02Lecture-ch6 - Manufacturing and Production Processes ENGR...

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Manufacturing and Production Processes ENGR 3190U – Lecture 02 Chapter 6 - Introduction to metals Sections 6.2.2, 6.2.3, 6.2.4, 6.3 – all, 6.5 . 1. Alloys 1. Ferrous Metals 1. Nonferrous Metals 1. Super-alloys 1. Guide to the Processing of Metals
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Metals: The Most Important Engineering Materials They have properties that satisfy a wide variety of design requirements The manufacturing processes by which they are shaped into products have been developed and refined over many years Engineers understand metals
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Why Metals Are Important High stiffness and strength ‑ can be alloyed for high rigidity, strength, and hardness Toughness ‑ capacity to absorb energy better than other classes of materials Good electrical conductivity ‑ Metals are conductors Good thermal conductivity ‑ conduct heat better than ceramics or polymers Cost – the price of steel is very competitive with other engineering materials
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Starting Forms of Metals used in Manufacturing Processes Cast metal - starting form is a casting Wrought metal - the metal has been worked or can be worked after casting Powdered metal - starting form is very small powders for conversion into parts using powder metallurgy techniques
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Classification of Metals Ferrous ‑ those based on iron Steels Cast irons Nonferrous ‑ all other metals Aluminum, magnesium, copper, nickel, titanium, zinc, lead, tin, molybdenum, tungsten, gold, silver, platinum, and others Superalloys
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Metals and Alloys Some metals are important as pure elements (e.g., gold, silver, copper) Most engineering applications require the enhanced properties obtained by alloying Through alloying , it is possible to increase strength, hardness, and other properties compared to pure metals An alloy = a mixture or compound of two or more elements, at least one of which is metallic Two main categories: 1. Solid solutions 2. Intermediate phases
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Solid Solutions An alloy in which one element is dissolved in another to form a single‑phase structure A phase = any homogeneous mass of material, such as a metal in which the grains all have the same crystal lattice structure In a solid solution, the solvent or base element is metallic, and the dissolved element can be either metallic or nonmetal
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Intermediate Phases There are usually limits to the solubility of one element in another When the amount of the dissolving element in the alloy exceeds the solid solubility limit of the base metal, a second phase forms in the alloy The term intermediate phase is used to describe it because its chemical composition is intermediate between the two pure elements Its crystalline structure is also different from those of the pure metals
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Ferrous Metals Based on iron, one of the oldest metals known to man Ferrous metals of engineering importance are alloys of iron and carbon These alloys divide into two major groups: Steel Cast iron Together, they constitute approximately 85% of the metal tonnage in the United States
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  • Spring '10
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  • Tool Steels, Its Alloys

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