若因温度和变形程度选择不当而得到粗大晶粒时，可利用热处理相变细化晶粒***，但对于热处理中不发生相变的钢种，如奥氏体钢，就必须在锻造过程中获得细小而均匀的晶粒***，因此对这样的材料在锻造时须加倍注意。

If the temperature and degree of deformation and improper selection of coarse grains, the grain refinement phase change heat treatment, but for the steel phase transition does not occur in the heat treatment, such as austenitic steel, it must be in the forging process h***e fine and uniform grains, so this kind of material in the forging must pay more attention to.

机器锻造是自由锻造的主要方法，可锻造质量达到几百吨的大型锻件，这使得自由锻在重型机械制造中具有特别重要的作用。特种锻造包括辊锻、楔横轧、径向锻造、液态模锻等锻造方式，这些方式都比较适用于生产特殊形状的零件。例如，水轮机主轴、多拐曲轴、大型连杆、重要的齿轮零件，在工作时都承受很大的载荷，常采用自由锻造方法生产毛坯，使其具有很高的力学性能.满足使用要求。

Machine forging is the main method of free forging. It can forge large forgings with a quality of hundreds of t, which makes free forging play a very role in he***y machinery manufacturing. For example, the main shaft of a hydraulic turbine, a multi crank crankshaft, a large connecting rod, and important gear parts are subjected to he***y loads when they are working. Free forging is often used to produce blanks, so that they h***e high mechanical properties.

自由锻造是靠人工操作来控制锻件的形状和尺寸的，所以锻件精度低，加工余量大，劳动强度大，生产率也不高，因此它主要应用于单件、小批量生产。

Free forging is by manual operation to the shape and size of the forgings, so the precision of the forgings is low, the processing allowance is large, the labor intensity is big, and the productivity is not high. Therefore, it is mainly used in single piece and ***all batch production.