JPS639011B2 - - Google Patents

Description

[Detailed Description of the Invention] 6201 aluminum alloy is a strong alloy consisting of aluminum, magnesium, and silicon, and has a tensile strength of 32.85 Kg/mm ² (46000 PSI) or more in the case of wire or in a heat-treated state.
It has an elongation rate of 3% or more, and its electrical conductivity is 52.5% or more compared to IACS (International Standard for Annealed Copper).

Conventionally, commercial 6201 aluminum alloy re-stretched rods and similar aluminum alloy re-stretched rods were manufactured using aluminum ingot DC casting.
The ingot is reheated to 371.1℃ (700〓) to 454.4℃ (850〓), the ingot is hot-rolled to re-stretch the rod, and the rod is solutionized at a temperature of 537.8℃ (1000〓). The bar was manufactured by a method that included steps such as treating the bar and then water-quenching the bar.

The rod is made into wire by cold drawing, and the wire is heated between 121.11℃ (250〓) and 232.22℃.
Artificially age hardened at a temperature of (450〓). By this method, wires with tensile strength and conductivity properties similar to or superior to those of 6201 aluminum can be produced.

Although it is possible to obtain the desired product according to the above-mentioned manufacturing method, only a limited amount of bars can be manufactured using such batch manufacturing method or discontinuous casting method. In other words, for a piece of steel with a certain size, it is only possible to prepare a bar with the corresponding mass; to make a longer bar, separately manufactured bars must be joined together by welding. Must be. When a steel billet is reheated and rolled to form a bar, the tip of the bar typically must be cut off. This is because the quality of the tip has deteriorated. Thus, conventional manufacturing resulted in substantial waste. When welding different lengths of rods made by batch manufacturing, the welded parts have a poor grain structure, which has a negative effect on tensile strength and electrical conductivity. Additionally, it is virtually impossible to reheat, roll, and weld different pieces of steel, each typically having different grain characteristics, to a uniform overall condition.

When reheating the bar in the batch system described above, the bar must be handled carefully to ensure uniform heating and a uniform product. For example, a furnace in which rods are placed for solution treatment must be constructed to distribute heat evenly in order to heat the rods evenly. Still further, a configuration is required to provide sufficient air or gas circulation within the furnace to maintain proper heat distribution among the coils. Typically, the multiple rod coils are placed on portable racks that keep them separated. However, the rack itself occupies space within the furnace, reducing the space available for accommodating the rods to be heated.

Since the purpose of reheating the bar is to solutionize the bar, it is desirable to prevent the bar from reaching a temperature substantially higher than the temperature at which it will be solutionized. This is because the overlapping portions of the coiled bars tend to be tacked or welded together. This tacking condition creates surface stains when the bars are pulled apart, and the tacking condition often causes the coils of several bars to be unwound together. Therefore, an even distribution of heat within the solution furnace is necessary so that the bar can be rapidly and evenly solutionized with minimal risk of tacking.

According to the prior art batch process, the ingot is cooled and reheated, the bar exiting the rolling mill is cooled and reheated for solution treatment, and the melt exiting the reheating furnace is cooled and reheated for solution treatment. When the bar is cooled, it takes a considerable amount of time for the aluminum to oxidize. As a result, the bar is considerably oxidized. This makes it relatively hard for re-pulling. The oxidation process also gives it a relatively dull color. Hard bars that are highly oxidized are difficult to draw, and the dies used for drawing them quickly degrade. Thus, the prior art 6201 aluminum alloy forming process by batch process is expensive, requires individual processing of the bars for each step, and requires careful handling of each product, as well as requirements are necessary.

US Pat. No. 3,613,767 discloses an improved method for continuously casting and rolling 6201 aluminum alloy. The invention disclosed in the above-mentioned U.S. Pat. No. 3,613,767 encompasses a method for continuously manufacturing aluminum base alloy rods, such as 6201 aluminum alloy rods, without requiring reheating of ingots or rods during the manufacturing process. ing.

That is, the bar material coming out of the continuous casting machine is continuously cooled after passing through a rolling mill, a quenching tube, etc. The heat of the cast bar emerging from the continuous caster is not dissipated, and the temperature of the cast machine is maintained within the solution temperature range of the metal even when the cast bar is fed into the rolling mill.

The wire rod is hot worked in the rolling mill,
Since the bar is quenched immediately after coming out of the rolling mill, the time required from the time the bar is put into the rolling mill until it is quenched to a temperature below the crystallization temperature of the alloying element is is less than the time it takes for the metal to precipitate at the grain boundaries of the metal.

After the bar has been hardened, the temperature of the bar is below that at which substantial precipitation immediately occurs. When the rod is subsequently cooled and drawn into wire, it has an unusually high tensile strength, relatively high electrical conductivity, and a shiny appearance.

In this way, in the prior art, the problem of having to treat each step separately is solved by the US patent.
This can be eliminated by implementing the invention disclosed in No. 3613767. However, in solving the problems inherent in batch production of 6201 aluminum alloy, the aluminum bar loses heat from the casting wheel of the continuous caster until the bar enters the rolling mill, where precipitation occurs. Because the temperature is relatively high, precipitates with sizes in the range of 20,000 Å are formed.

Also, by solving the above problem using the batch method of US Pat. No. 3,613,767, a new problem arises.

That is, column 5, item 38 of the above patent No. 3613767.
The statement starting with the line ``In this process the temperature and other conditions may be varied within reasonable limits without loss of product properties. For example:
The temperature of the molten metal in the casting pot and the temperature of the metal bar exiting the casting wheel will not affect the quality of the 6201 alloy bar unless the temperature is reduced below the solution temperature. is attracting attention.

Although the above description is correct regarding the properties of 6201 alloy, it is inaccurate regarding the properties of cast bars and bars rolled from cast bars.

U.S. Pat. No. 3,613,767 discloses that the cast bar exits the casting wheel at a temperature above the solution temperature and that the cast bar remains at a temperature above that temperature until it enters a rolling mill where hot working and quenching are subsequently performed. states that there needs to be.

In order to meet requirements such as those set forth above, the cast bars of U.S. Pat. No. 3,613,767 must exit the casting wheel at a temperature substantially above the solution temperature of the alloy. In order to separate the cast bar from the casting wheel at the temperatures indicated in U.S. Pat. It must be cooled in such a way that it does not become completely solid until it reaches a point where it cannot be buried.

If the above-mentioned voids occur on the surface of the cast bar, oxidation will occur in the voids, and when the bar is rolled, the oxide will be trapped in the finished bar. as a result of which the rod becomes brittle in the areas where the oxide is present. And the tensile strength of the rod decreases. If there is a solidification shrinkage void in a place where oxidation does not occur, that is, inside the rod,
If the rod is stretched, this void will affect the ductility of the rod. In other words, it causes internal micro-fractures that directly affect the properties after cold working.

It has been found that the solution temperature of the 6201 alloy varies depending on the concentration of alloying elements present in the alloy, so the more alloying elements there are, the lower the solution temperature range of the alloy. Therefore, given the preferred concentration in the 6201 alloy, the solution temperature is 454.4°C
(850〓) to 615.6℃ (1140〓).

U.S. Pat. No. 3,613,767 therefore describes a method suitable for continuously producing 6201 alloy rods having concentrations of alloying elements such that the alloy will be solutionized at temperatures in the upper part of the solution temperature range of the 6201 alloy. Not provided.
Therefore, there continues to be a need for significant improvements in the method of manufacturing continuously heat treatable aluminum alloy rods from aluminum alloys such as 6201.

It must be clarified here that the heat treatable aluminum alloys used in the specification are those that have high solid solubility in aluminum at high temperatures and solid solubility in aluminum when cooled to room temperature. It refers to an aluminum alloy that contains alloying elements to lower the aluminum alloy. Such alloys are hardened by precipitation of a heat-treated second phase, and the alloying elements remain in solid solution by rapid cooling from high temperatures.

Furthermore, it must be clarified that the aluminum alloy of the roughly drawn wire used in this specification is an aluminum alloy containing alloying elements that have low solid solubility at both high and low temperatures. The alloy is normally hardened by work hardening, a hardening mechanism that operates during cold working of the alloy.

It is an object of the present invention to provide an improved method for manufacturing aluminum alloy products from heat treatable aluminum alloys.

Another object of the present invention is to provide a method for continuously manufacturing heat treatable aluminum alloy rough drawn wire in order to obtain a product with high tensile strength and high conductive properties without reheating the ingot or bar. There is something to do.

Another object of the present invention is to eliminate the formation of large precipitated intermetallic particles in its particle structure.
To provide an improved product of 6201 and its manufacturing method.

Another object of the present invention is to provide an economical and convenient method for producing 6201 aluminum alloy rough drawn wire.

Still another object of the present invention is that the solution temperature is 454.4.
6201 heat treatable from 6201 aluminum alloy within the range of ℃ (850〓) to 582.2℃ (1080〓)
The object of the present invention is to provide a method for continuously manufacturing aluminum alloy rough drawn wire.

Still another object of the present invention is to provide a method for continuously casting and rolling a heat-treatable 6201 aluminum alloy rough drawn wire rod in which the cast rod material is not solidified and shrunk.

Another object of the present invention is to provide an improved 6201 heat treatable aluminum alloy product that has uniform heat treatment throughout its length.

Hereinafter, a preferred embodiment of the present invention will be described based on the accompanying drawings.

First of all, regarding the drawings, the same numbers indicate the same parts in the drawings, and Fig. 1 shows the casting machine 10,
A heater 11, a rolling mill 12, a quenching tube assembly 13, a coiler 14, etc. are shown. In summary, the method according to the invention transfers molten metal from a furnace (not shown) to a casting wheel 10a of a casting machine 10.
This includes injecting into.

The molten metal is cooled and solidified in the casting wheel 10a and drawn out as a solid bar 15 at a temperature below 504.4°C (940°C) and guided to the heater 11, where the solid bar 15 is heated to a temperature of 454.4°C. (850〓)
It is continuously heated in the range of 582.2℃ (1080℃). Thereafter, the heated bar 15 is transferred to a rolling mill 12.
You will be guided inside. The product is elongated in a rolling mill 12, its cross section is reduced, and a rough drawn wire 17 is produced.

The bar 17 has a first stage quenching tube 18,
Pinch roller 19, second stage quenching tube 2
0, pinch rollers 21, rod conduit 22, etc., through a hardening tube assembly 13.
Upon exiting the wire conduit 22, the rod is formed into a coil by the coiler 14.

Pump 23 receives quenching fluid from oil sump 24 and pressurizes first stage quenching tube 18 . The above-mentioned quenching liquid passes through the quenching tube 18 in the traveling direction along the course of the rough drawn wire 17. It then passes through a conduit system to a cooling tower 26 where it is cooled and recycled to the sump 24.

The pump 27 receives the quenching fluid from the oil sump 28 and pressurizes the second stage quenching tube 20 .
The quenching fluid in the second stage quenching tube passes through the quenching tube 20 in a counter-current relationship to the movement of the rough drawing line 17, and then passes through the conduit system to the cooling tower 31, where it is cooled. It is circulated to pump 28. In that way the quenching fluid is maintained at a controlled temperature during the quenching process.

More specifically, the molten metal passing through the apparatus is a heat treatable aluminum alloy.
If the product to be formed is a 6201 aluminum alloy, the silicon and magnesium contents are approximately 0.50-0.9% and 0.60-0.90%, respectively.
It is.

If desired, the silicon and magnesium contents in the metal can be varied from 0.3 to 1.2% and from 0.3 to 1.2%, respectively. The metal is passed through a fiberglass mesh in a molten state at a temperature of approximately 648.9°C (1200°C),
It is usually injected into a support pot maintained at 687.8°C (1270°C).

The metal is passed from the support pot to the casting wheel 10a.
for example, when casting a 21.3 cm ² (3.3 square inch) bar at a rate of 9.14 m (30 feet) per minute, at a rate at which reverse polarization is substantially minimized. When casting a bar of the same cross-section at a casting rate of 12.2 m (40 feet) per minute at a rate of 13.3°C (24〓), and a bar of the same cross-section at a rate of 17.8°C (32〓) per second, Casting rate 15.2m (50 feet) per minute
During casting, the rod is cooled and solidified at a rate of 27.8°C (50°C) per second to form a cast bar 15.

Cast bar material 15 is approximately 371.1℃ (700〓) to
It exits the casting wheel 10a at a temperature of 504.4°C (940°) and is fed to a heater 11 where the temperature of the bar 15 is increased to a temperature at which the alloying elements are dissolved.

The heater 11 continuously supplies energy to the rod to increase the temperature of the rod to 454.4°C (850°C).
〓)～582.2℃(1080〓), usually 510℃(950〓)
〓) to 548.9℃ (10220〓), and depending on the alloying element, the temperature increases from 548.9℃ (1020〓) to 582.2℃ (1080〓).
〓) increases.

When the cast bar material exits the heater 11, it is transferred to the rolling mill 1.
You will be guided to 2. The rod 15 is then hot worked and surrounded by soluble oil having a concentration of about 40% and maintained at temperatures of 93.3°C (200°), normal and 71.1°C (160°).

The rolling mill 12 rolls the cast bar 15 from the top to the bottom.
It also includes a plurality of rolling stands that alternately compress from side to side, which extends the length of the cast bar 15 and reduces its cross section, so that the cast bar 15 is gradually transformed into a rolled bar or a rough rolled bar. The wire rod 17 is formed. The amount of soluble oil in the rolling mill 12 is maintained at a level of approximately two-thirds of the amount of oil in a continuous casting system for EC bar stock.

The temperature and amount of the cooling liquid applied to the bar in the rolling mill 12 is adjustable, so that when the rolled bar or rough drawn wire 17 is taken out of the rolling mill 12, the temperature of the rolled bar or rough drawn wire remains the same. The temperature is 343.3℃ (650〓) or higher, which is within the hot working temperature range.
Alloying elements are therefore not precipitated from the aluminum.

If a low amount of coolant is applied to the bar in the rolling mill, a higher concentration of lubricant is required, approximately 40% compared to 10% for EC bar systems. Additionally, the flow is adjustable so that an average amount of coolant is always flowing to each roll stand.

Figure 2 shows the temperature of magnesium, silicon and magnesium silicide in aluminum at 440℃ (825〓).
This is a three-dimensional graph schematically showing the solubility in the temperature range from 535°C to 995°C. Straight line 40 is 6201
It is shown that as the temperature of magnesium, silicon and magnesium silicide in the alloy system increases to 535.6°C (995〓), their solubility also increases.

Point 42 on line 40 indicates the amount of magnesium, silicon, and magnesium silicide dissolved in the continuously cast rod when 6201 alloy is continuously cast using prior art heat treatment methods. Point 43 indicates the amount of magnesium, magnesium silicide, and silicon retained in the 6201 aluminum alloy when the 6201 aluminum alloy is continuously cast using the heat treatment method of the present invention.

As shown in the diagram of FIG. 2, when an alloy continuously cast and rolled by continuous casting and rolling operations is subjected to the heat treatment of the present invention, the amount of magnesium silicide in the 6201 alloy is It has increased by 162%.

The improved properties are due in part to increased solubility of the magnesium silicide in the alloy matrix prior to subsequent age hardening and precipitation. Continuously cast 6201 aluminum alloy was treated by a prior art heat treatment method with the following results.

The maximum tensile strength of the final finished wire is 32.1Kg/mm ² (45700PSI), the elongation rate is 8.3%,
And the conductivity is 52.5% of IACS. The above is set as a reference line, and in the present invention, the temperature of the bar between the inlet of the casting machine and the rolling mill is set at 482.2°C (900〓) to 548.9°C.
(1020〓), and then the bar is rolled to become a rough wire, and then a wire.
Its characteristics are as follows.

Maximum tensile strength - 35.7Kg/mm ² (50800PSI) Elongation - 7.9% Electrical conductivity - 52.5% Figure 3 shows the results of continuous heat treatment of 6201 aluminum alloy rod according to the prior art and the results of continuous heat treatment of 6201 aluminum alloy rod according to the method of the present invention. The results of continuous casting and heat treatment of the alloy are graphically illustrated, with curve 50 showing the relationship between electrical conductivity and ultimate tensile strength of wire made from 6201 aluminum alloy bar according to the prior art. , curve 52 shows the relationship between electrical conductivity and ultimate tensile strength of wire made from 6201 aluminum bar by the method of the present invention.

[Brief explanation of the drawing]

Figure 1 is a side view of the casting machine, rolling mill, quenching tube, and coiler, and Figure 2 is a three-dimensional graph diagrammatically showing the solubility of magnesium, silicon, intermediate metal alloy magnesium silicide, etc. in aluminum at various temperatures. FIG. 3 is a diagram showing the effects of the heat treatable 6201 aluminum alloy of the present invention in comparison with the 6201 aluminum alloy of the prior art. (Explanation of main symbols shown in the drawings), 1
0... Casting machine, 11... Heater, 12... Rolling machine, 14... Coiler.

Claims (1)

[Claims] 1. A method for producing a long shelf-life wire of an aluminum alloy containing, by weight, 0.3-1.2% Si, 0.3-1.2% Mg, the balance being basically aluminum, comprising: Contains 0.3~1.2% Si, 03~1.2% Mg by weight,
injecting a molten aluminum alloy, the remainder of which is essentially aluminum, into a casting groove of a continuous casting wheel at a temperature above the melting point of the aluminum alloy;
The aluminum alloy is solidified in the casting groove to form a cast bar, and the cast bar is taken out from the casting groove at a temperature of 504°C (940°C) or less, and is continuously hot worked and roughened. In the method of forming a drawn wire rod and continuously quenching the rough drawn wire rod, the cast bar solidified in the casting groove is heated to a temperature of 371°C to 504°C.
(700〓~940〓), the cooling rate at this time is such as to minimize reverse segregation, and the cast bar is passed through a heating device to a temperature of 454℃~582℃ (850〓
The temperature of the cast bar is maintained within the solution treatment temperature range of ~1080〓), the rough drawn wire is formed in the hot working process, and the temperature of the rough drawn wire upon exiting the hot working process is
A method characterized by controlling the time that the cast bar is at the solution treatment temperature so that the temperature is 343°C (650°C) or higher and precipitation during natural aging of the product is controlled. 2. The hot process of forming rough drawn wire from cast bars at temperatures of 454°C to 582°C (850〓 to 1080〓) may cause the cast bars during rolling to be heated to temperatures below 93°C (200〓). A method according to claim 1, characterized in that the temperature of the cast bar is controlled by adding molten oil. 3 The roughly drawn wire is further drawn into a wire, and the wire is
The method of claim 1, having a tensile strength of 35.7 Kg/mm ² (50800 psi) or more, an elongation of 7.9% or more, and an IACS conductivity of 52.5% or more.