SEM micrograph using backscattered electrons showing fatigue slip lines on the surface of a polished AISI 304 steel after 1000 cycles (with stress amplitude 320 MPa).
 
 

                   SEM micrograph showing a shot-peened surface of normalized plain carbon steel SAE 1045.
 
 
 

Light microscopic micrograph showing the crack tip of bimodal Ti-6Al-4V and the plastic zone at the begining of a K_IC-test.