Abstract
Fatigue crack propagation behavior in polycrystalline aluminum under cyclic tensile load is observed, and the controlling of crack growth by plastic treatment method is studied in detail. Destruction of structural components is almost always correlated with metal fatigue. Stop-hole and shot peening are well-known methods to control or to increase durableness for the improvement of its fatigue strength. Stop-hole method is required for repairing places where it is hard to change the base metal immediately and it has dual nature. However, some results of the observation show that the crack propagates faster than untreated one despite the impact of work-hardening. It's suggesting the importance of the location of indentation from the crack tip and it enable us to grasp the concept of cracking control by observing unexpected rapid propagations. As a concrete method, we tried to make indentation at 2 to 3mm horizontal length from the crack tip and analyze the experiment from the view point of effects on strain-hardening and residual stress.
