Forged parts are produced through the forging process. Forging is divided into two types: hot forging and cold forging. Hot forging is forging performed above the metal recrystallization temperature. Increasing the
temperature can improve the plasticity of the metal, which is beneficial to improving the intrinsic quality of the workpiece and making it less likely to crack. High temperatures can also reduce the deformation resistance of
metal and reduce the tonnage of required forging machinery. However, there are many hot forging processes, the workpiece precision is poor, and the surface is not smooth. The resulting forged parts are prone to
oxidation, decarburization and burning damage.
Cold forging is forging performed at a temperature lower than the recrystallization temperature of the metal. Generally speaking, cold forging refers to forging at room temperature, while forging at a temperature
higherthan normal temperature but not exceeding the recrystallization temperature is called forging. For warm forging. Warm forging has higher precision, smoother surface and low deformation resistance.
Forged parts formed by cold forging at room temperature have high shape and dimensional accuracy, smooth surface, few processing steps, and are convenient for automated production. Many cold forged and cold
stamped parts can be directly used as parts or products without the need for machining. However, during cold forging, due to the low plasticity of the metal, cracking is easy to occur during deformation and the
deformation resistance is large, requiring large-tonnage forging machinery.
Hot forging is used when the workpiece is large and thick, the material has high strength and low plasticity. When the metal has sufficient plasticity and the amount of deformation is not large, or when the total amount
ofdeformation is large and the forging process used is conducive to the plastic deformation of the metal, hot forging is often not used, but cold forging is used instead.
In order to complete as much forging work as possible in one heating, the temperature range between the initial forging temperature and the final forging temperature of hot forging should be as large as possible.
However,if the initial forging temperature is too high, it will cause the metal grains to grow too large and cause overheating, which will reduce the quality of the forged parts.The generally used hot forging temperatures
are: carbon steel 800~1250℃; alloy structural steel 850~1150℃; high speed steel 900~1100℃; commonly used aluminum alloy 380~500℃; titanium alloy 850~1000℃; brass700 ~900℃. When the temperature is
close to the melting point of the metal, melting of intergranular low-melting point substances and intergranular oxidation will occur, resulting in overburning. Over-burned blanks
tend to break during forging
Post time: Sep-15-2023