Wrought processing

In aU wrought processes, the flow of metal is caused by application of an external force or pressure that pushes or pulls a piece of metal or alloy through a metal die. The pressure required to produce plastic flow is determined primarily by the yield stress of the material (cf. Section 5.1.4.3) which, in turn, controls the load capacity of the machinery required to accomplish this desired change in shape. The pressure, P, used to overcome the yield stress and cause plastic deformation is given by... 

In spite of good castability, strength and corrosion behaviour of the AZC1231 secondary alloy, suggesting that this alloy may be a suitable alternative for many applications, it cannot be used in places where ductility is important. For wrought processing or more ductile cast applications an additional secondary Mg alloy group is required. 

From an engineering viewpoint, the most significant results, other than the absolute values, are those concerning the anisotropy of wrought material. The results of tensile tests at room temperature along the three primary axes demonstrate this well-known consequence of wrought processes. At -320 F the anisotropy is even more evident, particularly with respect to the ductility. But the properties are not worse. 

Wrought lead—calcium—tin alloys contain more tin, have higher mechanical strength, exhibit greater stabiUty, and are more creep resistant than the cast alloys. RoUed lead—calcium—tin alloy strip is used to produce automotive battery grids in a continuous process (13). Table 5 Hsts the mechanical properties of roUed lead—calcium—tin alloys, compared with lead—copper and roUed lead—antimony (6 wt %) alloys. 

Copper Development Association P.O. Box 1840 Greenwich, Conn. 06836 Standards for wrought and cast copper and copper alloy products a standards handbook is pubUshed with tolerances, alloy data, terminology, engineering data, processing characteristics, sources and specifications cross-indexes for six coppers and 87 copper-based alloys that are recognized as standards. 

Ferrophosphoms is produced as a by-product in the electrothermal manufacture of elemental phosphoms, in which iron is present as an impurity in the phosphate rock raw material. The commercial product contains ca 23—29% P and is composed primarily of Fe2P [1310-43-6] and Fe P [12023-53-9] along with impurities such as Cr and V. Ferrophosphoms is used in metallurgical processes for the addition of phosphoms content. Low concentrations (up to - 0.1%) of phosphoms in wrought and cast iron and steel not only increases the strength, hardness, and wear resistance but also improves the flow properties. In large stmctural members and plates, it is desirable to use a type of steel that does not need to be quenched or tempered, and thus does not exhibit weld-hardening. This property is afforded by the incorporation of a small quantity of phosphoms in steel. Ferrophosphoms from western U.S. phosphoms production is used as a raw material for the recovery of vanadium (see Vanadiumand vanadiumalloys). 

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. 

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. 

The cmcible process gave steels that were not only homogeneous throughout but were free from occluded slag originating in the wrought kon used to make cement steel. Cmcible steel was so superior to cement steel for many purposes that the cmcible process quickly became the leader for the production of the finest steels. Its drawback was, however, that each cmcible held only ca 50 kg steel. 

Beryllium and aluminum are virtually insoluble in one another in the soHd state. The potential therefore exists for an aluminum—beryllium metal matrix composite with lower density and higher elastic modulus, ie, improved specific modulus, than conventional aluminum alloys produced by ingot or powder metal processing. At least one wrought composite system with nominally 62 wt % Be and 38 wt % A1 has seen limited use in aerospace appheations (see Composites). 

The output from brass mills in the United States is spHt nearly equally between copper and the alloys of copper. Copper and dilute copper alloy wrought products are melted and processed from electrically refined copper so as to maintain low impurity content. Copper alloys are commonly made from either refined copper plus elemental additions or from recycled alloy scrap. Copper alloys can be readily manufactured from remelted scrap while maintaining low levels of nonalloy impurities. A greater proportion of the copper alloys used as engineering materials are recycled than are other commercial materials. 

The process requires considerable equipment, and skills ia castiag must be acquired. Coatiauous castiag is useflil where souadness and high volume of parts are needed. The process is also used to produce shapes, such as billets, bars, and cakes, as starting materials for the wrought-product iadustry. 

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