High cycle fatigue life improvement of superferritic stainless steel by laser shock peening without coating

HEREÑÚ, SILVINA; STRUBBIA, RENATA; CARLOS RUBIO-GONZÁLEZ; LETICIA SPADARO; RAÚL BOLMARO; GILBERTO GÓMEZ ROSAS

OPTICS AND LASER TECHNOLOGY

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2022 vol. 152

0030-3992

The excellent mechanical properties, high thermal conductivity and corrosion resistancecombined with moderate cost make superferritic stainless steels (SFSS) commercially attractive.Though these steels are finding increase uses in many applications where fatigue loadings areapplied, few studies are devoted to study this theme. Even fewer works aim to investigate thefatigue improvement by surface treatments. Laser shock peening without coating (LSPwC), is asurface modification technology using high-energy laser with no absorbent coating that increasesthe fatigue life in many alloys. However, though LSPwC in SFSS UNS44600 has reported toproduce beneficial compression residual stresses (CRSs) and strain-hardening surface layer, italso causes intergranular corrosion which avoids the improvement of low fatigue life (LCF). Thus,attempting to discern if this result remains in the HCF regimen, the present paper is focused onstudying the influence of LSPwC on the high cycle life (HCF) of SFSS UNS S44600. The resultsshowed that LSPwC enhances the HCF of SFSS UNS S44600, being the fatigue life improvementmore pronounced with higher pulse density. This can be rationalized considering the main role ofthe induced CRS in slowing occurrence and growth of crack in corroded grains on HCF regimen.The examination of fracture surface by scanning electron microscopy (SEM) substantiates thesefatigue results.