JP2006169638A - Production method for boron-containing magnesium-based alloy and its alloy plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent boron-containing magnesium-based alloy capable of easily producing a thin-plate, wide and continuously-casted product which can not be produced heretofore by using a magnesium alloy, capable of preventing firing troubles to be caused by employing die-casting and thixomolding processes, and also having excellent rolling processability. <P>SOLUTION: This boron-containing magnesium-based alloy is produced by adding boron within the range of 0.002 to 1.0 wt% into a magnesium-based alloy. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnesium-based alloy to which boron is added, and more particularly to a boron-containing magnesium-based alloy that can be easily cast continuously and that has reduced the ignition / combustibility of magnesium powder.

  Conventionally, magnesium alloy is the lightest metal among practical metals and has rigidity, so various members such as automobile wheels and structural parts, frames of mobile phones, notebook computers, etc., and body members of MDs, etc. It is widely used as a material for weight reduction.

As a magnesium alloy used for these, for example, as shown in Table 1, JIS standard magnesium alloys 1 to 7 are typically listed.
These alloys are standardized as magnesium alloy plate (JIS H4201), magnesium alloy seamless pipe (JIS H4202), magnesium alloy rod (JIS H4203), magnesium alloy extruded profile (JIS H4204), etc., depending on the type. Has been.
In order to directly manufacture various members from such a magnesium alloy, die casting and a thixo mold are used, and after ingots and slabs are separately cast, they are manufactured by plastic processing such as rolling, forging, and extrusion. .

However, magnesium alloy has a dense hexagonal crystal structure and lacks high-temperature strength immediately after solidification, so it cannot go through a manufacturing process that uses continuous casting to produce a slab. There was a problem that it was difficult to increase efficiency.
Magnesium alloys are very easy to oxidize and ignite when powdered, and there is a risk that magnesium powder will ignite and explode during deburring finishing of die-cast and thixo-molded products.

  Accordingly, an object of the present invention is to provide a boron-containing magnesium-based alloy that can easily produce a cast product by wide continuous casting using a thin plate, which has been impossible in the past, using a magnesium alloy. It is another object of the present invention to provide a boron-containing magnesium-based alloy that can prevent ignition, which was inconvenient when using a thixo mold, and is excellent in rolling workability.

The boron-containing magnesium-based alloy of the present invention as a solution to the above-mentioned problems includes 0.50 to 1.5% by mass of Zn (zinc), 0.002 to 1.0% by mass of B (boron), As unavoidable impurities, Cu (copper) is 0.10% or less, Ni (nickel) is 0.005% or less, other elements are each 0.30% or less, and the balance is Mg (magnesium) (above,% is All are mass%), and are substantially free of Ti (titanium), Tl (tellurium) and In (indium).
Moreover, the manufacturing method of the boron containing magnesium alloy board | plate material of this invention forms a slab by the continuous casting method, and performs hot rolling after that for the boron containing magnesium base alloy of Claim 1.

According to the boron-containing magnesium-based alloy of the present invention, continuous casting that cannot be achieved with conventional magnesium alloys can be easily and satisfactorily performed.
In addition, using a conventional magnesium alloy, it is difficult to cause ignition that has occurred during the deburring finishing process mainly when die casting and thixo molding are performed, and explosive combustion can be prevented.

By adding B (boron) as an alloying element component in the magnesium-based alloy, the present inventors are in the vicinity of the solidification site of the slab when pulling the ingot from the continuous casting mold. Knowledge that excellent continuous castability, which has been difficult to achieve in the past, has been ensured, and that magnesium alloy powders are difficult to ignite and burn without cracking or cutting. The present invention has been completed.
That is, the present invention is a boron-containing magnesium-based alloy in which B (boron) is added and blended in the range of 0.002 to 1.0% by weight in the magnesium-based alloy.

Hereinafter, the boron-containing magnesium-based alloy of the present invention will be described in more detail.
The magnesium-based alloy used as the base of the boron-containing magnesium-based alloy of the present invention is based on four kinds of JIS standard magnesium alloys. That is, Mg as a main component, containing B as an essential component, Zn, Zr, etc. as alloying element components blended as necessary, and Ti (titanium), Tl (tellurium) and In ( Indium) is not substantially contained.

The slab obtained by continuously casting the boron-containing magnesium-based alloy of the present invention is inferior to that of a conventional magnesium-based alloy not containing boron in its hot / cold workability. Not only that, but rather good.
In addition, the boron-containing magnesium-based alloy of the present invention is not inferior to that of a conventional magnesium-based alloy not containing boron even when it is used for die casting or a thixo mold.

The boron-containing magnesium-based alloy powder of the present invention was unexpected, but was found to have very low ignitability.
Conventional magnesium-based alloy powders that do not contain boron are extremely easy to ignite and burn in the atmosphere, and when the powder is collected and deposited, and close to the flame, the whole amount burns explosively, Even if the powder of the boron-containing magnesium-based alloy according to the present invention collects and deposits the powder and approaches the flame, the surface portion of the deposited body only burns slowly for one skin, and the fire is extinguished. It was found that when the oxide was removed, unburned magnesium-based alloy powder remained.

  This means that when a product was manufactured by die casting or thixo mold, it was necessary to remove burrs generated at the joints of the combination mold, etc., and when cutting the burrs with a grinder, etc., the chips ignited.・ It means that it is difficult to ignite and explode, and it means that the deburring finishing process, which was inevitable for die casting and thixo molds, can be performed safely.

  B blended in the boron-containing magnesium-based alloy of the present invention is 0.002 to 1.0 mass%, preferably 0.005 to 0.3 mass%, more preferably 0.01 to 0.05 mass%. It is blended within the range. If this value is less than 0.002% by mass, the effect when B is added does not remarkably appear. On the contrary, the upper limit is not particularly problematic, but if it exceeds 1.0% by mass, it is produced as an alloy. It is difficult to do this, and there is a cost problem, which is not preferable.

Hereinafter, specific embodiments of the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited to these descriptions.
[Examples 1-6, Comparative Examples 1-4]
Four kinds of JIS standard magnesium alloys are used as base alloys, and various magnesium-based alloys having different chemical components (particularly, B component) as shown in Table 2 are continuously cast with an ingot width of 50 mm and a thickness of 10 mm. Endless casting was performed, slabs were cast, and continuous castability was evaluated.
The casting conditions for continuous casting are as follows.
That is, the casting atmosphere: the inside of the vacuum pot was replaced with argon gas, the molten metal temperature: 780 ° C., the slab drawing speed: 150 mm / min, the slab drawing force: 0.2 kg / mm in an argon gas atmosphere with a flow rate of 5 liters / min. ^{2. The} total pulling force was 100 kg.
The obtained slab was rolled at a heating temperature of 200 to 400 ° C. and a one-pass reduction rate of 10 to 30% to produce a plate material, and the rolling processability was evaluated.
On the other hand, it was pulverized to form a deposit, and the anti-ignition property was evaluated. The results are also shown in Table 2.
The evaluation criteria are as shown below.

(Evaluation criteria)
1. Continuous castability A: Continuous casting was successfully performed.
○: Continuous casting was possible.
Δ: Cracks occurred in the slab during continuous casting.
X: Continuous casting could not be performed.

2. Rollability ◎ ... Good spreadability.
○… It has spreadability.
Δ: Rollability is slightly poor.
X: Rollability is poor.

3. Ignition preventive properties ◎ ... Mg powder deposits are extinguished only by burning the surface part slowly for one skin.
Δ: Mg powder deposits are moderately ignitable and are not explosive combustion.
X: The whole amount burns violently explosively.

[Evaluation results]
As is clear from the results shown in Table 2, the boron-containing magnesium-based alloys of the present invention according to Examples 1 to 6 were all capable of continuous casting, whereas the magnesium according to Comparative Examples 1 to 4 All of the base alloys have drawbacks in continuous casting.
In addition to the above-mentioned continuous casting evaluation, the boron-containing magnesium-based alloy according to the present invention obtained good results for rolling workability and ignition prevention, whereas the magnesium-based alloy according to the comparative example In either evaluation, there was a defect and it was inappropriate.

  According to the boron-containing magnesium-based alloy of the present invention, it is possible to obtain a slab by a continuous casting method, to manufacture a plate material with high efficiency by rolling, and to ignite chips and the like during processing from the plate material. Therefore, it is important to contribute to the technical field of manufacturing magnesium alloy products.

Claims (2)

  Including 0.50 to 1.5 mass% of Zn (zinc), 0.4 to 0.8 mass% of Zr (zirconium), 0.002 to 1.0 mass% of B (boron), unavoidable As impurities, Cu (copper) is 0.10% by mass or less, Ni (nickel) is 0.005% by mass or less, other elements are each 0.30% by mass or less, and the balance is Mg (magnesium), and A boron-containing magnesium-based alloy substantially free of Ti, titanium, Tl (tellurium) and In (indium).   A method for producing a boron-containing magnesium alloy sheet, comprising forming a slab of the boron-containing magnesium-based alloy according to claim 1 by a continuous casting method, and then performing hot rolling.