43 Lead and Lead Alloys.pdf

4«5 Lead and Lead Alloys
F. E. GOODWIN
International Lead Zinc anization, Inc.
Research Triangle Park, North Carolina
A. INTRODUCTION
Lead is a malleable, heavy (50% more dense than steel) material that, despite its amphoteric nature,
forms insoluble corrosion products under many conditions. This has made it useful in the chemical
industry, particularly for its resistance to sulfuric acid, in batteries, and as sheet and pipe for building
construction. It enjoys widespread use as solder in the electronics industry because of its low melting
point. The low strength of lead often necessitates its support by wooden or steel structures for
chemical process equipment or by use of lead clad steel.
There are mon types of lead: (1) pure lead (also called corroding lead), and (2) common
lead, (3) chemical lead, and (4) acid-copper lead. The first two contain % minimum lead while
the latter two both contain % minimum lead. These grades are covered in ASTM B29. Higher
purity (%) is also available mercial qualities.
"Corroding lead" refers not to a corrosion characteristic of this grade, but rather to a process in
which it was formerly used, the Dutch manufacturing process for producing white lead, a pigment.
Corroding lead is nearly as corrosion resistant as chemical lead and is the most widely used grade of
lead today.
"Chemical lead" takes its name from its widespread use in the chemical industry. Small amounts
of copper and silver are contained increasing corrosion resistance and mechanical strength.
"Common lead" contains higher amounts of silver and bismuth than corroding lead and is used for
battery oxide and general alloying. "Acid-copper lead" provides corrosion parable to
that of chemical lead in most applications that require high corrosion resistance. This grade has a
higher bismuth tolerance than chemical lead and is used in several types of fabricated lead products.
B. GENERAL CORROSION CHARACTERISTICS
The amphoteric na