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机械设计制造及其自动化专业英语翻译.doc
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Unit 1 Metals
金属
The use of metals has always been a key
factor in the development of the social systems
of man。 Of the roughly 100 basic elements of
which all matter is composed, about half are
classified as metals. The distinction between a
metal and a nonmetal is not always clear
—
cut。
The most basic definition centers around the
type of bonding existing between the atoms of
the element, and around the characteristics of
certain of the electrons associated with these
atoms。 In a more practical way, however, a
metal can be defined as an element which has a
particular package of properties.
Metals are crystalline when in the solid
state and, with few exceptions (e 。 g 。
mercury), are solid at ambient temperatures.
They are good conductors of heat and
electricity and are opaque to light. They usually
have a comparatively high density 。 Many
metals are ductile—that is, their shape can be
changed permanently by the application of a
force without breaking。 The forces required to
cause this deformation and those required to
break or fracture a metal are comparatively
high , although , the fracture forces is not
nearly as high as would be expected from
simple consideration of the forces required to
tear apart the atoms of the metal.
One of the more significant of these
characteristics from our point of view is that of
crystallinity。 A crystalline solid is one in which
the constituent atoms are located in a regular
three-dimensional array as if they were located
at the corners of the squares of a
three—dimensional chessboard. The spacing of
the atoms in the array is of the same order as
the size of the atoms, the actual spacing being a
characteristic of the particular metal. The
directions of the axes of the array define the
orientation of the crystal in space. The metals
在人类社会的发展中,金属的应用起
着关键性的作用。构成物质的大约 100 种基
本元素中,大约有一半为金属。金属和非金
属之间的区别不是特别明显.最基本的定义集
中在元素原子间存在的连接形式和与这些原
子相关联的电子的某些特性.然而,在实际应
用中,可以将具有某些特性集合金属定义为
某种元素。
除了少数例外金属在常温下是固态
的。它们是热和电的良导体,不透光.它们往
往具有较高的密度。许多金属具有延展性,也
就是说,在不被破坏的情况下它们的形状在
外力的作用下可以发生变化。引起永久变形
所需的力和最终使金属断裂所需的力相当大,
尽管发生断裂所需的力远没有像所预期的撕
开金属原子所需的力那么大。
从我们的观点来看,在所有的特性中结
晶性是最重要的。结晶体是这样一种结构,
组成它的原子定位在规则的三维排列中,仿
佛位于三维棋盘的方格的角上。原子间距随
着原子大小呈规律性变化,原子间距是金属
的一种特性。三维排列的轴线决定了晶体在
空间中的方向。在工程实践中应用的金属由
大量的晶体组成,这些晶体称之为晶粒。在大
多数情况下,晶粒在空间中是自由排列的。
在原子范围内,晶粒之间相互接触紧密结合。
晶粒之间连接区域被称为晶界。
绝对纯净的金属从来也没有被生产出来
过。即使绝对纯净的金属可以生产出来,工程
师们对它们也并不会特别感兴趣,因为它们
很柔软、脆弱。实际应用中的金属往往都包
含着一定数量的一种或多种外来金属或非金
属元素,这些外来元素可能是有害的也可能
是有益的或者它们对某种特定的属性没有影
响.如果是有害的,这些外来元素被认为是杂
质。如果是有益的,它们被认为是合金元素。
在工程材料中往往被特意地加入一定数量的
合金元素。得到的物质被叫做合金。
金属和合金区别不大。金属这个词可以
包括工业用纯金属和它的合金。也许可以这
Commented [zhb1]: 以…为中心
Commented [zhb2]: 某种电子
Commented [zhb3]: adj.晶体的
Commented [zhb4]: 极少例外
Commented [zhb5]: 周围环境的
Commented [zhb6]: 不透明的
Commented [zhb7]: 柔软的;易延展的
Commented [zhb8]: 永久地,长期不变地
Commented [zhb9]: =far from,much less than
Commented [zhb10]: crystallinity [,kristə'linəti]
Commented [zhb11]: n. 棋盘
commonly used in engineering practice are
composed of a large number of such crystals,
called grains. In the most general case , the
crystals of the various grains are randomly
oriented in space。 The grains are everywhere in
intimate contact with one another and joined
together on an atomic scale 。 The region at
which they join is known as a grain boundary。
An absolutely pure metal (i 。 e. one
composed of only one type of atom) has never
been produced. Engineers would not be
particularly interested in such a metal even if it
were to be produced, because it would be soft
and weak 。 The metals used commercially
inevitably contain small amounts of one or
more foreign elements , either metallic or
nonmetallic. These foreign elements may be
detrimental, they may be beneficial, or they
may have no influence at all on a particular
property. If disadvantageous, the foreign
elements tend to be known as impurities 。 If
advantageous, they tend to be known as
alloying elements 。 Alloying elements are
commonly added deliberately in substantial
amounts in engineering materials. The result is
known as an alloy.
The distinction between the descriptors
“metal” and “alloy” is not clear-cut。 The term
“metal” may be used to encompass both a
commercially pure metal and its alloys 。
Perhaps it can be said that the more deliberately
an alloying addition has been made and the
larger the amount of the addition , the more
likely it is that the product will specifically be
called an alloy。 In any event, the chemical
composition of a metal or an alloy must be
known and controlled within certain limits if
consistent performance is to be achieved in
service。 Thus chemical composition has to be
taken into account when developing an
understanding of the factors which determine
the properties of metals and their alloys.
Of the 50 or so metallic elements, only a
few are produced and used in large quantities in
样说,合金元素越故意的被添加,被添加的
合金元素的量越大,那么生产出来的产品越
倾向于被称之为合金.不管怎样,如果想使一
种金属或合金在使用中表现出稳定一致的特
性,在其中添加何种化学成分,它的量多大
都应该在控制范围之内.因此,当想了解决定
金属和合金性质的因素时,应充分考虑它们的
化学组成。
在 50 种左右的金属元素里,工程实践中
只有少数金属被大量生产和使用.到目前为止
最重要的是铁,以它为基础构成了处处可见的
钢和铸铁。(主要由铁和碳构成的合金)它们
的重量占所有生产出来的金属重量的 98%.
在结构应用(也就是说,可以承受载荷的结
构)中居于其次位置的是铝、铜、镍和钛。
在所有的金属产量中,铝占 0.8%,铜占 0.7
%,剩下的占 0。5%。剩下的金属用于相对
特殊的用途。例如,镍合金主要用于抗磨损
和耐高温的用途,由于钛合金具有高强度和
低密度的综合特性,钛被广泛应用于航空工
业中。镍合钛有高成本和高质量的使用特性,
事实上,它们高的成本限制了它们的应用。
我们不能在这里讨论这些深奥的特性。
在合金材料被采用和应用于工程实际之前,
掌握其结构强度和它的综合性质就够了.举例
来说,它可以强度很高,并且有好的耐磨性;
它可以被例如拉伸加工,机械加工,或焊接等
特殊工艺来加工出来;它可以被循环利用;
它的成本和实用性是首要的。
Commented [zhb12]: 晶粒
Commented [zhb13]: 一般情况下
Commented [zhb14]: 也就是
Commented [zhb15]: 不可避免地
Commented [zhb16]: metallic [mi'tælik, me-]adj. 金属的,
含金属的
Commented [zhb17]: 有害的
Commented [zhb18]: 杂质
Commented [zhb19]: 合金元素
Commented [zhb20]: 故意地,蓄意地
Commented [zhb21]: adj. 大量的;实质的;内容充实的
substantial evidence:实(质)体证据|实质性证据|实质证据
substantial order:大宗订单|大订单
Commented [zhb22]: 无论如何,不管怎样
Commented [zhb23]: 一致的
engineering practice 。 The most important by
far is iron, on which are based the ubiquitous
steels and cast irons (basically alloys of iron
and carbon)。 They account for about 98% by
weight of all metals produced 。 Next in
importance for structural uses ( that is, for
structures that are expected to carry loads) are
aluminum, copper, nickel, and titanium。
Aluminum accounts for about 0.8 % by weight
of all metals produced , and copper about
0.7% , leaving only 0 。5% for all other metals.
As might be expected, the remainders are all
used in rather special applications. For
example, nickel alloys are used principally in
corrosion—and heat—resistant applications,
while titanium is used extensively in the
aerospace industry because its alloys have good
combinations of high strength and low density。
Both nickel and titanium are used in high-cost,
high-quality applications, and, indeed, it
is their high cost that tends to restrict their
application.
We cannot discuss these more esoteric
properties here. Suffice it to say that a whole
complex of properties in addition to structural
strength is required of an alloy before it will be
accepted into, and survive in , engineering
practice. It may, for example , have to be
strong and yet have reasonable corrosion
resistance ; it may have to be able to be
fabricated by a particular process such as deep
drawing, machining, or welding; it may have to
be readily recyclable ; and its cost and
availability may be of critical importance.
Unit 2 Selection of Construction Materials
工程材料的选择
There is not a great difference between “this"
steel and “that” steel ; all are very similar in
mechanical properties。 Selection must be made on
factors such as hardenability
,
price , and
availability, and not with the idea that “this" steel
can do something no other can do because it
在钢之间没有太大的区别;所有的钢在机
械性能方面都是近似的。它们的选取标准是诸
如脆硬性,价格,和可用性等。不仅仅是因为
这种钢含有 2%的合金元素另一种钢含有 1%
而使前者具有了后者没有的某些能力,或者是
某种钢具有神奇的名字。经过热处理后,任何
Commented [zhb24]: 铁
Commented [zhb25]: 普遍的,无处不在的
Commented [zhb26]: 铝
Commented [zhb27]: [tai'teiniəm, ti-]n. [化]钛(金属元素)
Commented [zhb28]: 相当
Commented [zhb29]: 主要地
Commented [zhb30]: 广泛地
Commented [zhb31]: adj. 秘传的;限于圈内人的;难懂
的
Esoteric Buddhism:密宗|密宗,特别是指西藏的喇嘛教。
Commented [zhb32]: 1. Suffice it to say that you love
me.
只要说你爱我就够了。
2.Suffice it to say that the gun was his.
只需说这枪是他的就够了。
Commented [zhb33]: 容易地
Commented [zhb34]: [,hɑ:dənə'biləti]
n. 可硬化性;淬硬性
Commented [zhb35]: [ə,veilə'biləti]
是产品在被调用时能够运行(即未处于失效或修复状态)
的概率。此量度考虑了产品的可靠性(多久会失效)和可
用性(多久能被修复)。
contains 2 percent instead of 1 percent of a certain
alloying element, or because it has a mysterious
(神秘的,不可思议的) name。 A tremendous
range of properties is available in any steel after
heat treatment ; this is particularly true of alloy
steels。
一种钢都具有大范围的特性;这种性质同样在
合金钢中存在.
Considerations in fabrication(制造)
The properties of the final part ( hardness,
strength , and machinability ) , rather than
properties required by forging, govern the selection
of material 。 The properties required for forging
have very little relation to the final properties of the
material; therefore, not much can be done to
improve its forgeability。 Higher—carbon steel is
difficult to forge 。 Large grain size is best if
subsequent heat treatment will refine the grain size.
关于加工的考虑
最后零件的特性(硬度、强度和可加工性)
而不是锻造特性决定了材料的选择.可锻性与
材料的最后特性联系不大;因此,提高金属的
可锻造性价值不大。高碳钢很难锻造。如果在
随后的热处理过程进行细化,大尺寸晶粒是最
好的。
Low—carbon, nickel—chromium(铬) steels
are just about as plastic at high temperature under
a single 520—ft
·lb(1
ft
·lb=1。35582J)
blow
as plain steels of similar carbon content。 Nickel
decreases forgeability of medium—carbon steels,
but has little effect on low-carbon steels.
Chromium seems to harden steel at forging
temperatures , but vanadium ( 钒 ) has no
discernible( 可 辨 别 的 ) effect; neither has the
method of manufacture any effect on high-carbon
steel。
在 高 温 下 低 碳 , 镍 铬 合 金 钢 在 受 到
520-ft
·lb
的冲击下表现出与相同碳含量普通
钢几乎同样的塑性。镍减少了中碳钢的可锻性,
但对低碳钢影响不大。铬在锻造温度下时使钢
硬化,但钒没有明显的效果;两种加工方法对
高碳钢没有影响。
Formability
The cold-formability of steel is a function(功
能) of its tensile strength combined with ductility.
The tensile strength and yield point must not be
high or too much work will be required in
bending( 弯 曲 ) ; likewise( 同 样 地 ), the steel
must have sufficient(充足的) ductility to flow
to the required shape without cracking. The force
required depends on the yield point, because
deformation starts in the plastic range above the
yield point of steel. Work—hardening also occurs
here , progressively( 日 益 增 多 地 ) stiffening
( 使 变 硬 ) the metal and causing difficulty,
particularly(独特的,显著的) in the low-carbon
steels.
成形
钢的冷成形是它的拉伸强度和延展性相结
合的结果。拉伸强度和屈服点不能太高否则在
发生弯曲时需要做很多工作;与之相类似,钢
应该有高延展性,使其在没有断裂的情况下成
形。加工力的大小取决于屈服点,因为钢在屈
服点之上才开始变形。与此同时,加工硬化也
同时发生,金属变得越来越硬,增加加工难度,
尤其在低碳钢中容易发生。
It is quite interesting in this connection(关于
这一点,就此而论) to discover that deep draws
在这方面,相当有趣的是你将发现有时可
通过一次快速加载完成大拉伸,但以缓慢的方
Commented [zhb36]: [mi'stiəriəs]
adj. 神秘的;不可思议的;难解的
Commented [zhb37]: adj. 极大的,巨大的;惊人的
Commented [zhb38]: [mə,ʃi:nə'biləti]
n. 切削性;机械加工性
Commented [zhb39]: 无论做什么都是 白费力,都改变不
了既定的现 实
Commented [zhb40]: 几乎,差不多
j
Commented [zhb41]: at a single blow
= at one blow
at a single blow:一下子|一举|一击
Commented [zhb42]:
can sometimes be made in one rapid operation that
could not possibly be done leisurely(缓慢地,从容
不迫地) in two or three。 If a draw is half made
and then stopped, it may be necessary to anneal
(退火) before proceeding, that is(换句话说),
if the piece is given time to work-harden 。 This
may not be a scientific statement, but it is actually
what seems to happen.
式两三次加载却不能实现。如果拉伸进行了一
半就停止了,那么在再加工之前应先退火,也
就是说工件是否有时间进行加工硬化。这不是
一种科学的叙述方法,但确实是发生了。
Internal stresses
Cold forming is done above the yield point in
the work—hardening range, so internal stresses can
be built up easily 。 Evidence of this is the
springback(回弹) as the work leaves the forming
operation and the warpage(翘曲,扭曲) in any
(任何一种) subsequent heat treatment。 Even a
simple washer might, by virtue of( 依靠) the
internal stresses resulting from punching ( 冲 压 )
and then flattening ( 整 平 ), warp ( 弯 曲 )
severely(严格地,激烈地) during heat treating。
(virtue n。德行, 美德, 贞操, 优点, 功效, 效
力, 英勇 believed in the virtue of prayer.相信祈祷
的力量
内应力
在高于屈服点的加工硬化区进行冷加工很
容易产生内应力。例如工件停止成型加工后会
发生回弹,在随后的热处理后,工件会发生翘
曲。即使是一个简单的垫圈,由于打孔和随后
的平整加工中产生内应力,也会在热处理中呈
现严重的翘曲。
When doubt exists as to(关于) whether internal
stresses will cause warpage, a piece can be checked
by heating it to about 1100 and then letting it cool.
If there are internal stresses, the piece is likely to
(可能) deform. Pieces that will warp severely
while being heated have been seen, yet (然而)
the heat-treater was expected to put them through
and bring them out better than they were in the first
place.
当是否内应力会引起翘曲的怀疑存在时,
可以通过将工件加工至 1100 然后进行冷却来
验证。如果存在内应力,工件会发生变形。经
过热处理的工件像我们看到的那样会发生严
重的翘曲,但是我们仍然希望工件被扔到热处
理炉中被处理,这样好过它存在内应力的状态.
Welding
The maximum carbon content of plain carbon
steel safe for welding without preheating or
subsequent heat treatment is 0.3%。 higher-carbon
steel is welded every day, but only with proper
preheating. There are two important factors: the
amount of heats that is put in ; the rate at which it
is removed.
焊接
不需要预热或之后进行热处理就能安全焊
接的最高碳含量为 0.3%。高碳钢通过合适的
预热通常也可焊接。有两点值得注意:吸收热
量的多少;移除速度。
Welding at a slower rate puts in more heat and
heats a large volume of metal, so the cooling rate
due to loss of heat to the base metal is decreased
(减少). A preheat will do the same thing。 For
example, sae4150 steel, preheated to 600 or 800,
低速焊接带来了更多的热量,这对金属的
大量体积进行了加热,所以冷却速度降低。预
热可以取得与之相当的效果.例如当 被预热
至 或 时可以很好的焊接.由于周围金属
的较高温度,当焊接弧移开焊接点后,冷却速
Commented [zhb43]: 由于,凭借
Commented [zhb44]: 热处理炉
Commented [zhb45]: 有望做某事;被期待做某事
Commented [zhb46]: put through 完成
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