What are the spring shot blasting effects ?
The principle of spring shot blasting is shown in Figure 1 . Shot blasting is to spray the surface of the spring with a high-speed projectile to plastically deform the surface layer of the spring to form a surface strengthening layer of a certain thickness .
The role of spring shot blasting:
1. From the stress state, a high residual compressive stress is formed in the strengthening layer ( Fig. b) . Due to the existence of residual compressive stress on the surface of the material, when the spring is subjected to a variable load, the maximum tensile stress under a part of the variable load can be offset, thereby increasing the fatigue strength of the spring.
2. From the perspective of organizational structure, dislocations with extremely high density are formed in the strengthening layer ( Fig. c) . Under the influence of subsequent stress, temperature, or both, the dislocations are gradually arranged to form a polygon, that is, strengthening. More tiny subgrains ( substructures ) are formed in the layer ( Fig. d) . The result of this surface layer being cold hardened also has the effect of increasing the fatigue strength.
