.

  Patent Document 2 describes a spinning process and a method for producing a high-strength aluminum alloy pipe by artificially aging the spun pipe. Then, the entire 7000 series high hardness aluminum alloy extruded pipe, which is naturally aged after solution treatment, is locally applied to a temperature range of 150 ° C. to 250 ° C. using frictional heat generated by spinning or heat generated by plastic deformation. Spinning is performed after a restoration process in which the temperature is raised and lowered in a short time.

  Patent Document 3 describes a method for producing a 7000 series high-strength aluminum alloy extruded tube as an outer tube material of a motorcycle having excellent tube expansion workability even after long-term natural aging. And after T4 tempering the aluminum alloy extruded tube, when the whole is heat treated at a temperature of 105 ° C. to 250 ° C. for 30 seconds to 180 minutes, the heating rate from 100 ° C. to the heat treatment temperature is less than 1 ° C./second. It has been proposed to perform restoration processing. In the examples, the tensile strength, proof stress and elongation after two-stage aging are excellent, and the stress corrosion cracking life is also excellent.

  Patent Document 4 discloses that, in order to improve the stress corrosion cracking resistance of a high strength aluminum alloy extruded tube for an outer tube, the 7000 type high strength aluminum alloy extruded tube is subjected to solution treatment and quenching, and the time of 100 hours or more at room temperature. After natural aging, heat treatment is performed at a temperature of 150 to 250 ° C. for 30 seconds to 10 minutes, and a restoration treatment is performed with a rate of temperature increase from 100 ° C. to the heat treatment temperature being 1 ° C./second or more. Finally, an artificial aging treatment is performed. A technique to do this has been proposed.

  Although not in the extruded shape field, Patent Documents 5 and 6 disclose that the restoration treatment is partially performed on an aluminum alloy plate in order to improve press formability.

Japanese Patent Laid-Open No. 7-305151 JP 2005-194620 A JP 2007-119853 A JP-A-10-168553 JP 2011-111657 A JP 2009-161851 A

  These conventional restoration processes are performed uniformly over the entire material in the longitudinal direction and the entire width direction, except for the conditions of Patent Document 2. For this reason, a relatively large heat treatment facility is required particularly when applied to long parts characteristic of extruded profiles. However, such a large-scale facility has a problem that the processing cost increases with the cost increase of the apparatus itself. Further, considering application to an extruded profile that has the advantage of easily obtaining various cross-sectional shapes, a highly versatile heat treatment method that can be easily applied even when the cross-sectional shapes are different is desired.

  In the example of Patent Document 2, it can be said that only the spinning processed part is partially restored by utilizing the frictional heat generation between the roller and the material pipe by the spinning process and the heat generation by the plastic deformation of the pipe. However, in this method, as described above, the shape of the material is limited to the aluminum alloy pipe, and it cannot be applied to an extruded shape or the like for general purposes. In addition, when the frictional heat generated between the roller and the material pipe by spinning and the heat generated by plastic deformation of the pipe are used, it is difficult to control the restoration processing condition, and the variation of the condition becomes large. For this reason, there is a problem that it is difficult to accurately and uniformly heat the necessary part of the material.

  In addition, as described above, in order to expand the application range of the aluminum alloy profile, bending processing with a smaller R and variable cross-section processing that changes the shape of the cross-section in the longitudinal direction are desired. As described above, by adding a restoration process before forming processing, the processing limit of the aluminum alloy shape material is improved, and the processing limit of the parts is improved accordingly. Therefore, there is a demand for a technique that can improve the limit of bending and crushing with a small R.

  Furthermore, these conventional restoration processes are all likely to be a complete O material treatment when estimated from conditions such as the heating temperature and the length of holding time. That is, in order to avoid the O material treatment, as in the restoration processing of the present invention described later, rapid heating by a specific heating rate, a specific actual temperature of a material such as a 7000 series aluminum alloy extruded shape, a specific It is necessary to satisfy various conditions such as holding for a very short time. However, many of these conventional restoration processes do not disclose these conditions, and the possibility of a complete O material process increases. For this reason, even if the tempering treatment is performed after the yield strength is once lowered by the restoration treatment, there is a great limit to the strength that can be improved by the artificial age hardening treatment. Incidentally, the description of these conventional restoration processing temperatures is an ordinary furnace atmosphere temperature, and not an actual temperature in many cases. For this reason, the actual temperature is often different due to the influence of the structure and performance of the furnace, the shape of the material, and the like, and this also becomes a factor that the material characteristics after the restoration process are not stabilized.

  In addition, the partial restoration process for the aluminum alloy plate in Patent Documents 5 and 6 for improving the press formability is also affected by the thermal expansion of the restoration process because the plate thickness is thin in the case of the plate. A big problem is that the plate is thermally deformed. For this reason, it is necessary to perform the restoration process by restraining the front and back of the material with a mold, but it is complicated. Moreover, even with the same alloy system, the restoration process effective for improving the formability of the rolled sheet is not necessarily effective even with an extruded shape having a different manufacturing method and structure from the rolled sheet.

  The present invention has been made in view of such problems, and in performing restoration processing before forming processing to a member accompanied by plastic working, a high-strength 7000 series subjected to restoration processing that can be expected to improve the working limit at a lower cost. It aims at providing the manufacturing method of an aluminum alloy member and a high-strength 7000 series aluminum alloy member.

  In order to achieve the above-mentioned object, the gist of the high-strength 7000 series aluminum alloy member of the present invention is only a part in the longitudinal direction or the width direction in a state of natural aging without being tempered after production by extrusion. 7000 series aluminum alloy extruded profile that has been subjected to a restoration process in advance, the restoration process part or an aluminum alloy member that has been molded at the restoration process part and the peripheral part thereof, wherein the restoration process is performed by the extrusion The material is heated in the range of 200 to 500 ° C. at the actual temperature of the material, and is kept under this temperature range for 0.1 seconds or more and less than 20 seconds and then cooled, and this restoration process is performed. The molding process was performed within a time of 100 minutes after the end of cooling.

  Moreover, the summary of the manufacturing method of the high-strength 7000 series aluminum alloy member of the present invention for achieving the above-mentioned object is that the longitudinal direction or the width in the longitudinal direction or the width in the state of being naturally aged without being tempered after manufacturing by extrusion. A method for producing an aluminum alloy member, comprising subjecting a 7000 series aluminum alloy extruded profile that has been subjected to a restoration process to only a part of a direction, to the restoration process part or the restoration process part and a peripheral part thereof, The restoration process is performed under the condition of heating to the actual temperature of the extruded shape member in the range of 200 to 500 ° C. and cooling in this temperature range for 0.1 seconds or more and being held only for a short time of less than 20 seconds, The forming process is performed within 100 minutes after the cooling of the restoration process is completed.

  In the present invention, the actual temperature of the 7000 system is relatively high, and the restoration process under a specific condition such as a short time is absolutely natural aging without being tempered after production by extrusion. The aluminum alloy extruded shape is completely different from the conventional restoration process, and is performed only on a part in the longitudinal direction or the width direction, or only on a part of the cross section of the extruded shape. Then, molding is performed only in the region (part) of the partial restoration process, the region including the peripheral portion of the partial restoration processing portion, or the region of only the peripheral portion.

  Accordingly, even if the 7000 series aluminum alloy material is a long extruded shape, a simple and stable restoration process can be performed with a relatively small facility. Also, in order to leave most of the extruded shape without heat treatment, unlike the conventional restoration processing and O material treatment that are uniformly applied to the entire extruded shape, the member strength required for post-molding artificial age hardening treatment Can be secured.

  Especially in the case of bending, which is often performed on extruded profiles, the processing (breaking) limit bending radius is achieved by lowering the material's yield strength and increasing the n-value by applying the restoration process only to the bent part. , That is, bending can be performed with a smaller R. At the same time, the partial yield strength reducing effect by the restoration process can improve the shape accuracy by reducing the spring back and improve the SCC (stress corrosion cracking) resistance accompanying the reduction of the residual stress.

  Furthermore, it is possible to further improve the bending limit by performing this restoration process not only partially in the longitudinal direction but also partially in the cross section.

It is a top view which shows the aspect of this invention which restored only the inner side of the bending neutral axis | shaft, and shows only the arc-shaped bending process (bending deformation | transformation) part after an extruded shape member is bent. It is a top view which shows the aspect of this invention which restored only the outer side of the bending neutral axis | shaft, and shows only the circular arc-shaped bending process (bending deformation) part after an extruded shape member is bent. The plane which shows only the outer side of a bending neutral axis | shaft, and the aspect of this invention which restored the peripheral part of the bending process part, and shows only the circular arc-shaped bending process (bending deformation) part after an extruded profile is bent. FIG. FIG. 4 is a plan view showing an embodiment of the present invention in which only the outer side of the bending neutral axis and the peripheral portion of the bent portion are restored as in FIG. 3. It is explanatory drawing which shows the reduction effect of the largest distortion in FIG. It is explanatory drawing which shows the improvement effect of the bending fracture limit in Example 1. FIG. It is explanatory drawing which shows the improvement effect of the bending fracture limit in Example 1. FIG. It is explanatory drawing which shows the bending process test conditions in Example 2. FIG. It is explanatory drawing which shows the improvement effect of crushing workability in Example 3. FIG. It is sectional drawing which shows the crushing processing test body in Example 3. FIG. FIG. 10 is an explanatory diagram showing crushing processing test conditions in Example 3.

  Hereinafter, embodiments of the present invention will be specifically described in order for each requirement.

(Restore process)
The restoration process of the present invention is a 7000 series aluminum alloy extruded shape produced by extrusion, and after its production (extrusion process), prior to the restoration process of the present invention, solution treatment and quenching treatment or artificial age hardening Extruded shapes that have been subjected to natural aging (natural aging hardening, room temperature aging hardening) without being subjected to any tempering treatment such as treatment are intended. In other words, the restoration process of the present invention is applied to a 7000 series aluminum alloy extruded shape material that has been subjected to natural aging (room temperature aging, room temperature aging) without being subjected to the tempering treatment after manufacturing by extrusion. Apply. For the first time, the 7000 series aluminum alloy member has a strength of 0.2% proof stress and a high strength of 300 MPa or higher by tempering treatment such as artificial aging treatment after molding the extruded shape subjected to the restoration treatment. The effect which can be ensured is acquired.

  On the other hand, even after the manufacturing (extrusion process), the 7000 series aluminum alloy extruded shape which has been subjected to a tempering process such as solution treatment and quenching process or artificial age hardening process may be subjected to the restoration process of the present invention. , The effect is not demonstrated. Unlike the normal O material treatment for softening, the restoration processing of the present invention cancels the tempered 7000 series aluminum alloy extruded shape structure (can be canceled), unlike normal O material treatment for softening. It is not a thing.

(Restore processing conditions)
The conditions for the partial restoration process in the present invention are also important for the effect expression by the restoration process. As this condition, the partial restoration process of the present invention is heated to a range of 200 to 500 ° C. at the actual temperature of the extruded profile, and within this temperature range only for a short time of 0.1 second or more and less than 20 seconds. It is performed under the condition of being cooled after being held, and is molded within a time of 100 minutes after the completion of the cooling of the restoration process. In the present invention, even if the actual temperature of the extruded profile is in the re-solubilized region near 500 ° C., including all the conditions such as holding in the short time and cooling after holding, the “restoration process” is performed for that purpose. It is called.

  When the actual temperature of the extruded material of the 7000 series aluminum alloy at the time of the restoration process is less than 200 ° C., the restoration process becomes insufficient. In particular, the formability is not improved and the applied residual stress is also increased. On the other hand, it is not necessary that the substantial temperature exceeds 500 ° C., and if the temperature is higher than this, the heat treatment time including the time required for the temperature rise becomes too long, and the complete O material treatment (annealing treatment) The strength after the artificial aging treatment after the molding process may not be improved to 300 MPa or more with a 0.2% proof stress.

  At this time, it is preferable to heat the substantial temperature of the 7000 series aluminum alloy extruded shape material to a range of 200 to 500 ° C. by rapid heating (rapid heating) at a heating rate of 0.5 ° C./second or more. If the heating rate is as low as less than 0.5 ° C./second, the holding time in a warm or high temperature state becomes long, and there is a possibility of complete O material treatment (annealing treatment). There is a possibility that the strength after the aging treatment is not improved to 300 MPa or more at 0.2% proof stress.

  Next, the heating and holding time in the above temperature range is also important, and the heat treatment time in the restoration process is instantaneously short when the temperature of the extruded shape material is in the temperature range of 200 ° C. or more and 500 ° C. or less. Even if it is time, it is effective if the temperature of the material is within this temperature range. For example, as will be described later, even if the heating body is in direct contact with the extruded profile and immediately separated, the temperature of the material substance is about 0.1 seconds, which is a measure of instantaneous holding (time). Is effective in this temperature range. On the other hand, if the holding time is longer than 20 seconds or more, depending on the temperature condition, the fine precipitate B that contributes to the bake hardness due to the restoration process is re-dissolved, or conversely, precipitation proceeds. It will end up. Further, if the holding time is too long, it is likely to be a complete O material treatment (annealing treatment). As a result, the strength cannot be increased to 300 MPa or more with a 0.2% proof stress even by the artificial aging treatment after molding. For this reason, the heating and holding time is set to 0.1 seconds or more and less than 20 seconds as described above.

  In order to hold the temperature within the above temperature range for a very short time of not less than 0.1 seconds and less than 20 seconds, immediately after this holding, forced cooling (air cooling, water cooling) to room temperature at a cooling rate of 0.5 ° C./second or more is performed. Mist cooling). At this time, the room temperature referred to in the present invention may include a temperature of room temperature or less (cooling to about 18 to 25 ° C.) such as several degrees C., 0 ° C. or 0 ° C. or less.

(Partial application to the shape of restoration process)
In the present invention, a region (part) where the extruded shape material is processed, a region (part) including the peripheral portion of the region (part) to be processed, and a region including only the peripheral portion of the region to be processed are extruded. The condition restoration process is partially performed only on a part in the longitudinal direction or the width direction of the profile.

  In the conventional restoration process, the restoration process is uniformly or uniformly performed over the entire length or width of the extruded profile. On the other hand, the present invention is different from the tempering process such as the conventional restoration process and the O material process, in addition to the region (part) subjected to the restoration process of the predetermined condition. Most regions (portions) are characterized in that they remain as the natural aged tissue without being subjected to the restoration process itself.

  Then, the extruded shape in a state of partial restoration processing is selected from bending processing, pressing processing, and punching processing in the restored processing portion or the restoration processing portion and the portion including the peripheral portion thereof, and these Forming processing is also performed, including processing combining the above. Here, the restoration processing portion or the peripheral portion of the restoration processing portion to be molded is the whole restoration portion, a part of the restoration processing portion, all or part of the restoration processing portion and the restoration processing portion. It refers to a portion including a peripheral portion (peripheral adjacent portion) or a peripheral portion (peripheral adjacent portion) not including these restoration processing portions.

  By such a partial restoration process of the extruded shape of the present invention, even if the 7000 series aluminum alloy material is a long extruded shape, using only existing relatively small equipment and jigs, The operation is simple and stable heat treatment is possible. And the required intensity | strength as a member is securable by the artificial age-hardening process after shaping | molding an extruded shape material as mentioned above.

  In particular, in the case of bending, which is often applied to extruded profiles, by applying the restoration process only to the bent portion of the extruded profile, the partial low strength of only the restored part And high n-value can be achieved. For this reason, the bending (breaking) limit bending radius of bending can be reduced, and bending can be performed with a smaller bending radius (small R). At the same time, the strength reduction effect by the restoration process can improve the shape accuracy by reducing the spring back, and can improve the SCC (stress corrosion cracking) resistance accompanying the reduction of the residual stress.

  The area of the area (part) to be restored is effective for improving the processability of the restoration process compared to the area of the area where the extruded shape deforms during molding. Further, it is determined based on the balance that the restoration process of the area beyond that is unnecessary. And from this range, the partial site to be restored, the material properties coming from the composition and manufacturing method of the material 7000 series aluminum alloy extruded shape, the progress of natural aging after manufacture (strength increase), And it sets in consideration of the relationship of the molding process conditions of the extruded material.

(How to apply partial restoration processing to extruded profiles)
As described above, the partial restoration process of the extruded profile is performed only on a part of the extruded profile in the longitudinal direction or the width direction. In this way, by performing the restoration process not only partially in the longitudinal direction but also partially in the width direction of the extruded profile, that is, in the cross section of the extruded profile, the molding process limit can be further improved.

For bending:
In particular, the bending process that is often performed on the extruded profile is a process in which the longitudinal direction of the extruded profile is the circumferential direction. In the case of such a bending process, as a partial restoration process of the extruded profile, part or all of the area corresponding to the bent part (bending deformation part) of the extruded profile (the entire area), and further Then, the entire region including the bent portion and the region including the adjacent straight side portion or a part of the region is partially subjected to the restoration processing of the present invention in advance and then bent. In this case, the bending process limit is further improved by partially performing the restoration process of the present invention not only in the longitudinal direction of the extruded profile but also in the width direction of the extruded profile, that is, in the cross section of the extruded profile. Is possible.

  Then, the bending of the extruded shape member is performed in such a restoration processing portion or a portion including the restoration processing portion and the peripheral portion thereof.

For press working and punching:
Even in the case of a molding process selected from a press process (partial crushing of a cross section of a profile) that changes the cross-sectional shape of a part of the extruded profile in the longitudinal direction and a punching process that provides a hole in the extruded profile, Molding is performed in advance after partially performing the restoration process of the present invention in advance. That is, a part or all of the portion of the extruded profile corresponding to the molding portion (processing deformation portion) or the portion corresponding to the peripheral portion of the molding processing portion (processing deformation portion) is included. In addition, the entire region or a partial region of the region corresponding to the molding processing part is partially subjected to the restoration processing of the present invention in advance before the molding processing. In this case, by performing the restoration process of the present invention not only in the longitudinal direction of the extruded profile but also partially in the width direction of the extruded profile, that is, in the cross section of the extruded profile, the molding process limit is further improved. Is possible.

  Then, the pressing process or the punching process of the extruded shape material is performed in such a restoration processing portion or a portion including the restoration processing portion and the peripheral portion thereof. As an example, in the case where the forming process applied to the extruded profile is a press process performed to change the cross-sectional shape of a part of the profile in the longitudinal direction, a part of this press processed part (press processed deformed part) The restoration processing of the present invention is partially performed in advance including the entire side (all areas) or in the vicinity of the press-processed portion and including a straight side portion that does not come into contact with the punch or the mold during the molding process.

  As an example of pressing that changes the cross-sectional shape of a part of the extruded shape in the longitudinal direction, both ends and part of the extruded shape having a uniform rectangular cross-section in the longitudinal direction, such as a mouth mold, a die, and an eye shape. There is an example of partial crushing. Such a crushing process is performed in order to secure a shape restriction on design and to secure an attachment portion with other parts. For example, in the case of Japanese Patent Application Laid-Open No. 2008-120110, application to energy absorbing parts such as door impact bars and tower bars is also suggested, and application to bumper reinforcements with severe end-side space restrictions is also expected. The If the present invention is used in such a case, it is only necessary to partially restore the crushed portion of the both ends or the portion including the crushed portion and the peripheral portion without restoring the entire bumper reinforcement. Further, the both ends can be crushed without deteriorating the strength and impact energy absorption characteristics of the bumper reinforcement itself. In addition, a large furnace and apparatus for the restoration process are not necessary.

Different restoration conditions within the extruded profile:
Especially when bending extruded shapes, the portions corresponding to the inside and outside of the bending neutral axis of the bending deformation portion of the extruded shape, or the portions corresponding to the inside and outside of the bending neutral shaft And the present invention restoration processing under different conditions may be performed between portions corresponding to the peripheral edge of the bending deformation portion. Thus, by performing the present invention restoration process under different conditions within the cross section of the extruded profile, it is possible to provide a difference in properties such as strength on the material inside and outside the bending neutral shaft, Formability can be improved. Here, the restoration process of these different conditions includes not performing the restoration process of the present invention on either side.

  1, 2, 3, and 4 each show an aspect of the present invention in which either the bending inner side or the outer side of the bending neutral shaft is restored and the other side is not restored. 1-3, in order to easily understand the relationship between the portion to be restored and the bending process, the member after the extruded shape material is bent is subjected to an arc-shaped bending process (bending deformation). Only the portion is shown in a plan view. Here, it does not matter whether the cross section of the extruded material or the bent member is a solid shape such as a round bar or a square bar, or a cross section having a hollow portion is a mouth shape or a square shape. In other words, whether it is solid or hollow, the effect of the restoration process of the present invention is the same.

  1 and 2, in the arc-shaped bending (bending deformation) portion, the arc-shaped bending neutral axis N0 extending in the longitudinal direction of the member (extrusion direction of the extruded profile) indicated by a one-dot chain line, A mode is shown in which only one or all of the deformed portion (processed portion) in the outer region of the member or all or part of the deformed portion (processed portion) in the inner region of the member is restored. That is, in the case of the extruded shape member, a state is shown in which only one or all of the portions corresponding to the inner side and the outer side of the bending neutral axis of the arc-shaped bending deformation portion are restored.

  FIG. 1 shows a state in which the entire region of a deformed portion (processed portion) inside a neutral axis N0 (positioned on the lower side of the figure) of a member (extruded profile) is restored in an arc-shaped bending process (bending deformation) portion. Is shown. In FIG. 1, a region enclosed by a dotted line in a square is the entire deformed portion (processed portion) inside the neutral axis N0 of the member (extruded profile). In this case, the side of the outer deformed portion (processed portion) located above the neutral axis N0 in the figure is not subjected to the restoration processing of the present invention.

  On the other hand, FIG. 2 shows the arcuate bending (bending deformation) part as a square with dotted lines, not all (all areas) of the deformation part (working part) in the outer region of the neutral axis N0 located on the upper side of the figure. The mode which restored only the part enclosed is shown. In this case, the side of the deformed portion (processed portion) in the inner region of the extruded profile located on the lower side of the neutral axis in the figure is not subjected to the restoration process of the present invention.

  In FIG. 1, when this inner region is restored, two parallel bending neutral axes N0 and N1 indicated by the one-dot chain line in the arc shape are at the center in the width direction of the (original) extruded profile before restoration. The bending neutral axis N0 {denoted as neutral axis (usually)} (inside of the figure) is converted into the bending neutral axis N1 {neutral axis (outside of the figure) as indicated by two upward and downward arrows by the restoration process. Move to “describe restoration process application)”. This is a mode in which only one of the portions corresponding to the inner side and the outer side of the bending neutral axis N0 of the arc-shaped bending deformed portion when viewed as an extruded straight material extruded shape is restored. This is a common effect. Therefore, the same effect is produced even when the restoration process is not all of the inside of the bending neutral axis N0 (all areas) but part of the inside of the bending neutral axis N0 (partial area) as shown in FIG. .

  For this reason, of two parallel diagonal vertical lines (solid lines) S0 and S1 indicating the strain amount during bending, S0 shown on the right side (original) before the restoration process is four diagonally upper left corners. As shown by the small arrow pointing to the left, it moves to S1 shown on the left side, and the amount of tensile strain generated on the outer surface of the bend during bending is small, and conversely, the amount of compressive strain generated on the inner side of the bend increases. . For this reason, it is particularly effective when bending a part in which breakage becomes a problem during bending.

  Further, in the case of FIG. 1, the lowering of the yield strength and the increase of the n value of the bending process (bending deformation) portion of the inner region of the extruded profile are achieved by the restoring process of the inner region. Although the compressive strain toward the inside of the bending increases with the movement of the neutral axis, there is an advantage that shape defects such as wrinkles are less likely to occur due to the change in the material characteristics.

  In FIG. 2, when only a part of this inner region is restored, the (original) bend neutral axis N0 before the restoration process among the two parallel bend neutral axes N0 and N1 indicated by the one-dot chain line in the arc shape. However, as indicated by two downward arrows on the left and right, the restoration process moves to the bending neutral axis N1 inside the drawing. This is the same as in the case of FIG. 1 described above, in the portion corresponding to the inner side and the outer side of the bending neutral axis N0 of the arc-shaped bending deformed portion when viewed as an extruded straight material extruded shape. This is an effect common to the mode in which only one of them is restored. Therefore, the same applies to the case where the restoration process is performed not on a part (partial region) outside the bending neutral axis N0 as shown in FIG.

  In this case, of the two oblique vertical lines (solid lines) S0 and S1 indicating the amount of strain at the time of bending, S0 shown on the left side before the restoration process moves to S1 shown on the right side. The amount of compressive strain generated inside the bend during bending is reduced, and this is particularly suitable for bending a part in which wrinkle suppression is a problem.

  In the case of FIG. 2, the amount of tensile strain generated on the outside of the bend increases, but the material properties in the outside of the bend are restored by reducing the yield strength and increasing the n-value by the restoration process. The fracture limit is higher than that of a normal material that does not apply, and it can be said that the fracture itself is less likely to occur.

Of course, even if the region subjected to the bending process is only partially restored in the longitudinal direction, as described above, the formability is improved by the low yield strength and high n-value effect by the restoration process. This is an effect of being able to reduce the degree of processing for obtaining a predetermined product shape by improving the breaking limit, improving the buckling wrinkle generation limit, and reducing the spring back.
As described above, the bending process limit can be further improved by performing the restoration process not only partially in the longitudinal direction of the extruded profile but also partially in the cross section. That is, as described above, the position and region of the bending neutral axis N is positively utilized by utilizing the effect that the position of the neutral axis N during bending can be freely changed by selecting and designing the position and region where the restoration process is performed. It is possible to control the processing limit of bending by controlling. When it is desired to change the position of the neutral axis N more greatly, it is of course possible to change the temperature of the restoration process and the heating time condition between the inside and outside of the bend. Even if the heat treatment is performed only on one of the inside and the outside of the bend, a great effect can be obtained.

  FIG. 3 shows a case where only the bent portion (bending deformation portion) is restored as the softened region 1 in the arc-shaped bending processing (bending deformation) portion. In addition to this, in FIG. 4, the bending outer region with respect to the bending neutral axis in the peripheral portion (straight portion) region of the shape member located outside (away from) the boundary indicated by A of the bent portion is softened region 2. As shown in FIG. In the case of FIG. 4, when viewed as an extruded straight material extruded shape, including the peripheral region of the shape outside the boundary indicated by A of the bent portion, the outside of the bending neutral axis Only the portion corresponding to is restored.

  FIG. 5 shows the effect of reducing the strain amount during bending in the cases of FIGS. In FIG. 5, the vertical axis indicates the strain amount ε, and the horizontal axis indicates the distance S of the bending outer region of the profile from the bending center axis indicated by the dotted line in FIG. 3. In the relationship between the strain amount ε in FIG. 5 and the distance S of the outer shape bending area from the bending center axis, the strain distribution in the case of FIG. Thus, a constant high strain amount ε is obtained up to the boundary indicated by A in the bent portion, and the value decreases sharply after the boundary indicated by A.

  On the other hand, in the case of FIG. 4, as shown by the thick solid line on the lower side of FIG. It can be seen that the absolute value is lower than that in the case where the portion is not included, and strain is generated in a wide range up to the right region beyond the boundary A of the bent portion. This reduction in the amount of strain is because the deformation region widens due to the effect of lowering the proof stress due to the peripheral area restoration process.

  As shown in FIG. 4, by performing restoration processing including the peripheral region of the bent portion, the deformation range is widened due to the influence of low material strength and high n value, and the strain is uniformly affected over a wide range. Thus, the amount of strain during bending is reduced. This is an effect common to the aspect in which the peripheral region including the bent portion is restored in the arc-shaped bent portion (bending deformation) portion. Therefore, the same effect can be obtained even when the bending inner region side is restored or when the entire region in the cross section is restored. For this reason, it becomes easy to suppress shape accuracy defects, such as a fracture | rupture or a wrinkle in a bending process, a process limit bending radius can be reduced, and it becomes possible to bend with a smaller bending radius (small R). At the same time, the strength reduction effect by the restoration process can improve the shape accuracy by reducing the spring back, and can improve the SCC (stress corrosion cracking) resistance accompanying the reduction of the residual stress.

  By the way, also in FIGS. 1 to 3, the size of the region to be restored is determined by the composition of the material 7000 series aluminum alloy extruded shape, the material characteristics resulting from the manufacturing method, and the progress of natural aging after manufacture (strength of strength). It is set empirically or by trial and error from the range in which the effect occurs in consideration of the relationship of the molding processing conditions of the extruded material.

(Extruded shape restoration processing means)
As in the present invention, in order to perform the restoration process of the above condition only on a part in the longitudinal direction or the width direction of only the part including the part to be processed or molded part of the extruded shape member, It is impossible to perform the restoration process in a heating furnace used for heat treatment of a normal extruded profile. A heating furnace used for heat treatment of a normal extruded profile is intended to uniformly heat the entire extruded profile, and is not suitable for partial heating of the extruded profile.

  Therefore, in order to perform the restoration process according to the various partial application places of the restoration process to the extruded profile, and to perform the above-described temperature at the optimum conditions for a short time, the restoration process was heated to a predetermined temperature. It is preferable to press the jig against only a part in the longitudinal direction or the width direction of the extruded profile, and rapidly heat the pressed part.

  Such a jig is preferably a metal tool or an IH heater, and these jigs are pressed against an extruded shape (material) from at least one side and combined with the above-mentioned forced quenching means to obtain an extruded shape. The restoration process can be carried out only in part, under the above-mentioned temperature and optimum conditions for a short time, and in accordance with the various partial application places of the restoration process to the extruded profile.

  In addition, the method of pressing such a high-temperature jig against the material causes a problem of thermal deformation in the above-described aluminum alloy thin plate, but in the extruded shape having a relatively high rigidity due to the thick profile, the outer side of the cross section ( Even with heating from one side), thermal deformation hardly poses a problem.

(Molding)
In the 7000 series aluminum alloy extruded shape subjected to the restoration processing as described above, the restoration processing portion or the portion including the restoration processing portion is subjected to forming to obtain an aluminum alloy member. This forming process is selected from the bending process, the press process, and the punching process described above, and each of these forming processes alone or a forming process appropriately combining these forming processes is selected according to the shape of the member as a product. The

  The bending process that is often performed on the extruded profile is a bending process in which the longitudinal direction of the extruded profile (or member) is the circumferential direction. Press work, which is often performed on extruded profiles, uses a punch or die to change the cross-sectional shape of a part of the extruded profile (or member) in the longitudinal direction, partially crushing the profile section. It is processing. ) And press work that is often applied to extruded profiles, and fitting with other members and fasteners at a predetermined size (diameter) and number of pieces at a predetermined position of the extruded profile (or member), This is a punching process in which a hole for fastening is provided. These are forming processes into a member shape as plastic working accompanied by generation of residual stress.

Elapsed time to molding:
However, in order to exert the effect of the restoration process of the present invention, it is necessary to start the molding process within a short time within 100 minutes after the completion of the cooling of the restoration process. When the start of the forming process after the completion of the cooling of the restoration process exceeds 100 minutes, the 7000 series aluminum alloy having a high alloying composition is naturally aged and the effect of the restoration process of the present invention is diminished. In other words, in order to express this restoration processing effect in the molding process, after the restoration process (cooling), the molding process is performed as soon as possible (with no delay) before the natural aging progresses or while the natural aging progresses. Need to start.

  As a guideline, of course, it depends on the composition and manufacturing conditions of the 7000 series aluminum alloy extruded shape, or the restoration processing conditions of the present invention described above. The (required) time to start is within 100 minutes. If it exceeds 100 minutes, the high-strength 7000 series aluminum alloy extruded shape material has a natural aging that is excessively advanced as described above due to its composition, so that the formability is remarkably lowered and the significance of the restoration treatment is lost.

  That is, the natural aging (increased strength) of the extruded 7000 series aluminum alloy proceeds in a short time, in other words, the degree of aging (increased strength) greatly progresses at the initial stage of natural aging. For this reason, even if the molding process and its vicinity are reduced in yield strength and increased in n value by the restoration process, if the time from immediately after the restoration process is rapidly cooled to the start of the molding process becomes long, the natural aging is too advanced. . As a result, of course, the effect of the restoration process of the present invention is not sufficiently exhibited in the molding process, although it depends on the time until the molding process starts.

  Here, of course, the specified elapsed time of 100 minutes does not indicate a clear critical boundary point for an increase in the natural age hardening amount which varies depending on the alloy amount, composition, extrusion processing conditions, and the like. However, in the relationship between the composition range of a preferable 7000 series aluminum alloy to be described later and the above-described restoration processing conditions of the present invention, it can be a general purpose and good reproducible measure that the effect of the restoration processing of the present invention is reduced by natural aging. .

Tempering after molding:
In the present invention, it is preferable to perform an artificial age hardening treatment on the above-described member (7000-series aluminum alloy extruded profile member) to increase the strength required for the member. In the present invention, as described above, the tempering treatment is performed on the extruded shape material except for the quenching or quenching treatment that is continuously performed online on the extrusion process immediately after extrusion (on the exit side of the extruder). Absent. Therefore, in order to increase the strength required for the member, it is preferable to perform an artificial age hardening treatment after the above-described molding process.

  In order to improve the mechanical properties of the member, the artificial aging treatment is preferably performed by heating at 100 to 200 ° C., preferably for 12 to 36 hours (hr).

  According to the restoration process of the present invention, even in the case of a naturally-aged and high-strength 7000 series aluminum alloy extruded shape in combination with an artificial age hardening process of a molded member, the tempering by this artificial age hardening process The 0.2% proof stress of the later member can be 300 MPa or more.

(Manufacture of 7000 series aluminum alloy extrusions)
composition:
The 7000 series aluminum alloy extruded profile (raw material) in the present invention has an Al—Zn—Mg series composition or an Al—Zn—Mg—Cu series composition including JIS standards and AA standards. However, in order to satisfy the required high strength as a member, the strength of the member after the artificial aging treatment is 300 MPa or more at a 0.2% proof stress, preferably 400 MPa within the range of the artificial aging treatment conditions after the molding. The above is preferable.

  The preferable 7000 series aluminum alloy extruded shape (material) composition for this purpose is, in mass%, Zn: 3.0-8.0%, Mg: 0.4-2.5%, Cu: 0.05-2. 0.0%, Ti: 0.005-0.2%, Mn: 0.01-0.3%, Cr: 0.01-0.3%, Zr: 0.01-0. It is set as the composition which contains 3% of 1 type or 2 types or more, and the balance consists of aluminum and inevitable impurities. The% display of the element amount means the mass%.

  Here, in order not to deteriorate various properties as a material or member such as formability, corrosion resistance, or weldability, Fe, Si, etc., which are inevitably mixed in from ingots and scraps as melting raw materials as the inevitable impurities Is preferably reduced to Fe: 0.35% or less and Si: 0.3% or less in an economical range.

  Zn is a main element for improving the strength, and its preferable content range is 3.0 to 8.0%. If the content is less than the lower limit, the strength becomes insufficient. If the content exceeds the upper limit, the SCC resistance (stress corrosion cracking resistance) is significantly lowered. A more preferable content range is 6.2 to 6.8%.

  Mg is also a main element for improving the strength, and the preferred content range is 0.4 to 2.5%. If it is less than the lower limit, the strength becomes insufficient, and if it exceeds the upper limit, the SCC resistance is lowered. A more preferable content range is 0.6 to 1.5%.

  Cu is a main element that also improves the strength, and its preferred content range is 0.05 to 2.0%. If it is less than the lower limit, the strength becomes insufficient, and if it exceeds the upper limit, the extrusion processability is lowered. A more preferable content range is 0.08 to 0.2%.

  Ti has the effect of refining crystal grains during casting of a 7000 series aluminum alloy and improving the formability (crushing workability) of the extruded profile, and is contained in an amount of 0.005% or more. On the other hand, if it exceeds 0.2%, the action is saturated, and a coarse intermetallic compound is crystallized, which deteriorates the formability.

  Mn, Cr, and Zr are elements that are selectively contained, and by containing one or two or more of them, any of them makes the crystal structure of the material finer or fibrous and improves the SCC resistance. The preferable content ranges are Mn: 0.01 to 0.3%, Cr: 0.01 to 0.3%, and Zr: 0.01 to 0.3%, respectively. When both are contained exceeding the upper limit, a coarse intermetallic compound is formed, resulting in a decrease in ductility and a decrease in moldability.

Extruded shape manufacturing method:
A method for producing a 7000 series aluminum alloy extruded shape (molding material) will be described below. Note that all described temperatures in the heat treatment are actual temperatures, not the furnace atmosphere temperature.

Melting, casting;
First, in the melting and casting process, a molten aluminum alloy melt-adjusted within the above-mentioned 7000 series component composition range is cast by appropriately selecting a normal melting casting method such as a semi-continuous casting method (DC casting method). And

Homogenization heat treatment:
Prior to hot extrusion, the cast aluminum alloy billet (ingot) is subjected to homogenization heat treatment (soaking) in the range of 470 to 565 ° C. to homogenize the structure (segregation within crystal grains in the ingot structure). Etc.). The soaking temperature is selected from the range of 470 to 565 ° C., and the homogenization time is selected from the range of 2 hours or more. If the soaking temperature is too high, the dispersed particles in the shape structure become coarse, and the crystal grains cannot be refined and strengthened. On the other hand, even if the soaking temperature is too low, the billet structure cannot be homogenized.

Hot extrusion:
This homogenized 7000 series aluminum alloy billet is hot-extruded (direct extrusion or indirect extrusion), but it is hot-extruded under conditions that suppress the recrystallized grain layer of the extruded shape and refine and homogenize the structure. It is preferable to do. The extrusion start temperature of the billet is preferably 350 to 450 ° C.

  As for the cooling immediately after the hot extrusion, it is possible to carry out rapid cooling (on-line quenching) such as air cooling and water cooling from the extrusion (extruder) outlet temperature at the temperature of the solution zone (solution temperature). This is preferable in terms of preventing recrystallization structure on the surface of the shape material structure and coarsening of crystal grains in the internal processing structure. Incidentally, the quenching or quenching process that is performed on-line continuously on the extrusion process immediately after the extrusion (on the exit side of the extruder) is not performed in the present invention. Therefore, in the present invention, except for curing by natural aging, the restoration process is performed without tempering such as a solution treatment, and the extruded shape material is reheated off-line separate from the extrusion process. The restoration process is performed without any tempering such as solution treatment and quenching process.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not restrict | limited by the following Example from the first. For example, if the above-mentioned conditions and the following example conditions are replaced from extrusion to rolling as well as an extruded profile, it can be applied to a rolled sheet as a material, and is included in the technical scope of the present invention.

  Next, examples of the present invention will be described. The extrusion process (raw material) made of each 7000 series aluminum alloy shown in Table 1 is subjected to a restoration treatment under various conditions after completion of extrusion, without artificial tempering except for natural aging. Was investigated and evaluated.

  The first embodiment is for confirming an appropriate restoration processing condition (supporting an effective restoration processing condition range defined in the present invention). That is, a flat small test piece is collected from the hollow extruded shape member, and the entire test piece (entire surface) is subjected to a restoration process under various conditions shown in Table 2 to obtain the extruded shape material by the restoration process. The changes in tensile properties and the effect of improving the bending fracture limit were investigated. The results are shown in Table 2 and FIGS.

  Example 2 investigated the effect of improving the bending workability of the hollow extruded profile by the partial restoration process of the present invention. The results are shown in Table 3, and the bending test conditions are shown in FIG.

  Example 3 investigated the improvement effect of press workability (crushing workability) by the partial restoration process of the present invention. The results are shown in Table 4 and FIG. 9, and the press working test conditions are shown in FIG. This crushing test simulates the crushing of the cross-sections at both ends when the extruded shape material is made into a member such as a bumper reinforcement.

(Common conditions)
In common with each example, the manufacturing conditions of the hollow extruded shape (raw material) were first cast into billets (round bar ingots) made of each 7000 series aluminum alloy shown in Table 1. The billet was subjected to a homogenization heat treatment at 500 ° C. for 10 hours in the same manner as in each of the examples, followed by direct hot extrusion that was water-cooled (rapidly cooled) from a temperature of 500 ° C. at the extrusion start temperature of 440 ° C. As a result, a hollow extruded shape (long material) having a substantially rectangular shape in a cross section was obtained. By the way, the manufacturing conditions are the same for this hollow extruded shape, and the dimensions are slightly different depending on each embodiment, even though they have the same daily cross section. Moreover, the aluminum alloy of the alloy numbers 1 and 2 of Table 1 is in this invention component composition range.

  After the hot extrusion, in common with each example, after cutting to an appropriate length, after natural aging (room temperature aging) for 20 days (without artificial tempering other than this natural aging), a nitrite furnace Or by partially pressing a steel jig, which will be described later, onto the extruded profile, the restoration process is performed under various heating, holding temperature (substance temperature), holding time, and cooling conditions shown in each table. went.

  After completion of this restoration process (after completion of rapid cooling to room temperature), in common with each example, after various times shown in each table (required time until molding) have passed, artificial tempering is performed except for this restoration process. Without performing the above, each molding process accompanied by generation of residual stress was performed to form a member.

  When partially restoring the cross-section of the hollow extruded profile, press the steel jig heated according to the heating temperature of the restoration process only to the restoration process part on the one side of the extruded profile, This pressed portion was rapidly heated for a predetermined time, and the steel jig for cooling was also pressed only on the restoration processing portion on the one side and rapidly cooled. The actual temperature of the extruded profile was measured by bringing a commercially available contact thermometer into direct contact with the restored portion of the extruded profile.

Example 1
As Example 1, the investigation results of the change in the bending fracture limit strain (%) due to the restoration process are shown in Table 2 and FIGS. FIG. 6 shows the shape actual temperature (° C) of the restoration process on the horizontal axis in Table 3, 0.2% proof stress (MPa), elongation at break (%), and bending fracture limit strain (%) on the vertical axis. And it is a rearranged graph. FIG. 7 shows the time required to start forming (bending test) in Table 3 (min), 0.2% proof stress (MPa), elongation at break (%), and bending fracture limit strain ( %) Is a rearranged graph.

  At this time, as the time-dependent change in the 0.2% proof stress of the extruded shape material, immediately after the natural aging for 20 days after the production by the hot extrusion (T1 tempered material) and the rapid cooling in the restoration process The mechanical properties of the extruded shape material after and after (restoration treatment material) were measured according to the tensile test procedure described later.

Tensile properties:
Using a JIS No. 4 tensile test piece taken from an arbitrary position in the extrusion direction of the member, the proof stress was measured according to the metal material test method specified in JISZ2241. In addition, these measured values were made into the average value of the measured value of three collection test pieces in each example.

  Bending fracture limit strain is a 25 mm wide × 40 mm long plate-like material, bent in the extrusion direction with a V-shaped punch (tip angle 60 DEG) having a different bending radius at the tip, and for samples where no breakage occurred. Thereafter, bending was further performed at 180 degrees, and the amount of strain outside the bending tip at the time of fracture was investigated.

  The extruded shape members of the invention examples in Table 2 using the aluminum alloys of Alloy Nos. 1 and 2 in Table 1 are subjected to the restoration treatment within the preferable condition range described above. As a result, as shown in Table 2, each example of the invention improved the bending fracture limit strain (%) after the restoration process from a medium strength material of 220 MPa to a high strength material of 310 MPa during T1 tempering, The effect of the restoration process can be surely exhibited.

  On the other hand, the extruded shapes of the comparative examples in Table 2 are subjected to a restoration process within a range that is out of the preferable conditions. In Comparative Examples 1, 16, and 17, the actual temperature of the restoration process is too low. In Comparative Examples 8, 15, 19, and 30, it takes too long (too long) from the end of the restoration process (after cooling to room temperature) to the start of molding. As a result, as shown in Table 2, each comparative example has an improved bending fracture limit strain amount (%), but the improvement level is significantly lower than that of the inventive example.

  Moreover, the significance of performing the restoration process within the above-described preferable condition range is supported by the relationship with the fracture limit strain amount (%) from Table 2. Further, among the results shown in FIGS. 6 and 7, particularly in relation to the bending fracture limit strain amount (%) on the vertical axis, heating in the range of the actual temperature of the extruded profile in the restoring process is 200 to 500 ° C. The significance of molding within 100 minutes after the end of cooling to room temperature is confirmed.

  Furthermore, in the extruded shape material restored in the preferable condition range, not only the above-mentioned bending fracture limit strain is improved, but as shown in Table 2, the elongation at break during tensile deformation and the 0.2% proof stress are reduced. It can be confirmed that it is possible to expect effects such as improvement of the fracture limit in bending of the hollow shape member, improvement of shape freezing property by reduction of proof stress, and reduction of residual stress.

(Example 2)
As Example 2, the investigation results of the improvement effect of the bending workability in the bending process of the actual shape material by the restoring process are shown in Table 3, and the bending work test conditions are shown in FIG.

  In FIG. 8, the aspect of the bending process (test) of a bending die and a shape material is shown by planar view on the upper left side of the figure. In the lower left side of the figure, the mode of bending (testing) between the bending die and the profile is shown in cross section. As shown in the plan view, the shape is bent by clamping the right end of the shape and fixing it, and then rotationally displacing (rotating and bending) the center of the shape of the shape. Permanent deformation that gives an arc shape was given. In the upper right side of FIG. 8, the shape (size) of the daily cross-section material to be bent is shown. Further, in the lower right of FIG. 8, in the rectangular frame, when bending the cross section of the profile, the core bars inserted respectively in the two closed spaces of the cross section of the die to prevent deformation of the cross section. Show shape.

The processing range (region) of the extruded profile subjected to the restoration process prior to the bending process was as follows.
In the case where the part corresponding to molding in Table 3 is “both inside and outside the bending” and the processing range is “entire deformation area”, it corresponds to both the inside and outside of the bending neutral axis in accordance with the bending radius of 30 mm. As a part, it was set as the length over 80 mm from a clamp part to the longitudinal direction in the width direction whole region of the bending deformation equivalent part of an extrusion shape member.
In the case where the forming equivalent part to be processed in Table 3 is “only the bending inner side” in FIG. 1 and the processing range is “the entire deformed part”, the inner flange of the bending neutral shaft is heated in accordance with the bending radius of 30 mm. A steel jig was pressed to restore only the length corresponding to the bent portion.
When the forming equivalent part to be processed in Table 3 is “only the bent outer side” in FIG. 2 and the processing range is “the entire deformed part”, conversely, the heated steel jig is pressed only on the bent outer flange. Only the length portion corresponding to the bent portion of this portion was restored.
When the forming equivalent part to be processed shown in Table 3 is “only the bending outer side” in FIG. 3 and the processing range is “only the deformed peripheral edge”, it is 10 from the clamp part which becomes a substantially straight side part at the end of processing at the bending angle of 15 DEG. The heated steel jig was pressed against only the bent outer flange of the ˜30 mm portion (bending peripheral portion), and only the length portion corresponding to the bent portion of this portion was restored.

  The extruded profile of each invention example in Table 3 uses the aluminum alloy of Alloy No. 1 in Table 1, and the restoration treatment is performed within the above-described preferable condition range. The criteria for determination of breakage in Table 3 are that ◯ indicates no breakage or necking, Δ indicates that breakage has not occurred, but significant necking has occurred, and x indicates that breakage has occurred. The criteria for wrinkle evaluation are divided into “large”, “medium”, and “small” according to the depth of the wrinkles that occur, and is evaluated in four levels, where no noticeable irregularities are seen. .

  First, in the case of Invention Examples 34 and 35 in which the entire deformation portion is restored on both the inner and outer sides of the bend, due to the effect of increasing elongation at break in tensile deformation, a general T1 tempered material (Comparative Examples 31 to 33) is used. In comparison, even under conditions where the bending angle is stricter, bending can be performed without breaking. At the same time, since the bending inner flange has a reduced yield strength, the wrinkles generated in this portion are also reduced. However, in the case of the inventive examples 34 and 35, since both the inner side and the outer side of the bending are restored, the case shown in FIGS. 1 and 2 is different from the case where either the inner side of the bending or the outer side of the bending is restored. Thus, the (original) bending neutral axis N0 before the restoration process is not moved to the bending neutral axis N1 by the restoration process. As a result, the bending angle at which bending can be performed without causing breakage is inferior to Invention Examples 36 to 40 in which either the inner side of the bending or the outer side of the bending is restored throughout the entire deformed portion. However, since it is remarkably superior to Comparative Examples 31 to 33 that do not perform restoration processing, this technique for restoring both the inside and outside of the bending is useful when it is desired to suppress both fracture and wrinkle during bending. .

  Next, in the case of the inventive examples 36 to 38 in which only the bending inner flange is restored, the bending angle as the breaking limit is impossible to 75 degrees as in the inventive example 38, but up to 60 degrees as in the inventive example 37. Is significantly improved, as possible. That is, the fracture limit is remarkably improved as compared with a general T1 tempered material (Comparative Examples 31 to 33). In addition, the wrinkle generation state is limited to the same level as that of the T1 tempered material, although the bending angle is a severe condition. Therefore, the method of restoring only the inside of the bend is particularly useful when it is desired to suppress the bending breakage when the bend angle is large.

  In the case of Invention Examples 39 to 41 in which only the bending outer flange is restored, the fracture limit itself is the same level as that of a general T1 tempered material (Comparative Examples 31 to 33), but wrinkles on the inner side of the bending occur. It is greatly reduced. Therefore, this method of restoring only the outside of the bend is particularly useful when it is desired to suppress the generation of wrinkles in the bending process.

  Inventive Example 41 is subjected to a restoration process for a very narrow range of only the deformed peripheral edge compared to the other inventive examples, but the degree of breakage is larger than Comparative Example 32 having the same bending angle. It has been improved. From this example of the invention, it can be seen that the bending workability can be improved by restoring only the portion where the fracture is most likely to occur, such as the deformed peripheral edge during the molding process. This effect is due to the combined effect of the effect of improving the breaking limit and the effect of making it difficult for breakage to occur by widening the region where deformation occurs in accordance with the reduction in the yield strength of the peripheral portion of the bent portion. In addition, this invention example is preferable in that it does not have the effect of improving the fracture limit as much as Invention Examples 36 and 37, but the restoration processing apparatus itself is small and the cost can be reduced. What is necessary is just to select the application range of a process.

  From these facts, when partially performing the restoration process, by controlling the part and range to be processed in relation to the type of molding process and the intended effect, the above-described fracture and the wrinkles that contradict this It can be seen that the suppression can be controlled or selected including the degree of the effect. For example, a desired effect can be obtained by restoring the outer side of the bend if the member causes wrinkles, and the inner side of the bend if the member causes fracture. As described above, the partial restoration process of the present invention suppresses one of the fractures and wrinkles, which is a major problem of the member and the molding process, as compared with a normal T1 tempered material, and the problem of the member and the molding process. It is possible to perform control or selection such that the other, which is not the same, is kept at the same level as a normal T1 tempered material. That is, in the target member (product), the application position of the restoration process can be freely controlled or selected depending on whether the fracture in bending or the wrinkle opposite to the problem occurs.

(Example 3)
As Example 3, with respect to the profile whose end portion was restored, the crushing process at both ends was simulated, and the investigation results of crackability (breakability) when this end was crushed are shown in Table 4 and FIG. Show. Moreover, the test body of this crushing process is shown in FIG. 10, and the test conditions are shown in FIG.

  FIG. 10 shows the shape of a rectangular cross section of a crushed specimen (extruded profile). In addition, the upper side of FIG. 11 schematically shows the crushing process of the end section of the test specimen (extruded profile) in a cross section, and the profile (test specimen) sandwiched from above and below by a rigid body is shown in the vertical direction as indicated by the arrows. An embodiment in which pressure is applied and crushed is shown. The lower side of FIG. 11 is a side view in which the upper side figure is embodied more specifically, and shows a rectangular shape cross section of the end of the test body (extruded profile) placed on the rigid body from the upper side. Crushing with. Then, the test piece (extruded profile) is partially crushed only at the end, so that the cross section connected to this end also moves from the original cross section indicated by the dotted line toward the end on the right side of FIG. The aspect which is changing so that it may incline (longitudinal direction) is shown.

  FIG. 9 is a graph in which Table 4 is rearranged into the body temperature of the shape of the restoration processing on the horizontal axis (described as material arrival temperature, ° C.) and the crushing rate (%) of the shape on the vertical axis. is there. FIG. 9 also shows the crushing condition of the cross section of the die in the end cross-sectional view (upper side) and the bending outer surface fracture state of the web plate (lower side: cut sample near the fractured part). For example, the plot point of the black circle on the leftmost side of the figure (temperature 25 ° C.) is the crack occurrence (break occurrence) of the T1 tempered material (Comparative Examples 42 and 43), and the black circle whose other material arrival temperature is 200 ° C. or less. Each point indicates the occurrence of cracks (break occurrence) in Comparative Examples 44 to 47 in which the restoration processing temperature outside the scope of the present invention is too low.

  As can be seen from FIG. 9 and Table 4, in each comparative example, except for the comparative example 48, fracture or necking occurs from the stage where the crushing rate is small and the cross-sectional deformation is shallow. In Comparative Examples 42 and 43, the T1 tempered material aged at room temperature for a long time (20 days) after extrusion until bending is not subjected to a restoration treatment. In Comparative Examples 44 to 47, the restoration process is performed, but the actual temperature is too low, which is not preferable.

  On the other hand, in the inventive examples 49 to 51 restored at 220 ° C. to 400 ° C., the crushing rate increased to 93%, and even at the stage where the cross-sectional deformation became deep (crushed flat), at least the outer peripheral ribs No cracks (breaks) occur in the material, and it can be crushed.

  From these results, it is desirable that the actual temperature (material arrival temperature) of the restoration process in the crushing process is 200 ° C. or higher, and the significance of improving the crushing workability by performing the restoration process within the above-described preferable range is supported. It is done. Incidentally, in Comparative Example 48, there was a result that no cracks (breaks) occurred even when the restoration treatment was performed at 170 ° C. However, necking occurred in the comparative example 47 of 160 ° C., which is close to the restoration processing temperature, and it is necessary to suppress this, considering safety and reproducibility due to material variations, etc. Considering the results of Examples 1 and 2 and the like, in the present invention, the lower limit of the substantial temperature in the restoration process is defined as 200 ° C. or higher.

  Prior to the crushing process, the processing range (region) of the extruded shape that was restored in advance was set as follows. In the case where the forming equivalent part to be processed in Table 4 is “end part” and the processing range is “whole deformation part”, the part corresponding to the crushing part is the whole part in the width direction of the crushing deformation equivalent part of the extruded profile. The length extends in the longitudinal direction of 150 mm. When the molding equivalent part of Table 4 is “end part” and the processing range is “web surface only”, only the web plate (surface with a height of 60 mm) in the range extending 150 mm from the end part in the longitudinal direction is restored. Processed.

  From the above examples, the technical significance of improving the formability of the 7000 series aluminum alloy extruded shape material itself to the member even after natural aging of each specified condition of the restoration treatment in the present invention is supported.

  ADVANTAGE OF THE INVENTION According to this invention, even after natural aging, the manufacturing method of the high strength 7000 series aluminum alloy member and the high strength 7000 series aluminum alloy member which improved formability itself can be provided. For this reason, this invention can be used suitably for structural members, such as a member for automobiles which consists of a weight-reduced high-strength 7000 series aluminum alloy, or a reinforcement member, and for airplanes.

Claims (6)

  The 7000-series aluminum alloy extruded shape, in which only a part in the longitudinal direction or the width direction has been subjected to a restoration process in advance in a state of being naturally aged without being tempered after production by extrusion, It is an aluminum alloy member that has been subjected to a forming process in the restoration processing portion and the peripheral portion thereof, and the restoration processing is heated to a temperature range of 200 to 500 ° C. at the substantial temperature of the extruded profile, and in this temperature range 7000, characterized in that it is carried out under the condition that it is cooled after being held for a short time of not less than 0.1 seconds and less than 20 seconds, and the molding process is performed within 100 minutes after the completion of the cooling of the restoration process. -Based aluminum alloy members.   The bending process is a bending process in which the longitudinal direction of the extruded profile is a circumferential direction. As a partial restoration process of the extruded profile, an arc-shaped bending deformation portion of the extruded profile in the bending process The portions corresponding to the inside and outside of the bending neutral shaft, or the portions corresponding to the inside and outside of the bending neutral shaft, and the portions corresponding to the periphery of the bending deformation portion, The 7000 series aluminum alloy member according to claim 1 provided with a difference in conditions.   The 7000 series aluminum alloy member according to claim 1 or 2, wherein the forming process is a press process for changing a partial cross-sectional shape of the extruded shape member in a longitudinal direction.   A 7000 series aluminum alloy extruded shape that has been subjected to a restoration process in advance only in a part in the longitudinal direction or the width direction in a state where it is only naturally aged without being subjected to a tempering treatment after production by extrusion, the restoration treatment part or the A method for manufacturing an aluminum alloy member, which is subjected to a forming process at a restoration processing portion and a peripheral portion thereof, wherein the restoration processing is heated to a range of 200 to 500 ° C. at a substantial temperature of the extruded profile, and this temperature range 7000, characterized in that it is cooled for a period of 0.1 seconds or more and less than 20 seconds and then cooled, and the forming process is performed within 100 minutes after the completion of the cooling of the restoration process. Method for manufacturing an aluminum alloy member.   The bending process is a bending process in which the longitudinal direction of the extruded profile is a circumferential direction. As a partial restoration process of the extruded profile, an arc-shaped bending deformation portion of the extruded profile in the bending process The portions corresponding to the inside and outside of the bending neutral shaft, or the portions corresponding to the inside and outside of the bending neutral shaft, and the portions corresponding to the periphery of the bending deformation portion, The manufacturing method of the 7000 series aluminum alloy member according to claim 4 which makes a difference in conditions.   The method for producing a 7000 series aluminum alloy member according to claim 4, wherein the forming process is a press process for changing a partial cross-sectional shape of the extruded shape member in a longitudinal direction.