US1860095A - Lead alloy - Google Patents

Description

Patented May 24, 1932 UNITED STATES HENRY HARRIS, OF LONDON, ENGLAND LEAD ALIJOY Ho Drawing. Application filed-September 19, 1931, Serial No. 563,888, and in Great Britain May 6, 1930.

This invention relates. to alloys consisting for the most part of pure lead, and has for its I have found that the presence in lead of a quantity of zinc not greater than about 1 er cent. together with antimony or tin or 0th in quantities individually not more than about 1.8 per cent. has the efifectof producing an alloy which, while costing approximately the same as lead alone, has much improved physical properties. The alloy has a particularly high tensile strength, and is considerably harder and more ductile than pure lead.

In the manufacture of pipin sheet and the like from my new alloy, the nished article has a much smoother surface than is the case with articles made from lead alone. This surface will take a high polish, and is re 1 markably free from pitting and consequently does not readily corrode.

The alloy is highly resistant to corrosion especially when having a polished surface as above stated; the presence of tin is particularly effective in promoting this property, which is important in the manufacture of tea lead where it is essential that very thin sheets used for this purpose shall withstand the corrosion generally caused by exposure to sea air. The alloy has a greater fluidity in the molten state than has lead itself, and is therefore particularly suitable for the manufacture of piping and analogous articles with certain types of machinery designed to operate in a molten bath of the alloy. The alloy is also much less subject to oxidation in the molten state than is lead, and in consequence piping and like articles made from the alloy are particularly free from the small particles of oxide which are commonly responsible for the pinholing and failure of extruded articles generally.

There appears also to be a complete absence of segregation on solidfication from the molten state.

' The physical properties of the alloy can be improved by suitable heat treatment.

A particular advantage possessed by pipe made from this alloy is that it can be bent readily to any desired form without suffering any flattening or other deformatiomand that it is sufliciently rigid to retain its form without external support such as is generally necessary in the case of pipes made from pure lead; moreover its high tensile strength enables much higher internal pressures to be employed than is the case in pipe'made from pure lead, and therefore the pipe can be made of much lighter section and still be stronger in its resistance to both internal and external deformation than is the case with lead pipe. This enables a considerable saving to be effected in the manufacture Without detracting in any Way from the physical properties of the pipe. I V

The excess oftensile strength of these alloys over that of pure lead is very marked. In a tensile test, asample of pure lead showed an approximate yield point (i. e. oint at which the test piece begins to shrin in section area) of 0.16 tons/sq. in. and finally fractured at 0.86 tons/sq. in., whereas a lead alloy according to the present invention containing 0.14% of zinc and 0.5% of antimonytested under the same conditions yielded at approximately 0.22 tons/sq. in. and finally fractured at 1.31 tons/sq. in. If this latter alloy ismade with 0.25% of tin and 0.25% of antimony in place of the 0.5% of antimony alone, with the object of increasing the resistance to corrosion, the yield point remains approximately the same, and the fracture takes place at 1.25 tons/sq. in., which is verylittle lower than in the alloy with no tin.

Where great rigidity is required a lead alloy such as one containing Zn. 0.25% and Sb 1.50% can be used. A test made on this al- L loy. under the same conditions gave a yield f point of 0.3 tons/sq. in. and fracture took' place at 1.85 tons/sq. in. 1

Where great rigidity is to be combined with resistance to corrosion, it is desirable tohave some tin present, and a suitable lead alloy then would be one containing Zn 0.5%, Sb 1.0%, Sn 0.25%. This alloy tested under the same conditions yields at 0.28 tons/sq. in. and

fractures at 1.65 tons/sq. in.

A suitable lead allo in whichthe important properties require are hardness, smoothness of surface, and resistance to corrosion is one containing 1.00% of zinc 'and- 0.5% of tin;,this when tested under the' same conditions yielded at 0.26 tons/sq. in; and finally fractured at 1.61 tons/sq. in.

The particular com ositions above mentioned have'been foun very satisfactory in the manufacture of piping and sheet, but the invention is not limited to those particular proportions of the alloying metals, nor to any particular mode of incorporating them. Generally speaking it may be considered that tin improves resistance to atmospheric corros1on,also resistance to attack by acetic acid and sodium chlorlde; that antlmony 1mproves mechanical properties, reduces tendency towards oxidation, and increases hardness; and that zinc increases hardness and rigidity, and gives smoothness of surface. In the case of lead obtained from some sources it may already'contain some of the alloying metals so that it is only necessary to supplement them to the required extent.

What I claim is 1. An alloy consisting forthe most part of lead but containing also an appreciable.

amount of zinc not exceeding about 1 per cent. together with" tin and antimon in appreciable amounts .not exceeding individually about 1.8 per cent. I

2. An alloy consisting of zinc in the proportion of about 0.14 to 0.50- per cent., antimony in the proportion of about 0.25 per cent., tin in the proportion of about 0.25 per cent., and lead as the remaining metal.

3. An alloy consisting of zinc in the pro- I portion of about 0.5 per cent., antimony in the proportion of about 1.0 per cent., tin in the proportion of about 0.25 per cent., and lead as the remaining metal.

In testimony whereof I have name-to this specification.

HENRY HARRIS.

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