US1712608A - Ingot - Google Patents

Description

Patented May 14, 1929.

UNITED STATES EMIL GATHMANN, 0F BALTIMORE, MARYLAND.l

INGOT.

Original application iled March 15, 1927, Serial No. 175,527. Divided and this application led January 2o, 192s. serial No. 248.176.

The application for this patent. is a division of my application for patent tiled'March 15, 1927. Serial No. 175,527, patented February 2S. 1928. No. 1.661.039.

Thisinvention relates to the manufacture of ingots, the metal ot which contracts during soliditication from the molten to the -;solid, the horizontal length and width of which ingots are materially greater than the vertical height. Such ingots are more economically reduced by Jforging and rolling.; mill operations to plates, sheets and various other units than are ingots made by the more widely used method of so-called vert-ical casting.

Prior to my invention-ingots have been cast in what are known to those familiar with the art as horizontal molds, i. e., molds-in which the longitudinal axis of the mold chamber is disposed horizontally. In the use of such molds, however. longitudinally extending pipes or shrinkage cavities have heen formed in the ingot, and in steel and other alloyed metals cast in such molds segregation of the various elements has occurred to a dangerous degree, so that when the ingotis rolled into commercial shapes or.units, some parts are sound and uniform while others are unsound or have Widely varying physical and chemical characteristics, thus causing stresses to be set up in the semi-finished product, which render it liable to break or split during the process of manufacture or in its use.

By my improvements I am enabled to produce an ingot of the horizontally cast type, which is free from pipe and shrinkage cracks and in which the segregation may be to a great extent controlled. For certain products it is desirable to reduce segregation to a minimum, which I have made possible by reducing the depth of the ingot relative to its width to induce rapid freezing of the entire mass. For certain other products, such as boiler plate, segregation can be distributed substantially evenly over the upper plane of the ingot by providing any Well-known means (such as coke dust, powdered graphite or the like spread upon the top of the molten metal While the ingot is being cast) for retaining the metal molten at its upper surface for the desired length of time to obtain the amount of segregation required for the particular product.

The mold made in accordance with my invention preferably has a long, horizontallyarranged'major axis and a relatively nar'- rower transverse axis. The height or depth of the mold chamber is less than its Width for reasons hereinafter explained. The side walls defining the ingot-forming chamber preferably gradually decrease in thickness upwardly and the bottom wall, which is relatively thicker or more heat-absorptive than -the side walls. is formed with a camber or have these characteristics and/'the chamberV is properlvY dimensioncd, the freezing or@A solidifying of the molten meta-l will be completed in less time for a given mass ot metal than has heretofore been possible and the shrinkage :of the mass will be of such a character thatno pipe. is formed either at the top or at thek ends of the ingot and that segregation, due to the rapid rate of soliditication of the molten metal, will be readily controlled.

My improvements are illustrated in the accompanying drawings, in which- Figure 1 is a perspective view of a. horizontal mold made in accordance with my invention, portions of the mold being omitted for convenience of illustration.

Figure 2 shows a vertical transverse section on lines 2 2 of Figure 1.

Figure 3 shows a section similar to that shown in Figure 2 with the solidificdingot shown in cross section in the mold cavity.

Figure 4 shows a longitudinal section of the mold on lines 4t-4 ot Figure 1 and illustrates also a longitudinal central section of the ingot cast in the mold.

`Figure 5 is an enlarged view in perspective of a portion of the ingot.

Figure 6 is a perspective View of a portion ot a plate or sheet rolled from an ingot such as shown'in Figure 5.

The mold made in accordance with my i'nvention is preferably of cast iron, which is commonly used inthe manufacture of various types of ingot molds, the chamber Walls being formed as smooth as the state of the art permits.

As is well-known to those skilled in the art, well deo'xidized molten steel freezes and solidilies upwardly and inwardly from the mold chamber walls, usually through formation of dendriticcrystals, until soliditication is complete.

In vertical vmolds of now well-known design, this solidifying process of the ingot is so controlled by means of big end up mold chambers and refractory shrink head casings that the so-called pipe or shrinkage cavity is greatly reduced and confined to a -relatively small part of the ingot at its top. In the casting of ingots in horizontal molds, however, a decided shrinkage pipe, cavity or crevice has heretofore been formed, which usually extends longitudinally from one end of the ingot to the other, being deepest and most pronounced near the center of the mass of the ingot, which is always last to cool and solidify, at which zone segregation is likewise concentrated.

By my invention I so shape the mold chamber that the molten metal of the ingot will solidify in its central longitudinal portion in substantially the same period of time as the side or surrounding portions and the ingot is so formed that what is known as cleavage cones and ingotism or the formation of large crystals in the structure of the ingot are greatly reduced. The bottom or base of the ingot surface being inwardly bellied or cambered to an extent proportional to the width and depth of the mold chamber and in ratio to the volume of the shrinkage of the metal forming the ingot during` solidification, the formation of shrinkage cavities or pipes is prevented by compensating for and forcing the contraction of the metal in vertical planes during soliditication. A slightly dished or camber-ed portion at the upper face of the ingot is sometimesformed therein, but concentrated shrinkage cavities or piped zones are entirely prevented. In this way a great saving is effected, as the percentage of sound metal which can be rolled or forged into commercial shapesI is approximately the entire ingot, less only the usual scale and trimming loss of 4% to 6%.

An important feature of the invention is that the walls defining the mold chamber are of such contour and heat absorptive quality that the molten metal will cool, solidify and shrink in a substantially vertical direction from the bottom upward in approxin'iately the same period of time at all vertical planes, as the depth of the liquid ingot metal in the mold chamber at its central longitudinal port-ion is proportionately less and the cooling action of the mold walls greater than at adjacent portions of the chamber.

The drawings illustrate one way of constructing a mold in accordance with my invention. The mold is made of cast iron of the kind usually employed. The bottom B of the mold is relatively thick and heavy and the side walls A, which are materially thinner and less heat absorptive, gradually decrease in thickness vfrom their'lower to their upper ends, thus insuring that the soliditication of the molt-en metal of the ingot will be progressively upwards, the same rule applying-in the formation of the side walls of the horizontal molds as applies in the formation of side walls o'f vertical molds.

The bottom wall of my horizontal mold, however, diifers from the bottom wall of other molds. It will be observed that the bottom wall, in addition to being relatively thick and heavy and thus more heat absorptive than the side walls, is formed with a longitudinal rise or camber X, which projects to its highest lpart at the central or middle longitudinal portion of the mold cha-mber, so that as the molten metal cools, shrinks and solidiiies coincidently in the middle portion of the mold with that of all adjoining portions, the entire mass of metal becomes solidiiied without pipe or shrinkage cavity being formed therein. The rise X may have various contours but is preferably cambered in the form of a convex arc as shown, the amount of this rise being governed by the depth and width of mold chamber and the character of the ingot metal for which the mold is designed.

As previously stated, the height of the mold chamber or that part thereof in which the casting is made, is less than its width. I have found that the width should considerably exceed the depth of the chamber in order to obtain the best results. The exact ratio depends upon the type of material being cast and the product for which the ingot is intended, e. g.. for low-carbon de-gassified steel, which solidities relatively rapidly, a mold of the following dimensions might be used for sheet bar product.

If the width of the mold chamber at its top is l2, the greatest height of the chamber should be approximately 8, while its height from the top of the rise X should be about 7". The over-all height of the mold should be approximately 13, the distance from the bottom face of the mold to the top of the rise X thus being about 6". The taper of the mold chamber from top to bottom should be approximately 1/2.

These relative dimensions have given satisfactory results in actual test, but may and should be varied to correspond with specific conditions and requirements. The mold may be of any desired length within limitation. Any length to which the metal can flow without danger 'of laps or cold shuts may be utilized.

It will be understood by those familiar with the artthat the liquid metal of an ingot solidifying in a metallic mold is invariably hottest for a longer period of time at the central or portions'of the ingot unless means are utilized to accelerate its cooling. B my improvement there is less vertical height of ingot to cool at the center of the mass than at adjacent transverse parts, so that the rate of vertical cooling, within the limits specified, can be adjusted to obtain uniform solidification. The method of teeming or pouring the meta-'l into my improved type of mold and the stripping of the ingot therefrom is nota part of this invention. Various well-known methods have been found satisfactory.

Referring to Figure 5 of the drawings, I

have illustrated by dotted lines, a, I), c, and d, I

the manner in which solidification of the ingot occurs.

In Figure 6 of the drawings I have shown in perspective a portion of a plate showing the uniformly segregated zone portion in dotted lines, this portion having-been the last of the ingot to solidify.

, It will be observed that the ingot formed in the manner hereinbefore described, has two primary side walls, that is, the bottom and top of the ingot, and four secondary walls, namely, the longitudinal sides, and the ends. It will also be observed, by reference to Figure 5 particularly, that all corners are well rounded. By such a construction most elieient heating and rolling can be obtained without danger of burning or cracking dur- `ing these operations.

I claim as my invention: l. An ingot of slab-like contour, the depth of which slab is less than its width or length,

one of the primary sides of larger area being concaved to a. depth of not over one-fourth but to at least one-eighth of the thickness of said ingot.

2. A horizontally-cast ingot, the length of which is greater than its width and the depth of which is less than its Width, one of the sides of a larger area being concaved to a depth between one-eighth and one-fourth of the thickness of the ingot.

3. An ingot of slab-like contour formed of a metal that contracts in volume during solidification, said ingot having a lengththat is greater than its width and a depth which is less than its width, one of the sides of larger area of said ingot being concaved to a depth of at least one-eighth but not exceeding onefourth of the thickness of said ingot.l

4. A horizontally-cast ingot formed of a metal that contracts in volume during solidiication, the length of which is greater than its width and the depth of which is less than its width, one of the sides of larger area being concaved to an extent not exceeding onefourth of the depth of the ingot and the ingot throughout its entire structure being. free from pipe.

5. A horizontally-cast ingot formed of a metal that contracts in volume during solidification, the length of said ingot being greater than its width'and the width of the ingot being greater than'its depth and the bottom surface of the in got being formed of a concave o r inwardly-canibered contour, the depth of said concavity being more than one-eighth, but less than one-fourth of the thickness of the ingot. o

6. A horizontally-cast ingot formed of a metal that contracts in volume during solidification, the length of said ingot being greater than its width and the width of which ingot is materially greater than its thickness and the two major or primary surfaces of which is formed of a concave or inwardly-cambered contour, the thickness of said ingot being less at its central longitudinal section than at adjacent longitudinal portions. A

7. A horizontally cast ingot, the length of which is greater than its width and the depth of which is less than its width, both of the sides oflarger area being concave, the width gf szlxid ingot being at least four times its 8. A long thin slag ingot having a shallow concaved lower portion and a slightly eoncaved upper portion, the opposite side portions of the ingot being inclined outwardly from bottom to top.

9. A long thin slab ingot having a shallow concaved lower portion and a slightly eon- .from bottom to top, an the four corners of said ingot bein rounded.

10. A metalllc ingot of slab-like contour,

the bottom of which is concaved in a curve of substantially uniform radius, the top of which ingot is slightly coneaved and the sides of which are inclined outwardly from bottom 'to top.

scribed my name.

l EMIL GATHMANN.

Images