DE1533326C - Process for the production of magnesium-containing master alloy blocks - Google Patents

Description

According to a particular embodiment, however, the method according to the invention can also be used of one-part or multi-part molds of the usual nature and materials, such as cast iron, copper, Refractory material with or without additional cooling. This way they become container-free Manufactured master alloy blocks, which are placed in special containers suitable for transport and storage and so can be protected from external influences, e.g. B. in hobboks made of metal, cardboard or Plastic.

In some cases it can also be useful to insert a sheet metal sleeve into the mold as an outer jacket for the master alloy block to be produced in order to reduce the risk of breakage, especially with larger block weights to reduce. Finally, it has proven to be advantageous to add one more to the master alloy block Pour a suspension device (e.g. an iron hook), which facilitates the introduction and fastening of the Facilitated master alloy blocks in the dipping device.

The production of the master alloy blocks according to the method according to the invention takes place in the manner that pieces of a pre-made magnesium master alloy from about walnut to double the size of a fist in the already described containers or molds are introduced. This is done, for example, through Pouring in, shaking in or inserting. Between the most closely packed master alloy pieces cast a molten magnesium master alloy, which expediently has the same or similar composition as the presented lumpy Master alloy.

The amount of molten magnesium master alloy, which is used as "embedding melt" is expediently much less than that presented Amount of chunky magnesium master alloy. After loosening the edge zones of the master alloy pieces The master alloy melt solidifies very quickly, and the amount of heat released is absorbed by the master alloy pieces and partly also quickly absorbed by the walls of the container or the mold. In this way, segregation phenomena are avoided and segregation does not occur on. If the melt and lump master alloy have the same chemical composition, an in From an analytical and metallurgical point of view, a completely homogeneous alloy block is achieved.

The ingots made of magnesium-containing master alloys produced by the process according to the invention can be used particularly favorably for the immersion treatment of cast iron melts that serve to manufacture spheroidal graphite cast iron.

In particular, cast blocks produced by the method according to the invention can be used, in which the presented lumpy master alloy and the melt used for embedding made of alloys the composition consist of:

The method according to the invention has a number of advantages. This is how magnesium-containing master alloys can in block form in any technically sensible size and with unusually good homogeneity getting produced. Another advantage is that block-shaped and homogeneous master alloys with a particularly high magnesium content can be produced, which in spite of this particularly high magnesium content with a relatively small active surface, a smooth reaction and treatment process with a comparatively high magnesium yield, compared to a treatment with a lumpy master alloy of the same composition.

A general advantage of the method according to the invention is finally to be seen in the fact that the method according to the invention produced homogeneous and compact master alloy blocks containing magnesium allow comparatively smaller diving bells. These diving bells are more stable and durable and the heat loss during the immersion treatment is also reduced.

The volume of the master alloy blocks produced by the method according to the invention can are not only kept significantly smaller compared to the corresponding amount of lumpy master alloy, In addition, the master alloy block can also have a higher magnesium content, since the expected greater reaction force of the master alloy "by reducing the Surface compensated and thus a smooth reaction process is guaranteed. Let it go on In this way, particularly high master alloy yields can be achieved with an almost constant magnesium yield.

A great advantage of the method according to the invention can also be seen in the fact that the use the master alloy blocks produced according to the invention have significantly higher treatment temperatures allows the use of a lump master alloy of the same composition, which in turn due to the different ratios between master alloy volume and master alloy surface is.

The process according to the invention is explained in more detail using the examples below.

example 1

A magnesium-containing master alloy according to the following analysis is made in an induction furnace (graphite crucible) in a known manner and closed in an open hearth Sheets from 40 to 55 mm thick have been cast.

Mg
% Approx
% SE
° / o Fe
% Si
° / o 50.9 4.8 0.8 4.6 rest

20 to 60, preferably 41 to 55%

1 to 10, preferably 4.5 to 6.5% Ca

<20, preferably <10% ^feet

0 to 12, preferably <2% SE

The remainder is silicon, which can be completely or partially replaced by nickel and / or copper.

After cooling, the plates were smashed into pieces the size of a walnut or the size of a palm. In one Sheet iron containers open at the top were placed in tight packing with 2.7 kg of these master alloy pieces. the The diameter of the sheet metal container was 250 mm and its wall thickness was 2.5 mm.

The cavities were made with a molten and only slightly overheated magnesium master alloy between the sheet metal container described in

existing master alloy pieces are poured out. The melt was by remelting parts of the aforementioned magnesium master alloy and thus had almost the same chemical composition like the chunky magnesium master alloy. The use of 1.3 kg of pre-alloy melt resulted in a compact block with a net weight of 4.0 kg. This intended block weight was determined with the help of a scale which the tin container stood during packing and pouring, precisely set.

Example 2

In a foundry took place under operating conditions the production of spheroidal graphite cast iron in the immersion process. A single one was used for this Commercially available lumpy master alloy with a magnesium content of 30.4 7o and on the other hand one after Master alloy block produced according to the method according to the invention with a magnesium content of 50.9 70 from Example 1. A lump magnesium master alloy with a high magnesium content comparable to that of the master alloy block could be due to Do not use explosion hazard.

The following tables describe the master alloy sets and treatment of the cast irons melt:

Master alloy VL- "block" 4.0 kg Piece size Master alloy block Commercially available (of example 1) Lumpy master alloy according to the invention Master alloy Master alloy set about the size of a fist (see example 1) - -. 6.2 kg,., ·· in the sheet metal container in in the sheet metal container analysis bulk 50.9% 30.4 »/ 0 4.8% 4.5 7o 0.8% 0.8 7o 4.6% 7.6 »/ 0 rest rest - Mg Approx SE Fe Si

treatment Diving bell Diving bell Cast iron (kg) 1000 1000 analysis c (7o) · · · 3.7 3.7 Mn (7o) · · · 0.28 0.31 P (%) · · · 0.034 0.034 S (7o) ■ · · 0.018 0.017 Si ( ⁰ I ₀ ) ... 1.6 1.6

Master alloy
(see 0.) Commercially available VL
(6.2 kg / 30.4 mg) VL- "block"
(4.0 kg / 50.9 mg) Immersion temperature (° C)
Dive time (seconds)
FeSi-90 vaccination
GGG analysis
Si (%)
Mg (7o)
S (7o) 1485
50
5 kg Si
Start of pouring
. 2.4
0.064
0.009 1500
55
5 kg Si
Start of pouring
2.3
0.062
"■■ ■: ': o, oo6 ·

The following magnesium yields and the following master alloy yields are calculated from these results:

Magnesium yield (7o) =

Master alloy yield (7o) = - · Δ S ( ⁰ I ₀ ) + Mg (7 ₀ ) _GGG ) · 100

Mg (7o) vL sentence

100

VL (7 ") sentence

treatment Commercially available VL
(6.2 / 30.4 mg) VL- "block"
(4.0 / 50.9 Mg) Mg yield
VL yield 37.6%
11.4% 34.5%
17.6%

Claims (2)

1 2 claims to achieve a high cooling rate (German patent 1142 444). The shedding 1. Process for the production of master alloys of this type, for example in block form Treatment of cast iron melts for the production of inevitably leads to much slower cooling cast iron with spheroidal graphite cast ingots suitable 5 ment of the melt and usually to their entaus magnesium-containing master alloys, thereby mixing during solidification. The usage characterized in that magnesium-containing from magnesium master alloys in from relatively thin Lumpy master alloy in a container or a cast plate broken pieces has the consequence that Permanent form, preferably cylindrical shape, in the form of spheroidal graphite cast iron The closest possible packing was introduced and the required master alloy sets of large volume hollow volume with a molten pre-casting are large with a relatively low bulk density tion, preferably with one of the lumpy pre-immersion bells and the one to be treated alloy corresponding or similar composite cast iron melt a comparatively large Obermensetziing, poured out and offer surface by melting. The latter often leads to undesirable of the edge zones of the master alloy pieces the homogeneous 15 dissolution of the magnesium master alloy gene embedding of the. Pieces into a compact during the dipping process and too undesirable Master alloy block is brought about. violent reactions, especially the magnesium 2. The method according to claim 1, characterized in that the lumpy master alloy in the treatment pans is characterized by the fact that the coarse master alloy and, according to already known proposals, the embedding melt from an alloy can also be made from an alloy following 20 through the chemical composition and with the aid of gender composition: different Alloy components that are mutually “ _Λ,. , _ ·. .. ,. - ",",. should be available in each predetermined amount ratio, 20 to 60, preferably 41 to 55 "/" Magnes.um _{the Rea} ktionsverha] th of the magnesium Vorlegierun- ' 1 to 10, preferably 4.5 to 6.5% calcium gene affect, (German patent 1173 667). <20, preferably <10% iron 25 In the production of cast iron with spheroidal graphite however, there is a technical need for as much as possible 0 to 12, preferably <2% rare magnesium-rich master alloys and at the same time after earth metals high treatment temperatures. Here, in The remainder is silicon, which is partially or completely higher pre-alloy nickel due to a reaction that can be safely controlled and / or copper can be replaced. 30 yields and an improvement in slag separation can be achieved, so that with constant the master alloy set larger amounts of cast iron can be treated or with the same The present invention relates to a batch weight of the treatment process in advantageous for making compact master alloy ingots 35 adhesively by downsizing the master alloy magnesium-containing master alloys due to quantity, temperature loss and immersion bell casting can be made of pieces of a pre-made master alloy size, with a molten master alloy the same or To solve this problem, the present similar composition. It is also directed to the invention a method for producing cast die Use of blocks made of magnesium-containing master alloys according to the invention, Process produced magnesium-containing Vorlegie- 'for the treatment of cast iron melts in blocks for the production of cast iron with immersion processes are highly suitable and the Spheroidal graphite. with the same composition as compact It is known that magnesium-containing master alloys blocks show no signs of segregation, to bring in so-called diving bells and thus 45 This method consists in that one in known To treat cast iron melts in the "dipping process" Way of prefabricated chunky magnesium master alloy with the aim of producing spheroidal graphite cast iron. in a container or in a permanent form, preferably The magnesium-containing master alloys are generally cylindrical in shape, packed as closely as possible think in lump form, they are introduced into one and the resulting hollow volume of this Metal containers filled and so in the diving bells a 50 pack with a molten magnesium-Vorschlag. It is also known to cast magnesium-containing alloy and melt the Master alloys in preferably cylindrical block edge zones of the master alloy pieces the homogeneous form for the production of cast iron with spherical embedding of the pieces in a compact pre-alloy graphite to use. Another known preprocessing block is brought about. The molten one Schlag sees for this purpose a semi-cylindrical or a magnesium master alloy should preferably be a this body, assembled to form full cylinders, made of the chunky magnesium-pre-magnesium used in each case or magnesium alloys (German alloy corresponding or similar chemical additives) Utility model 1 711 729). have composition. For the production of cast iron with spherical For carrying out the invention it is expedient graphite used magnesium-containing master alloy 60 a casting mold used in the manner of a one-sided Due to their chemical open container, genes tend to be cylindrical in shape. The container settlement for segregation (segregation phenomena), the wall of such a simple pot can and it is often difficult to make them with as homogeneous a material as possible, for example from thin sheet iron (about 5 mm) Structure and constant analysis to pass. In some cases it should be useful To freeze. To avoid the need to cool the container walls and the heat Mixture of molten magnesium master alloys to quickly dissipate the introduced melt in order to During their solidification, therefore, a breakthrough of the melt is known to occur with a thin wall thickness It is wise to avoid producing panels with a relatively thin layer.