ABOUT THE BRASS

The brass alloys are the most important among the copper alloys, and consist essentially of alloys of copper and zinc. Brasses containing up to 36 per cent zinc, termed single phase alloys, are called Alpha brasses and have excellent cold-working qualities. Beyond 37 per cent zinc, a second-phase group comprises the Beta brasses, excellent in hot-working qualities.

In the low-zinc brass group (containing 5 to 20 per cent zinc) are alloys especially suited for use in costume jewelry and tube manufacture. Gilding metal (copper 95 per cent, zinc 5 per cent) is golden in color and is used for jewelry, emblems, and novelties that are to be gold-plated. It is very malleable, resists corrosion, and works well. Pinchbeck metal (88 per cent copper, 12 per cent zinc) was used by Victorian jewelers as a gold substitute, as it strongly resembles gold. Red brass (cop per 85 per cent, zinc 15 per cent) is the closest contemporary alloy to pinchbeck and is also used for costume jewelry.

Yellow brass (copper 65 per cent, zinc 35 per cent; melting point: 1660° F; annealing temperature: 800-1300° F) is especially suited to wire drawing, beads, chains, rivets, architectural grillwork, stamping, and spinning.

Muntz brass (copper 60 per cent, zinc 40 per cent; melting point: 1650° F; annealing temperature: 800-1100° F) is used for brazing rods and hot forging and in maritime and decorative architectural situations where high corrosion resistance is a factor. Leaded brasses contain 2 to 3 per cent lead which, when added to the copper-zinc alloys, makes them desirable for machining, as the particles form small chips when pared off and thus prevent tools from fouling and dulling. Naval brass (copper 60 per cent, zinc 39.25 per cent, tin 0.75 per cent; melting point: 1630° F) is used for welding rods, among other uses.