Investigation of fatigue performance improvement in SiCw/Al composites with different modified shot peening treatments by considering surface mechanical properties

In order to investigate the fatigue performance improvement of SiCw/Al composite under different shot peening (SP) treatments, conventional SP, warm peening (WP), stress peening (STP) and compound peening (CP) were carried out on SiCw/Al composite specimens. The fatigue test, residual stress measurement and full width at half maximum (FWHM) from X-ray diffraction measurement were conducted on different SP specimens. The fatigue strength of SiCw/Al composite specimen increases by 16%, 37%, 21% and 42% via SP, WP, STP and CP respectively. The surface mechanical properties such as quasi-static surface compressive yield strength (Re(c),s) and cyclic surface yield strength (Rcycle,s) were calculated via analyzing residual stress relaxation during cyclic loading. The results show that the decrement of Re(c),s and Rcycle,s caused by Bauschinger effect during shots' impact is compensated by dynamic strain aging effects in WP and CP. The degree of fatigue strength improvement is more obviously in WP and CP specimens, which is due to the improvement of stability of residual stresses caused by the dynamic strain aging effects in elevated temperature condition.