1. A PROCESS OF FABRICATING AN EXTRUDED FREE MACHINING ARTICLE COMPRISING CASTING A BILLET OF A COPPER BASE ALLOY CONTAINING BERYLLIUM AND 0.07-1.0% LEAD AND EXTRUDING SAID BILLET UNDER A PRESSURE OF FROM 45,000 TO 200,000 P.S.I.
5. THE PROCESS OF CLAIM 1, WHEREIN THE BILLET IS SOLUTION HEAT-TREATED AT ABOUT 1450*F., CLEANED AND DRAWN SUBSEQUENT TO EXTRUSION.
United States Patent 3,301,717 PROCESS FOR PRODUCING BERYLLIUM COPPER BASE ALLOYS AND PRODUCTS Paul Joseph Scherbner, Boyertown, Pa, assignor to The Beryllium Corporation, Reading, Pa., acorporation of Delaware N0 Drawing. Filed Sept. 22, 1964, Sier. No. 398,443
. 8 Claims. (Cl. 148-2) This invention relates to a process for producing free machining articles of beryllium copper base alloys containing lead. More specifically, it deals with a process of working beryllium copper base alloys containing beryllium, lead and cobalt or nickel or both by extrusion to produce rods, bars or tubes having high strength, good elongation and hardness while at the same time being readily machinable.
Machining beryllium copper base alloys has always been difficult. It has been found that the addition of small amounts of lead to these alloys will increase their machinability; however, this poses another problem. It is extremely difiicult to manufacture articles such as bars or rods from beryllium copper alloys containing lead, in the usual manner of hot rolling as these alloys being hot short tend to crack during fabrication. The instant invention obviates all of these problems. I have found a means of producing without cracking during fabrication rods or bars with good m achinability and the strength and other properties of the conventional alloy.
It is therefore an object of the present invention to produce beryllium copper alloys having high strength and machinability.
Another object of the instant invention is to set forth a process of working beryllium copper base alloys con taining lead whereby articles are produced \having high strength :and machinability with no cracking during working.
A further object of the instant invention is to set forth a process of producing free machining rods, tubes or bars from copper base alloys containing beryllium, lead and cobalt or nickel or both by means of extrusion.
Other objects and advantages of the instant invention will become apparent from the following detailed description and examples.
It has been found that the addition .of small amounts of lead to beryllium copper alloys will improve their machinability. Fabrication, however, by nromal hot rolling methods prohibits the use of lead much above 0.005% which has prevented the use of lead in this alloy up to the present. Amounts of lead above 0.005% will cause cracking during hot rolling of the alloy. We have now found that by use of extrusion methods and cold reduction of the extruded bar, tube or rod, we can overcome the objections to lead in these alloys. By means of extrusion we are :able to circumvent the cracking problem due to the fact that the material while being hot worked in extruding is held in compression and therefore cracking does not occur.
It has been noted, however, that if the extrusion billet is too small in diameter relative to the extrusion container size, then during the initial phase of extrusion when the billet is being upset within the container before extrusion occurs, the billet will tend to crack and the resulting extruded material will be cracked. It is, therefore, important to take into consideration the container size when forming the billet to be extruded therein.
It has been found that the addition of from 0.07% to 1.0% lead to beryllium copper base alloys produces rods having increased machin-ability, excellent strength and freedom from cracks. Microscopic examination of the material after being extruded into 1 diameter rods,
revealed a uniform dispersion of the lead in the alloy. Exploratory machining tests by turning have indicated that as the percentage of lead is increased the machinability increases and appears much improved over the standard beryllium copper alloy.
It is possible to produce leaded beryllium copper rods by cold rolling a billet and/ or bar. This method, however, is both costly and slow. Extrusion offers the fastest, most economical and the most satisfactory method of producing this alloy product.
Another method of producing rods from these alloys is by drawing a semi-finished bar through a series of dies; however, this would require a shaped bar to start with. Continuous casting of bars of proper starting diameter for subsequent drawing to finished size is an alternate method of producing rod of this alloy composition provided a sufiicient amount of reduction is put into the bars to work the material to a satisfactory quality.
In the present invention a billet .of beryllium copper alloy is cast by suitable means. The billet may be static cast, pressure cast, or continuously cast. The billet may then be overhauled and/ or homogenized. The billet is then extruded to produce the finished or intermediate product. The extrusion product may then be solution heat treated or stress relieved. It may then be cleaned and .finally cold drawn, if necessary, to produce the final product employing as many intermediate heat treatments and cleaning operations as necessary to permitdrawing the material to final temper and size.
Equipment, extrusion conditions and other factors pertinent to the production of a rod with the mechanical properties specified below were as follows:
EqIuiIpment1700 ton horizontal extrusion press liner5 Reduction ratio-21.4 1 (1 4 diameter rod produced). Die design included angle, 30 lead-in angle. Lubricants DieBro0ks forging compound. Container'lhermax 76. Tool temperatures Die-4=O0 F.500 F. Container600 ll.'700 l3.
Resistance to flow factor-K=19T SI.
In regard to variations in extrusion press operations, a change in billet extrusion temperature will change all of the other conditions. In addition, if extrusion press capacity were sufiiciently high, it might be possible to extrude cold. The billet may be extruded under pressures of from 45,000 to 200,000 p.s.i.
The preferred extrusion ranges for this alloy are:
Billet temperature--13001450 F. Unit extrusion force:
Upset p.s.i.8 0,000120,000 Running p.s.i.60,00095,000 End p.s.i.90,000125,000
Ram-in. per second-.15-.50 Extrusionin. per second-3-15 Resistance to flow factor:K= -21 Alloys having the following compositions were produced by the method disclosed above.
Heat N0. Be, C0, Analysis On,
percent percent Pb, percent percent 1. 88 0.26 0.17 Balance. 1.98 0. 0. 39 Do. 1. 0s 0. 25 0.40 Do. 1.98 0.25 0. 55 D0.
Mechanical properties of the above heats, after solution heat treating at 1450 F. and water quench, drawing 37% and aging for 3 hours at 600 F. are as follows:
Heat N o. U.T.S., Y.S. 0.2% Percent Hardness p.s.i. ofiset Elongation Some other alloys within the scope of this invention are:
Example 1 Percent by weight Be 1.80-2.05 Co or Ni 0.20-0.30
C11 Balance Example 2 Percent by weight Be 1.65-1.80 Co or Ni 0.20-0.30
Cu Balance Example 3 Percent by weight Be 0.45-0.70 Co 2.35-2.70
Pb 0.10-0.75 Cu Balance It is apparent from the foregoing that there is provided a new and novel extruded beryllium copper base alloy containing lead which has increased machinability, high strength and freedom from cracks and a process for producing the same. This alloy is produced by extrusion into rods, bars, or tubes as a final product or as an intermediate product which may be further treated in the usual methods of aging metal products.
As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereo, the present embodiment is therefore illustrative and not restrictive, and since the scope of the invention is defined by the appended claims, all changes that fall within the metes and bounds of the claims or that form their functional as well as conjointly cooperative equivalents are therefore intended to be embraced by those claims.
1. A process of fabricating an extruded free machining article comprising casting a billet of a copper base alloy containing beryllium and 0 .07-1.O% lead and extruding said billet under a pressure of from 45,000 to 200,000 p.s.i.
2. The process of claim 1, wherein the beryllium is present in an amount of from 0.45 to 2.05%.
3. The process of claim 2, wherein the billet contains from 0.20 to 2.70% of at least one metal selected from the group consisting of cobalt and nickel.
4. The process of claim 1, wherein the cast billet prior to being extruded is homogenized and heated to a temperature of from 1300-1450 F.
5. The process of claim 1, wherein the billet is solution heat-treated at about 1450 F., cleaned and drawn subsequent to extrusion.
6. An extruded free machining article produced by the process of claim 1.
'7. An extruded free machining article produced by the process of claim 3.
8. An extruded free machining article produced by the process of claim 5.
References (iited by the Examiner UNITED STATES PATENTS 2,172,639 9/1939 Hessenbruch -153 2,259,108 10/1941 Harrington 75163 X 3,133,843 5/1964 Scherbner 148-3 3,166,410 1/1965 Hanson et al 75153 DAVID L. RECK, Primary Examiner.
CHARLES N. LOVELL, Examiner.