Technological plasticity is the main property required for metal forming processes. The plasticity of metals depends on:
- alloy composition and its structure;
- working temperature;
- scheme of deformation;
- rate of deformation.
Pure metals possess higher plasticity than their alloys. The less carbon contents, the higher is the plasticity of steel. When temperature increases the resistance of metal to deformation decreases, because of decrease in strength and hardness.
In every point of stressed body elementary very small cube may be picked out so, that plane stresses should be perpendicular to its plane surfaces. There are 9 cases of stressed states with one, two and three main stresses (Fig. 4.5). An alloy has higher plasticity when it undergoes compressing stresses and it has lower plasticity in case of tensile stresses.
The degree of deformation at first decreases, then raises with the increase in deformation rate.