1、 外文资料翻译 Heat Treatment of Metal The generally accepted definition for heat treating metals and metal alloys is “heating and cooling a solid metal or alloy in a way so as to obtain specific conditions and I or properties.”Heating for the sole purpose of hot working(as in forging operations) is exclud
2、edfrom this definition Likewise，the types of heat treatment that are sometimes used for productssuch as glass or plastics are also excluded from coverage by this definition Transformation Curves. The basis for heat treatment is the time-temperature-transformation curves or TTT curveswhere，in a singl
3、e diagram all the three parameters are plotted Because of the shape of thecurves， they are also sometimes called C-curves or S-curves Material forming processes In this section ， a short description of the process examples will begiven. But assembly andjoining processes are not described here. Forgi
4、ng Forging can be characterized as: mass conserving, solid state of work material (metal), andmechanical primary basic process-plastic deformation. A wide variety of forging processes areused, and Fig.9.1(a) shows the most common of these: drop forging. The metal is heated to asuitable working tempe
5、rature and placed in the lower die cavity. The upper die is then lowered sothat the metal is forced to fill the cavity. 1Excess material is squeezed out between the die facesat the periphery as flash, which is removed in a later trimming process. When the term forging isused, it usually means hot fo
6、rging. Cold forging has several specialized names. The material lossin forging processes is usually quite small. Normally, forged components require some subsequent machining, since the tolerances andsurfaces obtainable are not usually satisfactory for a finished product. Forging machines includedro
7、p hammers and forging presses with mechanical or hydraulic drives. These machines involvesimple translatory motions. 金属的热处理 普遍认同对金属及合金热处理的定义是，以一定的方式加热或冷却固态金属或合金，以达到一定的条件和 /或获得某些性能。以热加工 (如锻造 )为目的的加热，不在此定义之列。同样地，有时用于生产诸如玻璃或塑料制品的热处理也不属于该定义的范畴。 相变曲线热处理的基础分别是时间 温度相变曲线，即 TTT曲线， 3 个参数都绘制在一个图中。根据曲线的形状特点，分别称
8、为 C 曲线或 S 曲线。 为了绘制 TTT 曲线，将特定的钢置于给定温度下，以预先确定的时间间隔检查其结构，记录发生相变的量。我们知道共析钢 (C80)在平衡条件下，在 723以上时全为奥氏体，而低于此温度，则为珠光体。为了形成珠光体，碳原子将产生扩散形成渗碳体。扩散是一种渐进过程，需要足够的时间完成奥 氏体向珠光体的转变。对于不同的样品，可以记录下在任一温度时产生相变的量。然后把这些点绘制在一条以时间和温度为坐标轴的曲线上。通过这些点就可以得到共析钢的相变曲线。左边的曲线表示任一给定温度下奥氏体 材料成型工艺方法 锻造： 锻造是对固态金属材料进行初步机械加工，是产生塑性成形的质量守恒的一种基本工艺方法。锻造有很多类型，最普通的锻造为金属加热到适合加工的温度，并放进下型腔里。上型腔与下型腔合拢，迫使金属充满型腔。多余的材料被从型腔接缝处挤出，并将被后续的清理型腔接缝工艺清除。当提到锻造术语时，通常意味热锻。冷 锻
