Views: 1 Author: Site Editor Publish Time: 2016-09-18 Origin: Site
Tend to exist some shortcomings in the forging process, the following will summarize some for you.
1. The large grain size
Large grain size is usually caused by a lack of forging temperature and deformation degree, or finish forging temperature is too high, or caused deformation degree fell into the critical deformation zone.Aluminum alloy deformation degree is too big, form texture;High temperature alloys deformation temperature is too low, the formation of deformation mixed can also cause bulky grain, coarse grains will reduce the plasticity and toughness of forgings, fatigue performance significantly decreased.
2. Uneven grain
Uneven grain size refers to the special thick grain forging parts, some parts are small.Produce uneven grain is the main reason of the billet throughout the deformation uneven grain crushing degree is differ, or local deformation degree fell into the critical deformation zone, or high temperature alloy local work hardening, or quenching heating local coarse grains.Heat resistant steel and high temperature alloy particularly sensitive to uneven grain.Uneven grain will make the forgings durable performance, fatigue performance significantly decreased.
3. The phenomenon of cold hard
Deformation due to the low temperature or deformation speed too fast, and too fast cooling after forging, both may be caused by recrystallization softening couldn't keep up with the deformation caused by the reinforcement (hardening), so that the hot forging forgings after internal organization is still keeping the cold deformation.The existence of this organization to improve the strength and hardness of the forgings, but reduces the plasticity and toughness.Serious hard phenomenon may cause cold forging cracking.
4. The crack
Crack is usually existed during forging large tensile stress, shear stress or stress caused by William gallas.Crack parts is often happened in billet the thinnest part of the largest stress and thickness.If the billet surface and internal micro cracks, or blank within tissue defect, improper or hot working temperature to lower material plastic, too much too fast or deformation, deformation degree, more than material allows the plastic handle, etc., are removed from the coarse, long pull, punching, reaming, bending and extrusion process can produce crack.
5. The crack
Cracks is present shallow tortoise in forging surface shape crack.The surface of the tensile stress in the forging forming (for example, not full of extruding part or the curved part) are most likely to produce this kind of defect.Cause the cause of cracks may be various: (1) raw materials of fusible element such as Cu, Sn and too much. (2) when heated to high temperature for a long time, steel material surface of copper precipitation and surface coarse grains, decarburization, or after a lot of heating surface. (3) fuel sulfur content is exorbitant, sulfur impregnation steel material surface.
Above are some of the defects existing in the forging process, the hope can help to you.