Influence of shot peening versus laser peening on the fatigue behavior of superferritic stainless steel.

L. SPADARO; S. HEREÑÚ; R. STRUBBIA; GILBERTO GOMÉZ ROSAS; CARLOS RUBIO GONZÁLEZ; ARTURO CHÁVEZ-CHAVÉZ,

Cancun

Congreso; XXV International Materials Reserch Congress; 2016

Laser shock peening (LSP) is an established mechanical surface treatment technology, which isgenerally utilized to improve fatigue performance. Compared with the conventional shot peeningmethod (SP), LSP induces deeper compressive residual stresses into the material surface with a lowersurface roughness. However, if absorbent coatings are not used in LSP operation, thermal effects canoccur on the metallic substrate which could cause detrimental effects on the fatigue life. The purposeof this work is to compare the influence of laser peening and shot peening on the low cycle fatiguebehavior of a superferritic stainless steel UNS S 44600.The LSP, without protective coating, was carried out using Q-switched Nd:YAG laser, operated atfundamental wavelength of 1064nm, energy of 1 J/pulse, repetition rate of 10Hz. The pulse densitywas 5000 pulses/cm2. The SP was performed using S-460 (1 mm) with Almen-intensity of 1 A.Roughness, residual stress and microhardness measurements were carried out on the treatedspecimens. Fatigue tests were conducted at room temperature under fully reversed plastic straincontrol, with plastic strain ranges of ??p = 0.1%. The steel microstructure was analyzed by opticmicroscopy (MO) and transmission electron microscopy (TEM).SP and LSP induce beneficial compression residual stresses on fatigue life. Whereas the advantages ofthese induced residual stresses compensate the intergranular corrosion in LSP samples, they cannotcounterbalance the detrimental effects of the high surface roughness of SP samples.