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 时间:2018-06-30 04:39:50 贡献者:风吹酒醒1

导读:最新消息1-2 the benefits of civilization which we enjoy today are essentially due to the improved quality of products available to us . 文明的好处我们享受今天本质上是由于改进质量的产品 提供给我们。the improvement in

《材料成型及控制工程专业英语阅读》翻译.do
《材料成型及控制工程专业英语阅读》翻译.do

最新消息1-2 the benefits of civilization which we enjoy today are essentially due to the improved quality of products available to us . 文明的好处我们享受今天本质上是由于改进质量的产品 提供给我们。

the improvement in the quality of goods can be achieved with proper design that takes into consideration the functional requirement as well as its manufacturing aspects. 提高商品的质量可以达到与适当 的设计,考虑了功能要求以及其制造方面。

The design process that would take proper care of the manufacturing process as well would be the ideal one. This would ensure a better product being made available at an economical cost. 设计过程中,将采取适当的照顾的生产过程将是理想的一个。

这将确保更好的产品被使可得到一个经济成 本。

Manufacturing is involved in turning raw materials to finished products to be used for some purpose. 制 造业是参与将原材料到成品用于某些目的。

the present age there have been increasing demands on the product In performance by way of desirable exotic properties such as resistance to high temperatures, higher speeds and extra loads. 在现在的时代已经有越来越多的产品性能要求的理想的异国情调的性能如耐高温,更高的速度和额 外的负载These in turn would require a variety of new materials and its associated processing. 这些反过来需要各 种新材料及其相关的处理Also, exacting working conditions that are desired in the modern industrial operations make large demands on the manufacturing industry. 这些反过来需要各种新材料及其相关的处理。

同时,严格的 工作环境,需要在现代工业操作使大型制造业的需求. Further, the economics of the manufacturing operation is a very important consideration. 此外,经济学 的生产操作是一个非常重要的考虑因素。

To be viable in the modern environment, a product has to be competitively priced besides having the functional and aesthetic appeal. 是可行的在现代环境中,一个产品必须具 有价格竞争力除了具有功能性和审美情趣。

Therefore, it is necessary for the engineer to give a proper thought to various aspects of manufacturing. 因此,它是必要的让工程师给适当的认为制造业的各个方面。

Manufacturing processes is a very fundamental subject since it is of interest not only to mechanical engineers but also to those from practically every discipline of engineering. 制造过程是一个非常基本的主题,因 为它是有趣的,不仅机械工程师但同样从几乎每个学科的工程。

It is so because engineering as a whole is meant for providing various materials for human consumption. 它是如此因为工程作为一个整体是用来提供各种材料供 人类食用For various products such as plant machinery required for chemical, civil, electrical, electronic, textile, etc., the manufacturing process forms a vital ingredient. 对于不同的产品,如植物机械所需的化工、土木、电气、 电子、纺织等,生产过程形成一个至关重要的因素. A detailed understanding of the manufacturing processes is thus essential for every engineer. 详细了解 生产流程是必不可少的每个工程师这样。

This helps him appreciate the capabilities, advantages and also the limitations of the various manufacturing processes. 这有助于他欣赏能力、优势和局限性,各生产工序。

This in turn helps in the proper design of any product required for him. 这反过来有助于正确的设计的任何产品需要他。

Firstly, he would be able to assess the feasibility of manufacturing from his designs. 首先,他将能够评估制造的可 行性从他的设计。

He may also find out that there more than one process available for manufacturing a particular product and so he can make a proper choice of the process which would require the lowest manufacturing cost and would deliver the product of desired quality. 他可能也发现有超过一种过程用于生产特定的产品,所以他可以使 一个适当的选择过程,需要最低的制造成本和交付产品的期望质量。

He may also modify his design slightly to suit the particular manufacturing process he chooses. 也可以修改自己的设计稍微适应特定的制造过程他选择. Manufacturing is defined by the Merriam Webster online dictionary as to make into a product suitable to use. 制造业是梅里厄姆-韦伯斯特词典定义的在线词典使成一个产品适合使用。

Manufacturing remained as a craft till the first industrial revolution towards the end of the 18thcentury withlow volumes and single-piece productions. 制造业仍然作为一个工艺直到第一次工业革命对18世纪末的低 量和单件生产。

It required highly skilled craftsmen to individually produce the pieces and fit them when the assembly was required. 它需要高度熟练的工匠来单独生产件和适合他们的需要时组装。

This was a slow and expensive process , but in the absence of any machines, that was the only thing that was possible. 这是一个缓慢而昂贵的过程,但在缺乏任何机器,这是唯一可能的。

The availability of the steam engine and coal-fire furnaces made the invention of a number of steam-power driven machinery to greatly increase the manufacturing capacity. 蒸汽引擎的可用性和煤火熔炉使发明一种数量的全局驱动 机械制造能力大大增加。

A large number of inventions related to machine tools took place during this

period and continued into the 19thcentury. 大量的发明与机床发生在这一时期,持续到19世纪。

对十九世th纪末的发明电力和更好的工程材料、生产操作变得更有效率。

Towards the end of the 19 century with the invention of electricity and better engineering materials, manufacturing operations became more productive. The developments in the automobiles at the beginning of the 20 century are instrumental in the growth of a variety of manufacturing methods and practices. 对十九世纪末的发明电力和更好 的工程材料、生产操作变得更有效率。

汽车的发展在20世纪初期是工具性成长的各种生产方法和实践。

There are a large number of processes available to the engineer for manufacture. 有大量的流程 提供给工程师制造。

These processes can be broadly classified into four categories. 这些过程可以 大致分为四类 Casting processes forming processes fabrication processes material removal processesth铸造工艺成形过程工艺制备材料去除的过程These are the only processes where liquid metal is used.这些是唯一使用过程中,液态金属。

Casting is also one of the oldest known manufacturing processes. 铸 造是一个已知的最古老的制造过程。

它需要准备一个腔通常在耐火材料类似于最终对象是。

It required preparation of a cavity usually in a refractory material to resemble closely the final object to be made. 它需要准备一个腔通常在耐火材料类似于最终对象是。

Molten metal is poured into this refractory mould cavity and is allowed to solidify. 金属熔液注入这耐火模腔和允许巩固。

凝固后的对 象被删除从模具。

The object after solidification is removed from the mould. 凝固后的对象被删除从 模具。

Casting processes are universally used for manufacture of a wide variety of products. 铸 造过程是普遍用于制造各种各样的产品The principal process among these is sand casting where sand is used as the refractory material. 其中的主要过程是砂铸,砂用作耐火材料。

The process is equally suitable for the production of a very small batch as well as on a very large scale. 这个过程同样 适用于生产的一个非常小的批量以及一个非常 大尺度。

求 Some of the other casting processes for specialized needs are一些其他的铸造工艺专业需Shell-mould casting. 壳型铸造permanent-mould casting硬模铸造Precision-investment. 精密的 die-casting铸造压铸Plaster-mould casting. 石膏型铸造Centrifugal casting离心铸造投资castingThese are solid state manufacturing processes involving minimum amount of material wastage and faster production. 这些都是固态制造过程涉及最少的材料损耗和更快的生产。

In a forming process, the metal may be heated to a temperature, which is slightly below the solidus temperature and then a large force is applied such that the material flows and takes the desired shape. 在成形过程中, 金属可能被加热到一个温度,略低于固相线温度,然后一个大力量是应用的材料流和需要所需的形状。

The desired shape is controlled by means of a set of tools called dies, which may be completely closed or partially closed during manufacture. 所需的形状是通过控制的一组工具称为死亡,这可能是完全封闭 或部分封闭在制造。

These processes are normally used for large-scale production rates. These are generally economical and in many cases improve the mechanical properties too. 这些过程通常用于大 规模的生产速度。

这些通常是经济和在许多情况下改善机械性能太

Some of the metal forming processes are rolling ,extrusion ,drop forging ,wire drawing ,press forging ,sheet metal operations ,upset forging . 一些金属成形过程是轧制、挤压、落锤锻造,拉丝,按锻造、金属板操作、顶锻 These are secondary manufacturing processes where the starting raw materials are processed by any of the previous manufacturing processes described . 这些是二次制造过程的起始原料处理前面的任何制造过程描述。

It essentially, envolves joining pieces either permanently or temporarily so that they would perform the necessary function. 它从本质上讲,envolves加入碎片要么永久或暂时如此,他们将执行必要的功能。

The joining can be achieved by either or both of heat and pressure and/or a joining material. 的加入可以达到的一种或两种热量和 压力和/或加入材料。

Many of the steel structural constructions we see are first rolled and then joined together by a fabrication process.许多钢结构建筑,我们看到的是第一卷,然后连接在一起的工艺过程。

Some of the processes of interest in this category are gas welding, cold welding, electric arc welding, brazing, electric resistance welding, soldering, thermit welding. 一些感兴趣的过程都属于这一类气体焊接、冷焊接、电弧焊、钎焊、电阻焊、钎焊、铝热焊。

These are also secondary manufacturing processes where the additional unwanted material is removed in the form of chips from the blank material by a harder tool so as to obtain the final desired shape. 这些是二次制造工艺,额外的不必要的材料去除的形式的芯片从空白材料的困难,得到了工具最终想要的形状。

Material removal is normally the most expensive manufacturing process because more energy is consumed and also, a lot of waste material is generated in the process. 材料去除的通常是最昂贵的制造过程, 因为更多的能量消耗,同时,大量的废弃物产生的过程。

Still this is widely used because it delivers very good dimensional accuracy and good surface finish. 这仍是广泛使用的,因为它提供了非常良好的尺寸精 度和良好的表面光洁度。

also generates accurate contours. Material removal processes are also called It machining processes. 它还生成精确的轮廓。

材料去除过程也称为加工过程。

The various processes in this category are turning, grinding, drilling, broaching, shaping and planning, sowing, milling.各种流程在这个类别是车削、磨削、钻孔、扩孔、塑造和规划、播种、铣削。

All these manufacturing processes have been continuously developed so as obtain better products at a reduced cost. 所有这些制造工艺不断发展,获得更好的产品在降低成本。

Of particular interest is the development of computer and their effect on the manufacturing processes. 特别感兴趣的是计算机的发展及其影响制造过程。

The advent of computers has remarkable difference to most of the above manufacturing processes. 电脑的出现有 显著差异,最上面的制造过程。

They have contributed greatly to both automation and designing the process.他们作 出了巨大贡献两个自动化和设计过程 An important responsibility of the engineer is to choose a manufacturing process, which makes the required quality of a product to the specifications and at the lowest cost possible. 工程师的一个重要职责是选择一个以尽可能低 的成本制造出所需质量的产品的制造过程。

To fulfil both the conditions, one would have to do a break-even analysis of the various processes suitable for the production of the given object. 为了实现这两方面的目标,工程 师必须针对给定的目标对不同的制造过程做出适当的盈亏平衡分析, In the break-even analysis, two types of costs are considered: 在盈亏平衡分析中要考虑两方面的成本, Fixed cost relates to the initial investment on the equipment and tools required for the process. This cost would be constant and does not vary with quantity produced. 固定成本与制造过程相关联的所有设备和工具的投资是固 定成本,固定成本是固定的,不以产量而异,另一方面是可变成本,因实际产量不同而有差别。

Variable cost on the other hand, varies with the actual number of objects made. This takes into account the raw material required, energy consumed, labour cost, cost of special toolings, cost of tools used and other administrative overheads. requirement of these are directly proportional to the quantity produced. 可变成本计算进的所需原材料消耗、能量消耗劳动力成本、特殊工具成本和其他的行政管理费用,这些通常和 产量是成比例的 The same is shown in graphical form in Fig. 1.1.Normally, as the quantity of produced decreases. This is due to the fact that the fixed cost associated with the production remains constant. 相同的显示在图形化的形式在图1.1。

通常,作为生产的数量减少。

这是由于这样的事实,即固定成本与生产有关 保持不变。

If the engineer has to make a choice between two different processes for manufacturing the same component, he may first estimate the fixed costs and variable costs for both the processes and then plot the total cost curves for both as in Fig. 如果一位工程师必须制造同一产品的两种不同工艺做出选择, 他必须首先估计两种工艺的总的固 定成本和可变成本,然后绘制总成本曲线,The point where both these curves intersect is called the break-even point. 这些曲线的交点叫做盈亏平衡点,It implies that the first process will be economical if the quantity of

production is less than that of the break-even point, that while beyond it the second process is economical.这意味 着如果产量比盈亏平衡点低第一种工艺是经济的,如果产量超过该点那么,第二种是经济的。

The break-even quantity, n, can also be obtained by equating the total costs in both the processes. 保本量,n,也可以把获得的总成本的过程。

This would give a positive value when a fixed and variable costs are lower than the other process, then the latter process is always uneconomical whatever may be the production quantity.这将给一个积极的价值当一个固定和 可变成本是低于其他过程,那么后者过程总是不经济的任何可能的生产数量。

The manufacturing of a component may involve more than one process or more variants of the same process. 制 造一个组件可能会涉及到多个进程或更多的变种相同的过程。

In the first case, it is necessary to consider the costs of all the processes while computing the total cost for each of the processes在第一种情况下,有必要考虑成 本的所有工序,同时计算总成本的每个过程 The deformation caused in a material is of two types, elastic and plastic. 在材料中引起的变形可以分为 两种类型,弹性变形和塑性变形Elastic deformation is that part of the deformed material which when the applied load is removed, would spring back to its normal shape. 弹性变形是指材料上所施加的载荷被移除后能恢复原来 形状的变形。

Plastic deformation is on the other hand , permanently set in a material and cannot be regained.,塑性 变形是另一方面,永久的不可回复的变形。

Tensile strength is measured by a tensile test carried out on a universal testing machine. 拉应力通过在一 种通用的测试机上实施的测试实验测得。

This involves the preparation of a test specimen as per standard shown in Fig.2.1包括图2.1所示作为标准的样本的准备。

The standard specimen can be either rectangular or cylindrical. 样 本可以是矩形的也可以是圆柱形的,Rectangular is generally used for plate-type specimens. 矩形的通常被用于板 式样本, Care has to be taken to see that the specimen is prepared in a way such that the surface is smooth and without any deep cracks or nicks.必须保证样本的表面是平滑的、没有任何裂缝或刻痕。

The tensile testing machine consists of a heavy test frame with a lower fixed beam, and an upper crosshead which is the moving beam used to apply the tensile force on the specimen as shown in Fig2.2. 拉伸试验机 由一个带有一个较低的横梁和一个在样本上施加拉力的联杆器的巨大测试机架组成。

The specimen is mounted between two grips ,one attached to the fixed beam and the other attached to the crosshead. 样本只能装在两个抓 爪间,一个附加在横梁上,另一个附加在连杆器上,An extensometer is attached to the specimen to measure the elongation of the test specimen as the force is being applied . 当施加负载时一个伸长仪被加到样品上来测量测试 样本的伸长量。

Then a uniformly increasing tensile load is applied on the specimen. 然后一个均匀增加的载荷被施 加到样本上,The movement of the crosshead relative to the fixed beam generates strain within the specimen and a corresponding load. 连杆器和横梁的相对运动在样本上形成张力和一个相应的载荷。

As the load increases, the specimen initially gets elastically elongated. As can be noted from Fig2.1, the central portion is smaller compared to the gripping section. 随着载荷的增加,样本首先产生弹性变形,如图2.1所示,相比之下中心部分比引人瞩目的 区域要小。

On further elongation, the specimen starts necking at some point (within the gauge marks) when the material goes beyond the elastic range. 继续加载荷,当材料超过弹性范围样本在一些点处会变窄。

The reduced width of he specimen would be reduced under the force of the load and finally develop fractures when the test is completed. 在载荷的作用下样本减少的宽度会减少,当测试结束时样本会最终断裂。

If the necking does not happen within the gauge marks, the test need to be repeated with a different specimen. 如果断裂没有在标准刻度 内发生,测试需要用不同的样本重新做。

During the test , a record is maintained of the load and the corresponding elongation. 在测试中应持续记载载荷和相应的伸长量。

The stresses and strains are calculated from the above data and plotted in a diagram as shown in Fig.2.3.应力和张力可以由上述数据计算并被绘制成图2.3所示图标。

It can be observed that there is a limit up to which the applied stress is directly proportional to the induced strain. 可以观察到所施加的力和诱发的张力直接成比例,This is represented by the linear portion of the curve up to A which is termed as the proportional limit. 这一点可以有延伸到A点的线性曲线表示,A点叫做比例极限。

The end of this linear portion is the yield point of the material above which the material starts plastically by the bow-shaped portion of the cube. 线性部分的终点叫做屈服点,在屈服点以上材料开始弹性变形,拱形曲线表明 在弹性范围内,应力与张力之间没有明显的线性关系。

Finally, the specimen breaks when the force of the applied load goes beyond the limit that can be borne by the material.最终样本在所施加载荷超过材料所能承受的极限时发 生断裂。

The proportional limit is often difficult to calculate, therefore, two practical measurements, offset yield strength (OYS) and yield by extension under load (EUL), were developed to approximate the proportional limit. 比例 极限通常难以计算, 因此, 两种特殊的测量方法, 补偿屈服应力和延伸屈服被发展用于近似代替比例极限。

Point B represents the offset yield strength and is found by constructing a line XB parallel to the curve in the elastic

region. 点b通过在弹性范围内构造一条平行线x-b表示补偿屈服应力。

Line X-B is offset a strain amount O-X that is typically 0.2% of the guage length. X-B线补偿了拉伸长度O-X所表示的的应力的0.2%。

Point C represents the yield strength by extension under load and is found by constructing a vertical line Y-C. 点C通过在在载荷下的拉伸量并构 成曲线Y-C来表示屈服应力。

Line Y-C is offset a strain amount O-Y that is typically 0.5% of the guage length. Y-C线补 偿拉伸长度O-Y所表示的应力的0.5%。

The ultimate tensile strength , or peak stress, is represented by the point C. 最终的拉伸应力或顶点应力由点D表示。

Total elongation, which includes both elastic and plastic deformation, is the amount of uniaxial strain at fracture and is depicted as strain at the point Z.Per cent elongation at break is determined by removing the fractured specimen from the grips; 总伸长量,包括弹性变形和塑性变形,是断裂时 的单轴应变, 由Z点的应变表示。

fitting the broken ends together and measuring the distance between guage marks. 断裂点的单一伸长量由移动抓爪间的断裂样本决定。

Per cent elongation at break reports the amount of plastic deformation only. The guage length used for measurement is reported with the result.他和断裂点相配合来测量定 位刻度间的距离。

Similar tests can also be conducted for measuring the compression and shear strength. Hardness is a very important property since the manufacturing depends on it to a great extent. 硬度是非常 重要的性能,因为制造在很大程度上依赖与他, Hardness is the resistance offered by a material indentation. Moh 的scale of hardness is based on ten standard minerals as shown in Table 2.1. 硬度是材料对压力的抵抗力莫氏硬度 测量基于表2.1所示的十种标准矿物。

can be measured by the indentation made by a harder material. . 通常可以 It 由一种坚硬的材料造成的压痕来测量。

The indentation made depends upon the applied load, the sharpness of the indentor and the time for which the applied load is maintained压痕取决于所施加负载, 压痕的清晰度取决于负载应 用的时间。

There are a number of indentation tests to measure the hardness of a material normally. 同场还有许 多硬度测试方法来测量材料的硬度。

These usually involve a ball, a cone or a pyramid of a harder material which is indented into the material under test with a specified load. 这些测试方法通常是在指定的负载下把由坚硬的材料 制成的团块、 圆锥体或球椎体压入材料,The permanent indentation thus made is measured to give an indication of the hardness on the given scale for the tests.偶测量这些所产生的永久压痕来在测试给定的范围内对材料的硬度 做出指示。

Some precautions that need to be taken during the use of Brinell test are that the surface of the material whose hardness is being tested should be smooth and even, and there is enough material underneath the indentation and on all sides to give a proper value for the indentation. 一些预防措施,需要在使用布氏硬度试验是材料的表面 的硬度测试应光滑、均匀,并有足够的材料在压痕和在各方面给予适当的缩进值。

The Brinell hardness of steel is roughly related to the tensile strength of the material utilizing the following empirical relationship for plain carbon steels. 这个布氏硬度的钢大致与抗拉强度的材料利用以下实证关 系碳素钢。

It may be noted that these conversions are only approximate. 可以指出,这些转换只是近似。

Also, the actual relationship depends upon the chemical composition of the alloy as well as the heat treatment process. 同时, 实际的关系取决于合金的化学成分和热处理工艺。

Comparative values for these are given in Table 2.2. 比较值在 表2.2中给出了这些。

There are number of indentation tests to measure the hardness of a material normally. 通常还有许多硬度测试方法来测量材料的硬度These usually involve a ball, a cone or a pyramid of a harder material which is indented into the material under test with a specified load. The permanent indentation thus made is measured to give an indication of the hardness on the given scale for the tests这些测试方法通常是在指定 的负载下把由坚硬的材料制成的团块、圆锥体或球椎体压入材料,偶测量这些所产生的永久压痕来在测试给定 的范围内对材料的硬度做出指示。

The most commonly used tests are the following: 最常用的测试有以下几种 Brinell hardness test where a sphere (usually of diameter 10+0.01mm) made of steel or tungsten Carbide is indented with a gradually applied load at right angles to the specimen surface and the indentation diameter made on the specimen measured.验Then the Brinell hardness number, BHN is given by布氏强度是通过施加90°的压力在 用钢或钨化物做成的试件表面,然后测试试件上压痕直接来获得的 BHN=2p/D[D-√D2-d2] Where P is the applied load in kg, D is the diameter of the ball in mm, and d is the diameter of the indentation in mm其中,P是所施加的载荷千克, D是球的直径,毫米,和d为压痕 的直径,用mm表示

The applied load P is based on the hardness of the specimen material being tested. 所施加的载荷P是根据被测试 的样品材料硬度 Some precautions that need to be taken during the use of Brinell tests are that the surface of the material whose hardness is being tested should be smooth and even, and there is enough material underneath the indentation and on all sides to give a proper value for the indentation. 贝氏硬度的测试使用过程中要采取某些预 防措施,需要被测试的材料的硬度,表面应是光滑和均匀的,并且压痕下应该有足够的材料,下面的压痕和各 侧面,应该有一个适当的压痕值 The Brinell hardness of steel is roughly related to the tensile strength of the material utilizing thefollow ing empirical relationship for plain carbon steels. 普通钢和布氏硬度相关的抗拉强度可利用下面的经验公式来 表达 Tensile strength (in MPa = 3.55 x BHN when BHN<≤175 Tensile strength (in MPa)= 3.38 x BHN when BHN > 175 It may be noted that these conversions are only approximate. Also, the actual relationship depends upon the chemical composition of the alloy as well as the heat treatment process. Comparative values for these are given in Table 2.2. 可能需要注意的是这些转化都是相互的。

当然,实际关系依赖于合金化学成分和热处理工艺,这些 比较值如2.2所示 Rockwell tests utilize the principle that the depth of penetration of the indentor is proportional to the material hardness. 洛氏硬度运用的规律是压痕仪的渗透深度和材料的硬度成正比的 Thus, the hardness measurement is faster compared to other methods. 这样的硬度的测试和其他的方法相比快得多In the Rockwell test, a sphero-conical diamond cone of 120angle and a spherical apex of 0.2-mm radius is used to make the indentation, and the depth of the indentation, t, is used as a criterion to calculate the hardness number.洛氏硬度 的测试是用一个成120°的金刚石球锥和直径为0.2mm的球形顶总来压痕, 压痕深度t则用来作为计算硬度的一个 标准The Rockwell hardness number (R) is given by 洛氏硬度值可以从下列式得出 R = 100-500 t Depending on the load used for indentation there are a number of scales, A, B, C, etc., available in Rockwell tests. 依据压痕所加负载,适用于洛氏硬度测试的一系列数据范围可为A.B,C,等,These are used for materials with different hardnesses. 这些都是用于不同硬度的材料In the Rockwell B test. a steel ball of 0.06t5-inch diameter is used with a load of l00kg. 在洛氏B测试。

0.06t5英寸直径的钢球用l00kg负载This test is normally used for low and medium carbon steels. It should not be used for materials whose hardness is above RB l00. 这种测试 通常用于低,中碳钢。

但它不允许测试硬度以上的材料For materials with hardness above this value, Rockwell C test (30 RB corresponds to O RC) is more generally used. 对于材料的硬度高于此值,通常用于洛氏C测试(30 RB 对应到O RC),This is the fastest way of measuring hardness because the hardness can directly be read from the scale on the Rockwell tester. 这是最快的方式,因为硬度可从洛氏硬度计上的刻度直接读取硬度测量值。

Besides, there are other tests available such as Vicker's and Knoop hardness tests to measure hardness over a small area. In Vickers hardness test, a square base pyramid diamond indentor having 136°betweern the opposite faces is used. 此外,在某些小范围内可以使用维氏硬度努氏硬度在维克硬度测试中,与136°的的相反面三角锥 压痕仪一个平面方面内进行测试, The Vickers hardness number (VHN) is calculated by 维氏硬度值通过下式计算 VHN = 1.854L/D2 where L is the applied load in kg which is normally about 30 kg, though provision up to 120kg would Be available on the testing machine for harder materials, and D is the measured average diagonal of the indentation in mm其中L是所施 加的负载(公斤),通常是约30公斤,虽然对较硬的材料增加到120千克中对测试仪来说也是可行的,D 表示压痕对角线长度,用mm 表示 The scleroscope uses a different principle to measure the hardness which is based on the rebound height of a ball from the specimen. 肖式硬度计用一个不同的规则来测试材料硬度, 它是基于从试件弹回的小球的高度 来的 The harder the material, the higher is the height to which the ball rebounds. 材料的硬度越高,小球弹回的 高度也越高 Because of these hardness tests being conducted under arbitrary conditions, it is difficult to have any proper correlation between the different scales An approximate relationship of these hardness values is presented in Table 2.2 merely as a guideline 由于这些 硬度是在变化的条件下进行导出的, 不同尺度之间很难有任何适当的 关联性 The hardness values are normally represented as 200 BHN, 32Rc ,etc. Representaive values of some commonly used materials are presented in Table2.3硬度值通常表示为200 BHN,32Rc,等。

一些常用的代表性材 料硬度值如Table2.3 It is the measure of the amount of plastic deformation a material can undergo under tensile forces without fracture. In quantitative terms it is normally measured as the ratio of elongation of the material at fracture during the tensile test to the original length, expressed as a percentage. 延展性是对一种材料在拉力作用下不断裂所能

承受的弹性变形量的估量。

材料到断裂时的伸长量与原始长度的比例定量地表示成一种百分关系 The final value of elongation obtained during the tensile test immediately after the fracture could be taken as the ductility . 材料在拉伸试验中突然断裂时的拉伸估计值可以被做延展性 Since the elongation is dependent upon the gauge length chosen for the tensile test, the length needs to be specified along with the elongation values. Alternatively, it may also be expressed as the ratio of reduction in cross-sectional area in the fractured specimen to the original cross-section area. 因为伸长量取决于拉伸试验选择的标距长度,所以标距长 度须由伸长估计值规定 This is independent of the gauge length and hence is a more convenient measure for ductility. it二者选一 的,他也可以被表示为断裂样本的代表性区域与原始区域的延伸比率is also termed as the ability of a material to be drawn into wires since only ductile materials can be drawn into continuous wires without breaking in between. Typical values of ductilities are given in Table 2.4 for engineering materials. 也可以表示为材料被拉成线状的能力,因为只有延展 性材料才可以在不断裂的情况下被拉成线状 Besides the tensile tests, special forms of ductility testing based on the desired application can be done using the bend test and cupping tests for the purpose of sheet metal forming applications. More details of these tests can be found in literature. 除了拉伸试验外,特殊的基于所期望功能的实验可以用弯曲试验,杯状测试来 测试薄片材料的延展性 Brittleness is the property opposite to that of ductility. 脆性属性延性相反 2.1.4 Toughness This is the property which signifies the amount of energy absorbed by a material at the time of fracture under impact loading. 这是表示材料在冲击载荷下断裂时吸收能量数量的性能。

In short, it is the capacity to take impact load. 简言之,就是抵抗冲击载荷的能力。

It can be considered as the total area under the stress-strain curve since it is an indication of the amount of work done on the material without causing fracture. 韧性可以被看 做应力应变曲线下方的整体区域, 因为韧性是不引起断裂情况下作用与材料的功的总量。

Thus toughness can be considered as a parameter consisting of both strength and ductility.因此韧性可以被看做是应力和延展性的组成 参数。

Toughness of a material is measured by means of impact tests, where a notched bar prepared as per standard from the test material, is held in a vice and a weight is allowed to swing from a known height in such a way that it hits the notched bar in its path and breaks it. Since the material has absorbed some amount of energy during its fracture, the swinging mass loses part of its energy and therefore will not be able to reach the same height from where it started, as shown in Fig. 2.4.一种材料的韧性可以通过冲击试验来测得,在这个实验中,一个有测试材 料做成的有凹口的棒被老虎钳夹住,然后一个重物沿棒的轨道从已知高度摆下并击断他,因为材料在断裂时吸 收了能量,所以摆动物块失去了一部分能量故而无法达到他的起始高度。

如图所示。

2.4。

The loss in height(h) multiplied by the weight represents the energy absorbed by the specimen during fracture, which can be directly measured from the indicator on the tester.高度损失随样品吸收的能量的增加而增加,这可以在实验中用显示计 直接测量。

In the Charpy impact test, the specimen is held between two grips whereas in the lzod impact test the specimen is held at one end like a cantilever as represented in Fig.2.4. 在卡氏冲击实验中,样品被夹住两端,而在艾氏冲击 实验中, 样品被如图2.4所示像悬臂梁一样只被夹住一端。

standard test specimens used in the Izod and Charpy The impact tests are made of bars with a square cross section of 10 mm , the details of which are given in Fig.2.5.在布 氏与艾氏冲击试验中标准样品被制成具有 10mm正方形横截面的棒状具体细节如图 2.5给出。

The impact resistance is dependent upon the material composition as well as the heat treatment process given to it. The annealed materials normally would have better toughness than the corresponding normalized or quenched specimens.冲击抗力取决于材料的成分及所用的热处理工艺。

煅烧过的样品通常比对应的未煅烧淬火样品具有 更好韧性Coarse-grained structures would tend to have higher ductility compared to fine grain structure and consequently better toughness.粗晶端口通常比细晶断口结构具有更高的塑性和韧性。

Typical values of impact resistance measured from these tests are given in Table 2.5 below.从这些测试中测得的耐冲击性的典型值在下面 的表2.5中给出。

2.2 RERROUS MATERIALS We use a variety of metals, non-metals and their compounds in our daily life.我们使用各种金属、非金属及其化 合物在我们的日常生活中。

For example, a typical automobile may contain the following materials例如,一个典 型的汽车可能含有下列材料 Based on their origin and composition these materials may be broadly classified as shown in Fig.2.6.根据其来源 和组成,这些材料大致可归类为图2.6所示。

Among these, ferrous materials are by far, used most extensively because of their better and varied mechanical

properties and lower costs.其中,有色金属材料,到目前为止,最广泛地使用,因为其更好的和多样化的机械性 能和较低的成本。

2.2.1 Iron The basic source of all iron and steels is iron ore, which is an oxide of iron mixed with alumina, silica, phosphorous,manganese,sulphur and other materials.所有的铁和钢的基本来源是铁矿石,铁矿石是铁,铝,硅, 磷,锰,硫和其他的材料的氧化物。

Major iron ores are haematite and magnetite, which contain about 55% iron. 铁矿石主要是赤铁矿和磁铁矿,其中包含约55%的铁。

Pig iron, the principal base material for all steel furnaces, is the product of the blast furnace. 所有钢炉的最主要 的基础材料:生铁,是高炉的产物。

Pig iron contains(about 4%)carbon,(1%) silicon, (1%) manganese and smaller percentages of phosphorous and sulphur.生铁含有碳(约4%),1%的硅,锰和更小的百分比(1%)的磷和硫。

Pig iron is hard and brittle. It lacks the great strength, ductility and resistance to shock that steel possesses.生铁是 硬而脆的。

它没有很大的强度,塑性和抗冲击性。

Absolute pure iron is very difficult to obtain. In this state, it is a soft and highly plastic metal of a light grey colour having a specific weight of 7.86. The mechanical properties of commercial grade iron containing 0.1 to 0.2% impurities are.The only application that can be found for pure iron is in making of magnets in view of its high permeability.纯铁是很难获得的。

在此情形下,这是一个软质、高塑性的浅灰色的,具有7.86的比重的金属。

包含0.1到0.2%的杂质的商业用铁的力学性能。

唯一应用是鉴于它的高磁导率将其制成磁铁。

Otherwise, the extensive use of iron is in the form of its large number of alloys. Iron can be alloyedwith many elements. Alloys of iron and carbon are most widely used in engineering. They contain certain amounts of silicon, manganese, chromium, nickel and other elements. 另外, 铁也被广泛的以合金的形式投入使用, 铁可以同许多元素形成合金, 铁和碳的合金广泛用于工程领域。

铁碳合金含有一定量的硅,锰,铬,镍等元素。

Before proceeding to study the properties of ferrous alloys, a brief survey of the structure of materials would be beneficial for better understanding of the subject.在开始学习铁合金的性能之前,对材料结构的简略了解对理 解这些是有益处的。

2.2.2 Structure of Materials A definite geometrical order is observed in all the crystalline solids in the internal arrangement of atoms and their constituent particles. 可以观察到在晶体中所有原子及其组成的粒子的排列都具有一定的几何股则 These particles are located in a solid in such a manner that in the aggregate,they form the space or crystal lattice. 所有离 子都聚集在晶体中形成晶格或晶粒间隙 The space lattice of any solid is made of a number of conjugate unit cells inside which the atoms are arranged in a definite order. 任何固体的晶格都是由许多原子按一定次序排列的晶胞组成。

The definite arrangement of atoms in three dimensions which remains the same throughout the material is called a unit cell. This is the simplest volume which completely fills space,and has all the characteristics of the whole crystal.材料中存在的原子的一定 的三维排列就叫做晶胞,这是晶体中最简单的体积单元,并且具有晶体的所有特点。

Figure 2.7 shows a unit cell of the type called body-centred cubic (BCC) cell wherein atoms are present at all eight corners of the cube and at the body centre. 表图2.7表示一个原子存在于8个顶点及立方体中心的体心立方晶胞 类型。

This unit cell is not in isolation but surrounded on all sides by similar unit cells. As a result,the corner atoms are shared by all of the adjacent eight unit cells. 这个晶胞并非孤立而是被四周同样的晶胞包围着的,这样以来, 顶点处的原子就被邻近的8个晶胞共有。

Similarly, there are other arrangements such as face-centred cubic (FCC) and hexagonally close packed (HCP).同 样也存在于其它的晶胞如面心立方和密排立方 Iron at room temperature has the structure of BCC with an edge radius (lattice constant) of 0.24824 nm. 铁在室温下具有BCC结构的边缘半径(晶格常数)为0.24824 nm。

周 Pure metals are seldom used as compared to the alloys which are commonly used.与常用的合金相比纯金 属很少使用。

Alloys are metallic solids,complex in composition,and are formed as a result of solidification of molten liquid of two or more elements. 合金是金属的固体,它成分复杂,是两种或多种元素的熔融液体凝固的结果。

An alloy normally has properties which are a compromise between those of its constituents and sometimes has properties, superior to and quite different from those of its constituents.一种合金一般是组成它的成分之间的中 和,同时有时他也具有与其成分不同的属性 Alloys are formed by combining different metals in a number of ways. 合金一般是由不同的金属通过多 种方式结合成的。

One predominant form is a solid solution. 一种重要的形式是固体的溶解。

A solution is formed when solute atoms are dissolved in solvent atoms. 这种溶解是溶质原子溶解在溶剂中。

Similar to the familiar liquid solutions, it is also feasible to have a solid solution. 就像液体的溶解一样,固体的溶解也是可行的If a solution is allowed to freeze without separating the

constituents, a solid solution would result. 如果溶解可以使成分在不分离的情况下凝固,则固体溶解是可行的In a solid solution, the materials are present only as a mixture but not as chemical compounds. 在固溶体中,材料仅 能作为混合物存在,而不能做化合物The solid solutions are the essential parts of an alloy.固溶体是合金的重要的 部分 There are generally two types of solid solutions; one called the interstitial and the other, the substitutional. 固溶体通常情况下有两种形式; 一种叫间质, 另一种是置换。

an interstitial solid solution, the solute atom would In be positioned in the interstitial sites (empty space between the adjacent atoms) formed by the solvent atoms. 间 质性的固体溶解, 溶质原子将被定位在通过溶剂原子形成的间隙位置 (空的相邻原子之间的空间) It is possible 。

only when the solvent atom is much larger compared to the solute atom. 这只有在溶剂原子比溶质原子大的多的 情况下才可能。

Also, the extent of solubility depends on the difference in the atomic sizes. 另外,溶解的程度依 赖于原子尺寸的差异For example, carbon would form an interstitial solid solution with iron.例如,碳将与铁形成 间隙固溶体.Carbon atomic radius = 0.0 750 nm Iron atomic radius = 0.1241 nm Iron changes to an FCC structure above 720℃. 铁在720℃以上变成FCC。

If a carbon atom is placed in the FCC structure of iron at 730℃,the iron atoms are to be displaced by a distance of 0.0430 nm. 如果铁的面心立方 中的碳原子在730℃时被替换, 那么距离 0.0430 nm范围的铁原子也将会被替换。

a carbon atom is to be located If in BCC structure at room temperature, the iron atoms are to be displaced by a distance of about 0.111 nm. 若室温 下的体心立方中的碳原子被替换, 那么距离0.111 nm范围内的铁原子也将被替换。

Because of this distortion, iron at room temperature would only dissolve a maximum of 0.006% carbon. 因为这种变形室温下铁中多溶解0.006% 的碳,But above 7300C, up to 2% carbon can be dissolved.但是温度超过7300℃时,可以溶解2%的碳。

In the substitutional solid solutions, the solute atoms would replace the solvent atoms在置换固溶体中, 溶 质原子会替换溶剂原子。

This is possible only if both the atoms are similar in size and also in nature.这只在原子的 尺寸相同时成立 Diffusion is the process of movement of atoms from one location of higher concentration to another of lower concentration or to a vacant place. 扩散是原子从高浓度向低浓度或空隙位子处移动的过程。

Diffusion of atoms would be faster at high temperatures and in liqujd phase. 在高温和液相中扩散进行的更快些。

It is also a time-dependent phenomenon as the atoms have to physically travel from one site to the other.这也是原子从一处向另一处运动的时间现象。

In an alloy system, the component metals may combine within a certain temperature range to form two homogeneous coexisting portions. 在一定的温度下,合金的成分金属会生成两种共存的均匀部分Each of these portions may have different compositions and con-sequently different properties. 每一部分都有不同的合成物和 不同的性能These homogeneous physically different portions of the alloy systems are termed as phase. 这些合金 中的不同的均匀部分被定义为相。

A phase may be defined as any part of achemical system that possesses distinctive physical characteristics. 每一种相都可以定义为具有独特的性能的化学系统。

An alloy may consist of one phase or a combination of different phases. In liquid state, alloys are entirely homogeneous and from the physical point of view, constitute a single phase.合金可以由一种相或多个相组成。

在液态下,合金在物理学方面看来是完全一 样的,并构成一种单一形态的相 Nonhomogeneity may appear when an alloy is transformed from liquid to solid state, i.e., several solid phases may be formed.当合金由液态转变为固态时可能出现不均性,也可能形成多种不同的固相 Sometimes, when the amount of alloyed metal that can be dissolved in a solid solution is exceeded, the 'parent' metal and the alloyed metal will together form an intermetallic compound. 有时当固溶体中克溶解的合 金过量时,固相金属会与合金金属一起形成金属间化合物。

Though the intermetal-lic compounds are shown with a chemical symbol such as Fe3C, they are not like the chemical compounds such as C02 which are actually formed by a chemical reaction.虽然金属间化合物可以用如Fe3C一样的化学符号来表示, 但他们并不是如C02一样的由化 学反应生成化合物。

the present case it is only an atomic arrangement. Intermetallic compounds are usually very In hard. 这只是一种原子间的排列,金属间化合物一般非常坚硬 Even if only a small amount of intermetal-lic compound is present, the alloy will combine the toughness of a solid solution with the hardness of the intermetallic compound.只要有少量的金属间化合物, 合金就能将固溶体的韧性 与金属间化合物的硬度综合一起。

Eutectic Composition In certain alloy systems, alloying causes a lowering of the melting points and at a certain composition, called the eutectic composition for the system, the melting point is the lowest. 共融成分在一 定的合金系中,合金在一定的成分下会引起熔点的降低,这种合金组成叫共溶成分,这时的熔点是最低的。

For example the alloy of 62% tin and 38% lead has a melting point of 183℃ whereas leact melts at 327 and tin melts at 232℃ as in Fig. 2.8. 例如锑与锂的合金熔点是183℃, 而锂的熔点是327℃。

low melting point of this The alloy called solder enables delicate parts of metal to be soldered without damage by heat .这种合金的低熔点使得 软焊条能够在不产生热的情况下进行精细焊接。

Equilibrium Diagrams A cooling curve is drawn with temperature against time for a given metal or alloy showing the phases present in it. 平衡相图: 绘制金属或合金的温度随时间变化的冷却曲线来表示其相变化。

But for an alloy system containing various compositions of the constituent elements, it is necessary to draw a phase diagram or equilibrium diagram wherein the phases found at various temperatures an d coim- positions are plotted in a single chart. 但是对含有多种组成元素的合金系来说,绘制不 同温度下的相交和相组成物曲线所构成的相图或平行相图是必要的。

The equi- librium diagrams are thus the generalized results of investigations into the solidification process and the structural and phase transformation of the given alloy system.这样的平衡相图是对给定合金系统的凝固过程和组成及相交的调直的产物。

These diagrams enable to determine the tem-perature levels at the beginning and end of m elting for alloys of various compositions, the structure ofalloys for various temperatures under equilib-rium conditions and also the transformation the alloys are subjected to during cooling and heating. 这种相图能使我们确定不同组成的合金的 开始熔化与结束熔化的温度曲线。

平衡条件下不同温度时的合金组织及加热与冷却合金转变。

Equilibrium conditions mean that sufficient time would be available for the changes of- phases to take place平衡意味着相变有 足够的时间来进行。

An equilibrium diagram is plotted by laying off the percentage concentrations of the two components along the abscissa and the temperature along the ordinate. Any point on. the diagram refers to a definite com-position of the alloy at a particular temperature, as shown in Fig. 2.8.平衡相图绘制沿横坐标的两个组成部分,沿纵坐标的温 度的百分比浓度。

上的任意点。

图指的是在特定温度下的合金的一个确定的位置 Nucleation and Grain Growth when the free energy of a parent phase is reduced by means of temperature or pressure then there is a driving force leading to crystallization.成核和晶粒生长的母相的自由能是通过温度或 压力减少时,则有导致结晶的驱动力。

For example, at the melting point, the thermal fluctuations result in the formation of tiny particles (containing only a few atoms) of the product phase within the parent volume. 例如,在 熔点,热的波动导致的微小粒子的形成(包含只有几个原子的)父卷内的产物相Such a tiny particle has an interface that separates It from the parer of atoms across its interface.这样一个微小的颗粒具有一个接口, 它在其 界面的原子削皮 The process of formation of the first stable tiny particles is called nucleation.被调用的过程中形成的第一个稳 定的微小颗粒的成核。

The process of increase in the sizes of these particles is called grain growth.增加的过程中,这些颗粒的大小被 称为晶粒生长。

The grain size in the product phase depends on the relative rates of nucleation and growth. Each nucleating particle becomes a grain in the final product. 在产品相的晶粒尺寸取决于成核和生长的相对速率。

每个成核粒子 成为在最终产品中的晶粒。

So a high nucleation rate means a larger number of grains, Also when this is combined with a low growth rate, more time is available for further nucleation to take place in the parent phase that lies between slowly growing particles. 因此,高的成核率意味着更大的晶粒数,此外,当结合了一个低增长率,更 多的时间是可进一步核发生在缓慢增长之间的颗粒,在于母相。

So a combination of a high nucleation rate and a low growth rate yields a fine grain size. On the other hand, a low nucleation rate combined with a high growth rate yields a coarse grain size. 所以,高成核率和低增长率的组合产生晶粒细小,另一方面,低成核率与较高的增长 速度相结合,产生粗晶粒尺寸。

a high nucleation rate and a relatively slow growth rateand,ultimately, yields a fine grain size. A representationOfgrains is presented in Fig. 2.9. In this figure, eachsquare represents a unit cell 一个高形核率和效率和增长较为缓慢,最终产生一个细粒度。

一个表示谷物呈现在图。

2.9。

在这个图中,每个 方块都代表一个单元 Coarse grain steels are not as strong and have ahigher tendency towards distortion than those havingfine grain, although they offer better machinability andgreater depth hardening qualities. 粗晶粒钢不强和具有更高的 倾向比那些拥有细晶粒变形,尽管他们提供更好的可加工性和大深度硬化的品质。

Fine grained steelsare tougher and more ductile and do not distort or crackduring heat treatment.细粒钢变得更坚强,更有韧性,不扭曲或裂纹在 热处理。

As has been mentioned earlier, iron in its purest form isnot used as an engineering material because it lacks tensilestrength and hardness.正如前面提到的,铁以最纯粹的形式不是用作工程材料,因为它缺乏抗拉强度 和硬度。

But when alloyed with other elements, the properties can be controlled greatly.但当合金与其他元素,属 性可以控制大大Out of thevarious alloying elements, carbon is the most important because it is found in all the alloys of iron.出各种合金元素,碳是最重要的,因为它存在于所有的合金的铁 .The maximum amount of carbon that can be alloyed with iron is 6.67%.最大的碳的数量可以糅合着 铁是6.67%。

Alloys Containing up to 2% carbonare termed steels and above 2% are called cast irons.合金含有2%碳 被称为钢和2%以上被称为铸铁铸造Besides carbon, these alloys also contain small amounts ofmanganese, sulphur, phosphorousand silicon.除了碳,这些合金也含有少量的锰、硫、磷和硅These are generally considered as

impurities and hence need tobe controlled.这些通常被认为是杂质,因此需要控制 However, in certain conditions some of these such as silicon are treated as alloying elements.然而,在特定条件下这些硅等被视为合金元素。

The properties of steel are influenced significantly by an increase in carbon content (Fig. 2.10) with a result that钢的性能影响显著的增加碳含量(图2.10)与结果, (i) tensile strength is increased.(1)的拉伸强度增加 (ii) greater hardness is obtained,(2)获得更大的硬度 (iii) ductility is decreased. and(3)韧性降低。

和 (iv) weldability is decreased(4)可焊性降低 A point however to be noted is that in all steels even when alloyed with other alloyingelements,themaximum hardness that can be obtained after heat treatment processes is basically a function of the carbon content一个点 但是要注意的是,在所有钢即使合金与其他合金元素,最大硬度,可以获得在热处理过程基本上是一个函数的碳 含量There are three classes of steels (plain carbon): 有三种类型的钢(纯碳): Low up to 0.30%低0.30% Medium 0.30 to 0.60%C中0.30到0.60% c High 0.60 to1.7% C高0.60 to1.7% C This is generally known as 'soft' or mild steel.这是通常被称为“软”或软钢。

It isused where ductility and softness are important and high tensile strength is not required. 它是用在哪里的韧性和柔软性是重要的和高的 抗拉强度不是必需的These are tough but not resistant to wear,sincethese are soft, can be very easily formed and later can be carburized to increase the hardness and wearresistance这些都是艰难的,但不耐磨损,因为这些都是 软的,可以很容易地形成,后来可以渗碳的增加硬度和耐磨性 Low-carbon steels are used for such operations as spinning, cold bending, rivetting, swaging, etc.低碳 钢材用于这样的操作作为纺丝、冷弯、铆接、模锻等。

These are not responsive to normal heat treatment but for case hardening.这些不是响应正常热处理但对表面硬化。

They form the largest percentage of steel produced, being the cheapest engineering material 他们形成了钢铁产量的比例最大,是最便宜的工程材料Products such as screws, nails, nuts, bolts, washers, wire fences, light and heavy structural members, machine parts forged parts can be made from low-carbon steel产品, 如螺丝、 钉子、 螺丝、 螺帽、 垫圈,铁丝栅栏,轻型和重型结构成员,机器零件锻造部件可以由低碳钢,It is also used for tin plate and automobile body sheet. it is available in form of sheets, squares, rounds, plates,and wires.它也用 于锡板和汽车车身钢板。

它可以在形式的床单,广场、轮,盘子,和电线。

They are less ductile but harder and have greater tensile strength than low-carbonsteels.他们是更少的延 性但困难和有更大的拉伸强度比低碳钢材。

They also have better machining qualities and are more responsive to heat treatment.他们也有更好的加工品质和 更适应热处理These are widely used in the industry. medium carbon steels are used for making shafts, connectingrods,spindles, rail axles, gears, turbine bucket wheels, steering arms and other machine parts requiring mediumstrength and wear-resisting surfaces. 这些是广泛应用于工业。

中碳钢用于制造轴、连杆、主轴、铁路轴、齿轮、汽轮机叶片轮、转向臂和其他机器 零件要求中等强度和耐磨的表面。

They have higher tensile strength and are harder than other plain- carbon steels.他们有较高的抗拉强 度和要比其他平原——碳素结构钢。

They also readily respond to heat treatment. These are used for making hand tools such as wrenches ,chisels punches. files, cutting tools such as drills, wood-working tools, railroad wheels, rails, bars for reinforcing,ofconcrete, etc.他们也容易应对热处理。

这些是用来做手工具,如扳手、凿子一拳。

文件,切 削刀具,如钻头、木工工具、铁路车轮,rails,酒吧加固,混凝土等 In addition to carbon, the plain carbon steels contain smallquantities of other elements more as impurities. They affect the properties in the following way.除了碳,碳素钢含有少量其他元素作为杂质多。

他们影 响属性以如下的方式。

Iron forms iron sulphide, FES with sulphur which solidifies along, the grain boundaries making the steel brittle and lowers hot working properties such as ductility铁形式铁硫化物,与硫磺这凝固的切身沿着晶界, 使钢的脆性,降低热加工性能如延性If equal amount of manganese is preset inthe steel then manganese sulphide, MnS, forms and the harmful effects of sulphur are reduced. 如果等量的锰是预设在钢然后锰硫化物,MnS,形式和 硫的有害影响是降低了。

it is geber-ally recommended that manganese should at least be 3 times that of sulphur. 这是格柏盟友建议锰至少应该是3倍的硫磺 However very small quantities(0.075 to 0.15%) that are generally present contribute to the better machinability. 然而非常少量(0.15%到0.075),通常呈现为更好的切削加工性能。

Phosphorous in small amounts increases the strength and hardness of steels. most of the steels contain a very small percentage of about 0.05% phosphorous.磷在少量增加钢的强度和硬度。

大多数的钢含

有一个很小的比例约0.05%的磷。

Silicon in very small amounts of the order of less than 0.2% do not have any effect.硅在非常少量的订单不到0.2%没有任何效果。

When it is between 0.2 and 0.4%,it raises the elastic limit and ultimate strength of the steel without greatly reducing the ductility.More than this percentage it reduces the ductility.当它是介于0.2和0.4%,它提高了弹性极限和极限强度的钢没有大大减少了延性。

超过这个比例降低延 性The main limitations of plain carbon steels are主要的限制是碳素钢 Low hardenability低淬透性 Loss of hardness during tempering失去硬度在回火 Low strength at elevated temperature高温强度较低 Lower resistance to corrosion and oxidation较低的抗腐蚀和氧化 Alloy steel have been specifically developed to overcome these limitations and they are discussed later in this chapter.合金钢有专门设计来克服这些局限,他们是在本章后面讨论。

王Silicon Silicon in very small amounts of the order of less than 0.2o2o do not have any effect. When it iS between 0.2 and 0.4%, it raises the elastic limit and ultimate strength of the steel without greatly reducing the ductility. More than this percentage it reduces the ductility. ~ \ The main limitations of plain carbon steels are . Low hardenability . Loss of hardness during tempering . Low strength at elevated temperature . Lower resistance to corrosion and oxidation Alloy steels have been specifically developed to overcome these limitations and they are discussed laterin this chapter. 2.2.4 Iron-Carbon Equilibrium Diagram 铁碳合金平衡相图 The structural form of pure iron at room temperature is called ferrite α- iron. 纯铁在室温下形成的组织叫铁 素体或α铁。

Ferrite is soft and ductile.铁素体软而可塑Since ferrite has a body-centred cubic structure, the inter-atomic spaces are small and pronouncedly oblate, and cannot readily accommodate even a small carbon atom.因为铁素体具有体心立方结构,原子间距很小而无法容纳很小的碳原子 Therefore, solubility of carbon in ferrite is very low, of the order of 0.006% at room temperature. The maximum carbon content in ferrite is 0.05% at 723 ℃ addition to carbon, 所 以 室 温 下 碳 在 铁 中 的 溶 解 度 很 低 , 最 高 才 达 到 0.006% 723℃时a certain amount of silicon, manganese and phosphorous may be found in ferrite.铁素体中的最大碳含量 为0.05%,除了碳外,铁素体也含有一定量的硅、锰和磷 The face-centred modification of iron is called austenite or γ-iron.面心立方结构的铁称作奥氏体或γ铁。

is It the stable form of pure iron at temperatures between 910℃ and 1400℃. 这些是纯铁在910℃至1400℃温度间的 稳定形式 At its stable temperature austenite is soft and ductile and consequently, is well suited for manufacturing processes. 在稳定温度下奥氏体柔软,可塑,因此很适用于制造过程 The face-centred cubic structure of iron has larger inter-atomic spacing than in ferrite. 铁的面心立方结构比铁素 体具有更大的中心原子间距 Even so, in FCC structure the interstices are barely large enough to accommodate carbon atoms, and lattice strains are produced.尽管如此,面心立方结构的间隙也难以大到足够容纳碳原子As a result, not all the interstitial sites can be filled at any on time. The maxrmum solubility is only 2% of carbon at 1130℃并且能形成晶格,结果是间隙任意时刻都能形成,1130℃时,碳的最大溶解度只有2% Above 1400℃, austenite is no longer the most stable form of iron, and the crystal structure changes back to a body-centred cubic phase called 8-iron. 超过1400℃时,奥氏体不再是最稳定的形式,晶格结构也变为叫做8铁 的体心立方结构 This is the same phase as the α-iron except for its temperature range.这是除了温度范围外与α铁相似的相 The solubility of carbon in 8-ferrite is small, but it is appreciably larger than in α-ferrite, 碳在8铁中的溶解度很小, 但也 稍大于α铁,because of higher temperature. The maximum solubility of carbon in 8-iron is 0.1% at1490℃这是因为 温度高的关系1490℃时,8铁中碳的最高溶解度为0.1% In iron-carbon alloys, carbon in excess of the solubility limit must form a second phase, which is called iron carbide or cementite. 在铁碳合金中,超过溶解极限的碳形成第二种相,这种相叫渗碳体足有

Fe3C 的化学成分Iron carbide has the chemical composition of Fe3C. This does not mean that iron carbide forms molecules of Fe3C, but simply that the crystal lattice contains iron and carbon atoms in a three-to-one ratio. 这并不意 味着铁的碳化物形成Fe3C分子,而是晶格间隙中含有 比例为3比1的铁与碳原子The compound Fe3C has an orthorhombic unit cell with twelve iron atoms and four carbon atoms per cell, and thus has a carbon content of 6.67% Fe3C化合物含有几个铁原子与4个碳原子形成 正 交晶胞,这样碳含量就达到了6.67% As compared to austenite and ferrite, cementite being an inter- metallic compound, is very hard and brittle.The presence of iron carbide with ferrite in steel greatly increases the strength of steel.相比于奥氏体与铁素体, 渗碳体是一种非常坚硬易碎的金属间化合物, 铁的碳化物和铁比例极大的增强了 钢的强度 The iron-carbon equilibrium diagram is shown in Fig. 2.11. The solidification of the liquid iron and carbon melt begins along the liquidus denoted in the figure by ABCD. 在图2.11所示的铁 - 碳平衡状态图的液态铁和碳 的熔体的凝固开始沿图中的表示由ABCD的液相。

Above the liquidus, the alloy is in a liquid state and is a homogeneous system. Along the liquidus AB, the crystals of the solid solution of carbon in y-iron are separated from the liquid.以上的液相线,该合金是在液体状态,是一种均匀的系统。

沿液相线AB,γ-铁中的碳的固溶体 的晶体从液体中分离。

Crystals of austenite are separated from the liquid along the line BC with the compositions ranging from 0.18% to 2.02%. The complete solidification of these alloys proceeds along the solidus line HJCE. 奥氏体的晶体沿 直线BC为0.18%至2.02%的组合物从液体中分离的完整的这些合金的凝固所得沿固相线HJCEAlloys containing 0.18 to 2.0% carbon become solid along, the solidus HJE. Those with 2.0% to 4.3% carbon are completely solidified on line .EC. 含有0.18〜2.0%的碳成为沿,固相线HJE的固体的合金...2.0%至4.3%的碳被完全凝固线EC的最后部 的液相的凝固,The solidification of the last portion of the liquid phase, enriched in carbon to4.3%takes along this line All this liquid is completely solidified at1130℃;same time crystals of austenite containing 2% carbon and cementite containing 6.67% carbon get separated from it.沿着这条线,所有这一切液体完全凝固at1130℃;奥氏体 含有2%的碳和渗碳体的同时晶体含有6.67%的碳开始浏览脱离它凝固的液相中的最后部分 The Solidification of alloys containing 4.3% to 6.67% carbon begins along line CD, with the separation of primary cementite from the melt.富集个碳to4.3%以含有4.3%至6.67%的碳的合金的凝固开始沿直线CD,与分离主渗碳体从熔体中。

At the lower temperatures, the eutectoid reaction, i.e., formation of two solids from a single solid occurs at a temperature of 7230C.在较低的温度下,发生共析反应,即,从一个单一的固体形成的两种固体7230C的温 度下 This is called the eutectoid temperature and the com position at which this reaction occurs (0.80% C) is called the eutectoid com position. The reaction may be shown as follows:这被称为共析温度和com该反应发生的位置, 在该位置(0.80%C)被称为共析的COM的位置。

该反应可如下所示 Solidl<~b~~ Solid2+Solid3 Austenite 0.77% C) b~~ Ferrite (0.02% C) + Cementite (6.67% C) In the reaction, the simultaneous formation of ferrite and cementite from austenite results at the temperature of 723℃and composition of 0.80% carbon. 在反应中,同时形成铁素体和渗碳体从奥氏体的查询结 果在723℃的温度和0.80%的碳的组合物。

There are nearly 12% of iron carbide and slightly more than 88% of ferrite in the resulting mixture. 有近12%的碳化铁和略多于88%的铁素体中的所得到的混合物。

Since the ferrite and cementite are formed simultaneously,they are intimately mixed. Characteristically,the mixture is lamellar, i.e, it is composed of alternate layers of ferrite and cementite. 同时形成铁素体和渗碳体,它们是紧密地混合, 典型地,该混合物的层片,即,它是由铁素体和渗碳体的交替的层This micro-structure is called pearlite which is very important in iron and steel technology, because it can be formed in almost all steels by means of suitable heat treatments.这种微结构被称为珠光体钢铁技术中这是非常重要的,因为通过合适的热处理可以在几乎所有的钢 形成 The alloy containing 0.80% of carbon is called the eutectoid steel. Upon cooling the eutectoid steel below 723℃, all of the austenite is transformed into pearlite. Alloys with less than 0.80% C are called hypo-eutectoid steels and those with higher composition are called hyper-eutectoid steels. 含0.80%的碳的合金称为过共析钢, 冷却后低于723℃时,所有的奥氏体转变为珠光体的共析钢,具有小于0.80%C的合金称为亚共析钢材和组合物 具有较高的称为超共析钢。

When hyper-eutectoid steels are cooled below line SE, the austenite decomposes with the separation of cementite. Since this cementite contains 6.67%C, the carbon concentration in the remaining austenite changes continuously along the line SE until the eutectoid composition of 0.80% C.当超过共析钢中冷却至低于线SE时,奥 氏体的分解与渗碳体的分离。

由于该渗碳体含有6.67%C,0.80%C,直到共析组合物中的碳浓度的残余奥氏体 的变化连续地沿行SE

 
 

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