Metal plastic deformation resistance and 1.
Plastic and plastic index (
Plastic is refers to the metal under the action of external force, stable to permanent deformation and not damage its integrity.
It reflects the deformation of metal, is a kind of important processing performance of metal.
Plasticity index in general plastic material began to destroy the amount of plastic deformation.
The commonly used plastic index are: elongation: (
Reduction of area: (
Heading a sketchy: (
Type of L0, A0 tensile samples original gauge length, the original sectional area;
LK, A K tensile sample final gage length, fracture of the broken area;
0 H, H K - upsetting sample original height, the height of the side surface appeared the first crack.
Plasticity index is concluded through the experiment, the experiment has its specific force and deformation condition, so the plastic index only relative and comparative significance.
Plastic deformation of deformation resistance and index, make metal plastic deformation force known as the deforming force, metal deformation resistance force called the deformation resistance.
Therefore, the deformation resistance reflects to the difficulty of the material to produce plastic deformation.
Equal, deformation resistance and deformation force in the opposite direction, commonly used in the metal and tool on the surface of the contact deformation force said its size in a unit area.
Compression deformation when the deformation resistance is applied to pressure per unit area on the surface of the tool, also known as unit flow pressure.
Usually with real stress as the size of the deformation resistance index.
But the deformation resistance and true stress are two different concepts, the true stress is in simple tension (
Test role in sample instantaneous stress on cross section, namely the initial and subsequent yield stress, or the flow stress.
Only under unidirectional stress state, deformation resistance is equal to the real stress material under certain conditions.
Most metal plastic working process is in two or three to a state of stress, for processing the same materials, the deformation resistance to commonly is much bigger than one-way stress state of real stress, up to 1.
5 ~ 6 times.
Therefore, in addition to the size of the deformation resistance depends on the material in a certain deformation temperature, deformation rate and deformation degree under the real stress, also depends on the stress of plastic processing status, contact, friction factor and relative size, etc.
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