Four Laws of Plastic Deformation for Titanium Alloy Forgings
Titanium forgings follow the following basic laws in plastic deformation:
1. Shear stress law
Under the action of external forces, plastic deformation is only possible when the internal shear stress of a forging reaches a critical value. The magnitude of critical shear stress depends on the type of forging (composition, microstructure) and deformation conditions (deformation temperature, degree of deformation, etc.), so the law of shear stress is a very important basic law related to plastic deformation.
2. Law of volume invariance
Forgings maintain volume during plastic deformation. However, in actual forging production, the looseness and cracks inside the ingots and other billets are compacted after forging, resulting in an increase in density and a slight decrease in volume of the forging blank; After cold deformation, the forging becomes more loose and the volume slightly increases; But these small changes can be ignored. Therefore, the law of volume invariance is one of the important basis for calculating the size of forging blanks, process dimensions, and designing molds.
3. Law of small resistance
When titanium alloy forgings undergo plastic deformation, each particle inside them always moves in the direction of low resistance, which is called the law of small resistance. According to the law of small resistance, the flow direction of each particle during metal deformation can be determined in many complex situations in forging production, thereby controlling the flow path during forging billet deformation, facilitating the forging forming of titanium alloy forgings, and achieving the goal of reducing energy consumption and improving productivity.
4. Elastic deformation law
Titanium metal undergoes both plastic deformation and elastic deformation. Moreover, there is still elastic deformation in the plastic deformation of metals beyond the elastic limit. In order for plastic deformation to occur, it is necessary to achieve a certain value of shear stress.
The size of metal deformation under external force is not equal to the size when the external force is removed. So the size of the forging is not completely consistent with the size of the mold chamber. However, due to its good plasticity and small elastic deformation, the rebound phenomenon of metals during thermal deformation can be ignored.
