第一课
Text:
It is known that metals are very important in our life. Metals have the greatest importance for industry. All machines and other engineering[7endVi5niEriN] constructions have metal[5metl] parts; some of them consist only of metal parts.
众所周知，金属在我们的生活中是非常重要的，金属对于工业而言是有巨大的重要性，所有机器和其他工程构造都有金属零部件，其中一些还只能由金属组成。
There are two large groups of metals:
1) Simple metal- more or less pure chemical elements[5elimEnt]
2) Alloys[5AlCi]- materials consisting of a simple metal combined with some other elements.
有两大类金属：（1）纯金属——或多或少的金属元素（2）合金——组成纯金属的原料结合其他元素。
About two thirds of all elements found in the earth are metals, but not all metals may be ud in industr
y. Tho metals which are ud in industry are called engineering metals. The most important engineering metal
is iron[5aiEn], which in the form of alloys with carbon[5kB:bEn] and other elements, finds greater u than any other metal. Metals consisting of iron combined with some other elements are known as ferrous[5ferEs] metals; all the other metals are called nonferrous[5nCn5ferEs] metals. The most important nonferrous metal are
copper[5kCpE], aluminum[E5lju:minEm], lead[li:d], zinc[ziNk], tin[tin], but all the metals are ud much
less than ferrous metals, becau the ferrous metals are much cheaper.
在地球上发现的所有元素中，大约三分之二是金属元素，但是并不是所有的金属都能够用于工业上。那些金属—我们用于工业上的金属—被称为工程金属，最重要的工程金属那就是铁，铁跟碳和其他元素结合形成合金的那些金属比其他金属发现有更大用途。铁与别的其他某些元素相结合而组成的金属称为黑色金属，此外所有其他金属都称为有色金属，最重要的有色金属是---铜，铝、铅、锌、锡。但是使
用这些有色金属比使用黑色金属要少的多，因为黑色金属便宜得多。
Engineering metals are ud in industry in the form of alloys becau the properties[5prCpEti] of alloys
are much better than the properties of pure[pjuE] metals. Only aluminum may be largely ud in the form of simple metal. Metals have such a great importance becau of their uful properties or their strength, hardness, and their plasticity[plAs5tisiti].
因为合金的特性比纯金属的好，所以工程金属以合金的形式用于工业，只有铝以纯金属的形式被广泛应用。金属因为具有强度、硬度和可塑性而发挥着特别重要的作用。
Different metals are produced in different ways, but almost all the metal are found in the forms of metal
ore[C:(r)] (iron ore, copper ore, etc[et cetra].)
以不同的方法生产不同的合金但是几乎所有的金属都是以金属矿的形式（铁矿、铜矿）被发现的。
The ore is a mineral[5minErEl] consistence of a metal combined with some impurities[im5pjuEriti]. In order to produce a metal from some metal ore, we must parate the impurities from the metal that is done
by metallurgy[me5tAlEdVi].
矿石是一种由金属与某些杂质相混合而组成的矿物质，为了用金属矿石来生产出一种金属，我们必须把杂质从金属矿中分离出去，那就要靠冶炼来实现。
2. Plastics and Other Materials
Text:
Plastics[5plAstik, plB:stik] have specific properties which may make them preferable[5prefErEbl] to traditional materials[mE5tIErIEl] for certain us. In comparison[kEm5pArisn] with metals, for example, plastics have both advantages and disadvantages. Metals tend to be corroded[kE5rEud] by
inorganic[7inC:5^Anik] acids[5AsId], such as sulphuric[sQl5fjuErik] acid and hydrochloric[7haidrEu5klC:rik] acid. Plastics tend to be resistant to the acids, but can have dissolved or deformed by solvent[5sClvEnt], such as carbon tetrachloride[7tetrE5klC:raid], which have the same carbon ba as the plastics. Color must be applied to the surface of metals, whereas it can be mixed in with plastics. Metals are more rigid[5ridVid] than most plastics while plastics are very light, with a specific[spi5sifik] gravity normally between 0.9 and 1.8.
Most plastics do not readily[5redili] conduct[5kCndQkt] heat or electricity[Ilek5trIsItI]. Plastics soften slowly and can easily be shaped[Feip] when they are soft.
塑料具有特殊的性能。对于某种用途而言，这些性能使得塑料比传统材料更为可取。例如，跟金属相比较，塑料既有优点也有缺点。金属易受到无机酸的腐蚀，如硫酸和盐酸，塑料能抵抗这些酸的腐蚀，但可被溶剂所洛解或引起变形，例如溶剂四氯化碳与塑料具有同样的碳基。颜色必定只能涂到金属的表面。而它可以跟塑料混合为一体。金属比大多数塑料刚性要好，而塑料则非常之轻，通常塑料密度在
0. 9-1. 8 之间。大多数塑料不易传热导电。塑料能缓慢软化，而当其还是在软的状态时，能容易成形。
It is their plasticity[plAs5tisiti] at certain temperatures[5temprItFE(r)] which gives plastics their main advantages over many other materials. It permits the large-scale production of molded[mEuld] articles, such
as containers, at an economic unit cost, where other materials require laborious[lE5bC:riEs] and often costly process involving cutting, shaping, machining, asmbly[E5mbli] and decoration.
冷的句子
在某一温度下塑料是处于塑性状态的，这就使塑料具备超过许多其他材料的主要优点。它容许大量生产单位成本低廉的模制式器件，例如，各种容器。于此，若用其他材料则需要大量劳力和往往需要很费钱的加工工艺，比如，切割、成形、加工、装配和装饰。
Plastics not only replace other materials. Their properties can be exploited[iks5plCit] for entirely[In5taIElI] new applications. For example, plastics heart valves[vAlv] and other human 'spare parts' have make possible many recent developments in surgery[5sE:dVEri].
布偶猫多少钱塑料不仅可以代替其他材料，而且它的特性能被开拓应用于全新领域，比如：随着最近外科手术的发展可能做成塑料的心脏瓣膜和其他人类的器官。
There is no single plastics material which is suitable for all applications. It is important that the most suitable plastics should be chon, and if necessary adapted[E5dApt], for each particular requirement. It is also important that the properties of the plastics chon should be exploited to the best advantage.
没有一种纯塑料材料适用于各个领域，如果有必要改进，对于每个有特殊要求的来说选择最合适的塑料是最重要的，被选择的塑料材料的特性被开拓得到更好的应用也是很重要的。
A plastics article may need to differ in design and appearance from a similar article made from another material such as metal or wood. This is due[] not only to the properties of plastics but also to the techniques[tek5ni:k] employed in fabricating[5fAbrikeit] plastics. The techniques include
injection[in5dVekFEn] molding[5mEuldiN], blow molding, compression molding, extrusion[eks5tru:VEn] and vacuum[5vAkjuEm] forming.
塑料器件可能需要用其他材料比如：与金属或木材制作的类似的器件从设计和外观上加以区别，这不仅是由于塑料性能不同的原因，也是由于制造塑料产品所用的技术不同所致，这些技术包括：注塑、模制、吹塑模制、压模、挤压和真空成型等。
3. Casting and Die-Casting Alloys
Text:
Casting[5kB:stiN] is one of the oldest metal working techniques known to man. Our country made metal castings as early as 2000 B.C., and the process ud then is not much different in principle[5prinsEpl] from the one ud today.
铸造是入类所掌握的最古老的金属加工技术之一。我国早在公元前2000 年就已把金属制成铸件，而所
使用的工艺从原理上和今天的工艺没有多大的区别。
8月29日
Foundry[5faundri] process consist of making molds, preparing and melting[melt] the metal,
pouring[pC:, pCE] the metal into the molds, and cleaning the castings. The product of the foundry is a casting, which may vary from a fraction[5frAkFEn] of a kilogram to veral hundred tons. It may also vary in composition[kCmpE5ziFEn] as practically all metals and alloys can be cast.
铸造工艺由制模、备料和金属熔炼，金属液浇注入模和铸件清砂等。铸造的产品是铸件，铸件可能从零点几公斤到几百吨范围变化。实际上所有金属在成分上也是变化的，而合金也可以铸造。
The metals most frequently cast are iron, steel, aluminum and so on. Of the, iron, becau of its low melting point, low price and ea of control, is outstanding for its suitability[9sjU:tE`bIlEtI] for casting and is ud far more than all the others.
最常铸造的金属是铸铁、钢、铝等等。这些金属中，铸铁，由于其低熔点，低价格和易控制，因而其铸造适应性是最突出的，而且使用也远比所有其他金属多。
Casting is a widely ud method of producing metal products, particularly tho which are
intricate[5intrikit]. Since molten materials will readily take the shape of the container into which they are poured, it is nearly as easy to cast fairly complex shapes as to produce simple forms.
由于熔融的物料能容易取得被浇注进去的容器（模型）的形状，因此，几乎像生产简单形状铸件那样颇为容易地铸造出复杂形状的铸件。
The place where the metals are cast is called a foundry. The most important of cast metals is cast iron which is made from pig iron by remelting it in a special melting furnace[5fE:nis] called a cupola[5kju:pElE].
铸造金属的地方叫做铸造车间。最重要的铸造金属是铸铁，铸铁是用生铁在一个特殊的熔炉—叫冲天炉的炉子中重新熔炼而制造出来的。
From the cupola, the cast iron flows into ladles[5leidl] of different size, and from the ladles it is poured into the molds.
从冲天炉中出来的铁水流入到不同规格的铁水包中，并从这些铁水包中被浇注到模型中。
生日祝福语大全The molds may be of two kinds: sand molds and metal molds. A metal mold consists of two hollow parts which should be joined for pouring the metal into it. The inside of this mold is covered with carb
on or graphite[5^rAfait] so that the metal could not stick[stik] to the wall of the form. When the metal has早恋的好处
solidified[sE5lidifai], the hollow parts are disjoined and the casting is taken out. There are also special molds in which large blocks of steel can be cast. The molds are usually made of cast iron and are called
ingot[5iN^Et] molds, which the blocks of steel produced by pouring the metal into the molds are called ingots and the process is called ingot casting.
模型有两种类型：砂模和金属模。金属模是由两个中空的部件组成，它们应被联结在一起以便将金属液浇入模箱中。这模腔的内侧是要涂以碳粉或石墨，因此金属不玫于粘贴到型腔壁上口当金属液凝固后，这中空的型箱部件被打开并取出铸件。也有一种特殊模型，在该模型中可以铸造大型钢块。这些模型通常用铸铁米制造，并被称为锭模。而浇注金属液到这些模子中生产出的钢块被称为钢锭。该工艺过程叫锭铸。
A relatively[5relEtIvlI] wide range of nonferrous alloys can be die-cast. The principal ba metals ud, in order to commercial importance, are zinc, aluminum, copper, magnesium[mA^5ni:zjEm], lead, and tin. The alloys may be further classified as low-temperature alloys and high-temperature all
oys; tho having a casting
temperature below 538C, such as zinc, tin, and lead, are in the low-temperature class. The low-temperature alloys have the advantages of lower cost of production and lower die-maintenance[5meintinEns] costs. As the casting temperature increas, alloy and other special steels in the best treated condition are required to resist the erosion[i5rEuVEn] and heat checking[5tFekiN] of die surface. The destructive[dis5trQktiv] effect of high temperatures on the dies has been the principal factor in retarding[ri5tB:d] the development of
high-temperature die castings.
相当大量的有色金属合金可以进行模铸}h 用的主要而基本的金属，按其在工业上应用的重要性的顺序是锌、铝、铜、锰、铅和锡。这些合金可以进一步进行分类为低温类合金和高温类合金。铸造温度低于538℃的那些合金，就像锌、锡和铅，是属于低温类合金。低温类合金具有低生产成本和低的模具维修费用等优点。当铸造温度上升时，需要最佳条件下处理过的合金钢和其他特种钢来抵抗腐蚀及防止模具表面的热裂纹。高温在模具上的损坏作用已经成为阻碍、延缓高温模铸发展的主要因素。
Another factor governing[5^QvEniN] the choice of alloy is the erosive[i5rEusiv] or solvent[5sClvEnt] action of the molten metal on the respective[ris5pektiv] machine parts and dies. This action increa
s with temperature, although it is more pronounced[pr5naunst] with some alloys than with others. Aluminum, in particular, has a destructive action on ferrous metals and, for this reason, is ldom melted in the machine, whereas the copper-ba alloys are never melted in the machine.
控制选择合金的另外一个因素就是熔融的金属在相关的机器零件上和模具上的腐蚀或溶解作用。
这种作用随着温度的升高而增加，甚至某些合金比另一些合金更为明显。特别是.铝对黑色金属有一种破坏作用，为此、铝几乎不熔混于机器零件中，而铜基合金是决不能熔混于机器构件中的。
4. Forging
Text:
Press forging[5fC:dViN] employs a slow squeezing[skwi:z] action in deforming[di:5fC:m] the plastic metal, as contrasted with the rapid-impact[5impAkt] blows of a hammer. The squeezing action is carried completely to the center of the part being presd, thoroughly working the entire ction[5kFEn]. The press are the vertical[5vE:tikEl] type and may be either mechanically[mi5kAnikEli] or
hydraulically[hai5drC:lik] operated. The mechanical press, which are faster operating and most co
mmonly ud, range in capacity[kE5pAsiti] from 500 to 1000 tons.
与锤锻的快速冲击不同，压力机锻造是用缓慢的挤压作用使塑性金属变形。这挤压作用完全被施加
到正在被压锻的零件中心位置上，直至彻底使整个工件得到加工。这些压力机都是立式的，可能是机械
操作也可能是液压操作的。机械操作压力机，操作速度比较快，使用最普遍，锻造能力从500 吨到10000 吨范围。
For small press forgings, clod impression dies are ud and only one stoke of the ram[rAm] is normally required to perform[pE5fC:m] the forging operation. The maximum[5mAksimEm] pressure is built up at the
end of the stroke which forces the metal into shape. Dies may be mounted[maunt] as parate units, or all the cavities may be put into single block. For small forgings, individual[7indi5vidjuEl] die unites are more convenient. There is some difference in the design of dies for different metals; copper-alloy forgings can be
对女朋友道歉的话made with less draft[drB:ft] than steel, conquently more complicated[5kCmplikeitid] shapes can be
produced. The alloys flow well in the die and are rapidly extruded
对于小型压力锻使用闭式锻模。通常要求锻锤仅一个冲程就完成锻造工艺。在冲程终端产生最大压力，该冲击压力迫使金属成形。模具可由各白独立的单元装配而成，即把所有个别模腔都放到一起，组
成整体。对于小型锻件使用分模装置更为方便。对于不同的金属在模具设计上有些区别.铜合金锻件比
钢件用较小的拔模斜度，因此可生产更加复杂形状的锻件。这些合金在该种模具中流动性好，而且能快
速挤压成形。
In the forging press, a greater proportion of the total work put into the machine is transmitted[trAnz5mit]
南京师范大学是属于985还是211to the metal than in a drop hammer press. Much of the impact of the drop hammer is absorbed by the machine
and foundation. Press reduction of the metal is faster, and the cost of operation is conquently lower. Most
press forgings are symmetrical[si5metrikEl] in shape, having surfaces which are quite smooth, and provide a clor tolerance[5tClErEns] than is obtained by a drop hammer. However, many parts of irregular[i5re^julE]
and complicated shapes can be forged more economically by drop forging. Forging press is often ud for
sizing operations on parts made by other forging process.
锻压机比落锤锻，输入到机器里的总能量中有更大部分的能量被传输到金属坯料上。落锤锻的冲击
能量被机器和基础吸收得较多(比起压力机来〕。金属上的压力衰减较快，因此生产成本比较低。大多数
手表品牌压力锻锻件形状、产生的表面都是对称的，而且表面非常光滑，并比落锤锻件的公差尺寸更加精确。然
而落锤锻造可以锻制形状复杂而不规则的锻件，因而较为经济。锻压机常常用来为其他锻造工艺所生产
的锻件进行整形和校正加工用。
In drop forging, a piece of metal, roughly[5rQflI] or approximately of the desired[di5zaiE] shape, is placed between die faces having the exact form of the finished piece, and forced to take thin form by drawing the dies together. Large ingots are now almost always forged with hydraulic press instead of with steam hammers,
since the work done by a press goes deeper. Further, the press can take a cooler ingot and can work to clor dimensions[di5menFEn]. The forging should be done at about the same temperature as rolling[5rEuliN]; the process improves the physical properties of the steel just as rolling does. In the final forging it is important not
to have the steel too hot, for overheated steel will have poor mechanical properties when cooled. In heating for forging, temperature is usually judges by the eye, but where large numbers of the same pattern are made, the
piece to be forged are heated in furnaces[5fE:nis] in which the temperature is indicated[5indikeit] by
