金属热处理简介

热处理Heat-treatment

Heat treatment is thermal cycling involving one or more reheating and cooling after forging the purpose of obtaining desired microstructure and mechanical properties in a forging.

热处理是锻后进行一次或多次重新加热和冷却操作的热循环过程，以便使锻件获得所需的显微组织和力学性能。

Few forgings of the types are produced without some form of heat treatment.Untreated forgings are usually relatively low carbon steel parts for noncritical applications or are parts intended for further hot mechanical work and subsequent heat treatment.The chemical compositions of the steel, the size and shape of the product,and the properties desired are important factors in determining which of the following production cycles to use.

有些类型的锻件生产没有某些形式的热处理。未经过处理的锻件通常是非关键结构的相对低碳钢部件或用于进一步热机运作和热处理的部件。钢的化学成分，产品的形状和尺寸和所需的性能是决定如何选择下一个生产周期的重要因素。

The object of heat treating metals is to impart certain desired physical properties to the metal or to eliminate undesirable structural conditions which may occur in the processing or fabrication of the material. In the application of any heat treatment it is desirable that the “previous history” or structural condition of the material be known so that a method of treatment can be prescribed to produce the desired result. In the absence of information as to the previous processing, a microscopic study of the structure is desirable to determine the correct procedure to be followed.

金属热处理的目的是使金属获得所需的物理性能或者消除那些在材料生产和加工中可能出现的不好的组织结构。在任何热处理的应用中，需要知道材料的“既往史”或组织结构，以便一种处理方法可以按规定产生期望的结果。在对以往加工信息缺乏时，结构的微观研究对接下来正确途径的确定是必不可少的。

The commercial heat treatments in common use are spheroidizing, normalizing, annealing, hardening,and tempering. They involve the heating of the material to certain predetermined temperatures,” soaking” or holding at the temperature, and cooling at a prescribed rate in air, liquids, or retarding media.The above treatment may be briefly defined as follows:

常用的工业化热处理有球化、正火、退火、淬火和回火。热处理包括把材料加热到某一预定温度，在此温度下进行“均热”或保温，在空气、液体或保温介质中按规定的速度冷却。以上热处理可以简单定义如下：

Spheroidizing----prolonged heating of iron-based alloys at a temperature slightly below the critical temperature range followed by relatively slow cooling,usually in air. Small objects of high carbon steel are more rapidly spheroidized by prolonged heating to temperatures alternately within and slightly below the critical temperature range.The purpose of this heat treatment is to produce a globular condition of the carbide.

球化----在空气中，对铁基合金在略低于临界温度范围内长时间加热，再以相对缓慢的速度冷却。在临界温度内及略低于此温度之间长时间交替加热，高碳钢小件将更迅速被球化。这种热处理的目的是为了获得球状的碳化物。

Normalizing-----heating iron-base alloys to temperatures approximately 50℃above the critical temperature range followed by cooling in air to below the range.The purpose is to put metal structure in a normal condition by removing all internal strains and stresses given to the metal during some processing operation.

正火----铁基合金加热到约高于临界温度范围50℃，然后在空气中冷却至低于此范围。正火的目的是去除金属内部在一些加工工程中产生的应力和应变，而使金属结构在一个正常的状态。

Annealing is a comprehensive term applied to heat treatments which may be used to remove stresses;induce softness;alter ductility, toughness, electrical, magnetic,or other physical properties,refine the crystalline structure; remove gases;or produce a microstructure. The temperature of the treatment and the rate of cooling depend upon the object of the treatment and the composition of the material being heat treated.

退火是一个概括性的术语，是用于去除应变，降低硬度，改变延展性、韧性、导电性、磁性或者其他物理性能，改善晶体结构，去除气体，或产生一种微观结构的热处理。热处理的温度和冷却的速度取决于热处理的对象和热处理材料的成分。

Hardening is the heating and quenching of certain iron-base alloys from a temperature either within or above the critical temperature range. The temperature of the heating and the length of time at this temperature, or “soaking period”, depend upon the composition of the material.The quenching media used may depend upon the composition, hardness desired,and the complexity of the design.

淬火是将某些铁基合金加热到临界温度范围内或略高于此温度范围并骤冷。热处理温度和保温时间，或“均热阶段”，取决于材料的组成。使用的淬火介质取决于材料组成、所需硬度和设计的复杂性。

Tempering is the reheating after hardening of iron-base alloys to some temperature below the critical temperature range, followed by any desired rate of cooling. The purpose of tempering is the removal of strains, and the reduction of hardness and brittleness.

回火是将淬火后的铁基合金重新加热到低于临界温度范围的某个温度，然后以任何需要的速率冷却。回火的目的是去除应力和降低硬度和脆性。