US2654144A - Method of forming big end up ingots - Google Patents

Description

Oct. 6, 1953 G. A. DORNIN METHOD OF FORMING BIG END UP INGOT 3 Sheets-Sheet 3 Filed Feb. 28. 1948 INVENTOR. GEORGE A.DORNIN, DECEASED. BY FLORENCE L.T. DORNIN, EXECUTIRIX awyuaa. 4

Patented bet. 6

METHOD OF FORMING BIG END UP INGOTS George A. Dornin, deceased, late of Youngstown, Ohio, by Florence L. T. Dornin, executrix, Warren, Ohio, assignor to George A. Dornin,

Jr., Warren, Ohio Application February 28, 1948, Serial No. 11,888

1 Claim. 1

This invention relates to multiple tapered big end up ingots of killed steel and to a method of making sound ingots of killed steel without employing a hot top. The elimination of the hot top results in the following advantages:

(1) All hot top cost is eliminated (including handling cost and cost of breaking off the hot topt from the ingot after the ingot has been cas (2) There are fewershut offs during pouring and consequently a shorter pouring time is required per heat. In casting ingots provided with hot tops it is customary practice to pour up to the bottom of the hot top, then to stop pouring to allow a seal to form between the hot top and ingot mold and thereafter to resume pouring. The shorter pouring time and fewer shut offs required where hot tops are not employed result in less stopper trouble.

(3) There is much less pouring difllculty when a. running stopper does occur.

(4) The mold life is increased. The erosive action of the pouring stream on the bottom of the mold is less because the head (distance from ladle to bottom of mold) is shorter. Also when canted nozzles occur, there is more room in which to move the ladle around to correct for the canted nozzle, which means that the plug or plate in the bottom of the mold will be hit much oftener and there will be fewer stream-cut" molds.

(5) There are fewer stickers for the rea sons outlined in (4) above, and because due to the shorter pouring time per heat it is practical to slow pour the bottom of each ingot for thirty seconds or so, which cuts down pressure of impingement on the mold bottom, thus forming a cushioning pool to protect the mold from the severe erosive effect of the full stream. Stickers have many disadvantages; they cause stripper delays, stripper breakdowns, poor mold life, increased cost of heating and increased surface conditioning costs since sticker ingots are charged into the reheating furnaces in a colder condition than the usual ingots. Stickers do not follow their heats through the mill and quite often become mixed with ingots of different analyses.

In the accompanying drawings which illustrate certain embodiments of my inVentiQ Figures through 4 illustrate the steps employed in carrying out the process of Dornin Patent 2,021,227. In these figures,

Figure 1 is a vertical section through an ingot showing the pipe cavity and underlying segregate zone;

Figure 2 is a vertical section through an ingot in which cleavage has been produced artificially between the core, which includes the metal to be isolated and the surrounding zone of sound metal;

Figure 3 is a vertical section through an ingot which has been treated as shown in Figure 2 and then upset to displace the surrounding zone of sound metal away from the core;

Figure 4 is a view in side elevation of the ingot of Figure 3 after reshaping to prepare the ingot for rolling;

Figures 5 through 7 are vertical sections of multiple tapered ingots according to the present invention;

Figures 8 and 9 are vertical sections of ingots having continuous tapers, the taper in Figure 9 being greater than that in Figure 8. These figures do not illustrate the present invention but are given for purposes of comparison;

Figures 10, 11 and 12 illustrate where the measurement of the horizontal narrower dimension is taken in determining the per cent taper of an ingot or any portion thereof.

The present invention constitutes an improvement over the invention disclosed and claimed in George A. Dornin Patent 2,021,227. Briefly that patent discloses and claims a method of isolating unsound metal of an ingot in which the unsound metal is included in a central core adjacent the top of the ingot and the unsound metal February 20, 1947, now Patent No. 2,585,096, is-- sued Februar 12, 1952, discloses and claims an improvement over the Dornin Patent 2,021,227. That application refers to the effect of ingot 3 taper in carrying out the process of the Dornin patent. In that application the reference is to taper in general and is broad enough to cover uniform taper or non-uniform taper. The present application is an improvement on the Dornin patent and the Dornin application. The present application is directed to an ingot having nonuniform or multiple taper and to a method of forming such ingots. Application Serial No. 729,777, as well as the present application, relate only to the treatmentof ingots which have been cast without the use of refractory hot tops. If an ingot were cast with a refractory hot top, the shrink head portion of the ingot within the hot top would be contaminated by the refractory material of the hot top. Thus the bulged per:

tion 8 shown in Figure 3 would be contaminated V on the surface with the refractory-material and the corresponding part of the forged ingot as.

shown in Figure 4 would be contaminated. This contaminated portion covers substantially the area above the line 9 as shown in Figure 4, which amounts to approximately the upper fourth or the ingot. If a hot to'p were used it would be necessaryito crop off this contaminated upper portion, which, of course, would be uneconomical.

The effect of taper of an ingot having a continuous taper in carrying out'the process of the Domin Patent 2,021,227 is as follows: Large taper tends to produce a shallow pipe cavity and a shallow segregate zone under the pipe cavity and insures reliable feeding of the ingot during solidification. fore, large taper in an ingot is desirable in carrying out the process of the Dornin patent. On the other hand, large taper of the ingot has certain disadvantages in this process. Large From these viewpoints, theretaper increases the difierence between-the top and bottom cross-sectional areas of the ingot and consequently increases the "difference between the rate of metal risein the lower part or the ingot and the rate of metal rise in the upper part of the ingot. The heavier the taper.

the {greater is the tendency to have either a rate of metal rise in the lower portion of the ingot ivhich is so fast as to produce a thin tender skin which often tears during forging or rolling operations or if the pouring rate is cut down 'so'as todeerease the rate of metal rise in the lower portion of the mold, a rate of metal rise in the "ripper portion "of the ingot which is so slow :as'to cause crusting during pouring with resulting more fully in application 729,777. Another 'objection to ingots having large continuous taper isv that they require more work to be performed upon them in upsetting and forging them as shown Figures 3 and 4.

It can be seen that in carrying out the process of the Dornin patent by employing ingots having a continuous taper, large taper produces some effects whichfare advantageous and other efiects jsecondary pipe and segregation as explained In accordance with my invention, this com- A,

promise is avoided by employing a multiple or non-uniformly tapered ingot, the taper in the upper portion A'being greater than that in the lower portion B. The upper portion Amay have a single taper as shown in Figure 5 or a multiple taper as shown in Figures 6 and 7. In Figure 4 6 the taper of sub-portion C is less than that of sub-portion D whereas in Figure 7 the taper of sub-portion C is greater than that of sub-portion D.

The overall per cent taper as used herein is defined by the formula where F represents the horizontal narrower dimension of the ingot at the top measured on or .adj acent a center line, E represents the horizontal narrower dimension of the ingot at the bottom of the body length measured on or adjacent a center line, and L represents the body length 'of the-iii'gbt; Thusthe ingot shown in Figure 5 which has a horiaontal narrower dimension (width) F atthetop of the ingot of 23 inches,

fa horizontal :narr'ower dimension (width) E at the bottom of' itsbody length of 16.4 inches and a body length L of 60 inches has an overall taper of about 11%.

Similarly the per cent taper for any portion of an ingot is defined as the horizontal narrower dimension (width) at the larger (upper) end of said,p ortion,measured on or adjacent a center linepmin'us' the horiz'ontal narrower dimension above stated, the horizontal narrower dimension'is the dimension measured at or adjacent the center, line of the ingot. In the case of ingots having a smooth contour, the measurement of the horizontal narrower dimension is 'measured at a center line of the ingot. Figures 10,1 1 and 12 illustrate where the measurement of the narrower horizontal dimension at or near the center line is made in the case of ingots having 'a fluted or corrugated contour. T-hus infigure 10, the ingot is afiuted round ingot. In this tease the width J is measured along a center line r-K-passing through a-pair of opposite valleys V.

Figure 11 illustrates a corrugatedrectangular ingot. In this case also the width J is measured alonga center line K passing through a pair of opposite valleys V.

Figure 12 illustrates a rectangular corrugated ingot in which a center line K passes through a pair of opposite crests In this case thewidth J is measured'on the line Q which is adjacent to the center line :K, is parallel to it, andpasses through the pair of opposite 'valleys V lying adjacent to the center line K.

The advantages of employing a multiple tapered ingot such as shown in Figures 5-41 may be seen by comparing these figures with Figure 8 si'i'ie'"solidii-lc'ation 'are shown on all four ingots and the zone or unsound-metal including the segregate zone is indicated. Since the top and bottom areas are the same on all four ingots the relative rates of metal rise in the lower and upper portions of the ingots will be the same.

Comparing the ingots of Figures 5, 6 and 7 with the ingot shown in Figure 8, the-depth of pipe cavity P in the three multiple tapered ingots is somewhat less than in the uniformly tapered ingot of Figure 8. This is true because the three multiple tapered ingots have smaller volumes than the uniformly tapered ingot while all top areas are the same. The volume of the pipe cavity will decrease with decreased ingot volume and the depth of pipe will be correspondingly less.

Even more important, however, is the decreased depth of the segregate zone S in the ingots of Figures 5-7 since the position of the bottom of this zone determines the depth of punching required to isolate the zone of unsound metal 3 from the surrounding zone of sound metal as shown in Figure 2, the amount of work required to upset the zone of sound metal as shown in Figure 3, and the amount of work required to forge the bulged portion 8 back to a size and shape suitable for rolling or further forging. All these factors directly affect the speed of processing according to the Dornin patent and consequently directly affect the cost of the process.

Furthermore, anything done to reduce the depth of the bottom of the segregate zone S materially reduces the variations in this depth from ingot to ingot and thus increases the uniformity of the processing. Actually in many cases a smaller top crop can then be safely taken with a corresponding increase in yield.

The taper in the upper portion A of the ingot controls the freezing lines in this part of the ingot and thus controls the shape and depth of the segregate zone S which may be thought of as being the last line of freezing. By using a relatively heavy taper in the portion A, I am able to secure a relatively shallow segregate zone. If, however, this heavy taper were continued to the bottom of the ingot, it would result in a very small bottom cross-section and a great difference between the rates of metal rise in the lower and upper portions of the ingot. Figure 9 shows such an ingot with uniform heavy taper throughout its length. The position of the bottom of the segregate zone S in this figure is about the same as that in the ingot of Figure 5. However, the uniformly tapered ingot of Figure 9 will have a very much smaller bottom area E than the multiple tapered ingot of Figure 5 and the difference between the rates of metal rise in the lower and upper portions will be correspondingly greater in the ingot of Figure 9. Thus the ingot of Figure 9 tends to form a thin skin on the lower portion of the ingot or if the pouring rate is decreased, to crust over the top of the ingot dur ing the latter stages of pouring.

I have found that the lower portion B of an ingot for use in the process of the Dornin patent may be satisfactorily fed with much less taper than is required in the upper portion A since the large upper portion acts as a feeding head supplying liquid steel to the lower portion as the steel solidifies and shrinks.

In most cases it is desirable that the length of the heavily tapered upper portion be between 20% and 50% of the body length of the ingot.

Best results are usually obtained when the length of the upper portion is between 30% and 40% of the body length.

If the length of the heavily tapered u'pp'er' poftion is less than 20% of the body length there is a possibility that the lower part of the segregate zone may extend down into the lighter tapered lower portion, where, following the shape of the freezing lines in this part of the ingot, it will become quite deep and somewhat variable in depth. On the other hand, a heavily tapered upper portion longer than 50% of the ingots body'length will often result in more overall taper than desirable for best results since this would mean too great a difierence in the relative rates of metal rise in the lower and upper portions of the ingot.

I have found that best results from my invention art obtained when the per cent taper in the upper heavily tapered portion is between 10% and 25%, preferably between 13% and 22%. If the taper in the upper portion is less than 10%, the depth of the segregate zone may become. deeper than desirable for reliable isolation by the method of Dornin Patent 2,021,227. If the taper in the upper portion is greater than 25%,. there is danger that the ingot may hang in the: upper part of the mold during solidification causing horizontal tears in the upper part of the in-- got skin known to the art as hanger tears. These: hangers are more likely to occur on long, slowly poured ingots, but I have found that tapers as;

great as 25% may ordinarily be safely used.

The chief aim of my invention is to produce an ingot that is sound throughout, has as shallow a pipe and segregate depth as possible, and yet has as little difference as possible between top and bottom areas, i. e., has as little overall taper as possible.

I have found that these desired ends can best be obtained when certain relationships are maintained between the per cent taper in the upper heavily tapered portion and the overall taper. While, according to the basic teaching of my invention, the per cent taper in the upper portion should be greater than the overall per cent taper, I have found that if it is too much greater there is some possibility that the hangers mentioned earier may occur. The per cent taper in the upper 35% of the ingot body length may usually be as much as 2 times the overall per cent taper without this danger. For best results the per cent taper in the upper 35% of the body length should be between 1.2: and 2 times the overall per cent taper, and preferably between 1.4 and 1.8.

The principles of my invention can be employed to accomplish the following improved results:

(1) To produce a shallower pipe cavity P and segregate zone S with the same overall taper and therefore with the same relative rates of metal rise in the lower and upper portions of the ingot (compare Figures 5-7 with Figure 8).

(2) By using less overall taper, I can reduce the difference between the rates of metal rise in the lower and upper portions of the ingot with no increase in the depth of pipe cavity P or segregate zone S (compare Figures 5-7 with Figure 9). In accordance with common practice, the steel ingots are cast in metal molds, usually cast iron molds.

The invention is not limited to the preferred embodiments but may be otherwise embodied or practiced within the scope of the following claim.

What is claimed is:

The method of forming an ingot which comprises casting without a hot top, a big end up inset f. fully deoxidized, steel, said ingot having upper and lower portions which taper down wardly, the taper of said. upper portion being much greater than the taper of saidlower portion, the length of said upper portion being between. 30% and 4.0% or the bodylength of the ingot, thereby forming an ingot having at its top a central core including unsound metal surrounded by a zoneoi sound metal, and displacing said zone of sound. metal axially of the ingot to isolate the core including the unsound metal.

FLORENCE L. T. Ezeeutria: of the estate of George A; Domin deceased,

References Cited in the file of this patent UNITED STATES PATENTS Number 7 Name Date 1371952 Fogarty May 10, 1921 1,546,796 Saunders July 21, 192 5 1,6513241 Gathmann Sept. '20, 192-? 2,021,227 Domin Nov. 19, 1935 OTHER REFERENCES The Ingot Phase of Steel Production, by liliriil Gethmenn; published 1937 by Selineidefithand Sons, Bammore Md., pp; 18-19; (copy iii Div 3.)

Pages 82-84, Ingot Phase of Steel Produetion, by Emil Gathmalnii (previously cited).

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