**3. Metallurgy forming and processing**

The importance of metals in modern technology is largely due to the ease with which it can be formed in useful shapes [10]. Hundreds of processes have been developed for specific applications of metalworking. However, these processes can be categorized into only a few classes based on the type of force applied to the workpiece when it is formed [11]. These classes are direct-compression-type processes, Indirect-compression processes, shearing processes, bending processes, and tension-type processes as shown in **Figure 1**. In direct compression processes, force is applied to the workpiece surface, and the metal flows at an angle based on the pressure direction. In indirect-compression processes, the basic applied forces are often tensile, but the indirect compressive forces are developed by the reaction of the workpiece with the die up to high values. These processes include extrusion, pipes, deep drawing of the cup and pulling wires. Therefore, the metal flows under the influence of a combined stress condition involving high pressure forces in at least one of the main directions. The best example of a tension-type forming process is the formation of expansion, where the sheet of metal is wrapped in a die contour under tensile forces. Shearing involves applying the shearing forces of sufficient size to tear the metal in the plane of shear, while bending involves applying the bending moments on the metal sheet. **Figure 1** shows these processes in a very basic way.

Metallurgy forming processes of are usually classified into hot and cold working processes. Hot working is defined as deformation under temperature and strain rate conditions so that recovery operations are performed together with the deformation. On the other hand, cold working is deformed in circumstances where recovery operations are not effective [12]. In hot working, the strain hardening and deformed grain structure caused by deformation are quickly eliminated by the formation of new strain-free grains as the result of recrystallization and grain growth. It is possible to have very large deformities in hot working because the recovery processes keep up with deformation [13]. Hot working occurs when the flow stress is essentially constant. The energy required for deformation is generally lower for hot working compared to cold working because of the flow stress decreases with increasing temperature. Since strain hardening is not alleviated in cold working, the flow stress increases with increasing the deformation. Therefore, the total plastic deformation without fracture is less for cold working compared with hot

**3**

**Figure 1.**

working temperature (**Figure 1**) [14].

*Typical metallurgy forming operations.*

**4. Mechanical testing and materials characterizations**

*Introductory Chapter: A Brief Introduction to Engineering Materials and Metallurgy*

working, unless the effects of cold work are mitigated through annealing process. It is important to understand that the difference between cold working and hot working does not depend upon any arbitrary deformation temperature. For most commercial metal alloys, hot working process should be performed at a relatively high temperature in order to obtain a rapid recrystallization rate. However, lead and tin recrystallize rapidly at room temperature after significant deformations so that the working of these metals at room temperature is like hot working. Similarly, the work of tungsten at 1093°C, in the hot work range of the steel, is a cold work because this high melting metal has a recrystallizing temperature higher than this

Whether a material is suitable for a given application is specified by the material properties. These properties can be measured using a series of mechanical tests, such as tensile, compressive, hardness and fatigue testing (**Figure 2**) as well as physical and chemical tests. Some of the mechanical tests are easily accessible like hardness. Others are difficult to measure such as tensile or yield strength where special samples must be formed. It is difficult to determine other properties such as fatigue, toughness strength as the tests need several

*DOI: http://dx.doi.org/10.5772/intechopen.86497*

*Introductory Chapter: A Brief Introduction to Engineering Materials and Metallurgy DOI: http://dx.doi.org/10.5772/intechopen.86497*

**Figure 1.** *Typical metallurgy forming operations.*

*Recent Advancements in the Metallurgical Engineering and Electrodeposition*

quantity of the metal production in that country [7].

**3. Metallurgy forming and processing**

and halides.

in a very basic way.

bridges, motor vehicles, railways, buildings structure, ships, aircrafts, agricultural tools, etc. Therefore, real economic growth can come from increasing quality and

Naturally, most metals occur in the combined state as minerals and they are reactive. Only a few metals like gold, silver, platinum and mercury, etc. are found as Free State in the earth's crust. Metals that have a low reaction show little convergence to air, moisture, carbon dioxide, or non-metals found in nature [8]. Materials that occurring naturally in which a metal or its compound occurs is called a mineral. A mineral from which a metal can be economically extracted is called an ore. The main active components found in nature, especially in the atmosphere are oxygen and carbon dioxide. In the earth's crust, silicon and sulfur are present in large quantities. Seawater also contains large amounts of chloride ions (obtained from dissolved salts). Most active metals are high electrically positive and therefore exist as different ions [9]. For this reason, most of the important ores of these metals occur as different components such as oxides, silicates, carbonates,

The importance of metals in modern technology is largely due to the ease with which it can be formed in useful shapes [10]. Hundreds of processes have been developed for specific applications of metalworking. However, these processes can be categorized into only a few classes based on the type of force applied to the workpiece when it is formed [11]. These classes are direct-compression-type processes, Indirect-compression processes, shearing processes, bending processes, and tension-type processes as shown in **Figure 1**. In direct compression processes, force is applied to the workpiece surface, and the metal flows at an angle based on the pressure direction. In indirect-compression processes, the basic applied forces are often tensile, but the indirect compressive forces are developed by the reaction of the workpiece with the die up to high values. These processes include extrusion, pipes, deep drawing of the cup and pulling wires. Therefore, the metal flows under the influence of a combined stress condition involving high pressure forces in at least one of the main directions. The best example of a tension-type forming process is the formation of expansion, where the sheet of metal is wrapped in a die contour under tensile forces. Shearing involves applying the shearing forces of sufficient size to tear the metal in the plane of shear, while bending involves applying the bending moments on the metal sheet. **Figure 1** shows these processes

Metallurgy forming processes of are usually classified into hot and cold working processes. Hot working is defined as deformation under temperature and strain rate conditions so that recovery operations are performed together with the deformation. On the other hand, cold working is deformed in circumstances where recovery operations are not effective [12]. In hot working, the strain hardening and deformed grain structure caused by deformation are quickly eliminated by the formation of new strain-free grains as the result of recrystallization and grain growth. It is possible to have very large deformities in hot working because the recovery processes keep up with deformation [13]. Hot working occurs when the flow stress is essentially constant. The energy required for deformation is generally lower for hot working compared to cold working because of the flow stress decreases with increasing temperature. Since strain hardening is not alleviated in cold working, the flow stress increases with increasing the deformation. Therefore, the total plastic deformation without fracture is less for cold working compared with hot

**2**

working, unless the effects of cold work are mitigated through annealing process. It is important to understand that the difference between cold working and hot working does not depend upon any arbitrary deformation temperature. For most commercial metal alloys, hot working process should be performed at a relatively high temperature in order to obtain a rapid recrystallization rate. However, lead and tin recrystallize rapidly at room temperature after significant deformations so that the working of these metals at room temperature is like hot working. Similarly, the work of tungsten at 1093°C, in the hot work range of the steel, is a cold work because this high melting metal has a recrystallizing temperature higher than this working temperature (**Figure 1**) [14].
