US3043682A - Lead-nickel-cadmium alloys - Google Patents

Description

United States Patent 3,043,682 LEAD-NICKEL-CADMIUM ALLOYS Kenneth R. Grube, Hilliards, and Dean N. Williams,

Columbus, Ohio, assignors, by mesne assignments, to The Bunker Hill Company, San Francisco, Calif., a corporation of Delaware No Drawing. Filed Feb. 19, 1960, Ser. No. 9,719 3 Claims. (Cl. 75-166) This invention relates to lead alloys and, more particularly, to lead alloys containing nickel and cadmium as alloy additions.

This application is a continuation-in-part of our copending application Serial No. 724,225, filed March 27, 1958, now abandoned.

In the past, lead metal has been limited in its applications because of certain undesirable characteristics, particularly poor creep resistance. 'Poor properties in this respect limit the applicability of lead to many uses of other low-melting-point metals. Since lead at room temperature is at a higher absolute temperature relative to its melting point than is aluminum, for example, design stress limitations due to creep resistance are intensified.

Such design stress limitations are dictated by creep resistance for lead then, whereas for aluminum, yield strength will dictate design stress limitations at room temperature. If the temperature, at which relaxation under applied stress occurs and where creep resistance, 7 rather than yield strength, governs stress-resisting capa- I bilities, could be raised, forlead, the metal could be used for applications not now available to it.

Lead alloys are used in a number of applications in which a material with exceptional resistance to corrosion is required. Examples of such uses include power and communication cable sheathing, liners for containers holding corrosive materials, and piping for chemical plants. Failure of the lead alloys in these applications is often traced to one of two distinctfailure mechanisms, corrosion fatigue or creep. Corrosion fatigue is quite common in cable sheathing and piping when small cyclic stresses are imposed during service- The variation in peak service load in cable sheathing, for example, imposes one 1 "ice apparent from the following detailed description thereof.

In general, this inventioncomprises alloys of lead containing from about 0.3 to about 4.0 percent cadmium and from about 0.05 to 0.8 percent nickel, nickel being present as a dispersant and cadmium as a solid solution strengthener. Preferred ranges include from about 0.3 to about 2.0 percent cadmium and from about 0.2 to 0.8 percent nickel, balance lead. An optimum composition is about 0.2 percent nickel, 1.5 percent cadmium, balance lead.

The alloys of this invention may be prepared in any convenient way. For example, the dispersion-containing alloys may be prepared by adding the dispersoid to the lead melt. This is conveniently done by adding nickel powder to the lead melt or the lead-cadmium melt while stirring. In practice, a stirrer comprising a motor-driven steel rod on which were mounted opposite pitch propellers has been used. By adjusting the speed of the stirrer, it is possible to control the degree of agitation. The powder is drawn into the vortex created by the stirrer and, thus, enters the melt at the bottom of the vortex, thereby being dispersed uniformly throughout the melt.

For commercial production of the alloy the following procedure is recommended:

1) Add nickel in finely divided form to molten lead leaving a temperature range of 750 to 850 F. If powdered nickel is used, it should be blown beneath the surface of the melt using an inert gas.

(2) Add cadmium in the form of ingot.

(3) Stir melt thoroughly during nickel and cadmium additions.

(4) A cover of ammonium chloride flux may be used to reduce surface oxidation and wetting of the nickel by the lead.

,( 5) Cast at a temperature near 750 F.

After alloying and casting into conventional ingot shapes, the alloys of this invention can be fabricated according to the usual procedures for lead alloys-extrusion, hot rolling, or cold rolling. The superior properties of the alloys are inherent in the composition, and when alloying is conducted as outlined above, subsequent processing can be carried out withoutdifficulty. Sheet products from these alloy compositions are readily fabricated into a number of desired shapes. Welding of the alloys by conventional hot forming processes is possible and the properties of the alloy are not impaired by the Welding process.

tion accomplish this desirable result and in-plant service exposures have indicated that exceptional improvements over all existing lead-base alloys have been made. 7

It is, therefore, an object of this invention to provide alloys of lead possessing improved properties as compared with unalloyed lead and existing lead alloys.

It is a further object-of this invention to provide lead alloys having greatly improved creep resistance as compared with unalloyed lead and existing lead alloys.

It is yet another object of this invention to provide lead alloys having good corrosion properties and bend properties as compared with unalloyed lead and existing lead alloys.

It is a further object of this invention to provide lead alloys having greatly improved creep resistance and bend properties as compared with unalloyed lead and existing lead alloys, while retaining good corrosion resistance.

Another object of this invention is to provide dispersions of nickel in an alloy of lead and cadmium, said dispersion-containing alloys having improved structural properties as compared with unalloyed lead.

Other objects and advantages of the invention will be In evaluating the alloys of this invention, both creeptest measurements and bend-test results have been particularly noted. Creep results have been obtained by using both tension-creep and cantilever-beam creep tests. Bend tests have been carried out in an apparatus which subjects experimental specimens to one complete cycle of strain per minute. The number of cycles necessary to proved resistance to creep is obtained without any notice able increase in tensile strength. The tensile data show that the strength remains almost constant with increasing amounts of nickel. Also, very little loss in ductility, as determined by the percentage of elongation, is apparent. In addition to improved resistance to creep a marked improvement of the resistance to cyclic bending is observed. About twice the number of bends (on the average) were required to cause rupture in the better 1ead-nickelalloys than were required torupture unalloyed lead. In one instance, a BOO-percent increase in resistance to bending was noted. Analysis of the data indicates that as little as 0.05 percent nickel is beneficial.

4 Sn, and Cu. Tests were run at stresses of 300, 500, and 1000 p.s.i. Each specimen remained in test for 3000 hours or 3.00 percent extension, whichever occurred first. These results are included in Table 2.

, Table 1.Mechanical Properties of Lead-Nickel Dispersion Alloys Tested in the Extruded Form Creep data76 F.

Bend data-ne cycle Intended Elongation Ultimate per min, total number N 1 content, in two tensile Cantilever Tension, 300 p.s.i.- Tension, 500 p.s.i.- of bends to produce fail- Heat No. weight inches, strength, beam, percent extension percent extension are at 0.6 percent strain percent percent p.s.i. deflection at end ofat end ofin 100 hr. at 1,000 p.s.i. inches 1,000 hr. 3,000 hr. 100 hr. 7 500 hr. 76 F 110 F 0. 16 1. 27 0.16 0.23 0.86 0.16 0.23 1.11 0.15 0.23 0.86 0.27 0.23 0. 67 0.10 0.23 l. 0.18 0.23 1. 0. 0.23 v 75 2, 260 2. 80 0. 23 88 2, 120 0.94 0. 20 0.20 0. 10 0.23 66 2,120 0.52 0.10 0.23 78 2,055 1. 0.05 0. 10 0.12 0.23 2, 075 1.07 0.23 59 2, 120 0. 73 0. 23 87 2, 120 1. 33 0.23 78 2, 120 1. 73 0.23 79 2,100 1. 93 0.23 79 2,100 0.60 0. 23 1, 930 0. 28 0.23 V 75 1, 950 0. 40 0.23 2,130

The dispersing of nickel powder in. a solution-hardening alloy. containing cadmium provides excellent and desirable properties. The presence of cadmium along with the nickel improves the quality of the dispersion formed by the nickel powder, thus permitting greater additionsof'nickel. Tensile strength can also be increased by the Studies indicate that, in general, resistance to failure by bending fatigue and resistance to creep at low stresses increases as the' cadmium content increases up to about 2.0 percent. However, creep properties at higher stresses are a function of both cadmium and nickel contents.

The resistance to corrosion by sulfuric acid at F.

to be somewhat superior to that of high purity lead.

Detailed results are set forth in Table 2.

Hardness measurements made on a number of leadv temperature. Specimens were solution treated for 1 hour cadmium-nickel alloys after aging at 75 and 150 F. inat 400 or 450 F. and water quenched before aging at dicate that the alloys do not show any appreciable tend- 75 and 150 F. The hardness was measured at frequent eney to age harden or overage during exposure at either intervals by the Brinnell method over a period of 8 weeks.

Table 2.Summary of Mechanical Properties of Extruded Lead-Cadmium-Nickel Alloys 'HIGH-PURITY LEAD Bend data-Total Tensile properties number of cycles to Tension creep data Intended composition produce failure at (balance lead), percent 0.6 percent strain Melt and indicated Elonga- Tensile temperature Percent deformation at end 01 indicated time, hr.

tion in 2 strength, Stress, inches, p.s.i. p.s.i. Cd Ni Cu percent 76 F. 110 F. 50 100 500 1,000 2,000 3,000

ARSENICAL LEAD 1, 000 2. 65 3. 00 0. 13 S11 56 2, 260 35, 475 1, 000 1. 80 3. 30 0. 16 As 0. 14 S11 54 2, 295 37, 850 24, 150 300 0. 05 0 05 0. 05 0 05 0. 05 0. 05 0.03 B1 05. 1, 000 3. 00

0.50 PERCENT CAD'MIUM PLUS NICKEL 537 0. 50 2 0. 10 48 3,050 30, 900 27, 115 300 0.09 0.10 0. 23 500 0. 10 0. 13 0. 1, 000 0.55 1. 00 3.00 1, 000 .0. 0. 60 3.00 538 0. l 0. 10 0. 05 48 2, 880 23, 850 31, 900 300 0. 05 0. 05 0. 15 500 0. 10 0. 17 0. 47 1, 000 0. 40 0.80 3.00 1, 000 0.55 1. 05 3.00 566 0. 50 0. 20 I 42 3, 185 19,000 18,000 1, 000 0.70 1.35 3.00 1, 000 0. 1. 25 3. 00 403 0. 50 0.23 48 3,085 22, 000. 18, 300 300 0. O5 0. 50 0. 10 WM 500 0.25 0.25 0.50 i 1, 000 0.90 1.50 3.00 450.--"; 0.50 0.23 47 3, 350 22, 900 20, 750

1.00 PER CENT CADIMUM PLUS NICKEL 1.50 PERCENT OADIMUM PLUS NICKEL 2.00 PERCENT OADIMUM PLUS NICKEL Bend data-Total Tensile properties number of cycles to Tension creep data Intended composition produce failure at (balance lead), percent 0.6 percent strain Melt and indicated 7 Elonga- Tensile temperature Percent deformation at end of indicated time, hr. tion in 2 strength, Stress, inches, p.S.i. p.s.i. d Ni Cu percent 76 F. 110 F. 50 100 500 1,000 2,000 3,000

4.00 PERCENT OADIMUM PLUS NICKEL 8 0.10 actual. 4 0.08 actual. B 0.18 actual. 0.24 actual. 7 0.12 actual. 0.19 actual. 0.23

lAppro ximately. @013 actual. actual.

, are, indeed, useful for all applications requiring extreme resistance to strain rate bending and/or exceptional resistance to creep. Cable sheathing is an application utilizing their strain rate bending resistance, While their creep properties make them useful as nuclear shielding materials or as corrosion resistant sheathing for use in the chemical industry, or as pipe and conduit alloys.

New and useful alloys having been described and disclosed, it is desired to further define the invention in the attached claims. I a

What is claimed is:

1. Lead-base alloys consisting essentially of from about 0.3I-to about 4.0 percent cadmium, about 0.05 to 0.8 percentnickel, balance lead, said alloys being characterized by greatly improved tensile strength, creep resistance, and bend resistance as compared with unalloyed lead.

2. Lead-base dispersion alloys consisting essentially of from about 0.3 to about 2.0 percent cadmium, about 0.2 to about 0.8 percent nickel, balance lead, said alloy being characterized by greatly improved tensile strength, creep resistance, and bend resistance as compared with un-. alloyed lead.

3. A lead-base alloy characterized by greatly improved tensile strength, creep resistance, and bend resistance as compared With"unalloyed lead and consisting essentially of about 0.2 percent nickel, about 1.5 percent cadmium, balance lead.

References Cited in the file of this patent UNITED STATES PATENTS 834,099 Allen Oct. 23, 1906 1,645,098 Friedrich on. 11, 1927 2,163,368 Betterton June 20, 19 39 FOREIGN PATENTS 666,856 Great Britain Feb. 20, 1952

Claims (1)

1. LEAD-BASE ALLOYS CONSISTING ESSENTIALLY OF FROM ABOUT 0.3 TO ABOUT 4.0 PERCENT CADMIUM, ABOUT 0.05 TO 0.8 PERCENT NICKEL, BALANCE LEAD, SAID ALLOYS BEING CHARACTERIZED LBY GREATLY IMPROVED TENSILE STRENGTYH, CREEP RESISTANCE, AND BEND RESISTANCE AS COMPARED WITH UNALLOYED LEAD.