US2781903A - Hot transformation of metals - Google Patents

Description

United States Patent I HOT TRANSFORMATION OF METALS Jean Buffet, Beaumont-sur-Oise, and Andr Gueussier,

Ugine, France, assignors to Comptoir Industriel dEtrrage at Profilage de Metaux, Paris, France, a corporation of France Application December 23, 1954, Serial No. 477,394

Claims priority, application France January 13, 1954 1 Claim. (Cl. 207-) The present invention relates to the hot transformation of metals with a view to obtaining elongated products such as rods, tubes or wires, starting from cast ingots or billets.

Certain metals and complex alloys lend themselves with difiiculty to the standard methods of transformation in the hot state, when it is desired to convert them to tubes, rods or wires. During the course of the first operations of conversion, such as blooming, rolling, piercing or extrusion, the metal or the alloy is disintegrated and it is, not possible to obtain satisfactory products without a large loss of the material employed. It even happens that alloys, such as certain alloys of aluminium or various refractory steels cannot at all be subjected to mechanical transformations of this kind.

On the other hand, it is known in the case of hot piercing operations to improve the centering by previously compressing the billet to be pierced in the casing in which it is placed to undergo the piercing operation.

The present invention has for its object a method of transformation of metals or of alloys by means of which rough pieces may be obtained from cast ingots or billets, and these rough pieces may be subsequently transformed by extrusion.

This method consists essentially in first of all compressing whilst hot, during the course of a first operation and in a closed receptacle, the billet to be transformed, which may be cylindrical, frusto-conical or of square section, with a high specific pressure, until an appreciable reduction in the length of the said billet is obtained, and then in subjecting the billet thus compressed, during the course of a second operation, either directly during the same heat or after re-heating, to the desired operation of mechanical transformation of elongation by extrusion. The pressure applied to the billet during the prior compression is preferably comprised between 10 and 100 kg./sq. mm. and the reduction in length of the billet between 3 and 7 Experience has shown that the two successive operations of compression and elongation then enable highquality products to be obtained without loss of metal, whilst such a transformation would have been diflicult or impossible with the use of standard methods.

The billet, which has been previously shortened by compression, is preferably placed in the casing of the extrusion press, in such a way that the part which corresponds to the head of the ingot is the last to be extruded. In this way, a transformation is effected in which the loss of metal is reduced to a minimum.

In the accompanying drawings which illustrate our invention,

Figure 1 is a vertical section through a closed container of a press which comprises the billet and shows the billet before it is compressed;

Figure 2 is a vertical section similar to Fig. 1 and shows the billet after it has been compressed in accordance with our invention; and

Figure 3 is a longitudinal section through a chamber ice of an extrusion press and through a die and die carrier forming a part of the chamber and shows the compressed billet partially extruded.

As shown in Figures 1 and 2, we place a heated billet 1' in a closed container 2 of 'an extrusion press and compress the billet with a ram 3. The ram 3 forces the billet of Figure 1 under a pressure of between 10 and kgs. per sq. mm. so that it is reduced in length be-- tween 3 and 40% and completely fills the lower part of the container 2, thus acquiring the shape shown in Fig-- ure 2. Next, we take the compressed billet 1 of Figure 2;. and place it in a chamber 4 of an extrusion press (see Figure 3). A ram 7 of the'extrusion press extrudes the billet in the same heat or after reheating through a die 5 located at one end of the chamber 4. The die 5 is held in position at the end of the chamber 4 by a die carrier 8. Preferably, the billet 1 is placed in the chamber 4 so that its end 6, which has been entered into the container 2 last, is extruded first through the die 5.

The examples which follow serve to bring out the results obtained'by operating in conformity with the invention.

Example 1 A high-speed steel, having the composition given below, was treated in the form of an ingot:

C 0.75 Si 0.30

(a) The rolling of a cast ingot of this steel, when carried out by the usual method, gave rise to a large amount of scrap during manufacture, generally caused by transverse cracks which have to be removed.

(1)) The extrusion of a cast ingot of a metal of the same composition, and carried out by the usual process, also gave rise to a large amount of scrap.

(c) On the other hand, the transformation by extrusion of an ingot of the same composition, preceded by a pre-compression under the conditions postulated for the method in conformity with the invention, was carried out practically without any loss of metal.

Thus, after having heated to 1095 C. in a salt-bath electric furnace a conical billet having the composition given above and being mm. in its major diameter, 120 mm. in its small diameter and weighing 45 kg., this billet was pro-compressed in a cylindrical casing of mm. in diameter at a pressure of 30 l(g./sq. mm., until a reduction of 25% in the length of the billet was obtained.

The pro-compressed billet was then re-heated up to 1100 C. and then it was extruded through a square die having 50 mm. sides, so as to obtain a bar of 1.8 metres in length, the feed-head having served as a base during the course of the extrusion operation.

Example 2 The same results have been obtained with analloy of the following composition:

C 0.05 Si 0.5 Mn 0.5 Ni 75 Cr 20 Ti 2 Al 1 Fe 5 What we claim is: The method of deforming a billet of alloy that is incapable of being directly extruded without large scrap losses such as a tungsten alloy containing 18% tungsten, 4% chromium, and 1% vanadium or a chromium-nickel base alloy containing about 75% nickel and about,20% chromium, comprising compressing said billet heated to about 1095 C. under a pressure between 10 and 100 kgs. per sq. mm. While confining it within a closed space to decrease its length to about 3 to 40% and extruding the compressed billet having a temperature of about 1100' C, through a die.

References Cited in the file of this patent UNITED STATES PATENTS

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