Nonferrous Metals: Industrial Applications and Properties Metallurgy for the Non-Metallurgist

Learning Objectives After completing this lesson, students will be able to : o List the significant properties of aluminum, beryllium, magnesium, titanium, copper, lead, tin, and zinc o Describe the primary applications for several nonferrous metals and alloys o Identify the precious metals and outline some of their principal applications

Introduction: Nonferrous Metals Light metals: Mg, Be, Al, Ti; density less than steel Sn, Zn, Mg largely used to protect steel Low MP’s good for die casting: Mg, Zn, Al Co alloys, Ti, and SS for implants Copper for conductivity Precious metals for catalysis, corrosion Ni superalloys: fortuitous precipitation

Aluminum Recovered electrolytically from bauxite Forms adherent protective thin oxide film Alloying(Mg, Cu, Si, Mn+) enhances strength Used cast(engine) or wrought(wheels) Amenable to die casting May be GMA, GTA, friction stir welded Many architectural uses

Typical applications of aluminum alloys. (a) Bodies of beverage cans, the largest volume alloy combination in the industry. (b) Castings such as gearboxes or wheels for automotive applications. (c) Formed sheet for parts such as internal door stiffeners. (d) Forgings for aerospace applications. (e) Architectural applications such as roof structures for arenas and gymnasiums. Photos courtesy of the Aluminum Association

Melting processes for used beverage can (UBC) scrap. (a) Early can scrap melter. (B) Swirl scrap charge melter using a continuous melting process

Magnesium Recovered from Great Salt Lake Very light, very reactive, anodize Used as anodes: hot water heater, pipeline, Gulf Amenable to die casting, rheocasting Readily formed, welded Readily machined, chips dangerous

Various applications of magnesium alloys. (a) Machine plates for hulls, hull stiffeners, decking, and superstructures for yachts and ocean liners. (b) Welded constructions for offshore oil rigs in high humidity and water exposure. (c) Die castings for wheel frame assemblies such as for wheelchairs (photo courtesy of International Magnesium Association). (d) Die castings for automotive parts such as seat frames and steering columns. (e) Girder systems for bridges. Photos courtesy of the Aluminum Association unless mentioned otherwise

Titanium Forms a highly protective oxide; resists oxidizing acids Nontoxic, biocompatible High strength, stiffness, toughness, low density, good corrosion resistance Now used in architecture CP for corrosion applications Burns at elevated temperature

Various applications of titanium alloys. (a) Aerospace structures. (b) Components for marine and chemical processing operations. (c) Cast knee and hip implants. (d) Tubing for heat exchangers, refrigeration systems, and bicycle frames. Photo courtesy of Timet

Copper

Typical applications of copper and copper alloys. (a) Copper cables used in building construction. (b) Connectors. (c) Ship propellers. (d) Architectural/ decorative uses such as the Statue of Liberty and this casting of the Great Seal of the United States (located at the Federal Deposit Insurance Corporation in Washington, D.C.)

Flow of copper from mining to end use

Copper for specialty applications Traveling wave tube amplifiers Rocket nozzles Coins Non-sparking tools: BeCu Bells and bearings: CuSn with hard intermetallic phases Welding rod: CuSi, good corrosion resistance, Si acts to deoxidize CuNi,NiCu marine exposures, heat exchangers

Stainless steels Corrosion resistance due to ~12% or more Cr, self healing film Martensitic(e.g., 410SS) limited to ~13%Cr so austenite can form; if annealed forms Cr carbide, loses corrosion resistance Ferritic: Higher Cr, never austenitic Austenitic: Ni stabilizes FCC, strengthened by working; 304, 316 Precipitation hardening: 14-17Cr plus alloy additions(Al, Cu, P) for heat treatment response. Processed soft, then aged. Better corrosion resistance than martensitic SS’s. Duplex and super SS, compete w/ Ni alloys

Lead

End uses of lead

Tin

Two principal applications of tin. (a) Tinplate for products such as these standard liquid measures and containers. (b) Solders, in this case precision tinning of conductor paths on thick-film circuits. Courtesy of International Tin Research Institute

Zinc

Refractory Metals Ta, Nb, Mo, W High melting points; used as heating elements Resistant to many corrosive environments Ta implants as plating on SS or CoCr alloys BCC, show BDTT, but Nb and Ta formable Oxidize, esp Mo and W

Applications of zinc. (a) Galvanized steel framing for residential and light commercial construction, produced on hot dip continuous galvanizing lines that submerge sheet steel into anticorrosive baths of zinc or zinc alloys. (b) Thicker zinc coatings are applied by hot dip galvanizing after fabrication to deploy thicker zinc coatings on components such as these highway guard rails. (c) Zinc die casting, used to mass produce high-quality parts quickly and efficiently. Courtesy of Zinc Institute

Superalloys Based on the NiAl system with Cr, Ti, Ta, W, Mo, Co, Y, Hf, Zr, C, B additions May have 60vol % precipitate Actually increase in strength from RT to ~1200F Creep resistant even at 2000F, especially in single crystal form Essential for gas turbine engines Other Ni alloys primarily for corrosion resistance

Comparison of nickel-base superalloy turbine blade cast structures showing macro- and microstructures of (from left) equiaxed, columnar grain, and single- crystal alloys

Summary: Nonferrous Metals Valued for different reasons: density, cost, conductivity, fabricability, corrosion resistance, wear resistance, melting point Example: copper for electrical and thermal conductivity, corrosion resistance Wide range in strength, e.g. Al alloys Essential for aerospace: Al, Ti, Ni alloys