US2394451A - Lead alloy - Google Patents

Description

, Patented Feb. 5, 1946 UNITED STATES PATENT OFFICE LEAD ALLOY Edward G. Hollman, Joplin, Mo., asslgnor to The Eagle-Picher Company, Cincinnati, Ohio, a corporation of Ohio N Drawing. Application April 15, 1944, Serial No. 531,291

2 Claims. (Cl. 75-167) have long been sought in order to increase its mechanical strength and at the same time-reduce the considerable weight which attends Diping installations of pure lead. By the practice of this invention the wall thickness of lead pipe can be materially reduced while its strength is increased. I have found that while magnesium is a very desirable strength conferring and hardening agent especially when stabilized with tin its allow with lead is subject to deterioration. The problem is to inhibit corrosion of such an alloy so that it will retain its high strength for many years of service.

Manganese has been found to be a suitable corrosion inhibitor. alloy embodying these constituents isgiven below. The figures show the bursting strength in pounds per square inch on extruded tubing which had a wall thickness of .090" and an inside diameter of /3". Analysis by weight: Mg, .057%; Sn, 25%; Mn, .024%; Pb, Balance; bursting strength, 880 p. s. i.

Accelerated corrosion tests on the Pipe showed that in corrosion resistance .after 60 days, the alloy is equal to lead, it shows no more corrosion than other alloys now on the market for this purpose but is considerably stronger. These tests were made-b7 passing an alternating current of Anexample of the preferred i. e. manganese. The balance of the alloy is, of

course, lead.

When I extrude pipe from these alloys, I find it essential to do so under the following conditions: We fill the cylinder of the press with any of my molten alloys under anti-drossing conditions. To do so, I melt the alloy in a kettle situated near the pipe press and run the molten metal thru an iron pipe to the top of the cylinder.

10 There the delivery pipe bends and extends down 15 0 c., above its melting point.

As the pipe leaves the press die, I prefer to pass it directly. thru a gas expansion chamber or a cooling-liquid chamber mounted on the exit end of the press cylinder. And cool the pipe at such a m rate that it is well below its meltingpoint as it reaches the outside atmosphere. I find that this treatment restrains crystal growth.

I prefer to make my alloys by melting the minor constituents together under nonoxidizing conditions and then adding these molten to the molten lead'at 100-1800 under conditions of good agitation and anti-drosslng, such as protecting the lead surface in the kettle with a blanket of powdered carbon. I

so I claim as my invention:

1. An alloy consisting of .01% magnesium, 25% to 1.25% tin, .01% to .10% ,manganese, and the balance lead.

2. An alloy consisting of 0.01% to 0.10% magneslum. 0.25% to 1.25% tin; 0.01% to 0.10%

. manganese. and the balance lead. said alloy being more resistant to chemical corrosion than the same alloy devoid of manganese.

EDWARD G. HOLIMAN.