There are three types of forging according to the deformation temperature: Hot Forging, Warm Forging and Cold Forging. Hot Forging and Warm Forging require heating, while Cold Forging does not require heating. Whether heating, what is the heating temperature and holding time, as well as the initial forging temperature and final forging temperature have a great relationship with forging quality and cost reduction.
The forging manufacturing process is performed above the recrystallization temperature and below the solidus line, which does not destroy the metallurgical features of the metal. At present, the forgings used in most industries are hot forgings, and warm forgings and cold forgings are mostly used in the mass production of parts such as automobiles and general machinery.
Why heat it up?
Heating can reorganize and recrystallize metal lattice, improve metal plasticity, reduce deformation resistance, facilitate metal deformation, and obtain good post-forging microstructure and mechanical properties. Heating has a great contribution to improving forging productivity, ensuring the quality of forging and saving energy. Direct forging without heating requires larger tonnage of equipment, and easily leads to lattice distortion of the material, resulting in internal stress, which is easy to cause cracks or ruptures in the forgings.
Advantages and Shortcomings of Hot Forging
If the temperature of the forging material is still much higher than the recrystallization temperature after the processing is completed, the grains will grow for a longer time, and coarser grains will be obtained, which can increase the fracture toughness.
1. Due to high temperature operation, the danger to personnel safety and material safety is greatly increased.
2. The material is prone to oxidation at high temperature, resulting in oxide scale, resulting in surface scale, poor finish and flatness.
3. After the Hot Forging is completed, the forging material has a phenomenon of cold shrinkage during the cooling process, which affects the accuracy of the forging size.
4. The equipment and maintenance costs required for high temperature operation are relatively high.
Typical Application Areas
- Brake system: brake disc, brake frame, brake cylinder, brake handle
- Drive gears: pinions, synchro rings, continuously variable transmissions
- Powertrain: flange yoke, pin frame, hub, drive shaft, universal joint, connecting plate
- Chassis: Wheel frames, journals, pivot bearings, bearing bushes, ball joints, steering rods, steering rods, front bridges, Y-forks
- Engine parts: pistons, connecting rods, cams, camshafts, crankshafts, valves, distributor housings, balance shafts
- Rotor systems: system accessories, rotor hubs, gearbox covers
- Fuselage parts: cabin doors, wings, window frames and other accessories
- Engine turbine blades, propulsion cones, control discs, control rods
Tail rail and its accessories
- Landing gear: brackets, some fasteners