【正文】 1 目錄UNIT 1 ADVANCED ENGINEERING MATERIALS ............................................................................................. 1 UNIT 2 HEAT TREATMENT OF METALS ........................................................................................................... 6 UNIT 3 CASTING PROCESSES............................................................................................................................. 15 UNIT 4 FORGING PROCESSES ............................................................................................................................ 21 UNIT 5 POWDER METALLURGY ....................................................................................................................... 26 UNIT 6 INJECTION MOLDING............................................................................................................................. 32 UNIT 7 METAL CUTTING..................................................................................................................................... 38 UNIT 8 GRINDING.................................................................................................................................................. 45 UNIT 9 LAPPING POLISHING ............................................................................................................................. 49 UNIT 10 SURFACE ENGINEERING..................................................................................................................... 51 UNIT 12 DRILLING AND MILLING .................................................................................................................... 63 UNIT 13 JIGS AND FIXTURES............................................................................................................................. 68 UNIT 14 LIMIT AND TOLERANCES................................................................................................................... 72 特種加工工藝（Ⅰ、Ⅱ） ........................................................................................................................................ 77 2 UNIT 1 Advanced Engineering MaterialsTypes of Materials材料的類型Materials may be grouped in several ways. Scientists often classify materials by their state: solid, liquid, or gas. They also separate them into anic (once living) and inanic (never living) ?？茖W(xué)家常根據(jù)狀態(tài)將材料分為：固體、液體或氣體。他們也把材料分為有機材料(曾經(jīng)有生命的)和無機材料(從未有生命的)。For industrial purposes, materials are divided into engineering materials or nonengineering materials. Engineering materials are those used in manufacture and bee parts of ，材料被分為工程材料和非工程材料。那些用于加工制造并成為產(chǎn)品組成部分的就是工程材料。Nonengineering materials are the chemicals, fuels, lubricants, and other materials used in the manufacturing process, which do not bee part of the 、燃料、潤滑劑以及其它用于加工制造過程但不成為產(chǎn)品組成部分的材料。Engineering materials may be further subdivided into: ①Metal ②Ceramics ③Composite ④Polymers, ：①金屬材料②陶瓷材料③復(fù)合材料 ④聚合材料，等等。Metals and Metal Alloys 金屬和金屬合金Metals are elements that generally have good electrical and thermal conductivity. Many metals have high strength, high stiffness, and have good ductility. 金屬就是通常具有良好導(dǎo)電性和導(dǎo)熱性的元素。許多金屬具有高強度、高剛性以及良好的延展性。Some metals, such as iron, cobalt and nickel, are magic. At low temperatures, some metals and intermetallic pounds bee ，例如鐵、鈷和鎳。在極低的溫度下，某些金屬和金屬化合物能轉(zhuǎn)變成超導(dǎo)體。What is the difference between an alloy and a pure metal? Pure metals are elements which e from a particular area of the periodic table. Examples of pure metals include copper in electrical wires and aluminum in cooking foil and beverage cans. 合金與純金屬的區(qū)別是什么？純金屬是取自元素周期表中特定位置的元素。例如電線中的銅和制造烹飪箔及飲料罐的鋁。Alloys contain more than one metallic element. Their properties can be changed by changing the elements present in the alloy. Examples of metal alloys include stainless steel which is an alloy of iron, nickel, and chromium。 and gold jewelry which usually contains an alloy of gold and 。合金的性質(zhì)能通過改變其中元素的存在而改變。金屬合金的例子有：不銹鋼是一種鐵、鎳和鉻的合金，以及金飾品通常含有金鎳合金。Why are metals and alloys used? Many metals and alloys have high densities and are used in applications which require a high masstovolume ratio. 為什么要使用金屬和合金？許多金屬和合金都具有高密度，因此被用在需要較高質(zhì)量體積比的場合。Some metal alloys, such as those based on aluminum, have low densities and are used in aerospace applications for fuel economy. Many alloys also have high fracture toughness, which means they can withstand impact and are durable.某些金屬合金，例如鋁基合金，其密度低，可用于航空航天以節(jié)省燃料。許多合金還具有高斷裂韌性， 3 這意味著它們能經(jīng)得起沖擊并且是耐用的。What are some important properties of metals?Density is defined as a material’s mass divided by its volume. Most metals have relatively high densities, especially pared to polymers. 金屬有哪些重要特性？密度定義為材料的質(zhì)量與其體積之比。大多數(shù)金屬密度相對較高，尤其是與聚合物相比較而言。Materials with high densities often contain atoms with high atomic numbers, such as gold or lead. However, some metals such as aluminum or magnesium have low densities, and are used in applications that require other metallic properties but also require low 密度材料通常由較大原子序數(shù)原子構(gòu)成，例如金或鉛。然而，諸如鋁或鎂之類的一些金屬則具有低密度，并被用于既需要金屬特性又要求重量輕的場合。Fracture toughness can be described as a material’s ability to avoid fracture, especially when a flaw is introduced. Metals can generally contain nicks and dents without weakening very much, and are impact resistant. A football player counts on this when he trusts that his facemask won’t 。金屬一般能在有缺口和凹痕的情況下不顯著削弱，并且能抵抗沖擊。橄欖球運動員據(jù)此相信他的面罩不會裂成碎片。Plastic deformation is the ability of bend or deform before breaking. As engineers, we usually design materials so that they don’t deform under normal conditions. You don’t want your car to lean to the east after a strong west wind. 塑性變形就是在斷裂前彎曲或變形的能力。作為工程師，設(shè)計時通常要使材料在正常條件下不變形。沒有人愿意一陣強烈的西風(fēng)過后自己的汽車向東傾斜。However, sometimes we can take advantage of plastic deformation. The crumple zones in a car absorb energy by undergoing plastic deformat