JP2011252212A - Method for forming processing of 6000 series aluminum alloy material, and forming processed product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming processing of a 6000 series aluminum alloy material, which can form a more complex shaped molding product, and after artificial aging, obtain a high strengthened molding product having a proof strength of 250 MPa or more.SOLUTION: There is provided the method for forming processing of a 6000 series aluminum alloy material that includes, by mass%, 0.3-4.0% Si, 0.3-2.0% Mg, 2.0% or less Cu, 1.5% or less Mn, 1.5% or less Fe, 2.0% or less Zn, 0.50% or less Cr, 0.50% or less Zr, 0.50% or less Ti, 0.50% or less V, and the balance aluminum with inevitable impurities. The method includes the steps of: performing a solution treatment of the aluminum alloy material; forming processing the material in a die after the solution treatment; and performing a quenching treatment of the material following the forming processing by cooling the material in the die to a temperature of 250°C or less.

Description

  The present invention relates to a 6000 series aluminum alloy plate material for molding a molded product requiring high strength such as a body sheet or various housings of automobiles, automobile parts such as bumpers and stehan beams, and frames for motorcycles. 6000-series aluminum alloy material such as 6000-series aluminum alloy extruded material for forming a molded product by bending or expanding / reducing the extruded tube or extruded shape as described above, and the molding method. Related to molded products. Here, the molding processing means all of three-dimensional processing by a mold, such as press molding, hydroforming (hydraulic molding), bulge molding, superplastic molding (hot blow molding).

  In recent years, as an energy-saving measure for environmental protection, for example, in automobiles, in order to secure the conventional strength and achieve weight reduction in members such as body seats and various housings, the materials of the above members are replaced with steel plates. For example, the use of a 6000 series aluminum alloy sheet is in progress.

  However, the 6000 series aluminum alloy sheet used as the material of the above member is inferior in formability compared to the steel sheet, so that it is difficult to process into a complicated shape. From the viewpoint of formability, the medium strength 6000 series aluminum alloy sheet Is used during molding. Therefore, molding processing is performed with a room temperature aging (natural aging) treatment material after solution treatment and quenching treatment, and in order to obtain high strength, paint bake hardening or about 200 ° C. when further strength is required Heat treatment for applying temperature, that is, artificial aging is required.

  The higher the final required strength, the higher the strength required for molding using room temperature aging treatment material, and the larger the springback during molding, the lower the dimensional accuracy and the trouble in the parts assembly process. As well as this, the moldability also deteriorates.

JP 2000-96175 A

  The present invention was made in order to solve the above-mentioned conventional problems, and its purpose is limited in cold formability, but in a high-strength 6000 series aluminum alloy material excellent in hardenability, 6000 series aluminum alloy material molding method that can be molded into a more complex shape, and can obtain a high-strength molded product having a yield strength of 250 MPa or more after artificial aging (after paint baking), and The object is to provide a molded product molded by the molding method.

  The forming method of the 6000 series aluminum alloy material according to claim 1 for achieving the above object is, in mass%, Si: 0.3% to 4.0%, Mg: 0.3% to 2.0%. % Or less, Cu: 2.0% or less, Mn: 1.5% or less, Fe: 1.5% or less, Zn: 2.0% or less, Cr: 0.50% or less, Zr: 0.50% or less , Ti: 0.50% or less, V: 0.50% or less, a method of forming a 6000 series aluminum alloy material, the balance being aluminum and inevitable impurities, in which the aluminum alloy material is solutionized A step of processing, a step of performing molding in the mold after solution treatment, and a step of quenching by cooling to a temperature of 250 ° C. or less in the mold following the molding. . Hereinafter, alloy component values are expressed in mass%.

  The method for forming a 6000 series aluminum alloy material according to claim 2 includes a step of solution-treating the 6000 series aluminum alloy material according to claim 1 and, after the solution treatment, cooling to a temperature of 250 ° C. or lower and quenching treatment. And a step of performing molding in a mold within 120 hours after the quenching treatment.

  The method for forming a 6000 series aluminum alloy material according to claim 3 includes a step of solution-treating the 6000 series aluminum alloy material according to claim 1 and a step of forming the mold in a heated mold after the solution treatment. And after the molding process, the mold is released from the mold, cooled to a temperature of 250 ° C. or lower, and quenched.

  According to a fourth aspect of the present invention, there is provided a method for forming a 6000 series aluminum alloy material according to the first or second aspect, wherein the solution treatment is performed at a temperature of 400 ° C. or higher and lower than the melting point.

  The method for forming a 6000 series aluminum alloy material according to claim 5 is the method according to claim 3, wherein the solution is formed at a temperature of 400 ° C. or higher and lower than the melting point, and is heated in a mold heated to a temperature of 350 ° C. or higher and lower than the melting point. It is characterized by performing.

  The method for forming a 6000 series aluminum alloy material according to claim 6 is the method according to any one of claims 1 to 5, wherein, in the quenching process, a cooling rate from 400 ° C to 250 ° C is set to 2 ° C / second or more. And

  According to a seventh aspect of the present invention, there is provided a method for forming a 6000 series aluminum alloy material according to any one of the first to sixth aspects, wherein the solution treatment is performed in a mold.

  The method for forming a 6000 series aluminum alloy material according to claim 8 is the method according to any one of claims 1 to 7, wherein the 6000 series aluminum alloy material is a rolled material, and the hot rolling of the rolled material has a start temperature of 350 ° C. It is what was performed as mentioned above.

  The method for forming a 6000 series aluminum alloy material according to claim 9 is the method according to any one of claims 1 to 7, wherein the 6000 series aluminum alloy material is an extruded material, and hot extrusion of the extruded material has a start temperature of 350 ° C. It is what was performed as mentioned above.

  The molded product according to the present invention is characterized by being molded by the 6000 series aluminum alloy material molding method according to any one of claims 1 to 9.

  According to the present invention, a 6000 series aluminum alloy material that can be molded into a more complex shape and can obtain a high-strength molded product having a yield strength of 250 MPa or more after artificial aging (after paint baking). A molding method and a molded product molded by the molding method are provided.

The significance and reasons for limitation of the alloy components in the present invention will be described.
Si:
Si functions to improve strength. The preferred content is in the range of 0.3% to 4.0%. If it is less than 0.3%, the strength is not sufficient, and if it exceeds 4.0%, the moldability is remarkably deteriorated. A more preferable content range is 0.6% or more and 2.0% or less, and a more preferable content range is 0.7% or more and 1.4% or less.

Mg:
Mg functions together with Si to improve strength. The preferred content is in the range of 0.3% to 2.0%. If the content is less than 0.3%, the strength is not sufficient. To do. A more preferable content range is 0.4% or more and 1.2% or less, and a more preferable content range is 0.6% or more and 1.0% or less.

Cu:
Cu contributes to strength improvement together with Si and Mg. The preferable content is in the range of 2.0% or less, and the higher the content, the higher the strength can be obtained. However, when the content exceeds 2.0%, the moldability is remarkably deteriorated and the corrosion resistance is deteriorated. A more preferable content range of Cu is 1.5% or less, and a range of 0.6% or more and 1.2% or less is preferable in consideration of molding processability.

Mn:
Mn refines crystal grains and improves strength. The preferred content is in the range of 1.5% or less, and if it exceeds 1.5%, ingot cracking tends to occur. A more preferable content range is 0.2% or more and 1.0% or less.

Fe:
Fe is likely to be contained as an impurity, and the higher the allowable amount, the better the recyclability. However, if the content exceeds 1.5%, the moldability deteriorates, and cracks are likely to occur during production. Therefore, the content of Fe is preferably in the range of 1.5% or less, and the more preferable content range is 0.5% or less. In addition, if the Fe content is less than 0.03%, it is necessary to use an expensive high-purity aluminum ingot, which increases the cost.

Zn:
Zn does not significantly affect the material properties, but the greater the allowable amount, the better the recyclability. If the content exceeds 2.0%, the corrosion resistance deteriorates, so the content is preferably 2.0% or less. A more preferable content range is 0.5% or less.

Cr, Zr, Ti, V:
Cr, Zr, Ti and V contribute to the improvement of strength by refining crystal grains. Preferable contents are each in the range of 0.50% or less, and when each exceeds 0.50%, ingot cracking and hot cracking are likely to occur and a coarse intermetallic compound is likely to be formed, and molding processing is performed. Deteriorates. The more preferable content ranges of Cr, Zr, Ti, and V are each 0.30% or less, and the more preferable content ranges are each 0.20% or less.

  The first characteristic step of the present invention is a method of forming a 6000 series aluminum alloy material having the above composition, a step of solution-treating the aluminum alloy material, and forming in a mold after the solution treatment. It includes a step of performing processing and a step of quenching by cooling to a temperature of 250 ° C. or lower in the mold following the molding process.

  When the quenching process is completed at a temperature exceeding 250 ° C., quenching becomes insufficient, the moldability deteriorates, and it becomes difficult to obtain sufficient strength by subsequent artificial aging.

  The process characterized by the second feature of the present invention is that the 6000 series aluminum alloy material is solution treated, cooled to a temperature of 250 ° C. or lower, quenched, and molded in a mold within 120 hours after quenching. Processing is performed. If the time until quenching after quenching exceeds 120 hours, the strength becomes too high due to natural aging, making the molding difficult. More preferably, the molding process is performed within 2 hours.

  According to a third feature of the present invention, the 6000 series aluminum alloy material is subjected to a solution treatment, molded in a heated mold, and then released from the mold to a temperature of 250 ° C. or lower. It is cooled to a quenching process. The quenching in this case may be performed in a mold different from the mold used in the molding process, or may be released from the mold and subjected to forced air cooling such as air blow or mist cooling to obtain a quenching effect. Any means that can be used is preferably employed.

  The solution treatment conditions are preferably 450 ° C. or higher and lower than the melting point. If the solution treatment temperature is less than 450 ° C., sufficient strength cannot be obtained. A more preferable solution treatment temperature is 500 ° C. or higher. The solution treatment time can be appropriately set according to the solution treatment temperature as long as the effect of solution treatment is obtained. For example, if it is close to the melting point, the effect of solution treatment can be obtained even if it is 1 second, but if a time that satisfies the entire solution treatment temperature range is set, 5 seconds or more and 600 seconds or less are adopted. If it is less than 5 seconds, it is difficult to obtain sufficient strength, and if it exceeds 600 seconds, the production cost increases.

  Moreover, it can also shape | mold after performing a solution treatment in multiple times. For example, by cooling the material subjected to the first solution treatment to room temperature and then performing the second solution treatment, the required strength and moldability can be easily obtained even if the second holding time is short. . In this case, regarding the cooling after the solution treatment, only the cooling rate during the molding process is defined in the process characterized by the first feature of the present invention, and in the process characterized by the second characteristic, If only the cooling rate is defined and only the cooling rate after the molding process is defined in the third feature step, the required performance can be obtained.

  The heating temperature of the mold in the third characteristic step of the present invention is preferably 400 ° C. or higher and lower than the melting point of the 6000 series aluminum alloy material. When the temperature is lower than 400 ° C., solid solution elements are precipitated during the molding process, and the molding processability is deteriorated and the strength after the molding process is lowered.

  In quenching, it is desirable that the cooling rate from 450 ° C. to 250 ° C. is a rapid cooling of 5 ° C./second or more. If the cooling rate in this temperature range is less than 5 ° C./second, the strength may decrease. A more desirable cooling rate is 20 ° C./second or more.

  Next, the desirable manufacturing method until the solution treatment of the aluminum alloy material of the present invention will be described. As the manufacturing method, mainly casting, homogenization treatment, hot working, and cold working steps are employed. In the case of a plate material, hot rolling is generally used for hot working, and cold rolling is generally used for cold working, but cold rolling is not necessarily required. In the case of an extruded material, extrusion is generally used for hot working, and drawing is generally used for cold working. Drawing can be omitted and solution treatment can be performed as it is extruded. In addition, said manufacturing method is one embodiment, It is not limited to this.

  Specifically, it is preferable that ingots are formed by a DC casting method, and the homogenization heat treatment is performed at a temperature of 400 ° C. or higher and lower than the melting point for 2 hours to 100 hours. If the temperature of the homogenization heat treatment is less than 400 ° C. or less than 2 hours, the moldability deteriorates. Further, if the time for the homogenization heat treatment exceeds 100 hours, the production cost may be remarkably increased.

  In the hot working, it is preferable that the starting temperature is 350 ° C. or higher and lower than the melting point. If the hot working start temperature is less than 350 ° C., the deformation load increases, which requires a lot of processing time, which may increase the manufacturing cost.

  Intermediate annealing may be performed after hot working, before cold working, or in the middle of cold working. When intermediate annealing is performed, the cold working rate after intermediate annealing is preferably 30 to 80%. When intermediate annealing is not performed, the cold working rate after hot working is 30 to 80%. Is preferable. The higher the cold working rate, the higher the strength due to the effect of crystal grain refinement, but there is a risk of increasing the manufacturing cost by cold working.

  The molded article produced by the processes characterized by the first, second and third features of the present invention has a high strength with a yield strength of 250 MPa or more after artificial aging.

  According to the method of forming a 6000 series aluminum alloy material according to the present invention, for example, in the production of automobile body seats, various casing members, automobile parts such as bumpers and stehan beams, motorcycle frames, etc., the 6000 series An aluminum alloy material can be easily and reliably formed and applied, and the required strength can be ensured and weight reduction can be achieved. Therefore, it can greatly contribute to environmental protection from the viewpoint of energy saving.

  Examples of the present invention will be described below in comparison with comparative examples to demonstrate the effects. In addition, these Examples are for showing one embodiment of the present invention, and the present invention is not limited to these.

Example 1 and Comparative Example 1
Aluminum alloys (E1 to E12) and aluminum alloys (C1 to C10) having the compositions shown in Table 1 were agglomerated by DC casting and subjected to homogenization heat treatment at 520 ° C. for 10 hours. Next, hot rolling is started at 500 ° C. and hot rolling is performed to a plate thickness of 4 mm, followed by intermediate annealing at 350 ° C. for 2 hours to cool the furnace to room temperature, and then cold rolling is performed. The plate thickness was 1.5 mm. The obtained cold-rolled material was cut into a plate width of 200 mm and a length of 250 mm (plate thickness of 1.5 mm) to obtain an aluminum alloy plate material (test material) for use in forming processing. In Table 1, those outside the conditions of the present invention are underlined.

The obtained test material (aluminum alloy plate material) was subjected to the following forming process, and the forming processability and mechanical properties were evaluated.
After applying a release agent to the aluminum alloy sheet in advance, the aluminum alloy sheet is mounted on an iron heating device composed of an upper mold and a lower mold, and is rapidly heated to a temperature of 540 ° C. and held for 60 seconds. After being performed, it is sandwiched and fixed between the upper mold and the lower mold constituting the mold set to 50 ° C., and simultaneously with press molding, it is rapidly cooled and quenched in the same mold, and a cross-sectional core having a bottom surface is obtained. A letter-shaped press-molded product was produced.

  The obtained press-formed product was observed for occurrence of cracks, and JIS Z2241 and JIS No. 5 test pieces were collected from the bottom surface of the press-formed product to measure mechanical properties (before paint baking treatment). After press molding, after aging for 1 week at room temperature, an artificial aging treatment was performed at a temperature of 170 ° C. for 8 hours, and the mechanical properties (after paint baking treatment) were measured. The results are shown in Table 2.

  As shown in Table 2, all of the test materials 1 to 12 according to the present invention exhibit good moldability without causing cracks in the press-molded product, and the proof stress close to 200 MPa even before the coating baking process, After baking, it was confirmed that it had high strength with a yield strength exceeding 300 MPa.

  On the other hand, since the test material 13 has a large Si content, the moldability is inferior. Since the test material 14 has a high Mg content, the hardenability is poor and the mechanical properties are inferior. Since the test material 15 has a high Cu content, the moldability is inferior. Since the test material 16 has a high Mn content, ingot cracking occurs, and since the test material 17 has a high Fe content, cracks occur in the manufacturing process, both of which produce test materials (aluminum alloy plate materials). could not.

  The test material 18 had a large content of Zn and was inferior in corrosion resistance, and cracking occurred in the molding process. Since each of the test materials 19, 20, and 21 has a large content of Cr, Zr, and Ti, all of them have poor moldability. Since the test material 22 had a low Mg content, the strength was low.

Example 2 and Comparative Example 2
Using the ingot of the aluminum alloy E1 formed in Example 1, this ingot was subjected to homogenization heat treatment at 520 ° C. for 10 hours, and then hot rolling was started at the hot rolling start temperature shown in Table 3, and the plate thickness was 4 mm. The steel sheet was hot-rolled to an intermediate annealing temperature of 370 ° C. for 1 hour, cooled in the furnace to room temperature, and then cold-rolled to a thickness of 1.5 mm. The obtained cold-rolled material was cut into a plate width of 200 mm and a length of 250 mm (plate thickness of 1.5 mm) to obtain an aluminum alloy plate material (test material) for use in forming processing. In Table 3, those outside the conditions of the present invention are underlined.

The obtained test material (aluminum alloy plate material) was subjected to the following forming process, and the forming processability and mechanical properties were evaluated.
After the aluminum alloy plate (test material) is rapidly heated to a temperature of 540 ° C. and held for 60 seconds, after the solution treatment, a quenching treatment is performed to cool to room temperature at a cooling rate of 50 ° C./s. After 10 minutes have passed, the room mold is clamped between the upper mold and the lower mold, press-molded using a low-viscosity lubricant, and a rectangular U-shaped press having a rectangular bottom A molded product was produced.

  The obtained press-molded product was observed for occurrence of cracks, and JIS Z2241 and JIS No. 5 test specimens were collected from the bottom surface of the press-molded product and measured for mechanical properties (before paint baking treatment). After press molding, after aging for 1 week at room temperature, an artificial aging treatment was performed at a temperature of 170 ° C. for 8 hours, and the mechanical properties (after paint baking treatment) were measured. The results are shown in Table 4.

  As shown in Table 4, all of the test materials 23 to 25 according to the present invention showed good forming workability without causing cracks in the press-formed product, and the proof stress and coating near 200 MPa even before the coating baking process. After baking, it was confirmed that it had high strength with a yield strength exceeding 300 MPa.

  On the other hand, since the test material 26 had a hot rolling start temperature that was too high, cracking occurred during hot rolling, and the test material could not be manufactured. Since the test material 27 has a low hot rolling start temperature, the hot rolling cost is remarkably increased, and the strength is also lowered.

Example 3 and Comparative Example 3
Using the ingot of the aluminum alloy E4 ingoted in Example 1, this ingot was subjected to homogenization heat treatment at 530 ° C. for 8 hours, hot rolling was started at 480 ° C., and hot rolling was performed to a plate thickness of 4 mm. Intermediate annealing at 370 ° C. for 1 hour was performed to cool the inside of the furnace to room temperature, and then cold rolling was performed to obtain a plate thickness of 1.5 mm. The obtained cold-rolled material was cut into a plate width of 200 mm and a length of 250 mm (plate thickness of 1.5 mm) to obtain an aluminum alloy plate material (test material) for use in forming processing.

  After applying a molybdenum disulfide-based release agent to the obtained aluminum alloy sheet (test material) in advance, solution treatment is performed under the solution treatment conditions shown in Table 5 to obtain 500 test materials after solution treatment. After pressing and molding between the upper mold and the lower mold constituting the mold set at ℃, the obtained press-molded product is once taken out from the mold, and the room temperature mold composed of the upper mold and the lower mold Then, it was rapidly cooled and quenched at a cooling rate of 50 ° C./second to produce a U-shaped press-formed product having a bottom surface. In Table 5, those outside the conditions of the present invention are underlined.

  The obtained press-molded product was observed for occurrence of cracks, and JIS Z2241 and JIS No. 5 test specimens were collected from the bottom surface of the press-molded product and measured for mechanical properties (before paint baking treatment). After the quenching treatment, the mixture was aged at room temperature for 1 week, then subjected to an artificial aging treatment at 170 ° C. for 8 hours, and the mechanical properties (after the baking treatment) were measured. The results are shown in Table 6.

  As shown in Table 6, all of the test materials 28 to 31 according to the present invention showed good moldability without causing cracks in the press-molded product, and the proof stress and coating near 200 MPa even before the coating baking process. After baking, it was confirmed that it had high strength with a yield strength exceeding 300 MPa.

  On the other hand, the test materials 32 and 33 were inferior in strength because the solution treatment time was short and the test material 34 was low in solution treatment temperature.

Claims (10)

In mass% (hereinafter, alloy component values are expressed in mass%), Si: 0.3% to 4.0%, Mg: 0.3% to 2.0%, Cu: 2.0% or less, Mn: 1.5% or less, Fe: 1.5% or less, Zn: 2.0% or less, Cr: 0.50% or less, Zr: 0.50% or less, Ti: 0.50% or less, V: A method of forming a 6000 series aluminum alloy material containing 0.50% or less, the balance being aluminum and inevitable impurities, a solution treatment of the aluminum alloy material, and after the solution treatment, A method of forming a 6000 series aluminum alloy material, comprising: a step of forming in a mold; and a step of cooling to a temperature of 250 ° C. or lower in the mold following the forming process and quenching. A solution treatment of the 6000 series aluminum alloy material according to claim 1, a step of cooling to a temperature of 250 ° C. or less after the solution treatment, and a quenching treatment within 120 hours after the quenching treatment. A method for forming a 6000 series aluminum alloy material, comprising a step of performing a forming process. A step of solution-treating the 6000 series aluminum alloy material according to claim 1; a step of forming a solution in a heated mold after the solution treatment; and A method for forming a 6000 series aluminum alloy material, comprising a step of cooling to the following temperature and quenching. The method for forming a 6000 series aluminum alloy material according to claim 1, wherein the solution treatment is performed at a temperature of 400 ° C. or higher and lower than the melting point. The method for forming a 6000 series aluminum alloy material according to claim 3, wherein the solution is formed at a temperature of 400 ° C or higher and lower than the melting point, and is formed in a mold heated to a temperature of 350 ° C or higher and lower than the melting point. . The method for forming a 6000 series aluminum alloy material according to any one of claims 1 to 5, wherein a cooling rate from 400 ° C to 250 ° C is set to 2 ° C / second or more in the quenching treatment. The method for forming a 6000 series aluminum alloy material according to any one of claims 1 to 6, wherein the solution treatment is performed in a mold. The 6000 series aluminum alloy material according to any one of claims 1 to 7, wherein the 6000 series aluminum alloy material is a rolled material, and the hot rolling of the rolled material is performed at a start temperature of 350 ° C or higher. Of forming aluminum-based aluminum alloy material. The 6000 series aluminum alloy material according to any one of claims 1 to 7, wherein the 6000 series aluminum alloy material is an extruded material, and the hot extrusion of the extruded material is performed at a start temperature of 350 ° C or higher. Of forming aluminum-based aluminum alloy material. A molded product formed by the method for molding a 6000 series aluminum alloy material according to any one of claims 1 to 9.