US2142836A - Lead alloys - Google Patents

Description

Patented Jam 3, 1939 UNITED STATES LEAD ALLOYS Jesse 0. Better-ton, Metuchen, Albert J. Phillips,.

Plainfield, and Albert A. .Smith, Jr.. Metuchen,

N. J., assignors to American Smelting and Refining Company, New, York, N. Y., a corporation of New Jersey No Drawing. Original application March 19,

1937, Serial No. 131,860. Divided and this application September 28, 1938, Serial No. 232,092

2 Claims (Cl. 75-167) This invention relates to lead alloys and pro- Vides certain new and novel lead alloy composi-' tions which, by reason of the properties they possess and exhibit, are definitely superior for use 5 in the manufacture of such lead products as battery grids, cable sheathing, etc.

Broadly speaking, the invention may be said to provide ternary alloys of lead, calcium, and magnesium possessing certain highly beneficial physical properties, and alloys comprising the base alloy of lead, calcium and magnesium with at least one additional alloying constituent imparting further desired properties to the alloy while at the same time retaining or enhancingthe beneficial physical properties possesed by the base alloy itself. I

More specifically, the invention provides alloys of lead, calcium and magnesium in which the combined calcium and magnesium content does not substantially exceed 0.4% of the alloy with the magnesium content being within the approximate limits of one quarter to three times the calcium content. While 0.03% to 0.05% each of calcium and magnesium is preferred, compositions containing magnesium and calcium within the limits of 0.01% to 0.3% and 0.01% to 0.1%, respectively, may be employed.

Among metals which may be added to the leadmagnesium-calcium composition are cadmium, copper, mercury and tin, all of which modify the behavior of the alloy under corrosive influences without adversely affecting the fundamental physical nature of the ternary alloy. In addition copper stiffens the alloy moderately and acceler- 3 ates its aging; mercury improves its lustre and to a moderate extent its casting properties; tin

slightly improves its fluidity and casting properties. The amount of modifying or improvement metal which may be incorporated should fall 40 within the approximate limits of 0.03% to, 3% with a minimum of about three or four times the magnesium content.

The superior properties exhibited by the alloys of the invention are best shown by the following data comparing same with several of the conventional alloy compositions available and often recommended for various specific purposes:

Brinell hardness 50 Lead alloyed with- Material tested 037 M 8% Sb 05% Ca ,52 i

Castings es" thlck 12.1 7.0 5. 2 Above aged 21 days at 30 C- 12.9 8.0 13.4 Same heated 2 hours at 100 C 13.4 9. 5 15.4 Grid castings )z" thick 11.8 5.0 5.0 Above aged 21 days at 30 C l3. 8 11. 4 14. 8 Same heated 2 hours at 100 C 14. l2. 15. 4

The above data clearly show that the new magnesium-calcium alloy is readily hardened withoutelaborate heat treatment to a value equal to or better than that of antimonial-lead grid metal, the latter in turn being superior to the calcium-lead alloy.

Tensile strength (lbs/sq. in.)

The superior strength of the rolled lead-magnesium-calcium sheet metal is quite evident from the above data and the high strength values developed by simply aging 9. rolled strip, either at room or an elevated temperature, are quite remarkable.

Composition stability In almost any process in which metal is cast there is always a certain amount of material in the natureof risers, gates, spillage and spoilage which must be returned to the process without special treatment or material loss if reasonably low costs are to be obtained. In the manufacture of storage battery grids the weight of material that must be remelted commonly approximates the weight of satisfactory grids produced but fortunately ordinary antimonial grid metal can be repeatedly remelted without a very great change in composition. This is illustrated by the following test in which grid metal analyzing 7.83% Sb and 0.222% Sn was tested in a special machine equipped with a revolving paddle which swept the surface of the molten metal (temperature 355 C.) at exactly 100 R. P. M. for 10 minutes. At the end of the test the composition analyzed 7.77% Sb and 0.215% Sn. Applying the same test to a calcium-lead alloy containing initially 047% calcium, the calcium content dropped to 023% calcium which represented a loss of 50% of the vital alloying constituent. However, when the test was applied to a calciummagnesium-lead alloy of the present invention which contained 047% Ca and .20% Mg, the calcium and magnesium contents were only very calcium-lead alloy suffered a decrease in' its 0511- clum content from 05% down to 005% with the same treatment.

Fatigue properties I The following table illustrates the fatigue properties of several typical lead alloys as compared with the magnesium-calcium-lead alloy of the invention modified with tin:

Composition xa 's 7 395 3? 0. 700 8 1,000 0.038% Ca, balance Pb 1,400 0.32% Sn, 045% Ca, 026% Mg, balance Pb 2 200 All tests were for 20,000,000 reversals on a rotating beam machine at 2,000 B. P. M.

Creep tests The following creep data were obtained from tests conducted at room temperature for periods of from 1 to 4 years and illustrate the marked superiority of the magnesium-calcium base alloys to all others:

Lead alloyed with Time to creep 1% g 33 Days . 350 190 175 233 220 232 240 437 1, 200 578 290 700 More than 1,200 732 Corrosion resistance Corrosion resistance of any series of alloys is very difficult to evaluate because an alloy that is superior in one particular set of circumstances may be inferior in another. For instance, in battery strength sulphuric acid a lead alloy containing 04% Mg and .05% Ca was found to have excellent corrosion resistance as measured by loss in weight but suil'ered from a peculiar penetration of the alloy in about 3 months time when the temperature was raised to 70 C. However, this dimculty was completely avoided by adding 0.25% tin to the alloy with no loss in physical properties. A lead alloy containing 03% Mg,

04% Ca and Sn was found to be equal to regular 8% antimony grid metal in general corrosion resistance and superior to it for battery purposes due to the former s freedom from the evils of sulphation and galvanic action which accompany the use of antimonial lead grid metal.

From the data herein adduced, it will be readily apparent that the alloys of the invention possess and exhibit properties 'which ideally fit them for numerous uses. Accordingly, while their value has been emphasized with respect to their use as grid metal, it will be understood that they may be successfully utilized in many other fields.

The alloy compositions of the invention may be readily compounded by conventional processes employed by those skilled in the art for producing other lead alloys, as, for example, by simply incorporating the requisite amounts of the alloying constituents in a proper quantity of molten lead without any particular regard to the sequence of their addition. Once compounded, the new alloy composition can be fabricated by well known methods.

This application is adivision of the co-pending application of Jesse O. Betterton, Albert J. Phillips and Albert A. Smith, Jr., Serial No. 131,- 860, filed March 19, 1937.

What is claimed is:

1. An alloy composed of 0.01% to 0.1% calcium, 99.98% to 99.6% lead, and 0.01% to 0.3% magneslum.

2. A battery grid containing about 0.01% to about 0.1% calcium and about 0.01% to about 0.3% magnesium, the balance being substantially all lead, characterized by its hardness and high tensile strength.

JESSE O. BETTERTON. ALBERT J. PHILLIPS. ALBERT A. SMITH'. JR.