PDA

View Full Version : Grades of lead



cbrick
09-21-2009, 06:52 PM
The following is from my article Cast Bullet Alloys (http://www.lasc.us/CastBulletAlloy.htm), I thought some here would find this info from the metals industry useful and interesting.

Unified Numbering System - (UNS) designations for various pure lead grades and lead-base alloys. If you acquire ingots with any of these numbers, this what you have.

Pure leads L50000 - L50099
Lead - silver alloys L50100 - L50199
Lead - arsenic alloys L50300 - L50399
Lead - barium alloys L50500 - L50599
Lead - calcium alloys L50700 - L50899
Lead - cadmium alloys L50900 - L50999
Lead - copper alloys L51100 - L51199
Lead - indium alloys L51500 - L51599
Lead - lithium alloys L51700 - L51799
Lead - antimony alloys L52500 - L53799
Lead - tin alloys L54000 - L55099
Lead - strontium alloys L55200 - L55299

Compositions and Grades of lead. Malleability, softness, lubricity and coefficient of thermal expansion, all of which are quite high; and elastic modulus, elastic limit, strength, hardness, and melting point, all of which are quite low are related properties that account for the extensive use of lead in many applications.

Grades of lead. Grades are pure lead (also called corroding lead) and common lead (both containing 99.94% min lead), and chemical lead and acid-copper lead (both containing 99.90% min lead). Lead of higher specified purity (99.99%) is also available in commercial quantities. Specifications other than ASTM B 29 for grades of pig lead include federal specification QQ-L-171, Canadian Standard CSA-HP2, and Australian Standard 1812.

Corroding Lead. Most lead produced in the United States is pure (or corroding) lead (99.94% min Pb). Called corroding lead because it exhibits outstanding corrosion resistance typical of lead and lead alloys.

Chemical Lead. Refined lead with a residual copper content of 0.04 to 0.08% and a residual silver content of 0.002 to 0.02% is particularly desirable in the chemical industries and thus is called chemical lead.

Copper-bearing lead provides corrosion protection comparable to that of chemical lead in most applications that require high corrosion resistance. Common lead, which contains higher amounts of silver and bismuth than does corroding lead, is used for battery oxide and general alloying.

Lead-Base Alloys. Because lead is very soft and ductile, it is normally used Commercially as lead alloys. Antimony, tin, arsenic, and calcium are the most common alloying elements. Antimony generally is used to give greater hardness and strength, as in storage battery grids, sheet, pipe, and castings. Antimony contents of lead-antimony alloys can range from 0.5 to 25%, but they are usually 2 to 5%.

Lead-calcium alloys have replaced lead-antimony alloys in a number of applications, in particular, storage battery grids and casting applications. These alloys contain 0.03 to 0.15% Ca. More recently, aluminum has been added to calcium-lead and calcium-tin-lead alloys as a stabilizer for calcium. Adding tin to lead or lead alloys increases hardness and strength, but lead-tin alloys are more commonly used for their good melting, casting, and wetting properties, as in type metals and solders. Tin gives the alloy the ability to wet and bond with metals such as steel and copper; unalloyed lead has poor wetting characteristics. Tin combined with lead and bismuth or cadmium forms the principal ingredient of many low-melting alloys.

Arsenical lead (UNS L50310) is used for cable sheathing. Arsenic is often used to harden lead-antimony alloys and is essential to the production of round dropped shot.

Type metals: A class of metals used in the printing industry, generally consist of lead-antimony and tin alloys. Small amounts of copper are added to increase hardness for some applications.

Cable Sheathing: Lead sheathing extruded around electrical power and communication cables gives the most durable protection against moisture and corrosion damage, and provides mechanical protection of the insulation. Chemical lead, 1% antimonial lead, and arsenical lead are most commonly employed for this purpose.

Sheet: Lead sheet is a construction material of major importance in chemical and related industries because lead resists attack by a wide range of chemicals. Lead sheet is also used in building construction for roofing and flashing, shower pans, flooring, x-ray and gamma-ray protection, and vibration damping and soundproofing. Sheet for use in chemical industries and building construction is made from either pure lead or 6% antimonial lead. Calcium-lead and calcium-lead-tin alloys are also suitable for many of these applications.

Lead Pipe. Seamless pipe made from lead and lead alloys is readily fabricated by extrusion. Because of its corrosion resistance and flexibility, lead pipes finds many uses in the chemical industry and in plumbing and water distribution system. Pipe for these applications is made from either chemical lead or 6% antimonial lead.

Solders in the tin-lead system are the most widely used of all joining materials. The low melting range of tin-lead solders makes them ideal for joining most metals by convenient heating methods with little or no damage to heat-sensitive parts. Tin-lead solder alloys can be obtained with melting temperatures as low as 182 °C and as high as 315 °C. Except for the pure metals and the eutectic solder with 63% Sn and 37% Pb, all tin-lead solder alloys melt within a temperature range that varies according to the alloy composition.

Lead-base bearing alloys, which are called lead-base Babbitt metals, vary widely in composition but can be categorized into two groups:

Alloys of lead, tin, antimony, and, in many instances, arsenic
Alloys of lead, calcium, tin, and one or more of the alkaline earth metals

Ammunition. Large quantities of lead are used in ammunition for both military and sporting purposes. Alloys used for shot contain up to 6% Sb and 2% As; those used for bullet cores can contain up to 5% Sb.