Special Alloy Technical Information

Resistance Alloy PDF's Copper Alloy PDF's Stainless Steel Alloy PDF's
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HSM Wire International produces a wide variety of stainless steel alloys known for their excellent corrosion and heat resistance. Ferritic (Chromium) grades are magnetic, non-nickel bearing alloys that have greater inherent strength and corrosion resistance than carbon steel. Most ferritic stainless steels are part of the 400 series (as are most of the martensitic grades). Austenitic (Chromium-Nickel) grades were developed for enhanced surface quality and formability and increased corrosion and wear resistance. These include the common 200 series and 300 series alloys. Austenitic alloys are non-magnetic in the fully annealed condition, but may become magnetic when cold worked due to martensitic formation. Superferritic and Superaustenitic alloys contain significant additions of chromium, nickel, molybdenum or copper and are used where extra corrosion protection, strength or heat resistance are required. Duplex grades are alloys that are partially ferritic and partially austenitic, giving them a combination of properties that is often superior to that of single phase alloys. Martensitic and Precipitation Hardened alloys are typically used in applications requiring very high strength.

HSM Wire International's nickel-based superalloys were developed for very high temperature service where relatively high stresses are encountered and where high surface stability is frequently required. They are also used for heat treating fabrications including furnaces, retorts and fixtures, for strength at temperature and resistance to oxidation, carbonization, sulfidation and nitrating.

Copper alloys are so widely used, many in complex applications, that there are over 370 commercial copper and copper alloy grades. The Copper family includes coppers, high-copper alloys, brasses, leaded brasses, bronzes, aluminum bronzes, silicon bronzes, copper nickels, and nickel silvers. Copper alloys provide good thermal and electrical conductivity, corrosion resistance, ease of forming, ease of joining, and color, but most have relatively low strength-to-weight ratios and low strengths at elevated temperatures.

Carbon steels and alloy steels are ferrous alloys that contain carbon and other alloying elements such as manganese, chromium, molybdenum, and nickel. They are used in a wide variety of industrial applications. Carbon steels and alloy steels vary in terms of alloying elements, strength, and durability. Plain carbon steels include both soft, non-hardenable, low carbon products and hardenable, high carbon steels. Most low carbon or mild steels can be fabricated by machining, forming, casting, and welding. Typically, carbon steels contain manganese or aluminum as alloying elements. By contrast, alloy steels contain chromium, molybdenum, vanadium, and nickel. Like plain carbon steels, alloy steels are based on iron and contain significant amounts of carbon. Common alloy steels include hardenable high alloy steels, high strength low alloy (HSLA) steels, maraging steels and specialty steel alloys. Commercially pure, unalloyed or very low alloy metals are free of or contain very small amounts of alloying elements such as copper, commercially pure titanium or palladium-modified titanium, or pure aluminum grades from the AA 10nn Series (e.g., AA 1000 to 1999).

Copper–manganese alloys (~84% Cu, 12% Mn with nickel, aluminum or germanium as the remaining constituent). These alloys are sold under various proprietary names, and manganin, the pioneer alloy of this group, was for many years the traditional material for high-grade standard resistors. The resistively is about 40 × 10−8 Ω m and varies approximately parabolically with temperature over the range 0 to 50 °C, with a maximum close to 20 °C. The temperature coefficient can be as low as 3 × 10−6 °C−1 over the range 15 °C to 20 °C. Its secular stability is very good and, if wires are supported in strain-free conditions, can be less than 1 in 107 per year. The thermo-e.m.f. of the alloys against copper is close to zero and may be positive or negative according to composition and heat treatment. Joints between the copper manganese alloys and copper are made most effectively by welding in an atmosphere of argon, and by hard soldering if welding is impracticable.

Copper–nickel alloys (~55% Cu, 45% Ni). These alloys are manufactured commercially under a wide range of proprietary names, and are used in the construction of standard resistors. The resistively is about 50 × 10−8 Ω m with a temperature coefficient which may lie between ±0.000 04 °C−1.
The alloys can be soft-soldered with ease, but their high thermo-e.m.f. against copper (~40 μV °C−1) is a disadvantage in d.c. resistors, although the effect is usually negligible in a.c. resistors dropping 1 volt or more. These alloys are also used for current controlling resistors when constancy is more important than low cost.

Nickel–chromium alloys (~80% Ni, 20% Cr). These alloys are also available under a variety of trade names and are used for heater elements as well as for resistors where high accuracy is not required. Their resistibility is about 110 × 10−8 Ω m with a temperature coefficient (20–500 °C) of 0.000 06 °C−1. They will operate satisfactorily at temperatures of up to 1100 °C. A ternary alloy (65% Ni, 15% Cr, 20% Fe) is less expensive than nickel–chromium and is satisfactory at temperatures up to 900 °C.

A particular development of 80/20 nickel–chromium for reference or standard resistors is the use of thick-film deposits on glass substrates. These resistors are essentially thermally-compensated strain gauges in which the change of resistance with temperature counteracts the change due to the strain imparted by the substrate. When suitably heat-treated after deposition, such resistors can achieve temperature coefficients of not more than a few p.p.m. and secular stability comparable with that of manganin or quaternary alloys. However, because of their very small size, they can be used at much higher frequencies than is possible with wire-wound types.

Quaternary alloys (~73% Ni, 21% Cr, 2% Al, with copper, iron, cobalt, manganese or molybdenum as the fourth main constituent). These alloys are again processed and marketed under many proprietary names, each of which is characterized by the fourth constituent; they are increasingly being used for standard resistors, especially those of high value. Their resistivity about 130 × 10−8 Ω m, with a temperature coefficient controllable by heat treatment and which can be made as small as ±0.000 002 °C−1. The thermo-e.m.f. of the alloys, like that of the copper–manganese alloys, is close to zero and may be slightly positive or negative. The tensile strength of the alloys is high, making possible the drawing of very fine wire. Welding in argon is by far the best method of joining with copper, with hard soldering as an alternative only if welding is not possible.