锻造是一种利用锻压机械对金属坯料施加压力，使其产生塑性变形以获得具有一定机械性能、一定形状和尺寸锻件的加工方法，锻压（锻造与冲压）的两大组成部分之一。通过锻造能消除金属在冶炼过程中产生的铸态疏松等缺陷，优化微观组织结构，同时由于保存了完整的金属流线，锻件的机械性能一般优于同样材料的铸件。
钢的开始再结晶温度约为727℃，但普遍采用800℃作为划分线，高于800℃的是热锻；在300～800℃之间称为温锻或半热锻，在室温下进行锻造的称为冷锻。用于大多数行业的锻件都是热锻，温锻和冷锻主要用于汽车、通用机械等零件的锻造，温锻和冷锻可以有效的节材。
根据成形机理，锻造可分为自由锻、模锻、碾环、特殊锻造。
锻造用料主要是各种成分的碳素钢和合金钢，其次是铝、镁、铜、钛等及其合金。材料的原始状态有棒料、铸锭、金属粉末和液态金属。
与铸件相比，金属经过锻造加工后能改善其组织结构和力学性能。铸造组织经过锻造方法热加工变形后由于金属的变形和再结晶，使原来的粗大枝晶和柱状晶粒变为晶粒较细、大小均匀的等轴再结晶组织，使钢锭内原有的偏析、疏松、气孔、夹渣等压实和焊合，其组织变得更加紧密，提高了金属的塑性和力学性能。
铸件的力学性能低于同材质的锻件力学性能。此外，锻造加工能保证金属纤维组织的连续性，使锻件的纤维组织与锻件外形保持一致，金属流线完整，可保证零件具有良好的力学性能与长的使用寿命采用精密模锻、冷挤压、温挤压等工艺生产的锻件，都是铸件所无法比拟的。
Forging is a processing method that uses forging machinery to apply pressure to metal blanks to produce plastic deformation to obtain forgings with certain mechanical properties, certain shapes and sizes, and is one of the two major components of forging (forging and stamping). Through forging, the defects such as loose casting state generated by the metal in the smelting process can be eliminated, the microstructure structure can be optimized, and the mechanical properties of forgings are generally better than castings of the same material due to the preservation of complete metal streamlines.
The initial recrystallization temperature of steel is about 727 °C, but 800 °C is generally used as the dividing line, and hot forging is higher than 800 °C; Between 300~800 °C is called warm forging or semi-hot forging, and forging at room temperature is called cold forging. Forgings used in most industries are hot forging, warm forging and cold forging are mainly used for forging parts such as automobiles and general machinery, and warm forging and cold forging can effectively save materials.
According to the forming mechanism, forging can be divided into open forging, die forging, ring grinding, and special forging.
The forging materials are mainly carbon steel and alloy steel of various compositions, followed by aluminum, magnesium, copper, titanium, etc. and their alloys. The raw state of the material is bar, ingot, metal powder and liquid metal.
Compared with castings, the microstructure and mechanical properties of metals can be improved after forging. After the casting structure is deformed by hot processing by the forging method, due to the deformation and recrystallization of the metal, the original coarse dendrite and columnar grains become the equiaxed recrystallization structure with finer grains and uniform size, so that the original segregation, looseness, porosity, slag inclusion and other compaction and welding in the steel ingot, its structure becomes more compact, and the plasticity and mechanical properties of the metal are improved.
The mechanical properties of castings are lower than those of forgings of the same material. In addition, forging can ensure the continuity of the metal fiber structure, make the fiber structure of the forging consistent with the shape of the forging, and the metal streamline is complete, which can ensure that the parts have good mechanical properties and long service life, and the forgings produced by precision die forging, cold extrusion, warm extrusion and other processes are incomparable to castings.