JPS59162261A - Production of hard aluminum alloy plate for forming - Google Patents

Abstract

PURPOSE:To produce inexpensively a hard Al alloy plate for deep drawing having high strength by subjecting a cast ingot of an Al alloy having the specific compsn. contg. Mn, Mg, Si, Fe, Cu, etc. to a homogenizing treatment and hot working then, cooling slowly followed by cold rolling. CONSTITUTION:A cast ingot of an Al alloy contg. >=1 kind of 0.1-2.0% Mn and 0.1-2.0% Mg, and 0.1-0.7% Si, 0.1-0.7% Fe, and 0.05-0.3% Cu and the balance substantially Al is subjected to a homogenizing treatment and is then subjected to hot rolling to the thickness of >=2 times of the final thickness in such a way that the hot rolling ends at >=300 deg.C. The hot-rolled Al alloy is cooled for >=2hr in the succeeding cooling stage by insulating the heat with a heat insulating material according to need in the temp. region from the end temp. of the hot rolling to 280 deg.C and thereafter the Al alloy is cold-rolled down to the final thickness without annealing, by which the hard Al alloy plate for forming, particularly for deep drawing having high strength and low anisotropy is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an aluminum alloy hard root used as a deep drawn material for producing aluminum alloy cans, caps, etc., and other forming materials.

In hard plates made of aluminum alloys used for cans, caps, etc., such as A3003 and A3004 (Al-Mn-based) alloys, it is possible to reduce the selvage in the 45° direction to the rolling direction that occurs during deep drawing. It is necessary, and the ear percentage is desired to be 3% or less.

Conventionally, a series of steps consisting of ingot formation, homogenization treatment, hot rolling, intermediate annealing, and cold rolling has been adopted to manufacture hard fabrics with a low selvage ratio.

However, the selvage ratio of the hard plate is determined depending on the conditions of intermediate annealing and subsequent cold rolling. In the series of steps mentioned above, especially if intermediate annealing is omitted, the selvage ratio increases due to the formation of cold rolling texture, so intermediate annealing becomes an important part of the hard plate manufacturing process. If there were a method that could provide the required formability to a hard plate without intermediate annealing, it would be possible to significantly reduce manufacturing costs, but such a method has not yet been proposed. Not yet.

Cold rolling after intermediate annealing gives the alloy plate sufficient strength. Generally, rolling is carried out at a rolling rate of 70 to 90%, and as a result, a texture is formed and the edges in the 45° direction due to deep drawing become high. Therefore, by reducing the rolling rate of cold rolling to reduce the strength and suppressing the 45° selvage, or by taking other measures to reduce the 45° selvage before cold rolling, cold rolling is improved. A method is being used to increase the strength of the plate by increasing the rolling rate.

The present invention provides a high-strength product that can reduce the selvage ratio of the product hard plate even if the intermediate annealing in the conventional manufacturing method is omitted, and can perform sufficient cold working in the process. The object of the present invention is to provide a method for manufacturing an aluminum alloy hard plate for forming, particularly deep drawing, with low anisotropy.

That is, the gist of the present invention is as follows.

Mn: 0.1-2.0% and Mg: 0.1-2.0% 1
species or more, Si: 0.1-0.7%, Fe: 0.1-0
．． After homogenizing an aluminum alloy ingot containing 7% Cu, 0.05 to 0.3% Cu, and the remainder being substantially Al, it is hot rolled to a thickness more than twice the final plate thickness. ni, and 3
In the subsequent cooling process, the temperature range from the hot rolling end temperature to 280°C is cooled for 2 hours or more, and then cold rolling is performed to the final thickness without annealing. It is characterized by applying rolling.
A method for manufacturing aluminum alloy hard plates for forming.

The present invention will be explained below.

The strength and anisotropy (ears during deep drawing) of aluminum alloy hard plates mostly depend on the amount of final cold rolling.

Figure 1 relatively schematically shows the relationship between the amount of cold rolling (rolling ratio) and the selvage ratio and strength of the finished hard fabric. In the case without intermediate annealing, C indicates the tensile strength (no unit). As seen in this figure, when the cold rolling rate is increased to increase the strength of the hard plate, the edge ratio in the 45° direction inevitably increases. This is not preferable as a monthly charge for molding.

Therefore, it has been conventional practice to control the selvedge ratio by adding intermediate annealing to the process as shown by curve A, thereby achieving a balance between anisotropy and strength.

Here, as a result of analyzing the effect of intermediate annealing on the selvage ratio, the present inventors found that by regulating the end temperature of hot rolling and the cooling rate after the end of hot rolling without performing intermediate annealing, the curve It was found that this method has the same effect as A, and that low anisotropy is lost in the finished hard plate. The present invention is based on this knowledge.

Next, the configuration of the present invention will be described.

In the present invention, first, Mn and Mg, which regulate the components of the aluminum alloy as a starting material, can be used without reducing corrosion resistance and workability.
Added to increase strength. If both amounts are less than 0.1%, there will be no effect of increasing strength, while if the amount exceeds 2.0%, workability will be impaired.

Si, Fe, and Cu are usually treated as impurities, but S
By adding i, Fe, Al-Mn-
Fine particles of Fo--Si compounds are formed, the presence of which can prevent seizure of tools in forming operations such as sawing. This effect is not sufficiently exhibited when both Si and Fe are less than 0.1%, and when added in excess of 0.7%, the compound becomes coarse particles, which impairs moldability, which is not preferable. The CU base cloth has the effect of increasing strength. However, if it is less than 0.05%, this effect will not be achieved, while if it is added in an amount exceeding 0.3%, work hardening will increase and moldability will deteriorate, and corrosion resistance will also decrease.

Next, the manufacturing conditions will be described.

Homogenization treatment is carried out to improve the formability of hard plates, and involves heating the ingot at 550C or higher for 5 hours or more to thermally decompose the coarse intermetallic compounds produced during solidification of the ingot. It is particularly preferable to make the particles finer in order to improve moldability.

As will be explained in detail later, hot rolling is carried out at a temperature of at least 300°C.
must be terminated. Hot rolling is carried out by heating the ingot to a sufficiently high temperature so that the finishing temperature is 300°C or higher. Since this involves a temperature drop, hot rolling is generally started after the ingot is heated to 500° C. or higher.

Note that the amount of lubricating oil used, temperature control, distribution of the rolling reduction ratio of each stand, rolling speed, etc. are adjusted so that the temperature drop is as small as possible during hot rolling.

Further, the hot thickness air volume is set to correspond to at least 50% of the rolling roughness in the final step of cold rolling, and to make the hot-rolled sheet thickness twice or more the final cold-rolled sheet thickness. It is more preferable that the above 50% is 70
%, and 2 times is approximately 3.3 times, which corresponds to 70%.

Cooling after completion of hot rolling will be described in detail below, but is most important in the present invention, and is controlled so that cooling to 280° C. takes 2 hours or more. As a result, the material after hot rolling is passed through a temperature range of 280° C. or higher for 2 hours or more.

By cooling the hot-rolled sheet as described above in the cooling process after hot rolling, recrystallization progresses in the same way as when intermediate annealing is performed, and as a result, the effect of reducing the ear ratio is achieved. arise.

The hot-rolled sheet is then cooled to a temperature below 280°C and then cold-rolled in the usual manner to finish it! 1! It is considered to be a trading board. This matter - In order to obtain a selvage ratio of 3% or less and high strength, which is preferable for deep drawing, the cold rolling is carried out at a rolling rate of 5%.
It is applied at 0% or more. Moreover, higher strength can be obtained when the rolling ratio is 70% or more.

Next, the significance of regulating the completion level of hot rolling and subsequent cooling, which is a key point in the present invention, will be described.

The graph in Figure 2 shows Mn: 1.05%, Mg: 1.20
%, Si: 0.20%, Fe: 0.42%.

Cu: 2 Al alloy ingots (approximately 5 tons) containing 0.12%
．． This chart shows the temperature drop after hot rolling to a thickness of 5 mm. (Outside air temperature 28C) The temperature curve shows the case where hot rolling was finished at 330℃, the coil was wound, and the coil was cooled without taking any particular heat insulation measures.Even in this case, the temperature of the coil after 2 hours was 294C
Met. Cooling in this case satisfies the conditions of the present invention. On the other hand, curve C shows the case where the coil was wound up after finishing rolling at 309C and was cooled without using any heat insulating means, and the coil humidity was 273°C after 2 hours. Cooling in this case does not satisfy the conditions of the present invention.

Curve B is an example in which the rolling end temperature was lowered to 304°C and cooling was regulated by covering the wound coil with a heat-insulating cover made of heat-resistant glass wool, and the coil temperature remained 286°C even after 2 hours. This cooling satisfies the conditions of the present invention. In addition, in this example, the heat insulation cover is 8
It was removed after a period of time. On the other hand, curve D shows the case where the coil is cooled with a heat insulating cover, but it is an example of hot rolling with the hot rolling end temperature set at 287°C, and the coil temperature after 2 cycles is 277°C. ℃, and this example does not meet the conditions of the present invention.

That is, in the present invention, both the vertical and horizontal axes of the graph in FIG.
Cooling is regulated so that the temperature curve does not pass through the unfavorable area (the area indicated by spots in the figure) surrounded by the line connecting the three points of 0C, and this regulation prevents the hot rolled Aluminum alloy sheets are kept at a temperature of 280C or higher for more than 2 hours each time they are cooled, and by setting the end temperature of hot rolling to at least 300C, the temperature range is at least several times higher than 295C. It will be held for minutes.

In this way, the hot-rolled sheet is held at 295° C. or higher for at least several minutes during cooling after hot-rolling, as this time and temperature are sufficient to cause recrystallization in the hot-rolled sheet.
The reason why the temperature is maintained at 0° C. or higher for 2 hours or more is to cause sufficient precipitation of alloy components during this time. These developments weaken the anisotropy in the finished cold-rolled sheet and improve formability. This point will be clarified by comparing the examples of the present invention and comparative examples shown below.

Example 1 Eight ingots of aluminum alloy with the chemical composition shown in Table 1 (
After homogenizing at 580C x 10Hr, hot rolling was started at 540-500℃, and the finishing temperature was changed to 4 ways as shown in Table 2.
．． It was made into a hot-rolled plate with a thickness of 5 mm and wound into a coil. The conditions for subsequent cooling, the presence or absence of intermediate annealing, and other factors were changed as shown in Table 2, and finally cold rolling was performed to produce hard plates each having a thickness of 0.4 mm. Therefore, the rolling ratio of cold rolling is 84%. Table 2 shows the properties of the finished hard board.
It was shown to.

Finished hot rolling at 300℃ or higher, and 280℃ after 2 hours.
Examples A and B of the present invention in which cooling is controlled so as not to become lower
The hard plate obtained by this method is superior in selvage ratio and LDR (limit drawing ratio) to those obtained by Comparative Examples C and D. Among the comparative examples, A', B', C', and D' all undergo intermediate annealing before final cold rolling, and correspond to the conventional method. When intermediate annealing is performed as in these comparative examples, the formability seen in the selvedge ratio and LDR is good regardless of the end temperature of hot rolling and the subsequent cooling conditions, but the intermediate annealing is If no annealing is performed and the removal conditions and hot rolling end temperature are not regulated, the selvage ratio of the hard plate will be high as shown in Comparative Examples C and D, and the LDR
will also be made smaller.

That is, it is only when the hot rolling end temperature and cooling are regulated as in Examples A and B of the present invention that good properties can be obtained in the finished hard plate without intermediate annealing.

Approximately 5 tons of ingots of alloys with the chemical composition shown in Table 3 are used for each alloy.
Make 6 pieces in total, 580℃ x 10 hours each
After homogenization treatment, hot rolling was started at 540C, and hot rolling was completed at a temperature not shown individually in Table 4, and a hot rolled sheet having a thickness of 2.0 mm was wound into a coil.

Of the 6 cases, 3 cases E, F, and G were slowly cooled by covering the coil with a heat insulating cover to prevent it from cooling, and the remaining 3 cases E' and F
′ and G′ were cooled to a normal temperature without using a safety cover.

Subsequently, each coil was unwound and cold rolled to a 0.
Finished with 40mm thick hard material. Table 4 shows the coil temperature and the characteristics of the finished hard mold 2 hours after the end of hot rolling.

The finished hard plates according to Examples E, F, and G of the present invention were prepared by regulating the hot rolling end temperature and the temperature after 2 hours elapsed after hot rolling, as in Comparative Examples E', F', and G'. The finish of the lifting platform that was not available has turned into a hard board, and the selvage rate is low and the LDR is difficult.

In the case of hard treatment according to these comparative examples, although the strength and tensile strength are excellent, the selvage ratio is high and the LDR is small, so that it is not suitable for deep drawing.

Therefore, the effects of the present invention were clearly recognized.

As explained above, according to the present invention, the same effect can be obtained by performing intermediate annealing by utilizing the amount of heat necessarily held by the alloy after hot rolling during cooling. This method is no different from the conventional method of performing intermediate annealing, and it is possible to obtain a hard preform of aluminum alloy with good selvage and high strength. Therefore, there is no need for heating costs required for annealing between the two, and there is also no need for annealing equipment. Note that a cooling chamber using heat insulating material is much cheaper than annealing equipment.

In other words, the present invention effectively achieves energy savings compared to conventional manufacturing methods.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relative relationship between the rolling ratio of cold rolling and the edge ratio and strength of the finished hard plate, and Figure 2 is a graph showing the temperature of the hot rolled plate at the cooling overculm after hot rolling. It is a graph showing the transition. Patent applicant Sumitomo Light Metal Industries Co., Ltd. Agent Patent attorney Hidetake Komatsu 0Lr＞Ritsuhe−+−6 Sokui 1 1111 (7,) This certificate, 9'F (%) ヰ扛, Oθ−O
(Tsu.) Aim N2

Claims (1)

[Claims] 1. Mn: 0.1-2.0% and Mg: 0.1-2.0%
one or more of the following, Si: 0.1 to 0.7%, Fe: 0.1
After homogenizing an aluminum alloy ingot containing ~0.7% Cu, 0.05~0.3% Cu, and the remainder being substantially Al, it is hot rolled to a thickness of at least twice the final plate thickness. In the subsequent cooling process, the temperature range from the hot rolling end temperature to 280°C is cooled for more than 2 hours, without performing an annealing process. A method for producing a hard aluminum alloy plate for forming, characterized by cold rolling to the final thickness. 2. The manufacturing method according to claim 1, wherein cooling is carried out in a temperature range from the end temperature of hot rolling to 280C by keeping the temperature with a heat insulating material.