DE1508146A1 - Method for producing a steel block free from edge blisters and voids - Google Patents

Description

1508U6

Dr.-lng. G. Eichenberg Dipl.-Ing. H. Sauerland 4 Dosseidorf, April 26, 1966 Patent Attorneys Ctchit «.» ·. 7 *

Bank account:

Deutsche Bank AG., Branch · DüiMldorf

Postal check account: Essen 8734

Telephone number 432732

V * rw * nd «n Si · im Sdiriftvtrielir avdi Dortmund-Hörder Hüttenunion Aktiengesellschaft, Dortmund, Rheinisohe Street 173

"Method for producing a 3tahlblook8 ⁿ

Bs is known to calm steel blocks or slabs, to shed unquieted or auoh half-calmed, being the unquieted baw. provides semi-settled solidification because of the reduction in the bottom curl in general. The elimination of the Bohwindungslunkers greatly reduced Measure the head red and thus lead to a not insignificant increase in the spread compared to reassured solidified steel

In the case of unsettled solidification, however, the block segregation becomes unpleasantly noticeable as the Alloy elements of the steel are unevenly distributed over the block cross-section. Biesen Haohteil have half-calmed, solidified blöoke} with them the distribution of the Bisen companions and alloying elements is

QQM10 / 0584

1508U6

To the letter of April 26th ... 196.6. on. "Method of . producing an a ,,. # _οΗ

relatively small shrinkage cavities and little head rot homogeneously over the block cross-section. On the other hand, blocks that have frozen in a semi-calm state have another defect, the consists in the fact that part of the carbon monoxide that forms remains in the form of small bubbles in the solidified layer of the hand of the block. Such hand bubbles represent a very unpleasant mistake that can especially in the further processing of the blocks has a very disadvantageous effect. The marginal bladder infestation is common so strong that a considerable part of the surface layer has to be removed by scarfing or the like.

It is known that the carbon monoxide formed during solidification leads, depending on the amount, to unconsolidated or semi-sedated solidification. The extent to which the freezing process is unsettled or semi-settled in individual cases is shown • ioh from how strong the steel is at a given temperature Ton «deviates from a carbon-oxygen balance. As a result of semi-calmed solidification, the carbon and oxygen content are either reduced by gate deoxidation or by setting a vacuum treatment so that they are noticeably below the relevant oil equilibrium value, however, this is exceeded by the carbon and oxygen segregation in the area of the solidification front. In the case of killed steels, the free oxygen in the steel is generally reduced by the addition of elements with an affinity for oxygen, such as Aluminum, silicon and titanium are so low that the

009810/0584 bad or, g, nal

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to write from April 26, 1966 on "Method for producing a ,,, 'bi _att >

Carbon-oxygen equilibrium during solidification is not reached,

Ee has now been found that a steel too then calms solidified when its carbon and oxygen content is increased, for example through a vacuum treatment low values are lowered and the steel has a manganese content determined by these values. Expressed differently this means that the steel solidifies with a given oxygen and manganese content if its carbon content is below a ™ certain value. For the dependence of the carbon content with regard to a calm solidification were found the following relationships!

for (* 0) »20. 10 ~ ³ is () tC) <- 0.0035 + 0.06 (#Mn), for (# 0) - ^{3010 ~ 3} is (#C) <- 0.0055 + 0.06 for (% 0) m 40. 10 ~ ³ is (#) <- 0.0075 + 0.06

The determined dependency of the contents of oxygen, carbon and manganese eei explained in more detail below using an example. A steel with 0.030 # oxygen, O _f 4296 manganese, less than 0.002 # aluminum, below 0.01 # silicon, using the above relationships, requires a critical carbon content of 0.02096. The steel was cast into two ten-ton slabs, one of which solidified completely calmly at a carbon content of 0.01796 and consequently had shrinkage holes.

009810 / 058Λ

1508U6

To the letter of April 26, 196 6 on ? Ίλχ ££ 3οχ & Ά JKlM ... Her st e 1 Jen e ine a, ...., % \ _att "

stared slab had a very clean surface, so
that a flaming or cleaning, as it is often indispensable with aluminum-killed slabs, was not necessary.

The second slab had a carbon content
of 0.022Ji and solidified without formation of bottom wrinkles, but had numerous marginal blisters. From this it follows
It is clear that the calmed or semi-calmed solidification behavior with a certain manganese content is only slightly dependent on the oxygen content, but to a large extent on the carbon content of the steel

Proceeding from this, the object on which the invention is based was to provide a both marginal bladder and also to produce a steel block free of winding voids. In accordance with the invention this object is achieved by directing the solidification of the block in such a way that the block is half-closed in the core. higt, in the edge zone, on the other hand, freezes calmly.

In one thing, the invention consists in one thing
In the core of a semi-calmed block with a calmed surface layer to be produced by pouring it into the still liquid block core of a steel calmed in a vacuum after the formation of a calmed, solidified surface layer one for one
Sufficient amount of carbon is given to semi- or unsettled solidification. In this way, if the respective disadvantages cease to exist, the advantages of the calmed freeze
with the advantages of unsettled or semi-settled

009810/0584

For the letter of April 26 ... I9fi.fi on ⁿ .Yβ] ^ iBJUEβΔ ... 2] m..H.ftr.β1ί · X.λβn .... iinβS. ₍ .,. »'Sheet V

S "

th steels united · That is, the block produced according to the method according to the invention is both blistered and auoh free of voids.

The point in time at which the carbon is added to the liquid block core depends on the diameter of the edge layer required for error-free further processing. If the diameter of the solidified surface layer increases steadily from the block head to the block base, the addition time λ point for the carbon is determined in two ways using the edge layer diameter on the block head. The time dependency of the solidification results for gravity die casting from the following formula:

d - 2.5 \ Tt,

where d is the diameter of the solidified surface layer in centimeters and t the leit naoh start of blurring in minutes. Thus, the key point for the addition of carbon after the start of solidification can be set according to the subsequent oiling be determined i

d is in this YaIl the most error-free Further processing to the required thickness of the border blemishes-free Randsohioht. Is therefore a blister-free layer of For example, 2.5 cm is required, the addition of carbon must take place 1 minute after the start of solidification.

The added amount required in each individual case is er-009810/0584

1508U6

To the letter of April 26, 1996. at ¹¹ YeX. to. Making a ... 'sheet

is also the difference between that for a semi-settled or unsettled solidification according to the above Conditions required carbon content of the melt and the actual carbon content for which calmed solidified slab of the example described above would therefore require an additional amount of carbon of 0.003 ^. In any case, however, it is advisable to use an amount of carbon in "To give the block core. Practice has shown that In general, carbon additions of less than $ 0.01 are sufficient, which for a ten-ton slab is an addition of Corresponds to 1 kg of carbon. As tests have shown, the slight increase in the carbon content caused by the addition of carbon leads to the Steels do not significantly impair their technological properties. Sa the carbon addition in the liquid block core is added to the block, after the solidification of the outer bubble-free outer zone to prevent the formation of shrinkage cavities, it is sufficient if the carbon content is only increased in the area of the block head.

According to the invention, the carbon is added by dipping carbon rods or rods made of carbonaceous material into the liquid block core. It However, containers with carbon or carbonaceous material that dissolve or decompose in steel can also be added to the liquid blook core. A wide

009810/0584

1508U6

To the letter of 26 April 1966 on _o "Yerf Ahren for producing a. ·· '' Wt V

re possibility of introducing carbon or carbonaceous Material in the block core consists of the use of a carrier gas or of those that decompose in the steel carbon-containing gases such as methane.

009810/0584

Claims (1)

Ί bUÖ146 To the letter of April 26th. 19.6.6 to !! procedure, .... for .... producing a ..... ».'blatt 5k Dortmund-Hörder Hüttenunion Aktiengesellschaft, Dortmund, Rheinische Strasse 173 Claims; ο A method for producing a steel block free from edge blisters and voids, characterized in that sufficient carbon is entered into the still liquid blockers of a steel that is preferably calmed in a vacuum after the formation of a calmed solidified surface layer. 2ο method according to claim 1, characterized that a carbon or carbon containing rod is immersed in the liquid block core will ο
> ο Method according to claim 1, characterized in that containers containing carbon or carbonaceous material which dissolve or decompose in the steel are introduced ο into the liquid block core ο Method according to claim 1, characterized in that ~ draws that carbon or carbonaceous material is blown into the liquid block core using a carrier gas.
0 09810/05 84 1508U6 In relation to the letter of April 26, 1966 to Verfahrenzum den Verfahren a .. .Wt ο method according to claim 1, characterized d u r ο h blowing in carbon and yourself in the steel decomposing gases in the liquid block core. 009810/0584