英语翻译Gears are often through-hardened by water or oil quenchi

英语翻译
Gears are often through-hardened by water or oil quenching in order to increase their resistance to wear.If a low degree of hardness is satisfactory,through-hardening is probably the most desirable heat treatment process to be used because of its inexpensiveness.
Case hardening is used for gear that require a hard surface and for which good accuracy is not necessary.The case hardening process results in gears that have much harder surfaces than cores.The advantage of case hardening is that,while the surface becomes hard and wear resistant,the toughness associated with the core remains.
Carburizing,cyaniding,and induction hardening are some of the processes commonly used to produce the case hardening effect.If great accuracy is required,the gear must be ground.For problems in which corrosion resistant surfaces are desirable,nitriding is the process most often used.However,nitriding is a relatively expensive process and is used only if other processes do not produce satisfactory results.Flame hardening and induction hardening are the methods usually used to harden larger gears.
To sum up this discussion of specially heat treated steels,the designer should make use of carbon or alloy steels without special heat treatment if the relatively low surface hardening of these untreated materials is satisfactory.As the hardness requirement increase,the heat treated steels should be considered,with the least expensive steel that satisfies the strength and wear requirements being chosen.
Nonferrous Metals Gears have been manufactured of nonmetallic materials for many years.Rawhide,nylon,various type of plastics,and so on,have been used.The advantages obtained by using these materials are quiet operation,internal lubrication,dampening of shock and vibration,and manufacturing economy.Their primary disadvantages are lower load carrying capacity and low heat conductivity,which results in heat distortion of the teeth and many result in a serious weakening of the gear teeth.
Recently thermoplastic resins,with glass-fiber reinforcement and a lubricant as additives,have been used as gear materials.The composite material has resulted in greater load carrying capacity,a reduced thermal expansion,greater wear resistance and fatigue endurance.
还漏了一段：Copper,zinc,aluminum,and titanium and titanium are materials used to obtain alloys that are useful gear materials.The copper alloys,known as bronzes,are perhaps the most widely used.They are useful in problems where corrosion resistance is important and also where large sliding velocities exist.Because of their ability to reduce friction and wear,they are usually used as the material for making the worm wheel in a worm gear set.Aluminum and zinc alloys are used to manufacture gears by the diecasting process.

Gears are often through-hardened by water or oil quenching in order to increase their resistance to wear.
齿轮通常都要经过在油介质或者水介质中的整体淬火,以达到增加耐磨性的目的.
If a low degree of hardness is satisfactory, through-hardening is probably the most desirable heat treatment process to be used because of its inexpensiveness.
如果对强度的要求较低,整体淬火可能是最适当的热处理方法,因为它的花费不高.
Case hardening is used for gear that require a hard surface and for which good accuracy is not necessary.
局部淬火使用在那些要求表面硬度较高的齿轮上,而且很难精确的达到.
The case hardening process results in gears that have much harder surfaces than cores.
局部淬火处理的齿轮具有比心部组织硬度高的表面硬度.
The advantage of case hardening is that, while the surface becomes hard and wear resistant, the toughness associated with the core remains.
局部淬火的优点是,表面具有高硬度和高耐磨性的同时,心部组织仍然保留着较高的韧性.

Carburizing, cyaniding, and induction hardening are some of the processes commonly used to produce the case hardening effect.
碳化、氰化、感应淬火是局部淬火中经常使用的处理方法.
If great accuracy is required, the gear must be ground.
如果对齿轮有精度要求,齿轮就必须经过磨削.
For problems in which corrosion resistant surfaces are desirable, nitriding is the process most often used. However, nitriding is a relatively expensive process and is used
only if other processes do not produce satisfactory results.
对于表面有抗腐蚀性要求的齿轮,渗氮是最常用的方法.然而,渗氮是一种相对较昂贵的热处理方法,并且通常只在其它热处理方法无法满足要求时才会使用.
Flame hardening and induction hardening are the methods usually used to harden larger gears.
火焰淬火和感应淬火是经常在大型齿轮上使用的热处理方法.
To sum up this discussion of specially heat treated steels, the designer should make use of carbon or alloy steels without special heat treatment if the relatively low surface
hardening of these untreated materials is satisfactory.
作为对特殊热处理钢材讨论的总结,设计师应当在未经热处理的低表面硬度材料能够满足使用要求时,使用不经过特殊热处理的碳钢或合金钢.
As the hardness requirement increase, the heat treated steels should be considered, with the least expensive steel that satisfies the strength and wear requirements being
chosen.
随着硬度要求的增加,应当考虑选择能够达到强度、耐磨性要求的最便宜的热处理钢材.
Nonferrous Metals Gears have been manufactured of nonmetallic materials for many years.
用非金属材料来制造齿轮已经有很长时间.
Rawhide, nylon, various type of plastics, and so on, have been used. The advantages obtained by using these materials are quiet operation, internal lubrication, dampening of
shock and vibration, and manufacturing economy.
生牛皮、尼龙、各种塑料、以及其它材料都得到应用.这些材料的优点有:静音操作、自润滑、减振性好、以及加工制造经济性好.
Their primary disadvantages are lower load carrying capacity and low heat conductivity, which results in heat distortion of the teeth and many result in a serious weakening of
the gear teeth.
它们的主要缺点是承载能力低和热传导性差,这些引起了轮齿的热变形和多种轮齿能力的降低.
Recently thermoplastic resins, with glass-fiber reinforcement and a lubricant as additives, have been used as gear materials.
最近,一种由玻璃纤维加固、并且带有自润滑剂的热塑性塑料,已经被用来做齿轮材料.
The composite material has resulted in greater load carrying capacity, a reduced thermal expansion, greater wear resistance and fatigue endurance.
合成材料具有更好的承载能力,更低的热膨胀系数,更好的耐磨性和更好的抗疲劳性能.
问题补充：Nonferrous Metals Nonmetallic Materials 麻烦翻译达人了!
补充这句是有点问题,Nonferrous Metals是有色金属.Nonmetallic Materials是非金属材料.用有色金属制非金属材料齿轮显然不对,我把那句翻成用非金属材料制非金属齿轮了.你对照下原文再.
问题补充：还漏了一段：Copper, zinc, aluminum, and titanium and titanium are materials used to obtain alloys that are useful gear materials.
铜、锌、铝和钛是经常使用在齿轮材料中的合金金属.
The copper alloys, known as bronzes, are perhaps the most widely used.
铜合金,比如青铜,可能是应用最广泛的合金.
They are useful in problems where corrosion resistance is important and also where large sliding velocities exist.
它们用在要求有较高耐腐蚀性的情况,以及有较大滑动速度存在时.
Because of their ability to reduce friction and wear, they are usually used as the material for making the worm wheel in a worm gear set.
因为具有减摩性和耐磨性的性能,它们通常用来制作涡轮减速器中的涡轮.
Aluminum and zinc alloys are used to manufacture gears by the diecasting process.
铝和锌的合金用来在模铸法中制造齿轮.