JP2517445B2 - A1 alloy plate for forming diaphragm and method for manufacturing the same - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

TECHNICAL FIELD The present invention relates to an aluminum alloy for forming a diaphragm of a thermoplastic resin composite material, that is, an aluminum alloy for performing a diaphragm forming process of a thermoplastic resin composite material at 200 to 450 ° C.

[Prior art]

In recent years, mainly in the field of aircraft, the demand for FRP (fiber reinforced composite material) having high strength and high elastic modulus is increasing. Initially, composite materials in which fibers such as carbon were impregnated with an epoxy thermosetting resin were developed, but these FRPs have the drawback of being inferior in heat resistance and impact resistance. Recently, in place of thermosetting resin, a fiber-reinforced composite material in which fibers are impregnated with a thermoplastic resin has been developed, and it is rapidly expanding into composite material products related to aerospace. PEEK (polyetheretherketone), PAK (polyaryleneketone), etc. are often used as the thermoplastic resin, but since they are all cured at room temperature, room temperature molding such as pressing cannot be performed. Therefore, these FR
P needs to be molded in a heat-softened state, cooled to room temperature and cured. More specifically, it is generally carried out by sandwiching it between thermoplastic resins in which fibers are impregnated with a material having excellent warm moldability such as aluminum and performing warm pressing or diaphragm molding (pressure molding).

[Problems to be solved]

In recent years, various studies have been conducted on superplastic aluminum alloy materials that show elongation of 300% or more at a high temperature of 400 ° C or more. As a superplastic aluminum alloy, Al-78% Zn, A
l-33% Cu, Al-6% Cu-0.4% Zr (SUPRAL), Al-Zn-Mg
-Cu alloy (7475,7075), Al-2.5-6% Mg-0.05-0.6%
Zr alloy and the like are known. However, these thermoplastic alloys, except SUPRAL, have low elongation at low temperatures, and 0.8T _M (T _M :
It is empirically known that heating at a melting point of about K) is required, which is much higher than the molding temperature of a resin such as PEEK. Actually, the superplastic aluminum alloy was tried to be used for the diaphragm molding of the thermoplastic resin-based composite material, but it was confirmed that there were the following problems. That is, although superplastic aluminum alloys are generally excellent in formability at high temperatures above 450 ° C, they are inferior in formability in the temperature range of diaphragm formation of thermoplastic resin-based composite materials over 200 to 450 ° C, and are optimal. Since the strain rate under the conditions is slow, it takes a long time to mold in the case of production on a factory scale, resulting in poor productivity. Al-6% Cu-0.4% Zr (SUPRAL) is the only aluminum alloy that has been used as an aluminum alloy for the diaphragm forming process of thermoplastic resin-based composite materials. Poor performance and high cost,
Furthermore, since it contains a high concentration of Cu, it is difficult to recycle even though it is a disposable application. The present invention was born in the background of the above circumstances,
To provide an aluminum alloy having excellent formability (especially elongation) in the temperature range of 200 ° C to 450 ° C in a warm diaphragm forming process of a thermoplastic resin composite material by a simple production method. The purpose is.

[Means for solving the problem]

As a result of intensive studies by the present inventors in order to solve the above-mentioned problems, the amounts of components of the aluminum alloy, particularly the amounts of Mg and impurity elements of main additive components, the grain size of the intermetallic compound after the final annealing, and the diaphragm forming It was found that an Al alloy suitable for diaphragm forming of a thermoplastic resin composite material can be obtained by appropriately adjusting the shape of recrystallized grains at that time, and the present invention was accomplished. That is, claim 1 contains Mg: 2.0 to 6.0% (by weight, the same applies hereinafter) Be: 0.0001% to 0.01%, and Ti: 0.001% to 0.15% alone or B: 0.0001 for grain refinement. % -0.05% at the same time, Fe as impurities: 0.2% or less, Si: 0.2% or less, Mn: 0.05% or less, Cr: 0.05%
Below, Zr: 0.05% or less, V: 0.05% or less, consisting of balance and other unavoidable impurities and aluminum, and the particle size of intermetallic compound particles based on impurities during diaphragm forming is 10 μm or less at the maximum, and A thermoplastic resin system characterized in that the recrystallized grains during diaphragm forming are (average of grain size in rolling direction / average grain size in sheet thickness direction) ≦ 1.5 in a cross section parallel to the rolling direction. Al alloy plate for diaphragm formation of composite materials. Claim 2 further contains, as an additive component, one or two of Cu: 0.05 to 2.0% and Zn: 0.2 to 2.5%.
An aluminum alloy plate for forming a diaphragm according to. According to claim 3, a semi-continuous ingot of the alloy having the chemical composition according to claim 1 or 2 is heated at 450 ° C to 580 ° C for 0.5 to 48 hours, and then hot rolled at a starting temperature of 400 ° C to 530 ° C. Manufacture of Al alloy plate for diaphragm forming of thermoplastic resin composite material characterized by cold rolling with intermediate annealing step depending on the above, and cold rolling by at least 15% before final recrystallization treatment Method. A fourth aspect of the present invention is a continuous cast sheet of the alloy having the chemical composition according to the first or second aspect, which is cold-rolled with an intermediate annealing step if necessary, and cold-rolled by at least 15% or more before the final recrystallization treatment. A method for producing an aluminum alloy plate for forming a diaphragm of a thermoplastic resin-based composite material, which comprises rolling. Is.

[Action]

First, the reasons for limiting the component composition of the present invention are shown below. Mg: Mg improves warm workability by promoting work softening or dynamic recrystallization during warm working. If it is less than 2%, the strength is insufficient and the warm workability is insufficient, and if it exceeds 6%, the hot rolling property / cold rolling property is deteriorated, and the production becomes difficult. Therefore, the amount of Mg is set to 2 to 6%. Be; Add Be to prevent Mg oxidation during melting and to prevent galling during diaphragm molding. When Be is less than 0.0001%, this effect does not exist, and when Be exceeds 0.01%, the effect is saturated. Ti, B; Ti is added alone or at the same time as B for refining the ingot crystal grains. However, if Ti is less than 0.001%, this effect does not exist, and if it exceeds 0.15%, primary TiAl ₃ particles are crystallized. Further, when B is added, if B is less than 0.0001%, there is no effect, and if it exceeds 0.05%, TiB ₂ particles are generated. Cu, Zn; Cu, Zn improves the strength, increases the stacking fault energy, and strengthens the dislocation cell structure during processing. If Cu and Zn are less than 0.05% and 0.2%, respectively, this effect is insufficient.If Cu and Zn exceed 2.0% and 2.5%, respectively, corrosion resistance decreases and Cu and Zn precipitate at grain boundaries, causing a warm elongation. Is reduced. Impurities Fe, Si, Mn, Cr, Zr, V, etc .; If Fe, Si, Mn, Cr, Zr, V, and other impurities are contained in large amounts, coarse intermetallic compounds are likely to be generated during casting. The formed intermetallic compounds cannot be removed by the subsequent thermomechanical treatment. These intermetallic compounds are
If it is 10 μm or more, it becomes a starting point of breakage during diaphragm molding, and the diaphragm moldability is remarkably reduced. Therefore
Fe 0.2% or less, Si 0.2% or less, Mn 0.05% or less, Cr 0.0%
5% or less, Zr is 0.05% or less, and V is 0.05% or less. The total amount of other impurities is 0.1% or less. Next, the reasons for limiting the metal composition are shown below. Particle diameter of intermetallic compound particles based on impurities; When the intermetallic compound has a particle size of 10 μm or more, it becomes a starting point of fracture during diaphragm molding, and the diaphragm moldability is remarkably deteriorated. Therefore, the intermetallic compound must be 10 μm or less at the maximum during the diaphragm forming process. Recrystallized grain shape during diaphragm forming process: In the temperature range of diaphragm forming of thermoplastic resin composite material that spans 200 to 450 ° C, "intragranular deformation" and "(dynamic and static) recrystallization repeat" Deform. If the recrystallized grain shape during diaphragm forming is flat, "intra-grain deformation"
In (3), local stress concentration is likely to cause fracture, and in "(dynamic and static) recrystallization", non-uniform recrystallization occurs, so that local stress concentration is likely to cause fracture. Therefore, in the present invention, as a measure of the flatness of the recrystallized grain shape during the diaphragm forming process, (average grain size in rolling direction / average grain size in plate thickness direction) is taken in a cross section parallel to the rolling direction. , Requires that this value be less than or equal to 1.5. The particle size and recrystallized particle shape of the intermetallic compound particles should be satisfied when the diaphragm is formed. Therefore, the value measured after the residual heat of the diaphragm forming process (for example, holding at 400 ° C. for 5 minutes) immediately before the actual diaphragm forming process may satisfy the above. However, this is usually impossible except in the case of performing simulation heating, and when recrystallized in the final annealing of the plate manufacturing process, there is little change in the structure between the final annealing and the diaphragm forming process. Therefore, for the sake of convenience, it is only necessary that the measured value at the stage of the final annealed plate satisfies the above. Finally, the manufacturing method will be described. Casting: As a casting method, semi-continuous casting (DC casting) is generally used. Ingot heating: The ingot is heated at 450 ° C to 580 ° C for 0.5 to 48 hours. This heating may be performed in one step or may be performed in multiple steps in combination with soaking. When performing in multiple stages, the condition at the highest temperature among them should satisfy this heat treatment condition. If heating below this condition, the hot rolling start temperature will be 400
It becomes difficult to bring the temperature to ℃, and there is no homogenizing effect. Heating above this condition may lead to coarsening of the intermetallic compound, impairing diaphragm formability, and possibly causing eutectic melting. Hot rolling start temperature: Hot rolling property deteriorates below 400 ° C, and exceeds 530 ° C
Due to the high temperature embrittlement of Mg, ear cracks are likely to occur during hot rolling. Therefore, it should be 400-530 ℃. Cold reduction rate before final recrystallization treatment: If it is less than 15%, recrystallization does not occur during final recrystallization treatment or non-uniform recrystallization occurs, resulting in deterioration of diaphragm formability. Therefore, it should be 15% or more. In the case of batch annealing, 250 ° C to 450 ° C for 0.5 to 24 hours, and in the case of continuous annealing, 300 ° C to 580 ° C without holding or for 5 minutes or less, hot rolling and cold rolling and / or Alternatively, the effect of the present invention will not be impaired even if intermediate annealing is appropriately performed during cold rolling. What is required is a cold reduction ratio of 15% or more before the final recrystallization treatment. Final recrystallization treatment: Generally, final annealing is performed to obtain a recrystallized structure. However, the diaphragm molding is the softening temperature of the thermoplastic resin,
That is, since the process is carried out at 200 ° C. to 450 ° C., the material in which the thermoplastic resin is sandwiched between the aluminum materials is recrystallized by being set in the heated molding machine and being held until the material reaches a predetermined temperature. Alternatively, if another preheating furnace is used for preheating and the temperature of this preheating is 250 ° C. or higher and recrystallization occurs during preheating, it is not necessary to make a recrystallization structure by final annealing in the plate manufacturing process. Absent. The conditions may be the temperature and the holding time for recrystallization, and when annealing, continuous annealing or batch annealing may be used. In the case of batch annealing, it is generally performed at 250 ° C to 400 ° C for 0.5 hour or longer, and in the case of continuous annealing, it is kept at 350 ° C to 550 ° C for no holding or at most 180 seconds. In the above, the casting method has been described by using the example of using semi-continuous casting (DC casting), but continuous casting (CC casting) may also be used. In this case, since hot rolling is unnecessary, it is not necessary to heat the continuous casting plate instead of heating the ingot. Summarizing the above, the method for producing an aluminum alloy plate of the present invention has the following viations. However,
Steps in parentheses are optional steps. Semi-continuous casting → Ingot heating → Hot rolling → (Intermediate annealing) → Cold rolling → (Intermediate annealing) → Cold rolling → (Final annealing) Continuous casting → (Continuous cast plate heating) → Cold rolling → (Intermediate casting Annealing) →
Cold rolling → (final annealing)

【Example】

An alloy with the composition shown in Table 1 was DC cast into a size of 1000 mm x 400 mm in cross section, and the ingot was homogenized at 530 ° C for 10 hours and heated at 500 ° C for 3 hours to 450 ° C. After that, hot rolling was started to finish the plate thickness to 4 mm, and this hot rolled plate was cold rolled to a plate thickness of 1 mm (cold rolling rate 75%), and then 350 ° C.
× Final annealing for 2 hours was performed. In addition, an alloy having almost the same composition as alloys 1 and 3 was CC cast into a size of 3.0 mm thick and 400 mm wide and cold-rolled to a plate thickness of 1 mm (cold rolling rate 66.
After 6%), a plate that was subjected to final annealing at 350 ° C. for 2 hours was also prepared, and alloys 1 ′ and 3 ′ were prepared. Polish the material after this final annealing parallel to the rolling surface, The maximum size of the intermetallic compound particles was measured using an image analyzer. The results are shown in Table 2. The size of the intermetallic compound particles of the invention alloy is smaller than that of the comparative alloy. Next, the elongation in a warm tensile test at 400 ° C. was measured to compare the diaphragm moldability of the thermoplastic resin-based composite materials. The results are shown in Table 3. The warm elongation of the invented alloy is larger than that of the comparative alloy, and this difference increases as the strain rate increases. Furthermore, the plate cold-rolled to a thickness of 1 mm was 350 ° C x 2
The material that has been finally annealed for a certain time, and the material that has not been finally annealed at this stage of the plate manufacturing process, but that is recrystallized by being kept at the elevated temperature in the next bulge forming machine. 8 layers of 0.1 mm PEEK resin are sandwiched and the temperature is 4
After holding at 00 ℃ for 5 minutes, perform diaphragm molding by performing bulge molding with a diameter of 100 mm. Measure the bulge molding height and the crystal grain size after holding at 400 ℃ for 5 minutes and measure the rolling direction. The ratio in the plate thickness direction (average grain size in rolling direction / average grain size in sheet thickness direction) was calculated. The results are shown in Table 4. The crystal grain shape of the invention alloy is flatter than that of the comparative alloy (average grain size in rolling direction / average grain size in sheet thickness direction) is 1.5 or less, and the forming height of the invention alloy is Compared to the comparative alloy, it is larger in a shorter time. Next, for reference, superplasticity and room temperature strength after warm forming are compared with a conventional Al-Mg-based alloy that is a typical structural material. JIS5 from the material that was warm-stretched at 400% at 50%
No. 4 test piece was cut out and a tensile test was performed at room temperature. The results are shown in Table 5. The invention alloy has a strength equal to or higher than that of the conventional alloy that was not subjected to warm drawing when compared at the same level of Mg content even after warm forming, and can be used as a superplastic forming material.

[Effect] From the above results, according to the present invention, it is possible to obtain a material having an unprecedentedly excellent thermoplastic resin composite diaphragm formability, and to measure the productivity of the thermoplastic resin composite. It is possible to improve without fail. Further, the material of the present invention can be used not only for diaphragm molding, but also for superplastic molding or warm molding as it is, a complex-shaped instrument or other, electric control storage housing,
It is suitable for applications such as measurement cabinets, VTRs and other chassis for weak electrical equipment, and parts such as automobile bodies, gasoline tanks, and oil pans.

Claims (4)

(57) [Claims] 1. Including Mg: 2.0 to 6.0% (by weight, the same applies hereinafter) Be: 0.0001% to 0.01%, and Ti: 0.001% to 0.15% alone or B: 0.0001% to refine grain size. 0.05% at the same time, Fe as impurities: 0.2% or less, Si: 0.2% or less, Mn: 0.05% or less, Cr: 0.05%
Below, Zr: 0.05% or less, V: 0.05% or less, consisting of balance and other unavoidable impurities and aluminum, and the particle size of intermetallic compound particles based on impurities during diaphragm forming is 10 μm or less at the maximum, and A thermoplastic resin system characterized in that the recrystallized grains during diaphragm forming are (average of grain size in rolling direction / average grain size in sheet thickness direction) ≦ 1.5 in a cross section parallel to the rolling direction. Al alloy plate for diaphragm formation of composite materials. 2. An additive component further containing one or two of Cu: 0.05 to 2.0% and Zn: 0.2 to 2.5%.
An aluminum alloy plate for forming a diaphragm according to. 3. A semi-continuous ingot of the alloy having the chemical composition according to claim 1 or 2 is heated at 450 ° C. to 580 ° C. for 0.5 to 48 hours, and then hot rolled at a starting temperature of 400 ° C. to 530 ° C. An aluminum alloy plate for diaphragm forming of a thermoplastic resin composite material, which is cold-rolled with an intermediate annealing step if necessary, and cold-rolled by at least 15% or more before the final recrystallization treatment. Production method. 4. A continuous cast sheet of an alloy having the chemical composition of claim 1 or 2 is cold-rolled with an intermediate annealing step if necessary, and cold-rolled by at least 15% or more before the final recrystallization treatment. A method for producing an aluminum alloy plate for forming a diaphragm of a thermoplastic resin-based composite material, which comprises rolling.