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1、As has been mentioned earlier, iron in its purest form isnot used as an engineering material because itlacks 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
2、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
3、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 conditionssome of these such as silicon are treated as
4、 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 aresult 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.
5、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,themaximumhardness 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
6、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% cHigh 0.60 to1.7% C高0.60 to1.7% CThis is generally known as soft or mild steel.这是通常被称为“软”或软钢。It isused where ductility andsoftness are important and high tensile strength
7、 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
8、 as spinning, cold bending, rivetting, swaging, etc.低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 forcase 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 s
9、crews, 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 usedfor tin plate and automobile body sheet. it is available in form of sheets, squares, rounds
10、, 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
11、 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 te
12、nsile strength and are harder than other plain- carbon steels.他们有较高的抗拉强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 reinforcin
13、g,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,
14、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 ar
15、e 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
16、。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 andultimate strength of the steel without greatly reducing the ductility.
