Metal deformation

J. A. Schey, Metal Deformation Processes, Marcel Dekker, New York, 1970. 

Enamel is appHed to steel in the flat before fabrication. Cans manufactured by the draw and ironing operation must be coated internally after fabrication because of the metal deformation with surface dismption that takes place. 

The Chin-Gilman parameters (H/G) are given in the figure captions. Note that the value for the bcc metals (0.02) is about five times greater than the value for the fee metals (0.0044). Thus the bcc metals deformation harden much more rapidly than the fee metals. 

Removal of welding operations that can cause metal deformations. 

Dispersion hardening or strengthening of a material means an increased resistance to deformation. The movement of dislocations in the metal facilitates metal deformation. Incorporated particles block the dislocation movement and thus strengthen the metal.4,11 12,21 Grain refinement of the metal due to the codeposition of particles has also been thought to contribute to the hardening effect, but this is not supported by experimental evidence. For several composites it was found that the grain structure of the metal matrix was not altered by the codeposition of particles. 

During cold working, polycrystaUine metals deform by mechanisms involving slip and, where slip is restricted, rotation of the individual grains. Both processes, of course, must satisfy the condition that the interfaces, along which the grains are connected. 

Better low-stress properties to eliminate stress-related failures such as metal deformation, cracked passivation and parameter shifts. This must be done without sacrificing strength. 

Bhattacharya et al studied the effect of molybdenum disulphide concentration on friction in metal deformation. Their results (Figure 13.G) .iiOvv un optimum at 3 - 4 wt.% and a steady decrease at higher concentrations for unannealed aluminium alloy, and two separate optimum concentrations for annealed alloy. Nandi also reported a drop in extrusion load for lead billets at certain specif concentrations. 

Efforts aimed at lowering the firing temperatures are motivated not only by economy but also by the quality of products (a reduced tendency to metal deformation and enamel peeling). The deformation of metal and creation of stresses in enamel is related to the polymorphic inversion of a-Fe (ferrite) to y-Fe (austenite) which takes place at 900 °C in pure iron the inversion temperature decreases with increasing carbon content down to 720 °C at 0.8% C. The aim is to fire the products below the temperature of this inversion. One of the ways is provided by use of low-carbon steels, the other by employing enamels with a reduced firing temperature. 

Bonderite [Occidental], TM for chemical compositions for producing a corrosion-inhibiting finish on metals, preparing metal surfaces for the subsequent application of finish coats, and conditioning metal surfaces to facilitate metal-deformation operations. 

Figure 12.34 The reason metals deform. A, An external force applied to a piece of metai deforms but doesn t break it. B, The externai force mereiy moves metai ions past each other through the eiectron sea.

The hot metal deformation portion of the FSW is complicated, and methods to decouple... 

Modeling the heat generation therefore requires some representation of the interface contact behavior together with the viscous dissipation behavior of the material. Simple analytical approaches are discussed in this section numerical methods, in which heat generation is calculated directly from coupled models of the temperature field and metal deformation, are discussed in section 10.3, Metal Flow. ... 

The effect of the medium on metal deformation commonly begins on reduction of the surface energy during physical adsorption. Afterwards, various secondary phenomena, including chemical, electrical, etc. are superimposed on this process. A certain activation energy, dependent on the process specifics, is necessary for these phenomena to occur. In the case of metal strain and failure in corrosion-active media, mechanical and electrochemical activation are of particular importance [18]. 

Metals are normally ductile, and plastic deformation can be considerable. This is a valuable property of metals and is used, for example, to fabricate dish shapes of one sort or another by impressing a die into a sheet of metal. The metal deforms plastically and retains the dished shape when the load on the die is removed. Ceramics are regarded as brittle, and normally the same fabrication process applied to a ceramic would shatter it. However, at high temperatures, many ceramic materials can deform plastically, and at low temperatures many metals become brittle and lose ductility. Thus, it is convenient to treat these two apparently dissimilar crystalline materials together. Polymers, which contain crystalline and amorphous regions, are considered in Section 10.1.11. 

The overwhelming evidence accumulated over several decades is that the crystalline lamellae of PE, much like in all crystalline ductile metals, deform plastically... 

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