US2384351A - Method of forming extended lengths of metal wire - Google Patents

Description

Patented Sept. 4, 1945 METHOD OF FORMING EXTENDED LEN GTHS OF METAL WIRE George H. Slagle, Temple, Pa, assignor, by mesne assignments, to Berks County Trust Company, Reading, Pa., a banking institution of Pennsylvania No Drawing. Application July 31, 1942, Serial No. 453,029

4 Claims. (CL 14811.5)

This invention relates to a method of forming extended lengths of wire from metals and alloys, particularly alloys of copper and beryllium containing from about .50 to about 3.0% Be.

One of the objects of the present inventionsis to provide an improved method of forming exin excess of the solubility limit at temperatures within the range 500-570 C.

Still another object is to provide an improved method of drawing copper-beryllium alloys containing beryllium in excess of the solubility limit at temperatures within the range SOD-570 C., but not substantially in excess of the solubility limit at temperatures Within the range '750-900 C.

A further object is to provide a wire consisting of a copper-beryllium, alloy containing beryllium in an amount within the range .50-3.0% which is uniformly and consistently responsive to solution annealing and precipitation hardening and which has a determined grain size.

Other objects and advantages will be apparent as the invention is more fully hereinafter disclosed. In accordance with these objectives, I have discovered that extended lengths of drawn wire consisting of a copper-beryllium alloy containing beryllium within the range .50-3.0% can be most economically and easily produced by a method which comprises:

' (l) A hot working and heat-treating operation 1 l loys, particularly those alloys containing beryllium performed in accordance with the invention described and claimed in Martin Patent No. 2,266,056, dated December 16, 1941, which patent is assigned to the same assignee as the present invention, which operation is modified to the extent that the hot working consists of hot rolling to round or square form and i conducted upon an ingot of such size and length as to provide an extended length of said round or square at thicknesses which on being solution annealed and rapidly cooled to condition the same for cold rolling and subsequently cold rolled to strip form will provide a width and thickness in said strip providing on longitudinal slitting a plurality of substantially square cross-sectioned lengths which on further cold rolling may be converted to a diameter and cross-section adapted for cold drawing through substantially round dies.

(2) End butt-welding the plurality of the said substantially square cross-sectioned strips together.

(3) Heat-treating the length of butt-welded strips at a temperature within the range 500-570 C. for an extended time interval in accordance with the invention described and claimed in the application of Matthew. J. Donachie, Serial No. 453,039, filed July 31, 1942, which application is assigned to the same assignee as the present 'invention, to establish therein a crystal structure consisting of a mixture -of alpha and gamma phases in which the gamma phase is substantially spheroidized and the alpha phase contains an equilibrium percentage of beryllium approximating 1%, and cooling the same to atmospheric temperatures.

(4) Cold drawing the heat-treated length to a smaller diameter withor without intermediate annealing at temperatures within the range 500- 570 C.

(5) whereupon the wire is (a) left as is, in its work-hardened condition; or (b) recrystallized by a short time heating at a temperature within the range 500-5'70 C. to impart thereto a determined grain size; or (c) heated for a short time at a temperature within the range 750-900 C; to return the alloy structure to the substantially pure alpha phase and then quenching the alloy to condition the same for precipitation hardening.

By the practice of the above described method steps, I have found that a material savings in time and expense is made in addition tothe production of a greatly superior final wire product in all of its physical properties.

As an example of the present invention, the following practice has been standardized for the forming of wire from copper-beryllium alloys containing about 2% beryllium. Heretofore in the art, the mechanical deformation of copperberyllium alloys containing beryllium over about 1.5% up to as high as about 3.0% of which the 2.0% alloy is a typical example, has been rendered difficult by reason of the fact that as these alloys are cooled, from a temperature at which they are molten to atmospheric temperatures, a high beryllium content constituent separates out,

quenched from a temperature approximating the maximum temperature of treatment to obtain resolution of this cast beta, approximates 2.4%,

it is further recognized that up to 3% beryllium may be present in the alloy before the amount of cast beta remaining seriously interferes with the cold workability of the beryllium-saturated alpha.

However, with the 2.0% beryllium alloy of the specific embodiment, starting from a cast ingot size approximating square, the major portion of the cast beta present therein may be eliminated and the metal thereby conditioned for cold working by heating the ingot for at least three hours at a temperature within the range 1400 1500 F. (760-815" 0.), hot rolling the ingot on a falling temperature gradient to a size approximating 2 crowned square, terminating the rolling before the temperature of the alloy has fallen to below about 700 F. (371 0.); reheating the 2%" square length of metal to 1400- 1500 F. (MO-815 C.) for another three hours time interval and hot rolling in the same manner to about a 4" crowned square: then reheating for a third time to 1400-1500" F. (760- 815 C.) for a final three hours, following which the metal is cooled rapidly to atmospheric temperatures as by quenching.

Following cooling, the surface of the metal is cleaned of surface scale and is fiat rolled cold to a strip approximating .250" thickness and 1'' width. This strip is then slit longitudinally into four lengths, each having a square cross-section approximating .250 x .250 inch. These several lengths are then passed several times through diamond-shaped grooves in the rolling mill to remove the edge burrs and to bring the sides to a somewhat convex shape, and the several lengths are butt-welded together end to end to form an extended length of the same approximating four times the length of the inch wide strip from which it was made.

The butt-welded length of crowned square material (cross-sectionally) is then heat-treated for from 6 to 8 hours at a temperature within the range 5005'70 C. (932-1058 F.), preferably at 570 C. (1058 F.), and is cooled preferably relatively rapidly, to atmospheric conditions, and following light pickling is given several preliminary passes through'substantially round drawing dies to a diameter of about .1875 inch.

The rounded Wire is then cold drawn down to about .118" in 3 passes; reheated for a short time interval approximating 2 hours to a temperature approximating 570 C. (1058 F.) surface cleaned and cold drawn in four passes to about .064"; again annealed for a short time interval at 570 C. (1058 F.); surface cleaned and cold drawn in about fourpasses to about .032"; again annealed for a short time interval at 570 C. (1058 F.) surface cleaned and then cold drawn to about .016" and again annealedat 570 C. (1058 F.) for a short time interval.

From this point on the drawing process may be widely varied depending upon the desired final size and the physical properties desired in the wire at final size. Reductions in area up to about 70-75% may be given to the metal from this point on following each annealing and the annealing time at temperature may be shortened to a matter of seconds where the maximum reductions are given.

It is believed apparent from the above description that the time factor in the practice of the above process is materially shorter than the time factor involved in the forming of wire from the same alloy in accordance with prior art practice which relies on repeated solution annealing heattreatments during the course of the hot and cold Working operations to relieve strain-hardening or hardening caused by the precipitation of the gamma phase from the unstable alpha phase at the temperature of working, either as a result of temperature or as a result of the working.

In such solution annealing heat-treatment, the time interval of heating required is at least three hours and the temperature employed is preferably about 810 C. (1490 F.). At these high temperatures and prolonged time intervals the grain structure of the cold worked alpha phase rapidly increases, particularly Where the percent reduction in area between anneals at a cold working temperature is sufficient to produce considerable grain fragmentation.

By the practice of the present invention and particularly by the practice of rolling in the early stages, instead of drawing in accordance with the invention of the Martin patent, the time interval required to condition the metal for cold working is materially shortened, as such operation is more effective in breaking up the cast beta than is drawing.

By cold rolling to a flat strip of appropriate width and thickness providing a plurality of substantially square cross-sectioned lengths of ma terial and butt-welding the lengths together end to end, a material savings in time also is made.

In View of the above disclosure and specific embodiment given, it is believed apparent that the present invention is adapted to wide modification without essential departure therefrom and all such modifications and adaptations thereof are contemplated as may fall within the scope of the following claims. I

What I claim is:

1. In the manufacture of wire consisting of a beryllium-copper alloy containing 1.5 to 3% Be, the improvement which comprises forming the alloy into an elongated strip having a width relative to its thickness adapted, on slitting lengthwise, to provide a plurality of substantially identical square cross-sectioned lengths; slitting said strip into said square cross-sectioned lengths; end butt-welding said square cross-sectioned lengths together to form an extended length; annealing said extended length to condition the same for cold working, cold rolling the annealed length to round section, and cold drawing the round sectioned length to smaller diameter. I

2. The method of claim 1, wherein said extended length is annealed for an extended time interval at 500-570 C. to impart thereto a thermally stabilized cold workable crystal structure consisting of a mixture of alpha and gamma phases, the said gamma phase being substantially spheroidized and the said alpha phase consistin of copper containing the equilibrium percentage of beryllium at the temperature of heating.

time recrystallization heatings at temperatures within the range 500-570 C.

4. The method of claim 1, wherein the said forming of the alloy to elongated strip consists of the steps of hot working the alloy from its cast size to said elongated strip form with intermittent annealings at 750900 C. to eliminate the cast beta phase from the alpha phase present in the alloy in the cast condition.

GEORGE H. SLAGLE.