Effect of biaxial cyclic tension on the fatigue life and damage mechanisms of Cr–Mo steel

Corrosion‐fatigue behaviour of Cr–Mo steel under biaxial tension

“…The fracture surfaces exhibit a mixture of intergranular and transgranular areas with a surface fraction of intergranular facets very much dependent on Δ K , as reported and discussed in previous article 21 . This fraction first increases with Δ K until it reaches a maximum around 40–45% for Δ K ≈10 MPa , and then, it decreases down to zero for Δ K ≈15 MPa .…”

“…The results of biaxial tension fatigue tests done in air at various biaxiality ratios were already discussed in previous papers 20,21 and are only briefly reported here, in Table 3 and Figure 4. Compared with uniaxial loading, the fatigue resistance of the material was slightly enhanced at low biaxiality ratio ( B =0.25) but slightly reduced under equibiaxial tension ( B =1).…”

“…The applied loading range Δ σ zz , according to Newman and Raju's expressions, 27 corresponded to Δ K I =10 MPa . This value was chosen because it was found to yield the highest fraction of intergranular facets 21 …”

“…The effects of load biaxiality on fatigue lives and damage mechanisms in air of the steel which constitutes the Clip‐Riser TM connectors were thus investigated and reported in two previous papers 20,21 . The present paper focusses on the combined effects of load biaxiality and the corrosive environment.…”

“…Several inclusions of an average size of 5 μm are present along with some less frequent but large pores and inhomogeneities (40–300 μm) (Figure 1). The detailed microstructural and texture analysis and the effect of these inclusions, pores or inhomogeneities on fatigue damage mechanisms in this material under different loading conditions has been discussed in previous papers 20,21 . Tensile tests were conducted on cylindrical specimens, 8 mm dia, at a constant strain rate of 10 −3 /s.The measured tensile properties are shown in Table 2.…”