Ultrasonic fatigue testing on high strength steel: Effect of stress concentration factors associated with corrosion pitting holes

Abstract

Ultrasonic fatigue tests at the frequency of 20 kHz were carried out on the hot rolled low alloy steel grade (known as R5), which according to the International Classification Society of offshore systems, it is a steel with the highest ultimate tensile strength to manufacture mooring chains and accessories intended to position mooring applications. Tests were carried out at constant load ratio R ¼ À1 on pre-corroded and no-corroded hourglass shape specimens; pre-corrosion was implemented according to ASTM standard G85. Stress concentration between two and three close hemispherical pitting holes on hourglass shape specimen undergoing uniaxial loading were obtained by finite element method. Experimental results show that fatigue life decreases with the proximity of two close pitting holes on the fracture surface. An exponential law is proposed for the stress concentration factor evolution with the proximity of two close pitting holes of identical radius; the trend of this law is confirmed by experimental results. Finally, fracture surfaces were analyzed and conclusions were listed concerning fatigue life, proximity of pitting holes on fracture surface, and the associated stress concentration factors.

A multi-scale corrosion fatigue damage model of high-strength bridge wires

“…With the interaction of corrosive environment and alternate loads, the anti-fatigue performance of wires is inferior to that in dry air significantly (Thierry Palin-Luc et al., 2010; Yang et al., 2016). Many researchers investigated the mechanism of the corrosion fatigue process from different aspects, such as the corrosion of zinc coating (Kuraoka and Sato, 2009; Ma et al., 2011; Nakamura and Suzumura, 2009), loading (Jiang et al., 2010; Wang et al., 2016; Yang et al., 2017), geometrical features of pits (Almaraz and Mora, 2013; Hao et al., 2010; Nakamura and Suzumura, 2013) and environments (Wu et al., 2017). Nevertheless, since the combined action of corrosive environment and alternate loads is so complex, corrosion fatigue process is still a challenging issue that needs further investigations.…”

Effects superposition under imposed deterioration and simultaneous fatigue in different regimes

“…The cumulation of effects of successive loadings was analyzed in several cases, such as influence of torsional and tensile pre-straining on the validity of ductile fracture criteria (Vilotic et al, 2014), cumulative fatigue damage (Jin et al, 2013), low cycle fatigue (LCF) and creep (Zhu et al, 2012(Zhu et al, , 2013, effects of stress concentration factors associated with corrosion pitting holes (Almarez and Mora, 2013), cumulation of effects in calculating the deterioration due to fatigue (Jinescu, 2012), corrosion -fatigue life prediction (Hu et al, 2012). The result of cumulation of successive cyclic loadings effects may be calculated using the empirical Palmgren-Miner law (Miner, 1945;Palmgren, 1924) or the theoretical law recently established (Jinescu, 2013b).…”