JPS61262446A - Method for forming finer crystal grains of al or al alloy - Google Patents

Abstract

PURPOSE:To form efficiently the finer crystal grains of an Al or Al alloy casting by filtering the melt of the Al or Al alloy to remove inclusions, etc. therefrom then adding continuously an agent for forming the finer crystal grains to the filtered melt while filtering said agent. CONSTITUTION:The melt of the Al or Al alloy is filtered to remove Al2O3 and other impurity inclusions therefrom and thereafter the agent for forming the finer crystal grains which is made into a rod shape and contains comps. such as Al-Ti-B is added thereto by using sintered aggregate consisting of 15-30 mesh refractories as the filter for the agent for forming the finer crystal grains. The finer crystal grains of the casting of the Al and Al alloy are stably and effectively formed by adding the agent for forming the finer crystal grains while the coarse oxide and TiB2 contained therein are filtered.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to a method for refining the crystal grains of Al*Takashi Al alloy, and more specifically, the present invention relates to a method for refining grains of Al*Takashi Al alloy. The present invention relates to a method for grain refinement of added Al or Al alloy.

[Prior Art] In general, Al* or Al alloys that have strict requirements for the surface characteristics of rolled or extruded products have surface defects caused by oxides contained in grain refiners, agglomerated TiB2, etc. In order to prevent this, a grain refining agent is added in the process before filtration of Al or Al alloy molten metal, and for At or Al alloys with mild surface property requirements, a grain refining agent is added after filtration of the molten metal. was being added.

However, in the former case, depending on the amount of filtered Al or Al alloy molten metal, the filter is clogged with inclusions contained in the Al molten metal, and the grain refinement effect is reduced by filtering out the grain refinement nuclei. In the latter case, although the grain refining effect is stable, oxides contained in the grain refining agent and agglomerated Ti There is a problem in that linear defects and the like are caused by B2 mixed into the ingot.

[Problems to be Solved by the Invention] The present invention solves the various problems in the prior art as explained above. Even in cases where the surface properties are relatively mild, Al or A remains stable.
This invention opposes a method for refining the crystal grains of Al or Al alloy, which can refine the crystal grains during casting of molten Al alloy.

[Means for Solving the Problems 1] The method for refining grains of Al or Al alloy according to the present invention is characterized by: After filtering aluminum or aluminum alloy molten metal, the filtered aluminum or aluminum alloy molten metal is The purpose is to continuously add the grain refining agent while filtering it.

The method for grain refinement of Al or Al alloy according to the present invention will be described in detail below.

As explained above, in order to stably refine the crystal grains of Al or Al alloy (hereinafter sometimes simply referred to as Al), it is necessary to use molten Al or Al alloy (hereinafter simply referred to as molten Al). After filtration, a grain refining agent must be added continuously, and in this case, foreign matter mixed in the grain refining agent, which causes surface defects in rolled or pressed products, may be mixed into the Al11 lump. Sometimes.

In the method for refining grains of Al or Al alloy according to the present invention, after filtering the molten Al, the Al
For example, a sintered refractory aggregate of 15 to 30 meshes is installed in 1 liter as a filter for the grain refining agent.
The grain refiner is added continuously after removing coarse oxides and agglomerated TiB2 present in and on the surface of the grain refiner (usually in the form of a rod due to continuous addition).

In this way, since the crystal grain refining agent, which has been purified by filtering out oxides and agglomerated TiBz, is continuously added to the molten Al, the surface of the cast At is free from any defects. is obtained.

However, when a rod-shaped grain refiner is added before a filter for molten Al, it has the effect of filtering out foreign substances that cause surface defects contained in the grain refiner, but at the same time
A large amount of inclusions contained in the molten metal are also filtered and adsorbed on the filter surface, so the filtration capacity increases according to the amount of molten Al processed, and TiB2, which is the core of crystal grain refinement, is removed from the molten Al. However, as explained above, in the method for refining grains of Al* or Al alloy according to the present invention, the molten Al is filtered. Later, since only the grain refiner is filtered, what is adsorbed on the surface of this filter is only the inclusions of the grain refiner, which is a very large amount.
The grain refining agent is effectively contained in the molten Al, and a stable refining effect can be obtained.

[Example 1] An example of the method for grain refinement of Al or Al alloy according to the present invention will be described.

Example I After filtering Al molten metal, it is filtered using a filter containing only a crystal grain refining agent (rod-shaped Al-Ti-B <15 to 30/filter made of sintered refractory) to remove Al. It is continuously added to molten metal and cast.

As a result, no linear defects were observed on the product surface, and a stable crystal grain refinement effect of 3III11 or less crystal grains was obtained.

Comparative Example I When A I-T i -B crystal grain refiner is added in front of the filtration device for molten Al, the grain refiner effect is observed in the initial stage of addition of this refiner, but after 100 to 200 tons. If molten Al is processed to a certain extent, the filter will be clogged with inclusions contained in the molten Al, and the Ti finer will be removed.
B2 is also filtered out, and the crystal grain refinement effect gradually decreases.

Therefore, the refinement effect of reducing the crystal grain size to 3 cm or less can only be obtained when the amount of molten Al processed is about 50 to 150 tons.

Comparative Example 2 After filtering molten Al, A of the grain refiner rod
When l-TiB is continuously added, the coarse oxides contained in this grain refiner and the agglomeration T! B2 is mixed into the Al1) lump, causing surface defects. This surface defect is a linear defect.

[Effect of the invention 1 As explained above, the method for grain refining of Al or Al alloy according to the present invention has the above configuration, so in the conventional method, the method for refining the grains of Al or Al alloy ingot is Although there was a constraining force f on grain refinement, almost all A
This is an excellent method that can be applied to L or Al alloys, and can also provide a stable grain refinement effect.

Claims (1)

[Claims] A method for refining grains of Al or Al alloy, which comprises filtering aluminum or molten aluminum alloy, and then continuously adding a grain refining agent to the filtered molten aluminum or aluminum alloy while filtering.