在鍛造時，金屬的脆性雜質被打碎 ，順著金屬主要伸長方向呈碎粒狀或鏈狀分布；塑性雜質隨著金屬變形沿主要伸長方向呈帶狀分布 ， 這樣熱鍛后的金屬組織就具有一定的方向性。

When forging, the brittle metal impurities to be broken down, the main direction of elongation is like particles of metal or plastic chain distribution; impurities with metal deformation distributed along the main direction of elongation, so after hot forging metal organization has certain direction.

在現(xiàn)代工業(yè)生產(chǎn)中，機器自由鍛已成為鍛造生產(chǎn)的主要方法，在重型機械制造中，它具有特別重要的作用。而產(chǎn)生的鍛件形狀和尺寸主要由操作工的技術水平?jīng)Q定。

In modern industrial production, machine free forging has become the main method of forging production, and it plays a particularly important in heavy machinery manufacturing. The shape and size of the forgings are mainly determined by the technical level of the operator.

鐓粗主要有以下形式：

完全鐓粗。完全鐓粗是將坯料豎直放在砧面上， 在上砧的錘擊下， 使坯料產(chǎn)生高度減小，橫截面積增大的塑性變形。

Upsetting mainly includes the following forms:

Full upsetting. Complete upsetting is to place the blank vertically on the anvil surface, hammering on the anvil, so that the height of the blank decreases, the cross-sectional area increases plastic deformation.