Manufacturing_Engineering_and_TechnologyCh04.pdfVIP

Kalpakjian ? Schmid Manufacturing Engineering and Technology ? 2001 Prentice-Hall 1 CHAPTER 4 Metal Alloys: Their Structure and Strengthening by Heat Treatment Kalpakjian ? Schmid Manufacturing Engineering and Technology ? 2001 Prentice-Hall 2 Induction-Hardened Surface Figure 4.1 Cross-section of gear teeth showing induction-hardened surfaces. Source: TOCCO Div., Park-Ohio Industries, Inc. Kalpakjian ? Schmid Manufacturing Engineering and Technology ? 2001 Prentice-Hall 3 Chapter 4 Outline Figure 4.2 Outline of topics described in Chapter 4. Kalpakjian ? Schmid Manufacturing Engineering and Technology ? 2001 Prentice-Hall 4 Two-Phase System Figure 4.3 (a) Schematic illustration of grains, grain boundaries, and particles dispersed throughout the structure of a two-phase system, such as a lead-copper alloy. The grains represent lead in solid solution in copper, and the particles are lead as a second phase. (b) Schematic illustration of a two- phase system consisting of two sets of grains: dark, and light. The dark and the light grains have separate compositions and properties. Kalpakjian ? Schmid Manufacturing Engineering and Technology ? 2001 Prentice-Hall 5 Cooling Curve Figure 4.4 Cooling curve for the solidification of pure metals. Note that freezing takes place at a constant temperature; during freezing the latent heat of solidification is given off. Kalpakjian ? Schmid Manufacturing Engineering and Technology ? 2001 Prentice-Hall 6 Nickel-Copper Alloy Phase Diagram Figure 4.5 Phase diagram for nickel- copper alloy system obtained at a slow rate of solidification. Note that pure nickel and pure copper each has one freezing or melting temperature. The top circle on the right depicts the nucleation of crystals. The second circle shows the formation of dendrites (see Section 10.2). The bottom circle shows the solidified alloy, with grain boundaries. Kalpakjian ? Schmid Manufacturing Engineering and Technology ? 2001 Prentice-Hall 7 Mechanical Properties