Wrought Metals

Coupled metal (wrought form) Uncoupled corrosion rale (mm/y) Acceleration factor- due to dissimilar metal coupling with Titanium Mild steel ... 

Pure iron, containing only about 0.01% of impurities, can be made by electrolytic reduction of iron salts. It has little use a small amount is used in analytical chemistry, and a small amount in the treatment of anemia. Metallic iron is greatly strengthened by the presence of a small amount of carbon, and its mechanical and chemical properties are also improved by moderate amounts of other elements, especially other transition metals. Wrought iron, cast iron, and steel are described from page 535 on. 

COPPERALLOYS-WROUGHT COPPER AND V/ROUGHTCOppEP AT,TOYS] (Vol 7) -in metallic pigments [PIGA4ENTS - INORG iNIC] (Vol 19)... 

Codification of Certaki Nonferrous Metals and Alloys, Cast and Wrought," specification no. ANSI/ASTM Annual Book ofASTM... 

Metals andMllojs Aluminum Association 900 19th Street, NW Washington, D.C. 20006 Standards for wrought and cast aluminum and aluminum alloy products, including composition, temper designation, dimensional tolerance, etc. 

High quaHty, wrought metals are clad without altering chemical composition. 

Heat Treatments. If the inherent porosity is taken into consideration, heat treatments performed on P/M parts do not differ substantially from the same treatments performed on cast or wrought metal. Results are also similar. 

P/M steels can be heat treated in the same manner as cast or wrought steels. They may be austenitized, quenched, and tempered. Surface hardening includes pack or gas carburization or nitriding, ie, heating in a nitrogen-containing atmosphere. Because of the greater amount of exposed surface area in the form of porosity, a protective atmosphere is needed (see Metal surface treatments). 

Excellent high strength welds have been produced by inertia-welding, or friction-welding, which develops essentially no heat-affected zone. The actual interface is wrought molybdenum because the molten metal and the adjacent soHd metal that has been raised to very high temperatures have been expelled from the joint. 

Wrought and cast nickel anodes and sulfur-activated electrodeposited rounds are used widely for nickel electro deposition onto many base metals. 

Hardness of the aimealed metals covers a wide range. Rhodium (up to 40%), iridium (up to 30%), and mthenium (up to 10%) are often used to harden platinum and palladium whose intrinsic hardness and tensile strength are too low for many intended appHcations. Many of the properties of rhodium and indium. Group 9 metals, are intermediate between those of Group 8 and Group 10. The mechanical and many other properties of the PGMs depend on the physical form, history, and purity of a particular metal sample. For example, electrodeposited platinum is much harder than wrought metal. 

Aluminum alloys are commercially available in a wide variety of cast forms and in wrought mill products produced by rolling, extmsion, drawing, or forging. The mill products may be further shaped by a variety of metal working and forming processes and assembled by conventional joining procedures into more complex components and stmctures. 

It has been known for many centuries that iron ore, embedded in burning charcoal, can be reduced to metallic iron (1,2). Iron was made by this method as early as 1200 BC. Consisting almost entirely of pure iron, the first iron metal closely resembled modem wrought iron, which is relatively soft, malleable, ductile, and readily hammer-welded when heated to a sufficientiy high temperature. This metal was used for many purposes, including agricultural implements and various tools. 

In ancient India, a steel called wootz was made by placing very pure kon ore and wood or other carbonaceous material in a tightly sealed pot or cmcible heated to high temperature for a considerable time. Some of the carbon in the cmcible reduced the kon ore to metallic kon, which absorbed any excess carbon. The resulting kon—carbon alloy was an excellent grade of steel. In a similar way, pieces of low carbon wrought kon were placed in a pot along with a form of carbon and melted to make a fine steel. A variation of this method, in which bars that had been carburized by the cementation process were melted in a sealed pot to make steel of the best quaUty, became known as the cmcible process. 

Another commercial development of the 1970s is the appHcation of superplasticity which is exhibited by a number of zinc alloys (135—138). Under the right conditions, the material becomes exceptionally soft and ductile and, under low stresses, extensions exceeding 1000% can be obtained without fracture. The grain size must be extremely small (about 1 micrometer) and stable. This grain size is less than one tenth that of common metals in the wrought condition. 

A summary of physical and chemical constants for beryUium is compUed ia Table 1 (3—7). One of the more important characteristics of beryUium is its pronounced anisotropy resulting from the close-packed hexagonal crystal stmcture. This factor must be considered for any property that is known or suspected to be stmcture sensitive. As an example, the thermal expansion coefficient at 273 K of siagle-crystal beryUium was measured (8) as 10.6 x 10 paraUel to the i -axis and 7.7 x 10 paraUel to the i -axis. The actual expansion of polycrystalline metal then becomes a function of the degree of preferred orientation present and the direction of measurement ia wrought beryUium. 

---