Appendix B - Fatigue properties of AISI 316 and Al-6061-T6
Fatigue properties of stainless steel AISI 316(L) and aluminium 6061-T6
as used in the ASTM Interlaboratory test program were collected from
literature26-37, see Table B-1. These references show
a substantial amount of test data, so a S-N curve could be fitted and a
fatigue limit at 2 million cycles could be determined. The stress ratios
of these fatigue data were \(R\) = 0.1 or -1. Fatigue data with a stress
ratio \(R\) = 0.1 were corrected to \(R\) = -1 (mean stress\(S_{m}=0\)) using Morrow’s equation24 for a mean
stress correction, see Eq. 9. The collected fatigue data are summarized
in Table B-1.
The physical properties for stainless steel AISI 316(L) and Al-6061-T6
were collected from the Metals handbook38. For AISI
316(L): density ρ = 8000 kg/m3, Young’s modulus, E =
193 GPa, and Poisson constant ν = 0.30, and for Al-6061-T6: density ρ =
2700 kg/m3, Young’s modulus, E = 69 GPa, and Poisson
constant ν = 0.33.
Based on the publications of Soyama46 and Ramulu et
al.47 and supported by publications for shot peening
and cavitation peening39-42, the constants (\(a\),\(b\), \(p_{wh,th}\)) in Eq. 11a to 11d, for the increase in surface
hardness and residual compressive stress as a function of the ‘water
–hammer pressure’ (\(p_{\text{wh}}\)) were defined. These estimated
trends are shown in Figure B-1. The numerical value are given in Table
B-2.
The threshold water-hammer pressures (\(p_{wh,th}\)) in Table B-2, using
Eq. 1a and 1b, give for stainless steel AISI 316 and Al-6061-T6,
respectively threshold impact velocities of \(v_{d}\) = 112 m/s and 92
m/s.