JP2623302B2 - Aluminum alloy for forming and female screw processing and method for producing the same - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to forming with excellent screw properties and manufacturing an aluminum alloy for female screw processing, and more particularly to forming and female screw processing with excellent female screw breaking torque strength. The present invention relates to an aluminum alloy for use and a method for producing the same.

(Prior Art) Recently, aluminum alloys have begun to be used for components such as chassis, heat sinks, panel boards, and the like of electric appliances, in particular, weak electric products such as VTRs and audios, in order to secure magnetic shielding properties and reduce weight. .

Aluminum alloys used for such applications are required to have excellent strength and formability, good corrosion resistance, etc., and therefore, conventionally, pure aluminum or Al-Mg alloy A5052, 5083 -O material or the like is used.

When the above product is manufactured, a rolled aluminum alloy plate is formed into an essential shape and then assembled with a female screw obtained by female screw processing and a steel male screw.

(Problems to be solved by the invention) However, pure aluminum and A5052 and 5083-
O material is excellent in formability and corrosion resistance, but when assembling the above parts, the female screw part made of aluminum has a low fracture torque strength compared to the high tightening torque of a male screw made of steel to improve accuracy. There was a problem that the part was broken and could not be screwed.

Therefore, as a method of solving this problem,
Although the thickness of the plate is increased to increase the breaking torque strength, the weight cannot be reduced.

On the other hand, Al-Mg-Zn based, Al-Cu
The use of a high-strength material such as a system can improve the screw properties, but on the other hand, there is a problem that the screw properties and formability are contradictory, such as poor moldability.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and has the necessary formability and strength, and provides an aluminum alloy for forming and female screw processing having particularly excellent screw characteristics, It is an object of the present invention to provide a method of manufacturing the same.

(Means for Solving the Problems) The present inventor has made intensive studies in view of the above problems, and as a result, has made possible by adjusting the chemical composition, optimizing the heat treatment and rolling conditions, and adjusting the structure of the material. It has been found that the present invention has been made.

That is, the present invention provides: Mg: 3 to 5% and Cu: 0.3 to 1.5%
As an essential component, further Mn: 0.03-0.3%, Cr: 0.03
~ 0.3%, Ti: 0.005 ~ 0.2% and B: 0.001 ~ 0.05% containing one or more kinds, the balance consists of Al and unavoidable impurities, and the average grain system on the plate surface has a structure of 40 μm or less. It is an object of the present invention to provide an aluminum alloy for forming and processing a female screw, which is characterized by having an aluminum alloy.

In addition, the method for producing the aluminum alloy for forming and female screw processing is such that after subjecting the aluminium alloy having the above chemical components to a homogenization treatment at 480 to 550 ° C. for 1 to 48 hours, hot rolling is performed. The steel sheet is characterized in that a predetermined thickness obtained by cold rolling at a cold working ratio of 30% or more and then softening treatment is performed to obtain a structure having an average crystal grain size of 40 μm or less on the sheet surface.

 Hereinafter, the present invention will be described in more detail.

First, the reasons for limiting the chemical components in the present invention will be described.

Mg: Mg is an element that contributes to the improvement of the screw properties and strength. However, if it is less than 3%, the effect is small. Manufacturing becomes difficult. Therefore, the Mg content is in the range of 3 to 5%.

Cu: Cu is an element particularly contributing to the improvement of screw properties, and its effect is further improved when coexisting with Mg. However, if it is less than 0.3%, the effect is small, and if it exceeds 1.5%, the effect of improving the screw characteristics is saturated, and ordinary industrial production becomes difficult. Therefore, the Cu content is in the range of 0.3 to 1.5%.

In the present invention, the above two elements Mg and Cu are essential components, but one or more of the following elements are added in an appropriate amount.

Mn: Mn is an element that contributes to the improvement of screw properties and formability, but less than 0.03% has little effect, and 0.2%
Exceeding the above results in poor screw characteristics and moldability. Therefore, the Mn content is in the range of 0.03 to 0.2%.

Cr: Cr is an element that contributes to the improvement of the strength and the screw properties, but the effect is small when it is less than 0.03%. Also 0.2
%, The effect of improving the strength and improving the thread breaking torque strength is saturated, and the formability is significantly deteriorated. Therefore, the Cr content is in the range of 0.03 to 0.2%.

Ti: Ti is an element that refines the cast structure and contributes to the improvement of formability. However, if it is less than 0.005%, it has no effect, and 0.2%
If it exceeds 300, a giant metal compound is formed, and the moldability deteriorates. Therefore, the Ti content is in the range of 0.005 to 0.2%.

B: Similar to Ti, B is an element that contributes to the refinement of the cast structure and the improvement of the formability. However, if it is less than 0.001%, there is no effect. Worse.

 Therefore, the B amount is in the range of 0.001 to 0.05%.

Although the aluminum alloy inevitably contains impurities, the impurities are allowed as long as the effects of the present invention are not impaired.

Next, the heat treatment and rolling conditions in the present invention will be described.

Aluminum alloy having the above chemical components is melted and cast by a conventional method, but for the obtained ingot, 480 to 550
A homogenization treatment is carried out at a temperature in the range of ° C. for 4 to 48 hours. By performing such a homogenization treatment, Mg and Cu, which are effective in improving the screw properties, are sufficiently diffused and solid-solved to eliminate microsegregation, and at the same time, stabilize the structure and affect the screw properties and strength. Mn, Cu, Ti, etc. can be finely and uniformly deposited. However, if the processing temperature is lower than 480 ° C., the above-mentioned effects are insufficient, while if it is higher than 550 ° C., burning may occur. When the treatment time is less than 1 hour, the effect is small, and when the treatment time is more than 48 hours, it is not economical by the usual industrial production method. Therefore, the conditions for the homogenization treatment are 480-550 ° C. × 1-48 hours.

After the homogenization treatment, hot rolling is performed by an ordinary method, and thereafter, cold rolling is performed at a final working ratio of 30% or more to obtain a predetermined thickness. However, if the final cold work ratio is less than 30% in cold rolling, recrystallization and refinement cannot be performed by the subsequent heat treatment, the average crystal grain size becomes 40 μm or more, and the solution treatment is not promoted. For this reason, the screw characteristics and strength are not sufficiently improved.

Next, a softening treatment is performed as a final heat treatment, but the conditions are not particularly limited. For example, normal batch furnace processing at 330-550 ° C, or continuous heating processing equipment (CAL)
The CAL method is more preferable than the batch method in that the crystal grain size can be reduced and the screw characteristics and bake strength can be improved.

The structure obtained after the final heat treatment by the above manufacturing process has an average crystal grain size of 40 μm or less. According to the experimental study of the present inventor, it has been found that the crystal grain size after rolling → final heat treatment has a large effect on the screw properties, and when it exceeds 40 μm, the screw properties deteriorate, so that it is necessary to control the crystal grain size to 40 μm or less. . Of course, it is needless to say that such a predetermined structure can be obtained only by the combination of the adjustment of the chemical components and the manufacturing conditions described above.

 Next, examples of the present invention will be described.

(Examples) Various aluminum alloys having the chemical components shown in Table 1 were melted and cast by a usual method, and the obtained ingot was subjected to a homogenization treatment under the conditions shown in Table 2, Board thickness 6mm
To hot rolling. Next, the steel sheet was cold-rolled to a thickness of 1 mm at a final cold working rate shown in Table 2 and subjected to softening treatment under the following two conditions as a final heat treatment.

(A) CAL treatment at 480-530 ° C x 10 seconds (B) Batch treatment at 350 ° C x 3hr The homogenization conditions, final cold working rate, and final heat treatment conditions for each aluminum alloy are combinations shown in Table 3. And

The obtained test piece (thickness: 1 mm) was subjected to M3 and M4 screw processing to form a female screw portion, and the screw characteristics (screw breaking torque) of a male steel screw were examined. The results are shown in Table 3 together with the mechanical properties.

In the measurement of the screw breaking torque, a female screw was formed by tapping the center of a 20 mm square test piece with a tap, and then the steel male screw was set on a torque detector using a washer, and the steel screw was set with an electric screwdriver. The torque at the time when the female screw part was broken by rotating and tightening the male screw made was measured. Lubrication is unlubricated.

As is clear from Table 3, alloys No. 1 to No. 4 within the component range of the present invention were subjected to heat treatment and rolling under the conditions within the range of the present invention (Examples of the present invention No. 1 to No. 4). In 7), it was confirmed that the screw characteristics were all excellent and the moldability and strength were also excellent.

On the other hand, Comparative Examples No. 11 to No. 13 for the conventional A1100, 5052, 5083, and Comparative Example No. 5 for those having a chemical component outside the scope of the present invention, and further, the chemicals within the scope of the present invention. Although Comparative Examples No. 8 to No. 9 having the components but heat treatment conditions or cold rolling conditions were out of the range of the present invention, the screw characteristics and the formability were all poor.

Preliminary tests were conducted on the rolling conditions in advance. First, the alloy No. 1 in Table 1 was subjected to the homogenization treatment of the production process (d) in Table 2, and then hot rolling was performed. However, surface cracks and edge cracks occurred during hot rolling, so the subsequent tests were mainly conducted.

In addition, when the condition of the final cold rolling reduction was less than 30%, except for the case of Comparative Example No. 9 in Table 3, the recrystallization grain size became too large in the subsequent heat treatment, and especially the screw characteristics Is bad,
Since the elongation and Erichsen value were low, and the moldability was significantly deteriorated, it was excluded from the test of this example.

(Effects of the Invention) As described in detail above, according to the present invention, a rolled aluminum alloy plate used for a formed product requiring screw properties and formability is equivalent to conventional 1100, 5052, 5083, etc. An aluminum alloy having the above strength and formability, and at the same time, having particularly excellent mechanical properties as a screw can be obtained.

Claims (8)

(57) [Claims] (1) Mg: 3 to 5% by weight (hereinafter the same) and
Cu: 0.3 to 1.5% as an essential component, and Mn: 0.03 to 0.
An aluminum alloy for forming and female screw working, characterized by containing 3%, with the balance being Al and unavoidable impurities, and having a structure having an average crystal grain size of 40 μm or less on the plate surface. 2. An alloy containing Mg: 3 to 5% and Cu: 0.3 to 1.5% as essential components, further containing Cr: 0.03 to 0.3%, and the balance consisting of Al and unavoidable impurities. An aluminum alloy for forming and machining a female screw, having a structure having a diameter of 40 μm or less. 3. An essential component containing Mg: 3-5% and Cu: 0.3-1.5%, and further Ti: 0.005-0.2% and B: 0.001-0.05%.
Containing either one or both, the balance consisting of Al and inevitable impurities, the average crystal grain size on the plate surface is 40μm
An aluminum alloy for forming and machining a female screw, having the following structure. 4. An essential component containing Mg: 3 to 5% and Cu: 0.3 to 1.5%, further containing Mn: 0.03 to 0.3%, Cr: 0.03 to 0.3%, with the balance being Al and unavoidable impurities. An aluminum alloy for forming and female screw working, characterized in that the plate surface has a structure having an average crystal grain size of 40 μm or less. 5. It contains Mg: 3-5% and Cu: 0.3-1.5% as essential components, and further contains 0.03-0.3% of Mn and 0.005-0.2% of Ti.
And B: including one or both of 0.001 to 0.05%,
An aluminum alloy for forming and female screw processing, characterized in that the balance consists of Al and unavoidable impurities, and has a structure having an average crystal grain size of 40 μm or less on the plate surface. 6. The alloy contains Mg: 3-5% and Cu: 0.3-1.5% as essential components, and further contains Cr: 0.03-0.3% and Ti: 0.005-0.2%.
And B: including one or both of 0.001 to 0.05%,
An aluminum alloy for forming and female screw processing, characterized in that the balance consists of Al and unavoidable impurities, and has a structure with an average crystal grain size of 40 μm or less on the plate surface. 7. It contains Mg: 3-5% and Cu: 0.3-1.5% as essential components, further contains Mn: 0.03-0.3%, Cr: 0.03-0.3%,
Ti: 0.005 to 0.2% and B: one or both of 0.001 to 0.05%, the balance consisting of Al and inevitable impurities,
An aluminum alloy for forming and female screw processing, characterized in that the plate surface has a structure having an average crystal grain size of 40 μm or less. 8. An aluminum alloy having the chemical composition according to any one of claims 1 to 7, which is 480 to 550 ° C. × 1.
After performing homogenization treatment for ~ 48 hours, hot rolling, cold rolling at a final cold work rate of 30% or more to a predetermined thickness, then softening treatment, average crystal on the plate surface Particle size
A method for producing an aluminum alloy for forming and machining a female screw, characterized by obtaining a structure of 40 μm or less.