NONFERROUS METALS

Nonferrous metals contain either no iron or only insignificant amounts used as an alloy. Some of the more common nonferrous metals Steelworkers work with are as follows: copper, brass, bronze, copper-nickel alloys, lead, zinc, tin, aluminum, and Duralumin.

NOTE: These metals are nonmagnetic.

Copper

This metal and its alloys have many desirable properties. Among the commercial metals, it is one of the most popular. Copper is ductile, malleable, hard, tough, strong, wear resistant, machinable, weldable, and corrosion resistant. It also has high-tensile strength, fatigue strength, and thermal and electrical conductivity. Copper is one of the easier metals to work with but be careful because it easily becomes work-hardened; however, this condition can be remedied by heating it to a cherry red and then letting it cool. This process, called annealing, restores it to a softened condition. Annealing and softening are the only heat-treating procedures that apply to copper. Seams in copper are joined by riveting, silver brazing, bronze brazing, soft soldering, gas welding, or electrical arc welding. Copper is frequently used to give a protective coating to sheets and rods and to make ball floats, containers, and soldering coppers.

True Brass

This is an alloy of copper and zinc. Additional elements, such as aluminum, lead, tin, iron, manganese, or phosphorus, are added to give the alloy specific properties. Naval rolled brass (Tobin bronze) contains about 60% copper, 39% zinc, and 0.75% tin. This brass is highly corrosion-resistant and is practically impurity free.

Brass sheets and strips are available in several grades: soft, 1/4 hard, 1/2 hard, full hard, and spring grades. Hardness is created by the process of cold rolling. All grades of brass can be softened by annealing at a temperature of 550F to 600F then allowing it to cool by itself without quenching. Overheating can destroy the zinc in the alloy.

Bronze

Bronze is a combination of 84% copper and 16% tin and was the best metal available before steel-making techniques were developed. Many complex bronze alloys, containing such elements as zinc, lead, iron, aluminum, silicon, and phosphorus, are now available. Today, the name bronze is applied to any copper-based alloy that looks like bronze. In many cases, there is no real distinction between the composition of bronze and that of brass.

Copper-Nickel Alloys

Nickel is used in these alloys to make them strong, tough, and resistant to wear and corrosion. Because of their high resistance to corrosion, copper nickel alloys, containing 70% copper and 30% nickel or 90% copper and 10% nickel, are used for saltwater piping systems. Small storage tanks and hot-water reservoirs are construtted of a copper-nickel alloy that is available in sheet form. Copper-nickel alloys should be joined by metalarc welding or by brazing.

Lead

A heavy metal that weighs about 710 pounds per cubic foot. In spite of its weight, lead is soft and malleable and is available in pig and sheet form. In sheet form, it is rolled upon a rod so the user can unroll it and cut off the desired amount. The surface of lead is grayish in color; however, after scratching or scraping it, you can see that the actual color of the metal is white. Because it is soft, lead is used as backing material when punching holes with a hollow punch or when forming shapes by hammering copper sheets. Sheet lead is also used to line sinks or protect bench tops where a large amount of acid is used. Lead-lined pipes are used in systems that carry corrosive chemicals. Frequently, lead is used in alloyed form to increase its low-tensile strength. Alloyed with tin, lead produces a soft solder. When added to metal alloys, lead improves their machinability.

CAUTION

When working with lead, you must take proper precautions because the dust, fumes, or vapors from it are highly poisonous.

Zinc

You often see zinc used on iron or steel in the form of a protective coating called galvanizing. Zinc is also used in soldering fluxes, die castings, and as an alloy in making brass and bronze.

Tin

Tin has many important uses as an alloy. It can be alloyed with lead to produce softer solders and with copper to produce bronze. Tin-based alloys have a high resistance to corrosion, low-fatigue strength, and a compressive strength that accommodates light or medium loads. Tin, like lead, has a good resistance to corrosion and has the added advantage of not being poisonous; however, when subjected to extremely low temperatures, it has a tendency to decompose.

Aluminum

This metal is easy to work with and has a good appearance. Aluminum is light in weight and has a high strength per unit weight. A disadvantage is that the tensile strength is only one third of that of iron and one fifth of that of annealed mild steel.

Aluminum alloys usually contain at least 90% aluminum. The addition of silicon, magnesium, copper, nickel, or manganese can raise the strength of the alloy to that of mild steel. Aluminum, in its pure state, is soft and has a strong affinity for gases. The use of alloying elements is used to overcome these disadvantages; however, the alloys, unlike the pure aluminum, corrodes unless given a protective coating. Threaded parts made of aluminum alloy should be coated with an antiseize compound to prevent sticking caused by corrosion.

Table 1-3.-Surface Colors of Some Common Metals

Duralumin

One of the first of the strong structural aluminum alloys developed is called Duralumin. With the development of a variety of different wrought-aluminum alloys, a numbering system was adopted. The digits indicate the major alloying element and the cold-worked or heat-treated condition of the metal. The alloy, originally called Duralumin, is now classified in the metal working industries as 2017-T. The letter T indicates that the metal is heat-treated.

Alclad

This is a protective covering that consists of a thin sheet of pure aluminum rolled onto the surface of an aluminum alloy during manufacture. Zinc chromate is a protective covering that can be applied to an aluminum surface as needed. Zinc chromate is also used as a primer on steel surfaces for a protective coating.

Monel

Monel is an alloy in which nickel is the major element. It contains from 64% to 68% nickel, about 30% copper, and small percentages of iron, manganese, and cobalt. Monel is harder and stronger than either nickel or copper and has high ductility. It resembles stainless steel in appearance and has many of its qualities. The strength, combined with a high resistance to corrosion, make Monel an acceptable substitute for steel in systems where corrosion resistance is the primary concern. Nuts, bolts, screws, and various fittings are made of Monel. This alloy can be worked cold and can be forged and welded. If worked in the temperature range between 1200F and 1600F, it becomes "hot short" or brittle.

K-Monel

This is a special type of alloy developed for greater strength and hardness than Monel. In strength, it is comparable to heat-treated steel. K-monel is used for instrument parts that must resist corrosion.

Inconel

This high-nickel alloy is often used in the exhaust systems of aircraft engines. Inconel is composed of 78.5% nickel, 14% chromium, 6.5% iron, and 1% of other elements. It offers good resistance to corrosion and retains its strength at high-operating temperatures.

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