US2023833A - Metallic ingot mold and ingot - Google Patents

Description

Dec. w, 1935. E. GATHMANN METALLIC INGOT MOLD AND INGOT Filed July 20, 1934 2 Sheets-Sheet l llsll=| 5E. GATHMANN METALLIC INGOT MOLD AND INGOT 2 SHeets-Sheet 2 v mum;

. Fild July 20, 1934 204 50; F/fiff' 0U/AX/AA CRYSmZl/ZAlW/V Patented Dec. 10, 1935 UNITED STATES V'PATENT OFFICE 9 Claim.

This invention relates to metallic ingot molds and ingots and more particularly molds and ingots of generally rectangular contour of the general character disclosed, for example, in my prior United States Patents 1,745,089 of January 28, 1930, 1,892,569 of December 27, 1932 and 1,913,924 of June 13, 1933.

As is now well known to those familiar with the art, a steel ingot, irrespective of its physical condition or chemical analysis, when stripped from the mold and placed in the soaking pit or reheating furnace, is merely a surface-chilled casting; and until work is done upon all its surfaces in the reduction of the coarse-grained crystals, the ingot inevitably has the weakness inherent in castings as compared to forgings. The reduction of the section of the ingot should, therefore, be so accomplished that no unworked surface portion receives appreciable deformation in reduction or working of adjacent portions.

In my Patent 1,745,089 referred to above, I have disclosed and claimed a mold and ingot contour in which the sides are provided with relativeiy narrow primary side portions which extend relatively outward beyond the adjacent corners so that during the initial deformation in the rolls the corners are not unduly worked and the side portions adjacent to the primary side portions are not appreciably stressed. By virtue of this contour, the ingot may be reheated without danger oi corner burning and the ingot metal will be consolidated in the rolling mill operations without the setting up of local strains which would have a tendency to produce cracks and tears.

When molten steel is poured into a metallic ingot mold, it solidifies through the formation of dendritic and free or equiaxlal crystals, due to the absorption of heat by the surrounding mold walls. The ingot metal immediately adjacent the mold walls is cooled rapidly and crystallizes in the form of dendrites, which grow into the mother liquid at right angles to the mold walls. As the dendrites progress in their growth and the temperature of the liquid adjacent the dendritic structure is lowered, the formation of free or cquiaxial crystals begins. The ratio of the depth in cross section of the ingot metal comprising dendritic crystalline structure to the cross sectionai width of the ingot as a whole depends upon such factors as the pouring temperature and the cross sectional area of the ingot, and, depending upon the latter factor, the depth of the area of dendrltic crystallization, with ordinary commercial pouring temperatures, is from one-sixth dritic crystallization extending inwardly from such surfaces will intersect within the zone of dendritic crystallization. This often results in the formation at their focal points of what are known as cleavage planes, which are zones of weakness in the ingot structure.

In my Patent 1,892,569, I have disclosed and claimed an ingot similar to that disclosed in my Patent 1,745,089, in that it comprises relatively narrow primary side portionsadapted to be initialiy contacted by the rolls, the contour of the ingot of Patent 1,892,569 difiering specifically however from that disclosed in Patent 1,745,089

in that the radii of the arcs defining the outward-' 'ly curved side portions are of such length that the theoretical lines of growth of dendritic crystals from the primary sides inwardly converge toward focal points lying within the zone of free, equiaxial crystals. ingots having this contour have been found to be more free from cleavage planes, due to the intersection of the lines of growth of the dendrites, than ingots of corrugated side contour previously made.

The present invention has for an object the provisionof a mold and ingot contour which still further avoids and practically eliminates the converging of the lines of growth of the dendrites towards foci, thus preventing the formation of cleavage planes. In the preferred form,

my invention consists in the provision of a mold and/or ingot contour including primary side portions which extend outwardly beyond the adiacent corners and which are flanked by spaced fiat or substantially fiat salients, whereby the lines of growth of the dendrites from the side portions inwardly from each side wall portion either diverge or are substantially parallel.

The more specific nature of the objects of the invention will become apparent from a reading of the following detailed description; the appended claims, and the accompanying drawings in which: I a

Figure 1 is a vertical sectional view of an ingot mold having a matrix contour in accordance with my invention;

Figure 2 is a horizontal sectional view taken on the line 2-4 of Figure 1, and drawn on an enlarged scale;

Figure 3 is an enlarged fragmentary horizontal sectional view of a mold having a contour in accordance with my invention;

Figure 4 is a perspective view of an ingot having a contour in accordance with the invention;

Figure5 is a horizontal sectional view oi? the ingot shown in Figure 4; drawn onan enlarged scale; and V Figure 6 is a fragmentary horizontal sectional view of the ingot shown in Figures t and 5 and drawn on an enlarged scale.

For purpose of illustration, a mold M of the blg-end-up Gathmann type, necked in at. the bottom as at l, is shown in Figures 1 and 2.

The preferred contour of the cross section of the mold matrix in accordance with the present invention is shown inFigures 2 and 3, from which it will be noted that the horizontal cross section of the mold matrix is of generally rectangular contour and is definedby four primary sides 2, each side being connected to an adjacent side by outwardly arched primary corners '3 by means of secondary corner portions i preferably of inwardly arched contour, and which converge inwardly from the primary sides 2, that is, the secondary corner portions are inclined inwardly from the primary sides 2 to the corner walls 3. Salients 5, which are flat or substantially flat, flank and are connected to the primary'sides 2, forming a part thereof. These salients 5 are interposed between and connect the primary sides 2 and the adjacent secondary corner portions 6 and are relatively narrow as compared with the width of the curved walls 2, preferably being about one-third the width of the latter. The salients 5 of each wall are disposed further from a plane a, passing through the center of the mold and parallel to the wall taken as a whole. than the inwardly curved portions 2 and. That is, the salients 5 lie in planes P which are parallel to but spaced outwardly from planes n tangent to the corners 3.

An ingot I of the kind produced in a mold such as described with reference to Figures 1, 2 and 3 is shown in Figures 4, 5 and 6. The con tour of the ingot, of course, will correspond sub stantially to the contour of the mold matrix. Accordingly, the various portions of the ingot walls are designated by reference characters same as those designating the corresponding wall portions of the mold, with the exception that the characters applied to the ingot are primed. Thus the ingot is of generally rectangular con tour and is defined by four primary sides 2', each side being connected to an adjacent side by outwardly arched primary corners ii and a secondary corner portion d which preferably is of inwardly arched contour. Flat, or substantially flat, salients 5' flank and form part of the primary sides 2, connecting them to the adjacent secondary corners The relative extents of the zones of dendritic and free or equiaxed crystals forming the ingot structure are shown graphically as merging one with the other by means of dotted lines X in Figure 6 ct the'drawings. For the reasons ere plainedin my Patent 1,745,089, of January 28, 1930, it lsdesirable'that the primary sides 2' be given an inwardly curved contour and that these sides be relativelynarrow as compared to the cross section of the ingot. As explained in my Patent 1,913,924, the'lengt h of the radii 8 of the corners 3 of the mold should be between one-eighth and avoided.

" In accordance with the present invention the advantages of the corrugated side contour ini5 eluding outwardly extended primary sides are retained and the crystalline structure still further improved by the provision of the flat or substantially fiat salients 5 in the mold, (5' in the ingot). The lines of growth I of the dendritic crystals 20 from the various surface portions of'the ingot inwardly areshown in Figure 6. It is apparent that these lines are substantiallyperpendicular to the ingot surface from which they grow and, since the surface portions 2' and 4' are inwardly curved, the lines of growth inwardly from each of these portions will diverge, whereas, the salients 5' being fiat, the lines of growth inwardly therefrom will be substantially parallel and the improved physical structure of ingots having a contour in accordance with my present inven-- tion is due principally to the employment of these fiat or substantially flat salients. The new contour is such that none of the lines of growth of dendrites from the sides of the ingot converge towards foci, whereby the danger of forming cleavage planes or segregation, previously due to converging of the lines of dendritic growth toward fool, is eliminated. Moreover, none of the advantages of a corrugated mold are lost by the use oi the fiat or substantially fiat salients or primary side portions 5' because the inwardly curved surfaces remain in thesame relative arrangement as heretofore has proved so successful in preventing the formation of surface cracks in t5 the ingot or the finished bloom or billet.

In the form shown, each side of the mold includes two spaced salients or primary wall portions 5 which are relatively narrow as compared to the side wall considered as a whole, i. e., the entire extent of the side wall from one corner wall 3 to the next, but it will be understood that the invention is not restricted to contours includlug only two such primary sedients or primary side portions.

I claim:

1. An ingot mold having a matrix wall cornprising a plurality of alternately arranged and connected flat portions and inwardly curved portions, the flat portions being relatively narrow as compared to the curved portions and being disposed further from a plane passing through the wall portions; an inwardly curved wall portion intervening between and connecting said primary wa l portions; and other wall portions connected to said primary wall portions and extending to the adjacent matrix corner walls, said other wall portions being inclined inwardly from the primary portions to the corner walls.

4. An ingot mold of generally rectangular contour including side walls joined by outwardly curved corner walls, two opposite side walls including substantially flat primary wall portions spaced from each other and each spaced from the nearest outwardly curved corner wall, inwardly curved wall portions intervening between and connecting the primary wall portions on each of said two sides, and other wall portions intervening between the outwardly curved comer walls and the adjacent primary wall portions.

5. An ingot mold 01' generally rectangular contour including side walls joined by outwardly curved corner walls, two opposite side walls in cluding substantially fiat primary wall portions spaced from each other and from the adjacent outwardly curved corner walls, inwardly curved wall portions intervening between and connecting the primary wall portions on each of said two sides, and other wall portions intervening between the outwardly curved comer walls and the adjacent primary wall portions, the primary wall portions of said two sides lying in planes respectively parallel to but spaced outwardly from planes tangent to the outwardly curved comer walls at the ends of the respective sides.

6. An ingot mold of generally rectangular contour including four side walls and four outwardly curved cornerwalls connecting the side walls, each side well including at least two spaced substantlally fiat primary wall portions, an inwardly curved wall portion intervening between and connecting adjacent primary side wall portions, and. other inwardly curved wall portions intervening between and connecting corner walls with ad-- jacent primary side wall. portions,

'7. A metallic ingot having convex corners and intervening sides of corrugated contour including three inwardly curvedl side portions and two substantially fiat side portions, the lines of growth of dendritlc crystals inwardly from said corners converging, the lines of growth of dendritic crystals inwardly from the inwardly curved side portions diverging, and the lines of growth inwardly from the substantially fiat side portions being substantially parallel.

8. A metallic ingotof generally rectangular cross-sectional contour, a side surface of which comprises a plurality of alternately arranged and connected flat portions and inwardly curved portions, the fiat portions being relatively narrow as compared to the curvedv portions and being disposed further from aplane passing through the center of the ingot and. generally parallel to said surface taken as a whole than the inwardly curved portions.

9. An ingot mold having a generally rectangular cross sectional contour including four side walls and four corner portions intervening between and connecting the side walls, two oppositely disposed side walls each including at least two relatively narrow substantially flat primary wall portions and inwardly curved, wall portions intervening between and connecting the said primary side wall portions, and other wall portions-intervening between and connecting the adjacent primary side wall portions with the corner portions, said other wall portions extending inwardly from the plane of the primary wall portions towards the corner portions.

EMIL GATHMANN.

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