Nickel is a hard, malleable, ductile metal. As an alloy, it will increase ductility, has no effect on grain size, lowers the critical point for heat treatment, aids fatigue strength, and increases impact values in low temperature operations. Both nickel and nickel alloys are machinable and are readily welded by gas and arc methods.
Uses. Nickel is used in making alloys of both ferrous and nonferrous metal. Chemical and food processing equipment, electrical resistance heating elements, ornamental trim, and parts that must withstand elevated temperatures are all produced from nickel-containing metal. Alloyed with chromium, it is used in the making of stainless steel.
Capabilities. Nickel alloys are readily welded by either the gas or arc methods. Nickel alloys can be machined, forged, cast, and easily formed.
Limitations. Nickel oxidizes very slowly in the presence of moisture or corrosive gases.
Properties. Pure nickel has tensile strength of 46,000 psi (317,170 kPa); Brinell hardness number 220; specific gravity of 8.9; and melting point of 2650°F (1454°C). Its alloys have Brinell hardness number of 140 to 230. Monel-forged nickel has tensile strength of 100,000 psi (689,500 kPa), and high strength and toughness at high temperatures.
Appearance. Pure nickel has a grayish white color.
Fracture. The fracture surface is smooth and fine grained.
**Spark test. **A spark test produces a very small amount of short, orange streaks which are generally wavy.
Monel metal. Monel metal is a nickel alloy of silver-white color containing about 67.00 percent nickel, 29.00 to 80.00 percent copper, 1.40 percent iron, 1.00 percent manganese, 0.10 percent silicon, and 0.15 percent carbon. In appearance, it resembles untarnished nickel. After use, or after contact with chemical solutions, the silver-white color takes on a yellow tinge, and some of the luster is lost. It has a very high resistance to corrosion and can be welded.