Forging materials are mainly carbon steel and alloy steel, followed by aluminum, magnesium, copper, titanium and their alloys. The original state of materials includes bar, ingot, metal powder and liquid metal. The ratio of the cross-sectional area of the metal before deformation to that after deformation is called the forging ratio. Correct selection of forging ratio, reasonable heating temperature and holding time, reasonable initial forging temperature and final forging temperature, reasonable deformation amount and deformation speed are closely related to improving product quality and reducing cost.
Generally speaking, small and medium-sized forgings use round or square bars as blanks. The grain structure and mechanical properties are uniform, the shape and size are accurate, the surface quality is good, and the organization of batch production is convenient. As long as the heating temperature and deformation conditions are reasonably controlled, forgings with excellent performance can be forged without large forging deformation.
Ingots are only used for heavy forgings. Ingot is a kind of casting structure with large columnar crystal and loose center. Therefore, in order to obtain good metal structure and mechanical properties, columnar crystals must be broken into fine particles through large plastic deformation and compacted loosely.
After being pressed and sintered, powder metallurgy preforms can be forged into powder forgings by flash free die forging in hot state. The forging powder is close to the general die forging density, with good mechanical properties and high precision, which can reduce the subsequent cutting. Powder forgings have uniform internal structure and no segregation, which can be used to manufacture small gears and other workpieces. However, the price of powder is much higher than that of ordinary bars, and its application in production is limited.
The required shape and performance can be obtained by applying static pressure to the liquid metal poured in the mold chamber to solidify, crystallize, flow, plastic deformation and molding under the pressure. Liquid metal die forging is a forming method between die casting and die forging, which is especially suitable for complex thin-walled parts that are difficult to form in general die forging.
In addition to ordinary materials, such as various components of carbon steel and alloy steel, forging materials are also forged or rolled, followed by aluminum, magnesium, copper, titanium and their alloys, iron base superalloys, nickel base superalloys, and cobalt base superalloys. Deformed alloys are also forged or rolled, but these alloys are difficult to forge due to their plastic regions. The heating temperature, forging temperature, and final forging temperature of different materials have strict requirements.