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.

碾环是指通过专用设备碾环机生产不同直径的环形零件，主要用来生产汽车轮毂、火车车轮等轮形零件。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。

Roller ring refers to the production of circular parts with different diameters through the roller ring machine of special equipment, which is mainly used to produce wheel hub, train wheel and other wheel shaped parts. Special forgings include roll forging, cross wedge rolling, radial forging, liquid forging and so on. These methods are suitable for producing parts with special shape.

镦粗 镦粗是对原坯料沿轴向锻打，使其高度减低、横截面增大的操作过程。这种工序常用于锻造齿轮坯和其他圆盘形类锻件。镦粗分为全部镦粗和局部锻粗两种。

Upsetting and upsetting is the process of forging the original billet along the axis, reducing its height and increasing its cross section. This process is usually used to forge gear blanks and other disc shaped forgings. The upsetting is divided into two kinds of upsetting and local forgings.